Lazarus Tutorial/it

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This is the start of a Lazarus Tutorial. Please feel free to add your experiences to it.

Overview

Lazarus è un strumento di sviluppo gratuito per il compilatore Free Pascal, anche esso gratis e open source. L' IDE Lazarus (screenshot) è uno stabile e ricco ambiente di sviluppo per la creazione di applicazioni grafiche e da console. Lazarus attualmente funziona su Linux, Mac OS X e Win 32 e fornisce un editor di codice personalizzabile ed un ambiente visuale per la creazione di form che include un package manager, un debugger ed una GUI completa, integrata con il compilatore Free Pascal.

Si inizia - Il tuo primo programma in Lazarus!

(Un ringraziamento a User:Kirkpatc)

Scarica, Installa (Installing Lazarus) ed esegui Lazarus con il quale sara' disponibile il compilatore FreePascal. Diverse finestre compariranno sul desktop. Il menù principale in alto, L'Object Inspector sulla sinistra, l'editor sorgente di Lazarus che occupa gran parte del desktop ed una finestra Form1 già pronta che invece occupa l'editor sorgente.

Nella finestra del menù in alto, sotto la linea del menù c'è una riga di tab. Se la tab 'Standard' non è ancora selezionata, selezionala cliccandoci con il mouse. Quindi cerca l'icona del pulsante (un rettangolo con la scritta 'OK') e cliccaci con il mouse. Quindi clicca sulla finestra Form1, in un punto qualsiasi a sinistra a partire dal centro. Un rettangolo ombreggiato con il nome "Button1" comparirà. Clicca ancora sul pulsante nella Standard tab quindi clicca ancora nel Form1 a destra dal centro: comparirà un rettangolo con il nome 'Button2'.

Ora clicca sul pulsante Button1 per selezionarlo. L'Object Inspector visualizzerà le proprietà dell'oggetto Button1. Vicino in alto c'è una proprietà che si chiama 'Caption' con visualizzato il valore 'Button1'. Clicca su questo riquadro e cambia 'Button1' con 'Press'. Se premi Enter o click in un altro riquadro, vedrai l'etichetta del primo pulsante su Form1 cambiato in 'Press'. Ora clicca sulla Events tab sull'Object Inspector per vedere i vari eventi che sono associati al pulsante. Questi includono OnClick, OnEnter, OnExit etc. Seleziona il riquadro a destra di OnClick: una piccolo pulsante con tre puntini compariranno. Clicca su questo. Sarai reindirizzato automaticamente sull'editor di codice e il cursore sarà collocato nel mezzo. Modifica il codice come segue:

procedure TForm1.Button1Click(Sender: TObject);
 begin
   {now type:}    Button1.caption := 'Press again';
   {the editor has already completed the procedure with}
 end;

Premi F12 per selezionare la finestra Form1 anzichè l'editor di codice. Ora modifica le proprietà di Button2: clicca su Button2 per visualizzare le sue proprietà nel Object Inspector. Cambia la proprietà Caption 'Exit' al posto di 'Button2'. Ora seleziona la tab degli eventi e clicca sul riquadro OnClick. Clicca su .... . Dopo verrai reindirizzato all'interno dell'editor di codice all'interno di un altra procedura. Modifica il codice come segue:

 procedure TForm1.Button2Click(Sender: TObject);
 begin
 {now type:}   Close;
 {the editor has already completed the procedure with} 
 end;

Premi F12 per vedere la finestra Form1 di nuovo. Sei pronto per compilare ora: Il modo più semplice per farlo è selezionare 'Esegui' dal menù principale in alto con l'opzione run che si trova nel sotto-menù. In alternativa potresti semplicemente premere F9. Questo prima eseguirà la compilazione e dopo (se è andato tutto bene) il link, quindi eseguirà il tuo programma.

Diverse finestre di testo appariranno e diversi tipi di messaggi verranno visualizzati, infine la tua finestra Form1 riapparirà ma senza la griglia di punti. Questa è la finestra principale della tua applicazione e sta aspettando che premi i pulsanti oppure che ci interagisci.

Prova cliccando sul pulsante 'Press'. Noterai che questo cambia in 'Press again'. Ora clicca sul pulsante 'Exit'. La finestra si chiuderà ed il programma cesserà di funzionare. La finestra orginale Form1 con la griglia di punti riapparirà, pronta ad accettare altre attività di modifica.

Puoi salvare il tuo lavoro ora selezionando Project > Save Project As > il tuo file .pas selezionato.

Second session.

Apri nuovamente il progetto che hai salvato. Sulla finestra Form1 clicca sul pulsante 'Press' (Button1) per selezionarlo. Seleziona la tab 'Events' sull'Object Inspector, clicca sul riquadro a destra dopo OnClick, clicca sui puntini (…), per ritornare sul punto esatto dell'editor sorgente.

Modifica il codice come segue:

procedure TForm1.Button1Click(Sender: TObject);

{Makes use of the Tag property, setting it to either 0 or 1}
 begin
   if Button1.tag = 0 then
   begin
     Button1.caption := 'Press again';
     Button1.tag := 1
   end else
   begin
     Button1.caption := 'Press';
     Button1.tag := 0
   end
 end;

Salva il tuo lavoro, ricompila ed esegui. Il pulsante sinistro ora cambierà in due messaggi alternati.

Il resto spetta a te!

Se preferisci scrivere programmi console o text-based (per esempio se stai seguendo un corso di base di programmazione Pascal, o hai bisogno di scrivere programmi per l'uso in modalità batch o per programmazione di sistema), è possibile comunque utilizzare Lazarus per modificare, compilare ed eseguire i tuoi programmi. Diventa un ambiente ideale per lo sviluppo in Pascal. Guarda Console Mode Pascal.

L'Editor

Quando si esegue Lazarus per la prima volta, appariranno sul proprio desk-top una serie di finestre autonome separate o fluttuanti.

La prima, in esecuzione sulla parte superiore del desk-top, è intitolata Lazarus Editor vXXXXXX - project1 (che verrà successivamente modificata per riflettere il nome del proprio progetto attualmente aperto). Questa è la finestra principale di controllo del proprio progetto e contiene il menù principale e la Component Palette (NdT: schede dei componenti).

It lazmain GTK2.png

Sulla riga sotto la barra del titolo c'è il Menù Principale con le consuete voci per File, Modifica, Cerca, Vista funzioni e così via, ed alcune selezioni che sono specifiche di Lazarus. Sotto a questo a sinistra c'è un gruppo di BitButtons (che permettono un accesso rapido a particolari opzioni del Menù Principale) e sulla destra c'è la Component Palette.

Sotto la finestra dell'Editor di Lazarus apparirà sulla sinistra la finestra dell' Object Inspector e sulla destra il Lazarus Source Editor. Ci può essere un'altra finestra più piccola, intitolata Form1, sopra alla finestra del Lazarus Source Editor. Se non è visibile direttamente, può venire visualizzata premendo il tasto F12, che scambia la vista tra il Source Editor e la Form. La finestra della Form è quella su cui si costruirà l'interfaccia grafica della propria applicazione, mentre il Source Editor è la finestra che mostra il codice Pascal associato all'applicazione che si sta sviluppando. Il funzionamento dell'Object Inspector è discusso in maggiore dettaglio più avanti, durante la descrizione della Component Palette.

Quando si inizia un nuovo progetto (o all'esecuzione iniziale di Lazarus) verrà costruita una Form predefinita, composta di uno spazio nel quale c'è una griglia di punti che facilita il posizionamento dei componenti della form e una barra nella parte superiore che contiene i consueti pulsanti Minimizza, Massimizza e Chiudi. Se si clicca con il cursore del mouse su qualsiasi parte di questo spazio, si vedranno le proprietà di questa form elencate sull'Object Inspector a sinistra del desk-top.

