delphi WinAPI: SetLayeredWindowAttributes

delphi WinAPI: SetLayeredWindowAttributes - 设置窗口的透明

//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.

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