How to use a TrayIcon

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About

TTrayIcon is a multiplatform System Tray component. You can find TrayIcon on the Additional tab of the Component Palette (0.9.23+).

TrayIcon used to be an optional component, but is part of LCL since Lazarus 0.9.23

To start quickly, please read the demonstration program.


Problems with newer Gnome based Linux

There are at least two reasons why a Linux system may fail to display the System Tray Icon, a clash between libappindicator1 and libappindicator3 and, secondly, a distribution's adherence to the Gnome hard line about not displaying System Tray Icons. See next section for the second case.

June 2019 I have submitted a patch related to https://bugs.freepascal.org/view.php?id=33778 but goes a little further. 33778 took a conservative approach and only used the (Unity inspired) libappindicator3 if libappindicator1 was not present. However, several distributions now exist that cannot use libappindicator1 but do work with libappindicator3. Not usually a problem as libappindicator1 is not installed automatically if it not usable. But an OS that has been upgraded from, say U18.04 to U19.04 will have both versions of the appindicator library. LCL will choose the older one and it will not display the System Tray Icon.

Patch https://bugs.freepascal.org/view.php?id=35723 fixes that. Users of Lazarus 2.0.2 or earlier (and fixes until and if patch is accepted) might like to apply that patch themselves.

Gnome 3.28 and later won't display Icon

The Gnome Developers have determined that Gnome should not support the System Tray Icon model at all, apparently to avoid screen clutter. If your end users are willing to risk a little screen clutter to achieve a usable desktop, keep reading.

Distributions such as RedHat and openSUSE will not, out of the box, display the LCL System Tray Icon. Sadly, it fails silently, giving a user no indication of whats happening. Fortunatly, there are a number of Gnome Extensions that can restore normal operation but be aware that each new release of Gnome appears (and maybe only 'appears') to take steps to stop even those extension from working. At the time of writing this, June 2019, a model that does work for Fedora 30 and openSUSE 15 is to install the Gnome Extension TopIcons-plus and a version 3 appindicator library. Note, both steps are required, doing one or the other alone will not be enough !

To install a Gnome Extension, you have to install, into (eg) Firefox an extension that allows you to control your collection of Gnome Extensions. Awkard process but OK if you want to play with the wide range of extensions available. An alternative approach that works at present is to download the extension from github and install it, maybe not a good long term suggestion (?) -

As root -

dnf install make libappindicator-gtk3 gnome-tweak-tool

As yourself -

git clone https://github.com/phocean/TopIcons-plus.git
cd TopIcons-plus
make install

Logout and back in again.

gnome-tweaks

In the app thats runs, click Extensions, turn TopIcons-plus ON and click close

Note that for OpenSUSE the appindicator library is called libappindicator3-1, its likely other distributions may call it the same thing. Distributions based on Ubuntu will have it installed already.

Issue On the Mac, OSX

In October, 2017 it was noted that on the Mac, Sierra, Carbon, Lazarus 1.8rc4 a small problem existed. Attempts to updates to the caption of a menu item in a popup menu associated with a TrayIcon do not happen as expected. Its not uncommon to want to update the menu text at run time, for example, to display a list of recently opened files. This problem has been logged, https://bugs.freepascal.org/view.php?id=32516 . A workaround that appears reliable is to call TrayIcon1.InternalUpdate; after making changes to the captions.

This problem does not exist on Linux, Windows or OSX using Cocoa Widget Set.

Note that TrayIcon on the Mac, Carbon (ie 32bit) has a memory leak.

Documentation

Below is a list of all methods, properties and events of the component. They have the same names and work the same way on the visual component and on the non-visual object.

A function works on all target platforms unless written otherwise.

Methods

Show

procedure Show;

Shows the icon on the system tray.

Hide

procedure Hide;

Removes the icon from the system tray.

GetPosition

function GetPosition: TPoint;

Returns the position of the tray icon on the display. This function is utilized to show message boxes near the icon. Currently it´s only a stub, no implementations are available and TPoint(0, 0) is returned.

Properties

Hint

property Hint: string;

A Hint will be shown the string isn't empty

PopUpMenu

property PopUpMenu: TPopUpMenu;

A PopUp menu that appears when the user right-clicks the tray icon.

Events

OnPaint

property OnPaint: TNotifyEvent;

Use this to implement custom drawing to the icon. Draw using the canvas property of the icon.

Note-icon.png

Note: Does not work on win32.

OnClick

property OnClick: TNotifyEvent;

OnDblClick

property OnDblClick: TNotifyEvent;

OnMouseDown

property OnMouseDown: TMouseEvent;


OnMouseUp

property OnMouseUp: TMouseEvent;

OnMouseMove

property OnMouseMove: TMouseMoveEvent;

Authors

Note-icon.png

Note: Windows: Ozz Nixon

License

Modified LGPL.