Altre finestre che potrebbero divenire visibili durante l'utilizzo: il Project Inspector, che contiene il dettaglio dei file inclusi nel proprio progetto, e permette di aggiungere file o di cancellarli dal proprio progetto; la finestra Messaggi, che mostra i messaggi del compilatore, gli errori o i rapporti di sviluppo del proprio progetto; se Lazarus viene eseguito da una finestra di terminale, tale finestra rimane visibile ed anche in essa si vedranno i messaggi del compilatore.


Il Menù Principale

Il menù principale contiene le seguenti voci: File Modifica Cerca Visualizza Progetto Esegui Package Strumenti Ambiente Finestre Aiuto

Come di consueto, le opzioni possono essere selezionate sia collocando il cursore del mouse sulla voce di menù e cliccando con il tasto sinistro del mouse, che digitando Alt-F sulla tastiera (purché il menù principale sia la finestra attiva: se non ce l'ha, premere ripetutamente il tasto TAB per passare da una finestra all'altra fino a che la finestra desiderata ha la barra del titolo attiva).

Le sotto-voci del menù File

FileMenu.png
  • Nuova Unit: Crea un nuovo Unit file (Sorgente Pascal).
  • Nuova Form: Crea una nuova Form: sia la finestra visibile sullo schermo che il file sorgente Pascal associato.
  • Nuovo ...: Presenta un menù a discesa (screenshot) con una varietà di nuovi tipi di documento da creare.
  • Apri: Presenta una finestra di dialogo a discesa che permette la navigazione del filesystem e la scelta di un file esistente per aprirlo.
  • Ripristino: Abbandona le modifiche effettuate e ripristina il file al suo stato originale.
  • Apri Recente: Presenta un elenco di file modificati di recente e la possibilità di sceglierne uno.
  • Salva: Salva il file corrente, utilizzando il suo nome file originale. Se è senza nome, il sistema ne proporrà uno (proprio come per Salva Come).
  • Salva Come: Permette di scegliere una directory ed un nome file per il salvataggio del file corrente.
  • Salva Tutto: Salva tutti i file presenti sull'editor, non solo quello selezionato.
  • Chiudi: Chiude il file corrente, proponendo se salvare tutte le modifiche effettuate sull'editor.
  • Chiudi tutti i file dell'editor: Chiude tutti i file attualmente aperti sull'editor. Propone di salvare le modifiche.
  • Pulisci directory: Presenta una finestra di dialogo con una serie di filtri modificabili per la rimozione dei file dalla directory corrente. Utile per rimuovere i file .bak ed i file residui di precedenti progetti Delphi.
  • Stampa: Utilizza la stampante di sistema per stampare il file selezionato. Questa voce di menù non appare in modo predefinito; è necessario installare $Lazdir/components/printers/design/printers4lazide.pas e ricompilare la IDE
  • Riavvia: Riavvia Lazarus - utile se i file si sono mescolati disperatamente!
  • Esci: Esce da Lazarus, dopo aver proposto il salvataggio di tutti i file modificati.

Le sotto-voci del menu Edit

EditMenu.png
  • Annulla: Annulla l'ultima azione eseguita riportando l'editor allo stato precedente all'azione.
  • Ripristina: Reimposta l'ultima azione che è stata annullata da Undo.
  • Taglia: Rimuove il testo selezionato o un altro elemento e lo copia negli appunti.
  • Copia: Copia il testo selezionato, lasciando il testo originale a posto e lo copia sugli appunti.
  • Incolla: Incolla il contenuto degli appunti alla posizione del cursore. Se il testo è stato selezionato alla posizione del cursore. Il contenuto degli appunti rimuoverà il testo selezionato.
  • Indenta Selezione: Sposta il testo selezionato a destra in base al valore specificato in Ambiente - Opzioni dell editor - Generale - Indentazione di blocco. Questa caratteristica è utilizzata di frequente per la formattazione del tuo codice Pascal per mostrare blocco di struttura sottostante.
  • De-Indenta Selezione: Rimuove un livello di indentazione, muovendo il testo a sinistra in base al valore specificato nell'indentazione.
  • Chiusura selezione: Fornisce un menu popup con un numero di opzioni per chiudere il testo selezionato.

(begin ... end; try ... except; try ... finally; repeat ... until; { ... } etc).

  • Selezione in maiuscolo: Converte il testo selezionato in maiuscolo.
  • Selezione in minuscolo: Converte il testo selezionato in minuscolo.
  • Tabulazioni nella selezione in spazi: Converte ogni tabulazione nel testo selezionato in spazi specificati in Ambiente -> Opzioni dell editor -> Generale -> Lunghezze di Tabulazioni. Il numero di spazi non e' una quantita' fissa, ma e' il numero necessario per riempire il testo residuo con una tabulazione.
  • Linee spezzate nella selezione: Quando ogni linea nel testo selezionato e' piu' lunga di 80 caratteri o del numero specificato in Ambiente -> Opzioni dell editor -> Visualizza -> Margine Destro Visibile, questa viene spezzata con un delimitatore e continua nella riga successiva.
  • Commenta la selezione: Inserisce il testo selezionato all'interno di commenti inserendo // su ogni linea.
  • Decommenta la selezione: Rimuove i commenti.
  • Sort selection: Ordina le linee (parole oppure paragrafi) in ordine alfabetico; opzioni in ordine crescente o decrescente, case sensitive or insensitive. In mezzo al sorgente del programma, naturalmente, non ha senso, ma se hai una lista da ordinare, verra' applicato uno stratagemma.
  • Seleziona: Permette la selezione di un blocco di testo. Le opzioni includono seleziona tutto, seleziona in graffe, seleziona paragrafo o linea etc.
  • Inserisce dalla mappa caratteri: Permette l'inserimento di un simbolo non presente in tastiera come i caratteri accentati, scelti da una finestra popup con la mappa di caratteri.
  • Inserisci testo: Visualizza un menu pop-up che permette l'inserimento di un testo standard come parole chiavi del CVS (Author, Date, Header etc) oppure Note GPL, username o data e ora.
  • Completa codice: Completa il codice vicino il cursore. E' sensibile al contesto e ti aiuta molto. Per esempio: Completa le classi aggiungendo variabili private, Metodi di accesso Get e Set aggiungendo il corpo dei motodi. Sulle assegnazioni delle variabili (e.g. i:=03) aggiunge la dichiarazione della variabile. On forward defined procedures it adds the procedure bodies. On event assignments (OnClick:=) it adds the method definition and the method body. See Lazarus IDE Tools.
  • Estrai procedure: Usa il testo selezionato (una dichiarazione o una serie di dichiarazioni) per costruire una nuova procedure.

