如何检测剪贴板文本更改

Question

当剪贴板文本发生更改时，我的应用程序如何接收通知？

例如：

我想启用/禁用粘贴按钮并设置其Hint属性，以便显示剪贴板的文本(如'Paste "%s"'(

unit Unit1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;
type
TMyPasteForm = class(TForm)
MyPasteButton: TButton;
MyEdit: TEdit;
procedure MyPasteButtonClick(Sender: TObject);
procedure FormCreate(Sender: TObject);
private
procedure SyncMyPasteButton();
{ Private declarations }
public
{ Public declarations }
end;
var
MyPasteForm: TMyPasteForm;
implementation
{$R *.dfm}
uses
Clipbrd;
procedure TMyPasteForm.FormCreate(Sender: TObject);
begin
MyPasteButton.ShowHint := True;
end;
procedure TMyPasteForm.MyPasteButtonClick(Sender: TObject);
begin
MyEdit.Text := Clipboard.AsText;
end;
procedure TMyPasteForm.SyncMyPasteButton();
begin
MyPasteButton.Enabled := Length(Clipboard.AsText) > 0;
MyPasteButton.Hint := Format('Paste "%s"', [Clipboard.AsText]);
end;
end.

Answer 1

我发现了一个有趣的PDF arcticle，并用"使用剪贴板侦听器API">文章部分：

unit Unit1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;
type
TMyPasteForm = class(TForm)
MyPasteButton: TButton;
MyEdit: TEdit;
procedure MyPasteButtonClick(Sender: TObject);
procedure FormCreate(Sender: TObject);
private
procedure SyncMyPasteButton();
procedure WMClipboardUpdate(var Msg : TMessage); message WM_CLIPBOARDUPDATE;
protected
procedure CreateWnd(); override;
procedure DestroyWnd(); override;
public
{ Public declarations }
end;
var
MyPasteForm: TMyPasteForm;
implementation
{$R *.dfm}
uses
Clipbrd;
procedure TMyPasteForm.FormCreate(Sender: TObject);
begin
MyPasteButton.ShowHint := True;
SyncMyPasteButton();
end;
procedure TMyPasteForm.CreateWnd();
begin
inherited;
//making sure OS notify this window when clipboard content changes
AddClipboardFormatListener(Handle);
end;
procedure TMyPasteForm.DestroyWnd();
begin
//remove the clipboard listener
RemoveClipboardFormatListener(Handle);
inherited;
end;
procedure TMyPasteForm.MyPasteButtonClick(Sender: TObject);
begin
MyEdit.Text := Clipboard.AsText;
end;
procedure TMyPasteForm.SyncMyPasteButton();
begin
MyPasteButton.Enabled := IsClipboardFormatAvailable(CF_TEXT);
if(MyPasteButton.Enabled) then
MyPasteButton.Hint := Format('Paste "%s"', [Clipboard.AsText])
else
MyPasteButton.Hint := '';
end;
procedure TMyPasteForm.WMClipboardUpdate(var Msg : TMessage);
begin
//the clipboard content is changed!
SyncMyPasteButton();
end;
end.

注意：

• 适用于WindowsVista及更高版本。

• 如果您需要支持WindowsXP及更早版本，则必须使用剪贴板查看器方法(请参阅前面提到的文章的"使用剪贴板查看器链">部分。另请参阅SetClipboardViewer((和监视剪贴板内容(