这是来宾 Dolby 在 http://www.cnblogs.com/del/archive/2008/03/08/1081295.html#1096814
询问的问题.
//声明: SetLayeredWindowAttributes( Hwnd: THandle; {窗口句柄} crKey: COLORREF; {透明色} bAlpha: Byte; {Alpha 值} dwFlags: DWORD {LWA_COLORKEY(=1)表示使用透明色; LWA_ALPHA(=2)表示使用 Alpha 值} ): Boolean; {是否成功设置}
//举例(控制外部程序的透明度, 用计算器举了个例子): unit Unit1; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls; type TForm1 = class(TForm) Button1: TButton; Button2: TButton; procedure Button1Click(Sender: TObject); procedure Button2Click(Sender: TObject); end; var Form1: TForm1; implementation {$R *.dfm} {设定计算器的 Alpha 透明} procedure TForm1.Button1Click(Sender: TObject); var h: HWND; FormStyle: Integer; begin h := FindWindow('SciCalc', nil); FormStyle := GetWindowLong(h, GWL_EXSTYLE); SetWindowLong(h, GWL_EXSTYLE, FormStyle or WS_EX_LAYERED); SetLayeredWindowAttributes(h, 0, 128, LWA_ALPHA); end; {设定计算器中的白色透明} procedure TForm1.Button2Click(Sender: TObject); var h: HWND; FormStyle: Integer; begin h := FindWindow('SciCalc', nil); FormStyle := GetWindowLong(h, GWL_EXSTYLE); SetWindowLong(h, GWL_EXSTYLE, FormStyle or WS_EX_LAYERED); SetLayeredWindowAttributes(h, clWhite, 255, LWA_COLORKEY); end; end.