Il sotto-menu cerca

SearchMenu.png
  • Cerca: Simile alle funzionalita' in quasi tutti gli editor di testo: Visualizza una finestra di dialogo pop-up che permette l'inserimento di una stringa di testo per la ricerca con opzioni come case sensitive, parole intere, origine, visibilita e direzione di ricerca.
  • Trova successivo, Trova precedente: Cerca nuovamente il testo inserito precedentemente nella direzione specificata.
  • Trova nei file: Cerca la stringa di testo all'interno dei file: pop-up dialog with options all open files, all files in project, or all directories; masks available for selecting file types.
  • Find in files: Search for text string in files: pop-up dialog with options all open files, all files in project, or all directories; masks available for selecting file types.
  • Replace: Similar to Find; shows pop-up dialog with place to enter search text string and replacement text, and options for case sensitivity, direction etc.
  • Incremental find: Search for the string while you are entering the search string. Example: after you choose "Incremental Find" if you press "l" the first "l" will be highlighted. If then you press "a", the editor will find the next "la" and so on.
  • Vai alla linea: Muove il cursore di editing su una specifica linea del file.
  • Salta indientro: Salta alla posizione precedente. Ogni volta, saltando in un errore o cercando una dichiarazione l'ide salva la posizione corrente. Con questa funzione puoi saltare indietro con la cronologia.
  • Salta avanti: Salta alla posizione successiva.
  • Aggiunge un salto alla cronologia: Aggiunge la posizione corrente alla cronologia dei salti.
  • Visualizza cronologia salti: Visualizza la lista dei jump points: Non ancora implementato.
  • Salta al prossimo errore, Salta all'errore precendete: Jump to the positions in the source file of the next or previous reported error.
  • Set a free bookmark: mark the current line where the cursor is located with the next available (free) numbered bookmark, and add this to the list of bookmarks. Note that a pop-up menu (obtained by right-clicking with the mouse on the appropriate line of the source file) gives a larger range of Bookmark options, allowing the number of a bookmark to be specified, or allowing the user to jump to a numbered bookmark, not just the next or previous ones.
  • Jump to next bookmark, Jump to previous bookmark: Jump to next or previous bookmark in the numerical sequence.
  • Find other end of code block: If positioned on a begin, finds the corresponding end or vice versa.
  • Find code block start: Moves to the begin of the procedure or function in which the cursor is placed.
  • Find Declaration at cursor: Finds the place at which the selected identifier is declared. This may be in the same file or another file already open in the Editor; if the file is not open, it will be opened (so if a procedure or function is declared, for example, in classesh.inc , this will be opened in the Editor).
  • Open filename at cursor: Opens the file whose name is selected at the cursor. Useful for looking at Include files or the files containing other Units used in the project.
  • Goto include directive: If the cursor is positioned in a file which is Included in another file, goes to the place in the other file that called the Include file.
  • Find Identifier References: Produces a list of all the lines in the current file, or the current project or all attached files, in which an identifier is mentioned.
  • Rename Identifier: Allows developer to rename an identifier. A pop-up menu asks the developer to specify whether renaming is to occur in the current file only, or throughout the project, or in all open or attached files etc. You can even rename the identifier if it occurs in comments. You would use this feature, for example, if the compiler told you that an identifier already existed, so you need a new name for your own identifier.
  • Procedure List: Produces a list of all Procedures and Functions in the current file, with the line numbers where they are defined.

The View sub-menu

ViewMenu.png

Controls the display of various windows and panels on the screen.

  • Object Inspector: The window that usually occupies the left side of the Desktop, and displays the features of the Form which is on the desktop. Clicking with the mouse on any component of the form will cause the details of that component to be displayed in the Object Inspector. There is a panel at the top which shows the tree-structure of the current project, and the components of the form may optionally be selected in this panel: this will also cause the corresponding details to be displayed in the Object Inspector. The main lower panel has two tabs which allow selection of either Properties or Events to be displayed. Selection of Properties causes features such as name, color, caption, font, size etc to be displayed: there are two columns, the left showing the property, and the right showing the value associated with that property. Selection of Events displays two columns: the left lists the possible events such as MouseClick or KeyDown associated with that component, and the right shows the action that results from that event. If there is no action defined, then clicking in the appropriate box or on the
    ...
    button causes the Source Editor to be displayed, with the cursor already positioned in a dummy Procedure declaration, waiting for event-defining code to be typed in.
  • Source Editor: The main window in which source code is edited. Its behaviour is very like that of most other graphical text editors, so that the mouse can move the cursor over the displayed text, and clicking with the left mouse button while dragging the mouse will select and highlight text. Right clicking with the mouse displays a pop-up menu, it includes the usual Edit Cut, Copy or Paste functions, Find Declaration and Open File at Cursor. The top of the Source Editor window has a number of tabs, corresponding to the files that are open for the current project; clicking on any tab makes that file visible, and you can move easily from file to file, copying and pasting between files and performing most of the normal editing functions. The Source Editor performs color syntax highlighting on the code, with different colors for punctuation marks, comments, string constants etc. It will also maintain the level of indentation from line to line as you type in code, until you change the indentation. The function and appearance of the Source Editor are very configurable from the Main Menu by selecting Environment -> Editor options and then selecting one of several tabs in the pop-up dialog box.
  • Code Explorer: A window usually placed on the right of the Desktop which displays, in tree form, the structure of the code in the current unit or program. It usually opens with just the Unit name and branches for Interface and Implementation sections, but clicking on the
    +
    box to the left of any branch will open up its sub-branches or twigs, in more and more detail until individual constants, types and variables are displayed as well as procedure and function declarations. If you change the file displayed in the main Source Editor window, you need to click on the Refresh button of the Code Explorer to display the structure of the new file.
  • Units...: Opens a pop-up dialog window with a list of the unit files in the current project.Clicking with the mouse on a filename selects that file; click on Open to display that file in the Source Editor. Checking the Multi box allows several files to be selected simultaneously, and they will all be opened in the Source Editor (but only one at a time will be displayed). This Menu Option is rather like the Project -> Project Inspector option, but only displays the list of Unit files and allows them to be opened.
  • Forms...: Opens a pop-up dialog window with a list of the Forms in the current project, and allows the selection of one or more of them for display.
  • View Unit Dependencies: Opens a pop-up dialog window that shows, in a tree-like manner, the structure of dependencies of the currently open unit file. Most of the files listed as dependencies will have their own
    +
    boxes, which allow the dependencies of the individual files to be explored, often in a highly recursive manner.
  • Toggle form / unit view F12: Toggles whether the Source Editor or the current Form is placed on the top layer of the Desktop, and given focus. If the Source Editor has focus, then you can edit the source code; if the Form is given focus, you can manipulate the components on the desktop and edit the appearance of the Form. The easiest way to toggle the display between Editor and Form is to use the F12 key on the keyboard, but the same effect is achieved by selecting this option on the Main Menu.
  • Messages: A window that displays compiler messages, showing the progress of a successful compilation or listing the errors found.
  • Search Results: A window that displays the results of find in files.
  • Debug windows: Opens a pop-up menu with several options for operating and configuring the Debugger. See below where the debugger is described.

The Project sub-menu

ProjectMenu.png
  • New Project: Create a new project. A pop-up dialog window appears offering a choice of types of project to create.
  • New Project from file: A Navigation dialog window appears, alowing selection of a file from which to create a new project.
  • Open Project Open a project which has already been created and saved. A navigation dialog appears with a list of Lazarus Project Information (.lpi) files from which a project may be chosen.
  • Open Recent Project: Displays a pop-up list of recent projects on which you have been working, and allows selection of one of these.
  • Save Project: Similar to File -> Save: all the files of the current project are saved; if they have not previously been saved, there is a prompt for filename(s)- similar to Save Project As...
  • Save Project As...: Prompts for filename to save project. A default filename of Project1.lpi is offered, but you should choose your own filename. Lazarus will not permit you to use the same name for the Project file and the Unit File (see below).
  • Publish Project: Creates a copy of the whole project. If you want to send someone just the sources and compiler settings of your code, this function is your friend. A normal project directory contains a lot of information. Most of it is not needed to be published: the .lpi file contains session information (like caret position and bookmarks of closed units) and the project directory contains a lot of .ppu, .o files and the executable. To create a lpi file with only the base information and only the sources, along with all sub directories use "Publish Project". In the dialog you can setup the exclude and include filter, and with the command after you can compress the output into one archive. See Lazarus IDE Tools
  • Project Inspector: Opens a pop-up dialog with a tree-like display of the files in the current project. Allows you to add, remove or open selected files, or change options of the project.
  • Project Options...: Opens a pop-up dialog window with tabs for setting options for Application (Title, Output Target file name), Forms (allowing you to select among the available forms, make them Auto-create at start of application) and Info (specifying whether editor information should be saved for closed files, or only for project files).
  • Compiler options ...: (Recently moved here from the Run Menu). Opens a multi-page tabbed window which allows configuration of the compiler. Tabs include Paths which allows definition of search paths for units, include files, libraries etc, as well as allowing choice of widget type for the forms (gtk, gnome, win32); Parsing which allows choice of rules for parsing source programs, Code which allows choice of optimisation for faster or smaller programs, choice of target processor, types of checks, heap size etc; Linking allowing choice of whether or how to use debugging, static or dynamic libraries, and whether to pass options through to the linker; Messages to define what type of messages should be generated during error conditions; Other which allows decision to use default configuration file (fpc.cfg) or some other file; Inherited which shows a tree structure diagram to indicate how options have been inherited from units already incorporated; Compilation which allows definition of commands to be executed before or after the compiler is launched and can allow use of Make files.
  • Add editor file to Project: Add the file currently being edited to the Project
  • Remove from Project: Gives a pop-up menu of files available for removal from project.
  • View Source: No matter which file you are editing, takes you back to the main program file (.lpr)or the main .pas file if there is no .lpr.
  • View ToDo List:Opens a dialog box with a list of ToDo items associated with this project. This will list any ToDo comments in your project (lines commencing //TODO), and any others in the Lazarus units you have used. You need to Refresh the ToDo items in the dialog (using arrow symbol button of toolbar) before new 'ToDos' appear. The first column of the ToDo list contains numbers you have allocated to your ToDo comments; a simple //TODO comment will appear as a zero, but a comment of //TODO999 (for example) will place the number 999 in the first column. Remember there should be no spaces on the line before //TODO and ToDo comments added after the last save will not be shown!