Download

Status: Stable

Can be located at Lazarus 0.9.22 or inferior at the directory: lazarus/components/trayicon

And on Lazarus 0.9.23 or superior it is automatically installed with LCL

Example 1 - Using TIcon

As of Lazarus 0.9.26 TIcon has been fully implemented and it is no longer necessary to load the icon from a resource file on Windows. The icon can be loaded in the IDE or with usual code.

Go to the Additional tab of components, and add a TTrayIcon to your form. Then change it's Name property to SystrayIcon

Next add a button to the form. Double click the button and add this code to it:

procedure MyForm.Button1Click(Sender: TObject);
begin
  SystrayIcon.Icon.LoadFromFile('/path_to_icon/icon.ico');
  SystrayIcon.ShowHint := True;
  SystrayIcon.Hint := 'my tool tip';

  SystrayIcon.PopUpMenu := MyPopUpMenu;

  SystrayIcon.Show;
end;

Example 2 - Creating the icon with TLazIntfImage

You can use TLazIntfImage to draw quickly your icon, as in the example code below:

procedure TForm1.DrawIcon;
var
  TempIntfImg: TLazIntfImage;
  ImgHandle, ImgMaskHandle: HBitmap;
  px, py: Integer;
  TempBitmap: TBitmap;
begin
  try
    TempIntfImg := TLazIntfImage.Create(16, 16);
    TempBitmap := TBitmap.Create;
    TempBitmap.Width := 16;
    TempBitmap.Height := 16;
    TempIntfImg.LoadFromBitmap(TempBitmap.Handle, TempBitmap.MaskHandle);

    // Set the pixels red
    for py := 0 to TempIntfImg.Height - 1 do
      for px := 0 to TempIntfImg.Width - 1 do
        TempIntfImg.Colors[px, py] := colRed;

    // Copy it to a TBitmap
    TempIntfImg.CreateBitmaps(ImgHandle,ImgMaskHandle, False);
    TempBitmap.Handle := ImgHandle;
    TempBitmap.MaskHandle := ImgMaskHandle;

    // And copy the TBitmap to your Icon
    SystrayIcon.Icon.Assign(TempBitmap);
    SystrayIcon.Show;
 
  finally
    TempIntfImg.Free;
    TempBitmap.Free;
  end;
end;

Subversion

Located under components/trayicon/ on the latest subversion Lazarus.

Help, Bug Reporting and Feature Request

Please, post Bug Reports and Feature Requests on the Lazarus Bugtracker.

Help requests can be posted on the Lazarus mailling list or on the Lazarus Forum.

Change Log

  1. 17/01/2006 - Available as a preview on the Lazarus subversion. Still under heavy construction, however.
  2. 24/01/2006 - Stable under win32, gnome and gtk1, but still waiting for gtk2 support. Lazarus 0.9.12 was release with this version.
  3. 17/02/2006 - Added support for gtk2 on subversion.
  4. July 2008 - Implments support for Qt 4
  5. July 2008 - Implements support for Carbon through PasCocoa

Technical Details

A difficulty on the development of this component was the many differences on the system tray implementation on various OSes and even Window Managers on Linux. To solve this, the component tries to implement the minimal set of features common to all target platforms. Below is a list of the features implemented on each platform:

Windows - Multiple system tray icons per application are supported. The image of the icon can be altered using a HICON handle. Events to the icon are sent via a special message on the user reserved space of messages (>= WM_USER) to the Window which owns the Icon. No paint events are sent to the Window.

Note-icon.png

Note: for some odd reason the environment by default does not support WM_USER+ messages, you will need to add "-dPassWin32MessagesToLCL" (without quotations) to support the messaging code. The steps are, click Tools -> Configure "Build Lazarus"..., and add that compiler option to "Options". If you have any existing options, they are "space" delimited.

Linux (Gnome, KDE, IceWM, etc) - Multiple system tray icons per application are supported. The image of the icon is actually a very small Window, and can be painted and receive events just like any other TForm descendant.

Linux (WindowMaker, Openbox, etc) - Does not support system tray icons out-of-the-box. However, There are at least two softwares that provides support for it: Docker and WMSystray

Mac OS X - TTrayIcon support is implemented using the menu bar extras. Unfortunatelly the API to use menu bar extras is only available in Cocoa and not in Carbon, so we use the stable PasCocoa bindings in the Carbon interface to support menu bar extras even in older FPC compilers and in the Cocoa interface we will use the more modern Objective Pascal syntax.

Mn menubaritems.jpg

To read more about menu bar extras:

  1. http://developer.apple.com/documentation/UserExperience/Conceptual/OSXHIGuidelines/XHIGMenus/chapter_16_section_6.html
  2. http://developer.apple.com/mac/library/documentation/UserExperience/Conceptual/AppleHIGuidelines/XHIGMenus/XHIGMenus.html
  3. http://en.wikipedia.org/wiki/Menu_extra

With this in mind an approach which supports all Platforms was created:

  • Painting is done via a TIcon object. (Required by Windows)

The following extra features are already available or will be, but they won´t work on all platforms.

  • OnPaint event and Canvas property to draw the icon freely. Won´t work on Windows.


External Links