Clipboard
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Predefined types
TPredefinedClipboardFormat | MIME type |
---|---|
pcfText | text/plain |
pcfBitmap | image/bmp |
pcfPixmap | image/xpm |
pcfIcon | image/lcl.icon |
pcfPicture | image/lcl.picture |
pcfObject | application/lcl.object |
pcfComponent | application/lcl.component |
pcfCustomData | application/lcl.customdata |
pcfDelphiText | text/plain |
pcfDelphiBitmap | text/delphi.bitmap |
pcfDelphiPicture | Delphi picture |
pcfDelphiMetaFilePict | image/delphimetafilepict |
pcfDelphiObject | application/delphi.object |
pcfDelphiComponent | Delphi component |
pcfKylixPicture | image/delphi.picture |
pcfKylixBitmap | image/delphi.bitmap |
pcfKylixDrawing | image/delphi.drawing |
pcfKylixComponent | application/delphi.component |
Text
For use of simple text Clipboard offer property AsText which can be used for reading an writing plain text.
Writing text:
Clipboard.AsText := 'Hello clipboard!';
Reading text:
ShowMessage('Clipboard content: ' + Clipboard.AsText);
Clipboard is a TClipboard variable and the Clipbrd unit should be added in the uses clause in order to use the variable:
uses
..., Clipbrd;
Text oriented components
Some visual components like TEdit, TMemo, TStringGrid, TLabeledEdit, TMaskEdit, TSpinEdit and TFloatSpinEdit have ability to select a part of contained text and offer additional functionality for handling clipboard operations on selected text.
procedure CopyToClipboard;
procedure CutToClipboard;
procedure PasteFromClipboard;
HTML source
The ClipBoard supports reading and writing of HTML.
Example of reading from and writing HTML source to clipboard:
uses
Clipbrd, ...;
var
Html, PlainText: String;
...
begin
Html := ClipBoard.GetAsHtml;
...
Html := '<b>Formatted</b> text';
PlainText := 'Simple Text';
ClipBoard.SetAsHtml(Html, PlainText);
end.
Windows
Handling Html content on the clipboard in Windows requires fidling with headers on Windows.
While in the past users had to do this manually, this now is handled transparently by the ClipBrd unit.
Image
Load from clipboard
uses
Clipbrd, LCLIntf, LCLType, ...;
procedure LoadBitmapFromClipboard(Bitmap: TBitmap);
begin
if Clipboard.HasFormat(PredefinedClipboardFormat(pcfDelphiBitmap)) then
Bitmap.LoadFromClipboardFormat(PredefinedClipboardFormat(pcfDelphiBitmap));
if Clipboard.HasFormat(PredefinedClipboardFormat(pcfBitmap)) then
Bitmap.LoadFromClipboardFormat(PredefinedClipboardFormat(pcfBitmap));
end;
Save to clipboard
uses
Clipbrd, ...;
procedure SaveBitmapToClipboard(Bitmap: TBitmap);
begin
Clipboard.Assign(Bitmap);
end;
Custom format
Multiple objects
Getting notified of changes
The LCL does not pass on Windows messages. It only passes on messages > WM_USER. This means you have to write your own message handler. Processing non - user messages in your window
Sample code to implement message handler:
unit Unit1;
{$mode delphi}{$H+}
interface
uses
Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs,
Clipbrd, StdCtrls, Windows, Messages;
type
TForm1 = class(TForm)
Button1: TButton;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
private
FNextClipboardOwner: HWnd; // handle to the next viewer
// Here are the clipboard event handlers
function WMChangeCBChain(wParam: WParam; lParam: LParam):LRESULT;
function WMDrawClipboard(wParam: WParam; lParam: LParam):LRESULT;
public
end;
var
Form1: TForm1;
implementation
{$R *.lfm}
var
PrevWndProc:windows.WNDPROC;
function WndCallback(Ahwnd: HWND; uMsg: UINT; wParam: WParam;
lParam: LParam): LRESULT; stdcall;
begin
if uMsg = WM_CHANGECBCHAIN then begin
Result := Form1.WMChangeCBChain(wParam, lParam);
Exit;
end
else if uMsg=WM_DRAWCLIPBOARD then begin
Result := Form1.WMDrawClipboard(wParam, lParam);
Exit;
end;
Result := CallWindowProc(PrevWndProc, Ahwnd, uMsg, WParam, LParam);
end;
{ TForm1 }
procedure TForm1.FormCreate(Sender: TObject);
begin
PrevWndProc := Windows.WNDPROC(SetWindowLong(Self.Handle, GWL_WNDPROC, PtrInt(@WndCallback)));
FNextClipboardOwner := SetClipboardViewer(Self.Handle);
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
ChangeClipboardChain(Handle, FNextClipboardOwner);
end;
function TForm1.WMChangeCBChain(wParam: WParam; lParam: LParam): LRESULT;
var
Remove, Next: THandle;
begin
Remove := WParam;
Next := LParam;
if FNextClipboardOwner = Remove then FNextClipboardOwner := Next
else if FNextClipboardOwner <> 0 then
SendMessage(FNextClipboardOwner, WM_ChangeCBChain, Remove, Next)
end;
function TForm1.WMDrawClipboard(wParam: WParam; lParam: LParam): LRESULT;
begin
if Clipboard.HasFormat(CF_TEXT) Then Begin
ShowMessage(Clipboard.AsText);
end;
SendMessage(FNextClipboardOwner, WM_DRAWCLIPBOARD, 0, 0); // VERY IMPORTANT
Result := 0;
end;
end.
How to fix empty GTK2 clipboard on exit
Usually when your GTK2 app exits, it's clipboard becomes empty. Bad for usual user. This unit is a dirty fix, add it to "uses" somewhere.
unit fix_gtk_clipboard;
{$mode objfpc}{$H+}
interface
uses
gtk2, gdk2, Clipbrd;
implementation
var
c: PGtkClipboard;
t: string;
finalization
c := gtk_clipboard_get(GDK_SELECTION_CLIPBOARD);
t := Clipboard.AsText;
gtk_clipboard_set_text(c, PChar(t), Length(t));
gtk_clipboard_store(c);
end.