The Run sub-menu

RunMenu.png
  • Build: Causes Lazarus to build (ie compile) any files in the project that have been changed since the last build.
  • Build all: Builds all files in the project, whether or not there have been any changes.
  • Abort build: Stop the build process once it is running - either you have remembered that you did something silly and want to stop the build, or the system seems to be taking far too long and something is obviously wrong.
  • Run: This is the usual way to launch the compiler and, if compilation is successful, to start execution of the application. What actually happens is that Lazarus saves a copy of your files, then starts the compiler and linker, then begins execution of the final linked binary program.
  • Pause: Suspend execution of the currently running program. This may allow you to inspect any output that has been generated; execution may be resumed by selecting Run again.
  • Step into: Used in conjunction with the debugger, causes execution of the program one step at a time up to a bookmarked point in the source.
  • Step over: Causes stepwise execution up to the statement marked, then skips the marked statement, and continues execution at normal speed. Useful in trying to isolate a statement that introduces a logical error.
  • Run to cursor: Causes execution at normal speed (ie NOT one statement at a time) until the statement is reached where the cursor is located; then stops. Resume execution at normal speed by selecting Run.
  • Stop: Cease execution of the running program. Cannot be resumed by selecting Run; this will start the program again from the beginning (re-compiling if necessary).
  • Run Parameters: Opens a multi-page pop-up window which allows command-line options and parameters to be passed to the program to be executed; allows selection of display to run program (eg a remote X terminal may be used in Linux); some system Environment variables may be overridden.
One very important use of this sub-menu is to activate a terminal window in which conventional Pascal console input/output is displayed. If you are developing a console-mode Pascal program (ie one that doesn't use the Graphical User Interface with its forms, buttons and boxes) then you should check the box for "Use launching application". The first time you do this and try the Compile/Run sequence, you will probably get a rude message to say
"xterm: Can't execvp /usr/share/lazarus//tools/runwait.sh: Permission denied".  
If this happens, you need to change the permissions on the appropriate file (for example using chmod +x filename, or using the Windows utility for changing permissions); you might have to do this as root. After this, each time you launch you program, a console box will appear and all your text i/o (readln, writeln etc) will appear in it.
After your program has finished execution, a message "Press enter" appears on the screen. Thus any output your program generated will remain on the screen until you have had a chance to read it; after you press 'enter' the console window closes.
Note: as for the current version, there is no prepared console command for Windows users. Until the Lazarus team adressess that, the following line should work (on WinXP -- someone please update for other Windowses)
C:\Windows\system32\cmd.exe /C ${TargetCmdLine}
See the separate tutorial on Console Mode Pascal programming.
  • Reset debugger: Restores the debugger to its original state, so that breakpoints and values of variables etc are forgotten.
  • Build file: Compile (build) just the file that is currently open in the Editor.
  • Run file: Compile, link and execute just the currently open file.
  • Configure Build + Run File: Opens a multi-page tabbed window with options to allow for build of just this file when Build Project is selected, allows selection of the working directory, the use of various Macros, etc. Then Builds and Runs the file.
These last three options enable you to open (and maintain) a test project. Use File -> Open to open an .lpr file, pressing cancel on the next dialog to open this file as "normal source" file.

The Package sub-menu

  • Open Package: Displays a list of installed packages, with an invitation to open one or more of them, or to select various general or compiler options.
  • Open Package File: Open one of the files in the selected package.
  • Open Recent Package: Open a package that was opened recently.
  • Add Active Unit to Package: Place the unit file (currently in the editor) into a package.
  • Package Graph: Displays a graph showing the relationships of the packages currently being used (if you aren't using any other packages, the Lazarus package and the FCL and LCL will be displayed).
  • Configure custom components: If you have created some components, allows you to configure them.

The Tools sub-menu

ToolsMenu.png
  • Configure custom tools: Allows the user to add various external tools (usually macros) to the toolkit
  • Quick syntax check: Perform a quick check of the syntax in your source file without actually compiling anything. Essential step in developing long or complicated programs, where you don't want to waste time compiling if the code is wrong.
  • Guess unclosed block: useful utility if you have a complex nested block structure and you have left out an 'end' somewhere
  • guess misplaced IFDEF/ENDIF: useful if there is a complex or nested macro structure and you think you have left out an ENDIF directive
  • Make resource string: Makes the selected string a resource string by placing it in the resourcestrings section. An advantage of resource strongs is you can change them without the need to recompile your project!
  • Diff: Allows comparison between two files (or, usually, two versions of the same file) to find differences. Options to ignore white space at beginning or end of lines or differences in line termination: CR+LF versus LF). Useful for checking if there have been changes since last CVS update etc.
  • Check LFM file in editor: Allows inspection of the LFM file which contains the settings that describe the current form
  • Convert Delphi unit to Lazarus unit: Helps in porting Delphi applications to Lazarus; makes the necessary changes to the source file. See Lazarus For Delphi Users and Code Conversion Guide.
  • Convert DFM file to LFM: For porting from Delphi to Lazarus: converts the Form Description files from Delphi to Lazarus. See Lazarus For Delphi Users and Code Conversion Guide.
  • Build Lazarus: Launches a re-build of Lazarus from the most recently downloaded or updated SVN files. Hit the button and sit back to watch it happen! (track the process on your Messages window).
  • Configure "Build Lazarus": Allows the user to determine which parts of Lazarus should be re-built, and how. For example, you could select to have just the LCL re-built, or to have everything except the examples built; you can select which LCL interface to use (ie which set of widgets), and you can select the target operating system and specify a different target directory.

The Environment sub-menu

EnvironmentMenu.png
  • Environment options: Displays a multi-page window with tabs for
    • Files - allowing the user to specify path to default directory, compiler, source directory and temporary directory for compilation;
    • Desktop - options for Language, Auto save behaviour, saving desktop properties, hints for component palette and speed buttons;
    • Windows, to allow specification of size and behaviour of the various windows;
    • Form Editor - choose colours for editing forms;
    • Object Inspector - choose colour and height of items;
    • Backup - specify how to backup files when editing;
    • Naming - specify what extension to use in naming pascal files ('.pp' or '.pas'), whether to save files with names in lowercase, whether to perform auto-delete or auto-rename.
  • Editor options: Multi-page window, with tabs for
    • General - determines behaviour like auto-indent, bracket highlighting, drag-drop editing, scrolling, syntax highlighting, showing hints, size of block indent and tabs, limit of Undo;
    • Display - options for showing line numbers, presence of gutters, size and type of font for editor, and contains a preview panel showing the colours of the various syntax features such as comments, directives, punctuation, errors and breakpoints;
    • Key Mappings - options to select Lazarus or Turbo Pascal scheme;
    • Color - allows choice of colour scheme for text features, for a number of language types such as Object Pascal, C++, Perl, HTML, XML and shell scripts. It shows preview panel again (for whichever language is selected);
    • Code Tools - allows selection of features like Identifier Completion, tooltips, specification of template file names, specific templates for code completion.
  • Debugger Options: Multi-page window with tabs for
    • General - choose debugger: none, GNU debugger (gdb) or gdb through SSH, specify search paths for debuggers,and specific options for chosen debugger;
    • Event log - specify whether to clear log on run, and which messages to display;
    • Language Exceptions - select which exceptions can be ignored;
    • OS Exceptions - allows user to add certain signals which apply to current operating system (not implemented).
  • Code Tool Options: Multi-page window, tabs for
    • General - Allows entry of additional source search paths, specify Jumping Method;
    • Code Creation - determines whether created code is added before or after certain features;
    • Words - determines whether Pascal keywords are to be entered in upper or lower case, or as Capitalised Words;
    • Line Splitting - establish rules about where lines are allowed to be split (before or after punctuation, after keywords etc);
    • Space - decide whether a space is to be added automatically before or after certain syntactic features such as keywords or punctuation marks.
  • Code Tools Defines Editor: Here you can see all IDE internal definitions to parse sources. You will see all the defines, unit, source, include paths for all source directories. Beginning with the settings of the current FPC, the defines for the Lazarus Source directory, all package directories and project directories.

Most of these settings are auto generated and read only.


  • Re-scan FPC Source directory Looks through the directory again. Lazarus uses the fpc sources to generate correct event handlers and while looking for declarations. If somebody changes the directory in the environment options, then this directory is rescanned, to make sure lazarus uses the version stored in that location. But if this directory has changed without lazarus noticing, then you may get some errors when designing forms or doing "Find declaration". If you get such an error, you can do two things:
    1. Check the fpc source directory setting in the environment option.
    2. Re-scan FPC source directory.

The Windows sub-menu

WindowsMenu.png

Contains a list of the currently opened files and the available windows such as Source Editor, Object Inspector and Project Inspector. Clicking on the name of one of the windows brings it to the foreground and gives it focus.

The Help sub-menu

At present this has three selections:

  • Online Help which at present opens a browser window that contains a picture of the running cheetah and a few links to the Lazarus, FreePascal and WiKi websites
  • Reporting a bug opens the wiki page, which describe the bug reporting procedure
  • Configure Help which opens a pop-up menu with options to select viewers and databases from which to read Help information. This option allows the user to specify either the on-line documents section of the Lazarus-CCR website, some other website containing the documents, or a local store for the documentation (this would eventually become the default, when the Help system is fully developed).

At present by default, if you place your Editor cursor over any keyword from the FreePascal Components Library FCL, the RunTime Library RTL or the Lazarus Components Library LCL, and then press <<F1>> you will be taken by your default browser to the appropriate definition on the website. Be aware that your browser may be located on another desktop on your machine (eg in Linux), and you may not see the information immediately; of course if you are not connected to the internet you cannot get this information. THIS SECTION STILL REPRESENTS WORK IN PROGRESS

  • About Lazarus Displays a pop-up box with some information about Lazarus.

Eventually there will be a full on-line Help service, with information about Pascal syntax, the use of the IDE, how to use, modify or create Components, and hints on how to perform certain tasks. This part of the Documentation section (the thing you are currently reading) represents the beginning of the process. We need contributions from anyone who feels able to provide them: the WiKi is very easy to edit.

The Button bar

A small toolbar area on the left of the main editor window, just below the Main Menu and to the left of the Component Palette, contains a set of buttons which replicate frequently-used Main Menu selections:

New unit, Open (with a down-arrow to display a drop-down list of recently used files), Save, Save all, New Form, Toggle Form/Unit (ie show either form or source code of Unit), View Units, View Forms, Run (ie compile and Run), Pause, Step Into, Step over (the last two are Debugger functions).

The Component Palette

A Tabbed toolbar which displays a large number of icons representing commonly used components for building Forms.

Each tab causes the display of a different set of icons, representing a functional group of components. The left-most icon in each tabbed group is an obliquely leftward-facing arrow, called the Selection Tool.

If you allow the mouse cursor to hover over any of the icons on the Component Palette, without clicking on the icon, the title of that component will pop-up. Note that each title begins with a 'T' - this signifies 'Type' or more accurately 'Class' of the component. When you select a component for inclusion in a form, the Class is added to the type section of the interface part of the Unit (usually as part of the overall TForm1), and an instance of that class is added to the var section (usually as the variable Form1). Any Methods that you design to be used by the Form or its Components (ie Procedures or Functions) will be placed in the implementation part of the Unit

In the following list of the Components, you will find links to files that contain descriptions of the Units in which they are found. If you want to find out about the properties of a particular component, it is often worth looking at the Inheritance of that component and then inspecting the properties of the base type from which it is derived. For example, to understand TMaskEdit it is also useful to examine TCustomMaskEdit.

TABS (the names are largely self-explanatory):

Component Palette Standart.png
Frequently used components: TMainMenu, TPopupMenu, TButton, TLabel, TEdit, TMemo, TToggleBox, TCheckBox, TRadioButton, TListBox, TComboBox, TScrollBar, TGroupBox, TRadioGroup, TCheckGroup, TPanel, TActionList
Component Palette Additional.png
More, often-used components: TBitBtn, TSpeedButton, TStaticText, TImage, TShape, TBevel, TPaintBox, TNotebook, TLabeledEdit, TSplitter, TTrayIcon, TMaskEdit, TCheckListBox, TScrollBox, TApplicationProperties, TStringGrid, TDrawGrid, TPairSplitter, TColorBox, TColorListBox, TChart
Component Palette Common Controls.png
TTrackBar, TProgressBar, TTreeView, TListView, TStatusBar, TToolBar, TUpDown, TPageControl, TTabControl, THeaderControl, TImageList, TPopupNotifier
Component Palette Dialogs.png
TOpenDialog, TSaveDialog, TSelectDirectoryDialog, TColorDialog, TFontDialog, TFindDialog, TReplaceDialog, TOpenPictureDialog, TSavePictureDialog, TCalendarDialog, TCalculatorDialog, TPrinterSetupDialog, TPrintDialog, TPageSetupDialog


Several useful Dialog procedures or functions don't appear on the Palette, but are easily used as direct calls from your source program.

For several good examples of the use of Components see the $LazarusPath/lazarus/examples subdirectory of your source installation. Many of the programs show how to use dialogs and other components directly without using the IDE and component palette or having a separate form definition file: all the components are fully and explicitly defined in the main Pascal program. Other example programs make full use of the IDE.

Some examples don't work straight away: you may need to play about with paths and permissions of files or directories. If you want to compile any of the examples, make sure that you have read/write/execute permissions for the files and directories, or copy the files to a directory where you do have the appropriate permissions.

Try running the 'testall' program to see a menu of the available components together with small example test forms for most of them; then inspect the code to find out how they work!


  • Misc
Component Palette Misc.png
TColorButton, TSpinEdit, TFloatSpinEdit, TArrow, TCalendar, TEditButton, TFileNameEdit, TDirectoryEdit, TDateEdit, TCalcEdit, TFileListBox, TXMLPropStorage, TIniPropStorage, TBarChart, TButtonPanel, TIDEDialogLayoutStorage
Component Palette DataControls.png
Data-aware components, which largely replicate the Standard and Additional groups but are applicable to Databases: TDBNavigator, TDBText, TDBEdit, TDBMemo, TDBImage, TDBListBox, TDBComboBox, TDBCheckBox, TDBRadioGroup, TDBCalendar, TDBGroupBox, TDBGrid
  • Data Access
Component Palette DataAccess.png
TDatasource, TMemDataset, TSdfDataSet, TFixedFormatDataSet, TDbf
Component Palette System.png
TTimer, TIdleTimer, TLazComponentQueue, THtmlHelpDatabase, THtmlBrowserHelpViewer, TProcessUTF8, TAsyncProcess, TProcess, TSimpleIPCClient, TSimpleIPCServer, TXMLConfig, TEventLog
  • SynEdit
Component Palette SynEdit.png
A group of components to help interfacing with other languages and software tools. SynEdit is an advanced multi-line edit control, for Borland Delphi, Kylix and C++Builder. It supports Syntax Highlighting and code completion, and includes exporters for html, tex and rtf. It is a full-VCL/CLX control, meaning it is not a wrapper for Microsoft Windows controls, and no run-time library is required; this make SynEdit a crossplatform component. Compatibility with FreePascal is also planned, and SynEdit is the edit component in Lazarus IDE. see synedit at sourceforge. : TSynEdit, TSynAutoComplete, TSynExporterHTML, TSynMacroRecorder, TSynMemo, TSynPasSyn, TSynFreePascalSyn, TSynCppSyn, TSynJavaSyn, TSynPerlSyn, TSynHTMLSyn, TSynXMLSyn, TSynLFMSyn, TSynUNIXShellScriptSyn, TSynCssSyn, TSynPHPSyn, TSynTeXSyn, TSynSQLSyn, TSynPythonSyn, TSynVBSyn, TSynAnySyn, TSynMultiSyn

How To Use the Palette

To use the Palette, there must be an open form on view in the editor (if there isn't one, select File -> New Form). Click on the icon in the appropriate tab of the Palette for the component you want to use, then click on the Form, near where you want the component to appear. When the desired component appears, you can select it by clicking with the mouse, then move it to the exact place on the Form where you want it and adjust its size. Adjustments can be made to the appearance either by altering the picture itself on the Form using the mouse, or by changing the relevant Property in the Object Editor for that component.

If you install additional components, either those you have written yourself, or some coming as a package from some other source, then extra tabs with the relevant icons will appear in your Component Palette. These new components can be selected and used on your forms in the same way as those supplied by default.

How to use Standard Controls, Common Controls and Extended Controls

The Units StdCtrls, ComCtrls and ExtCtrls contain definitions and descriptions of many of the most commonly used controls for constructing Forms and other Objects in Lazarus Applications.

Many of the final target controls that the application developer wants to use, such as TButton, TMemo, TScrollBar etc, have a corresponding ancestor class such as TCustomButton, TCustomMemo or TCustomScrollBar. Several of the properties and methods relevant to the final target control are defined (and explained) more fully in the TCustomXXX class, and are inherited by the final target control.

If you drop a component on the form editor you don't need to add code explicitly to create it. The component is automatically created by the IDE together with the form, and destroyed when the form is destroyed.

However, if you create the component yourself by code don't forget to free it when it is no longer needed.

If you place a component on the Form Designer and look at the Object Inspector, you can observe the properties change as you move the component around.

For example, if you place a button (TButton) on the form, click on it to select it, then move it around the form with the mouse, you can watch the values of Top and Left change in the Object Inspector to reflect the new position. If you use the object's re-sizing bars to adjust its size, you can watch the Height and Width properties change as well.

On the other hand, by using the Object Inspector, you can select the value associated with a property such as height, and type in a new value; you can watch the size of the object on the form change to reflect the new value.

You can also explicitly change the properties of the object in code by typing (in the appropriate Implementation section of the Source editor), for example

         Form1.Button1.Height := 48;

If you type this new value into the Source Editor and then look back at the Form Designer, you will see that the button on the Form has taken the new size. The new value will also be shown in the Object Inspector.

In summary, there are usually about three different ways to determine each property of an object:

  • by using the mouse,
  • by setting the values in the Object Inspector,
  • or explicitly by writing code.

The components defined in these Units have several properties that are common to most of them, and other properties that are specific to the individual components. We shall describe the most common ones here. Unusual or control-specific properties will be described for the individual controls.

Additional Help can always be obtained by selecting a property or keyword, in either the Object Inspector or the Source Editor, and pressing F1. You will be taken by your Help browser to the appropriate page in the documentation.

If the description of a property on that page is insufficient, you can navigate to the corresponding description in the ancestor classes, by selecting the links in the Inheritance listing or by selecting the ancestor Type in the declaration of the object.

Constructors such as Create allocate memory and system resources needed by the object. They also call the constructor of any sub-objects present in the class.

Destructors: remove the object and de-allocate memory and other resources. If you call Destroy for an object which hasn't being initialized yet it will generate an error. Always use the Free method to deallocate objects, because it checks whether an object's value is nil before invoking Destroy.

Take the following precautions when creating your own Destroy method:

  • Declare Destroy with the override directive, because it is a virtual method.
  • Always call 'inherited Destroy;' as the last thing on the destructor code.
  • Be aware that an exception may be raised on the constructor in case there is not enought memory to create an object, or something else goes wrong. If the exception is not handled inside the constructor, the object will be only partially built. In this case Destroy will be called when you weren't expecting it, so your destructor must check if the resources were really allocated before disposing of them.
  • Remember to call Free for all objects created on the constructor.


Some commonly listed properties
PropertyMeaning
Action The main action or event associated with the object. For example selecting an 'Exit' Button might cause the 'Close' action
Align Defines the way in which an object is to be lined up with the parent object. Possible values are alTop (placed at the top and using the full available width), alBottom, alLeft (placed at the left and using the full available height), alRight. alNone (place anywhere on parent control) or alClient (takes all available space next to controls aligned to top, bottom, left or right)
Anchor Used to keep a control a certain distance from the defined edges of a parent control, when the parent is resized. For example [akBottom, akRight] will keep the control a fixed distance from the bottom right corner.
AutoSelect When True, an editing control will select all its text when it receives focus or when the Enter key is pressed.
AutoSelected True indicate that the edit or combobox control has just performed an AutoSelect operation so that subsequent mouse-clicks and keystrokes proceed normally without selecting the text.
BorderSpacing The space around the edge between an Anchored control and its parent.
Caption The text that is displayed on or near the control; it should preferably give some clue as to the function of the control, or an instruction such as 'Close' or 'Execute'. By default Caption is set to be the same as the 'Name' property, and the application programmer should substitute meaningful text instead of the default values.
CharCase Indicates how text is displayed in a text editing control: Normal (retaining the case of the letters typed by the user), converted to uppercase, or converted to lowercase
Constraints Sets the minimum and maximum sizes for a control. If a control is resized the new dimensions are always within the ranges given here. You should take care when setting these options that they do not conflict with the Anchors and Align settings.
Color The Colour to be used to draw the control or to write the text it contains.
Enabled A Boolean property to determine whether or not a control is capable of being selected and performing an action. If it is not Enabled, it is often Grayed out on the Form.
Font The Font to be used for writing the text associated with the control - either the caption or label, or the text-strings contained within the control. The entry on the Object Inspector usually has a (+) box on the left, and selecting this box reveals further options such as character set, colour and size.
Hint A short piece of informative pop-up text that appears if the mouse-cursor hovers over the control.
Items The list of 'Things' that the object contains, such as a group of images, a series of lines of text, a number of actions in an actionlist, etc
Lines An array of strings, containing the textual data in controls with more than a single line of data, such as an Edit-Box or a Combo-Box. The array is zero-indexed, ie the lines are numbered [0..numLines-1]
Name The identifier by which the control is known in the program. The IDE gives it a default name based on the underlying type, for example successive instances of TBitButton would be named Form1.BitBitton1 and Form1.BitButton2; it is up to the application programmer to give them more meaningful names such as ExitButton or OKButton. By default the Name of the control is applied to the Caption for the control, but the text of the Caption may be changed separately.
PopUpMenu A window containing context-sensitive menu information that pops up when the right mouse button is clicked on the object.
Position (or Top, Left) Determines where the control is located on the parent form or window
ReadOnly Boolean property which, if True, signifies that the contents of the control can be read by the user or the calling routine, but cannot be written or changed.
ShowHint Allows a small window containing a context-sensitive Help or other description to be displayed when the mouse cursor 'hovers' over the control.
Size (or Height and Width) The dimensions of the control
Style The options available for Style depend upon the sort of Control being considered: for instance the Style may be defined by TFormStyle, TBorderStyle, TButtonStyle etc.
TabOrder Integer defining where in the sequence of tabs on the Form this control is to lie
TabStop Boolean property which if True places this control in the sequence of objects that the user can reach by successively pressing the Tab key
Text The String of Text that represents the actual data that this control contains. Applies particularly to Text, Memo and StringList types of object. Most of the editing operations (such as Select, Clear, Cut, Copy) are performed in this part of the object, which holds the actual string being edited. If the control contains more than a single line of text, for example TMemo or TComboBox, then the textual elements are arranged as an array of strings (zero-indexed, ie numbered from [0..numLines-1]) in Lines.
Visible If true, the object can be seen on the Form; if False, object is hidden
WordWrap Logical flag to show whether or not word-wrap is enabled, ie if a word comes close to the end of a line and is going to be too long for the line, it is wrapped down to the next line.

Many actions are commonly listed in the 'Events' tab of the Object Inspector. If you select an entry in the list, a ComboBox appears with a DropDown list showing any actions that have aleady been defined, and allowing you to choose one to be associated with this event. Alternatively you can select the ellipsis (three dots ...) and you will be taken to an area of the Source Editor where you can begin typing your own action instructions for the selected event.

While a large number of events is available for any given control, in practice it is only necessary to populate a few of them. For most controls, it is sufficient to provide coding for 'OnClick'; for more complex controls it may be necessary also to provide for 'OnEntry' (when the mouse cursor enters the Control and gives it focus) and 'OnExit' (when the mouse cursor leaves the Control; or you may need to write an event handler for 'OnChange' or 'OnScroll', depending on the nature of the particular control with which you are dealing.

The pop-up menu that appears when you right-click an object in the Form Designer has, as its first item: 'Create default event' and selecting this option will have the same effect as selecting the ellipsis in the Object Inspector for the default event, usually OnClick: you are taken to the Implementation area of the Source Editor where you can type the code for the event handler.

A common strategy in Object-Oriented programming is to provide an ActionList with the facility for entering, removing or editing a number of pre-defined actions from which the most appropriate can be selected to use in any particular instance.


Some commonly listed Actions
Action Meaning
OnChange Action to be taken if any change is detected (eg mouse move, mouse click, key press, edit text, alter picture, etc)
OnClick Action to be taken when the (left) mouse button is clicked. This is usually the main or default action of the control; for example clicking on a button or checkbox initiates the action associated with the checkbox. It may alternatively initate a process of selection, for instance in a TextBox or Memo, or signal the beginning of painting with a Pen or Brush.
Click A method to emulate in code the effect of clicking on a control. This method is most often found in Button-type controls (TButton, TBitBtn, TSpeedButton etc). A procedure can be written that calls the same code as the OnClick action. This facility can be particularly useful if the activation of one control by clicking causes a cascade of other controls to be activated, and the Click method can be used to initiate the action rather than having the user explicitly click on a lot of controls.
OnDragDrop Action to be taken during Drag-Drop manoeuvres, ie when the mouse is used to 'capture' an item or some text etc and move it around the screen to a new location.
OnEntry Action to be taken when the mouse cursor enters the area occupied by the object, usually transfering focus to that object. This might include changes in the appearance of the object such as highlighting or raising the border.
OnExit Action to be taken when the mouse moves out of the area of the object, usually transferring focus out of the object.
OnKeyPress Action to be taken for any key-press. Subtly different from OnKeyDown, which simply responds to a key being down, whether or not it was already down when focus was given to this control. OnKeyPress requires that a key becomes pressed while focus is in this control.
OnKeyDown Action to be taken if a key is down while focus is in this control. Subtly different from OnKeyPress - for example the key might already have been down when focus entered this control, whereas OnKeyPress requires the key to become pressed while focus is in the control.
On Key Up Action to be taken if a key is up (ie not pressed) while focus is in this control.
OnMouseMove On Mouse Down - Action to be taken if the mouse cursor moves while focus is in this control.
OnMouseDown Action to be taken if the mouse button is down while focus is in this control.
OnMouseUp Action to be taken if the mouse button is up while the cursor is over this control. Implies that the mouse button was previously down and has been released. The case where the cursor enters the control but the mouse button has not yet been pressed is covered by OnEntry or OnMouseEnter.
OnResize Action to be taken when the control is resized. Might include re-alignment of text or selection of a different font size etc.

How to use Menus

Hints for creating Menus for your Forms

TMainMenu is the Main Menu that appears at the top of most forms; form designers can customise by choosing various menu items. TPopupMenu is a menu window that pops up with pertinent, usually context-sensitive, details and choices when the right mouse button is clicked near a control

Main Menu is a non-visible component : that is, if the icon is selected from the Component Palette and placed on the Form, it will not appear at Run-time. Instead, a Menu bar with a structure defined by the Menu Editor will appear. Popup menus, placed on the form by selecting the icon from the Component Palette, do not appear at all unless the right mouse button is clicked on a control that owns such a menu.

To see the Menu Editor, right-click on the Main Menu or Popup Menu icon on your Form. A pop-up box appears, that invites you to enter items into the Menu bar.

An Edit box is displayed, containing a Button labelled New Item1. If you right-click on that box, a pop-up menu is displayed that allows you to add a new item before or after (along the same level) or create a sub-menu with the opportunity to add further items below (or above) the new item in a downward column.

Any or all of the MenuItems that you add can be configured using the Object Inspector.

At the least you should give each item a Caption which will appear on the Menu Bar (you may also wish to give it a more meaningful Name). The caption should indicate the activity to be selected, such as "File Open" or "Close", "Run" or "Quit"

If you want a particular letter in the Caption to be associated with a shortcut key, that letter should be preceded by an ampersand. The Menu item at run-time will appear with the shortcut letter underlined, and hitting that letter key will have the same effect as selecting the menu item. Alternatively you can choose a shortcut key sequence (such as Ctrl-C for Copy or Ctrl-V for Paste - the standard Keyboard shortcuts) with the ShortCut property of the MenuItem.

It is often helpful to use the Menu controls in conjuction with an ActionList which contains a series of standard or customised Actions. Menu Items can be linked in the Object Inspector to Actions on the list, and the same actions can be linked to Buttons, ToolBar Buttons, SpeedButtons etc. It is obviously economic of effort to re-use the same code to respond to the various events, rather than writing separate OnClick event handlers for each individual control.

By default a number of standard actions is pre-loaded from StdActns or, if DataAware controls are being used, from DBActns, and these can be chosen using the ActionList editor which appears when you right-click on the ActionList icon on the Form Designer.

The Debugger

Still to be written.

see also category: IDE Window - Debug

The Lazarus files

   (Thanks to Kevin Whitefoot.)
   (Additions by Giuseppe Ridinò, User:Kirkpatc and Tom Lisjac)

When you save you will actually be saving two files:

  xxx.pas and yyy.lpr 

(You save more than that but those are the ones you get to name). The project file (lpr) and the unit file (pas) must not have the same name because Lazarus will helpfully rename the unit (inside the source code) to the same as the unit file name and the program to the name of the project file (it needs to do this or the compiler will probably not be able to find the unit later when referred to in the project file). Of course to be consistent it changes all the occurrences of unit1 to xxx.

So if you are saving a project called again, trying to save again.pas and again.lpr fails because unit names and program names are in the same name space resulting in a duplicate name error.

So here is what I ended up with:

e:/lazarus/kj/lazhello:

total 4740  free 76500
-rwxrwxrwx   1 kjwh     root  4618697 Mar 24 11:19 again.exe
-rw-rw-rw-   1 kjwh     root     3002 Mar 24 11:21 again.lpi
-rw-rw-rw-   1 kjwh     root      190 Mar 24 11:18 again.lpr
-rw-rw-rw-   1 kjwh     root      506 Mar 24 11:08 againu.lfm
-rw-rw-rw-   1 kjwh     root      679 Mar 24 11:08 againu.lrs
-rw-rw-rw-   1 kjwh     root      677 Mar 24 11:08 againu.pas
-rw-rw-rw-   1 kjwh     root     2124 Mar 24 11:08 againu.ppu
-rwxrwxrwx   1 kjwh     root      335 Mar 24 11:07 ppas.bat

Note that there are many more files than the two that I thought I was saving.

Here is a brief note about each file:

again.exe: The main program binary executable. Win32 adds an "exe" extension. Linux has none (just the name of the program). This file will be huge in Linux due to the inclusion of debugging symbols. Run the "strip" utility to remove them and substantially shrink the executable size.

again.lpi: (Lazarus Project Information). This is the main information file of a Lazarus project; the equivalent Delphi main file of an application will be the .dpr file. It is stored in an XML format and contains instructions about all the libraries and units required to build the executable file.

again.lpr: The main program source file or master file. Despite its lazarus specific extension it is in fact a perfectly normal Pascal source file. It has a uses clause that lets the compiler find all the units it needs. Note that the program statement does not have to name the program the same as the file name. This file is usually fairly small, with just a few statements to initialise, build the forms, run and close the application. Most of the work is done in the unit source files, with suffix '.pas'

againu.lfm: This is where Lazarus stores the layout of the form unit, in human readable form. It reflects the properties of the various components, as set in the Object Inspector. Each object description starts with a line:

object xxxx 
  then there follows a list of properties 
  (including embedded or nested objects) then an 
end 

line. Lazarus uses this file to generate a resource file (.lrs) that is included in the initialisation section of the againu.pas unit. Delphi dfm files can be converted to lfm format in the Lazarus IDE using the Tools->Convert DFM file to LFM utility.

againu.lrs: This is the generated resource file which contains the instructions to the program for building the form (if you look in the main Unit file, you will see in the initialization section the line

{$i againu.lrs} 

which instructs the program to load the resource file). Note that it is not a Windows resource file.

againu.pas: The unit that contains the code for the form; this is usually the only file that the application programmer needs to edit or inspect, and contains any code specifically supplied by the programmer (especially event handlers).

againu.ppu: This is the compiled unit which gets linked into the executable file together with any other units named in the Uses section.

ppas.bat: This is a simple script that links the program to produce the executable. If compilation is successfull, it is deleted by the compiler.

Original contributors and changes

This page has been imported from the epikwiki version.

  • Created initial page and template. T. Lisjac - 11/04/2003 VlxAdmin
  • Inserted a note containing instructions for writing your first Lazarus Program. Suggest an administrator places it in the appropriate place on the Tutorial menu. 3/09/2004 User:Kirkpatc
  • Per above, moved Chris's writeup to the main body of the tutorial VlxAdmin
  • Began to insert text describing the Lazarus Editor - more to follow! 24 Mar 2004 User:Kirkpatc
  • Added some more to Lazarus Editor section of Tutorial. 25 Mar 2004 User:Kirkpatc
  • Added screenshots and revised some of the page formatting VlxAdmin 3/25/2004
  • Moved some of kwhitefoot's comments into Tutorial section. Formatting not quite right, but have to go to bed now! 26 Mar 2004 User:Kirkpatc
  • Formatted, added credits and comments. Removed original notes. VlxAdmin 3/26/2004
  • More material added to Editor section of tutorial. 26 Mar 2004 User:Kirkpatc
  • More material added describing the Main Menu. Renamed 'Hello World' to 'Getting Started' and moved it to nearer the top. 31 March 2004 User:Kirkpatc
  • Inserted section on Run sub-menu. Some general editing (eg ended each entry with a period to ensure consistency). 9 Apr 2004 User:Kirkpatc
  • Inserted a new section on How to get started with MySQL in FPC/Lazarus. 13 Apr 2004 User:Kirkpatc
  • Deleted the section on MySQL from here: it has been copied to Lazarus Database section of tutorial. 14 Apr 2004 User:Kirkpatc
  • Added some more to the description of the Editor Main Menu. 18 Apr 2004 User:Kirkpatc
  • Added section on Environment sub-menu. 19 Apr 2004 User:Kirkpatc
  • Added section on Components sub-menu. 4 May 2004 User:Kirkpatc
  • Adding Tools sub-menu description (incomplete). 7 May 2004 User:Kirkpatc
  • Added some screenshots to Menu descriptions. 9 May 2004 User:Kirkpatc
  • Fixed a bit in Environment Options - thanks VincentSnijders. 14 May 2004 User:Kirkpatc
  • More additions to Tools sub-menu. 19 May 2004 User:Kirkpatc
  • Added a section on the Button Bar and started work on The Component Palette. 20 May 2004 User:Kirkpatc
  • Posted a description file for the StdCtrls unit of the LCL, in the hope that people will add comments. 26 May 2004 User:Kirkpatc
  • Edited the StdCtrls file, removing a lot of repetitive material and doing some formatting. It is still far too long. 28 May 2004 User:Kirkpatc
  • Expanding on the Components Palette. 5 June 2004 User:Kirkpatc
  • Added a lot to the DialogExamples page. 10 June 2004 User:Kirkpatc
  • Considerable revision of the StdCtrls page, hopefully making it clearer and encouraging people to contribute - particularly in the 'Description' sections. 14 June 2004 User:Kirkpatc
  • Added pages for Menus and Dialogs units (linked to Component Palette description) - please feel free to add to these pages. 14 June 2004 User:Kirkpatc
  • Added page for Common Controls (linked to Component Palette). 16 June 2004 User:Kirkpatc
  • Added MaskEdit page (linked to Component Palette). 17 June 2004 User:Kirkpatc
  • Added Buttons, ExtCtrls pages (linked to Component Palette). 17 June 2004 User:Kirkpatc
  • Edited MainMenu component description page. 23 June 2004 User:Kirkpatc
  • Some additions to Common Controls. 28 June 2004 User:Kirkpatc
  • A new tutorial on Text-mode Pascal programming has been added. 5 July 2004 User:Kirkpatc
  • Minor changes to ComCtrls, ExtCtrls, Environment Menu. 10 July User:Kirkpatc
  • Added FormsTxt, component description page for Component Palette. 20 July 2004 User:Kirkpatc
  • Some corrections to ConsoleModePascal. 21 July 2004 User:Kirkpatc
  • Some small changes to ComponentPalette. 22 July 2004 User:Kirkpatc
  • Returned after a long absence! Changed link for component descriptions in StdCntls group of ComponentPalette to point directly at the Lazarus on-line help html pages. 25 Sept 2007 User: Kirkpatc
  • Uploaded some more up-to-date screenshots and fixed links in descriptions of the Menus. 2 October 2007 User: Kirkpatc
  • Fixed links for component descriptions in Extra Controls section of Component Palette. 2 October 2007 User: Kirkpatc
  • Added sections on How to use Standard Controls etc and How to use Menus (based on topics in the LCL Documentation). Fixed some links in Component Palette. 4th June 2008 User: Kirkpatc
  • Some edits and additions to the Lazarus Files section. 12th July 2008 User: Kirkpatc
  • Some edits and additions to the Lazarus Component section. 23th Jan 2009 User: Miyatake

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