一个用UpdateLayeredWindow实现窗体半透明的delphi的代码

http://www.pudn.com/downloads171/sourcecode/windows/detail791686.html

unit Unit1;

interface

uses

Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

Dialogs, gdipapi, gdipobj, Menus, StdCtrls;

type

TForm1 = class(TForm)

PopupMenu1: TPopupMenu;

ChangeSkin1: TMenuItem;

N1: TMenuItem;

Close1: TMenuItem;

Button1: TButton;

procedure FormCreate(Sender: TObject);

procedure FormDestroy(Sender: TObject);

procedure ShowPNGForm1(PNGFile:string; nTran: integer);

procedure ShowPNGForm2(PNGFile:string; nTran: integer);

procedure FormMouseDown(Sender: TObject; Button: TMouseButton;

Shift: TShiftState; X, Y: Integer);

procedure Close1Click(Sender: TObject);

procedure ChangeSkin1Click(Sender: TObject);

procedure Button1Click(Sender: TObject);

private

{ Private declarations }

public

{ Public declarations }

end;

const

WS_EX_LAYERED = $80000;

LWA_COLORKEY = 1;

LWA_ALPHA = 2;

ULW_COLORKEY = 1;

ULW_ALPHA = 2;

ULW_OPAQUE = 4;

var

Form1: TForm1;

bmp, old_bmp : HBITMAP;

DC : HDC;

bitmap: tgpbitmap;

j:integer;

Function UpdateLayeredWindow(hWnd : HWND;

hdcDst : HDC; pptDst : PPoint; psize : PSize;

hdcSrc : HDC; pptSrc : PPoint;

crKey : COLORREF;

pblend : PBlendFunction;

dwFlags : DWORD): BOOL; stdcall;

implementation

{$R *.dfm}

Function UpdateLayeredWindow; external 'user32.dll';

procedure Tform1.ShowPNGForm1(PNGFile:string; nTran: integer);

var

graphics : TGPGraphics;

Image: TGPImage;

begin

graphics := TGPGraphics.Create(DC);

Image:= TGPImage.Create(PNGFile);

graphics.DrawImage(image, 0, 0);

//UpdateLayeredWindow(Handle, Canvas.Handle, @pt1, @sz, DC, @pt2,0, @bf,ULW_ALPHA);

end;

procedure Tform1.ShowPNGForm2(PNGFile:string; nTran: integer);

var

pt1, pt2 : TPoint;

sz : TSize;

bf : TBlendFunction;

begin

bitmap:=tgpbitmap.Create(PNGFile);

pt1 := Point(left,top); //窗口做上角的坐标

pt2 := Point(0, 0); //这个就不用说了，一看见（0，0）就应该明白了

sz.cx := bitmap.GetWidth; //尺寸不要超过图像大小，不然窗口就什么都没有了，连个影子都没有

sz.cy := bitmap.GetHeight; //同上

bf.BlendOp := AC_SRC_OVER; //这些死记就行了

bf.BlendFlags := 0; //同上

if (nTran<0) or (nTran>255) then nTran:=255;

bf.SourceConstantAlpha := nTran; //同上

bf.AlphaFormat := AC_SRC_ALPHA; //同上

DeleteObject(bmp); //前面就是在这里犯的错误，不然占用的内存会无限增大

bitmap.GetHBITMAP(0,bmp); // HBITMAP是windows标准位图格式，支持透明，这里是从tgpbitmap 转化成 HBITMAP

DeleteDC(DC);

DC := CreateCompatibleDC(Canvas.Handle); //API的含义我倒是明白，为什么写这句话我就不明白了，反正就是需要

old_bmp := SelectObject(DC, bmp); //同上

UpdateLayeredWindow(Handle, Canvas.Handle, @pt1, @sz, DC, @pt2,0, @bf,ULW_ALPHA);

end;

procedure TForm1.FormCreate(Sender: TObject);

begin

if SetWindowLong(Handle, GWL_EXSTYLE, GetWindowLong(Handle, GWL_EXSTYLE) or WS_EX_LAYERED) = 0 then ShowMessage(SysErrorMessage(GetLastError));

ShowPNGForm2('test.png',255);

J:=1;

end;

procedure TForm1.FormDestroy(Sender: TObject);

begin

SelectObject(DC, old_bmp);

DeleteObject(bmp);

DeleteDC(DC);

bitmap.Free;

end;

procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;

Shift: TShiftState; X, Y: Integer);

begin

if(Button = mbLeft) then

begin

ReleaseCapture();

Perform(WM_SYSCOMMAND, SC_MOVE or HTCAPTION, 0);

end;

end;

procedure TForm1.Close1Click(Sender: TObject);

begin

Close;

end;

procedure TForm1.ChangeSkin1Click(Sender: TObject);

var

dlgOpen: TOpenDialog;

begin

dlgOpen := TOpenDialog.Create(Self);

dlgOpen.Filter := 'PNG file(*.png)|*.png';

if(dlgOpen.Execute()) then

begin

ShowPNGForm2(dlgOpen.FileName,255);

end;

dlgOpen.Free;

end;

procedure TForm1.Button1Click(Sender: TObject);

begin

ShowMessage('aaa');

end;

end.

--------------------------------------------------

object Form1: TForm1

Left = 387

Top = 124

BorderStyle = bsNone

Caption = 'Form1'

ClientHeight = 165

ClientWidth = 260

Color = clBtnFace

Font.Charset = DEFAULT_CHARSET

Font.Color = clWindowText

Font.Height = -11

Font.Name = 'MS Sans Serif'

Font.Style = []

OldCreateOrder = False

PopupMenu = PopupMenu1

OnCreate = FormCreate

OnDestroy = FormDestroy

OnMouseDown = FormMouseDown

PixelsPerInch = 96

TextHeight = 13

object Button1: TButton

Left = 104

Top = 56

Width = 75

Height = 25

Caption = 'Button1'

TabOrder = 0

OnClick = Button1Click

end

object PopupMenu1: TPopupMenu

Left = 16

Top = 16

object ChangeSkin1: TMenuItem

Caption = 'ChangeSkin'

OnClick = ChangeSkin1Click

end

object N1: TMenuItem

Caption = '-'

end

object Close1: TMenuItem

Caption = 'Close'

OnClick = Close1Click

end

end

end

//背景穿透 （相当于锁定桌面）

procedure TForm1.N3Click(Sender: TObject);

begin

SetWindowLong(Self.Handle,

GWL_EXSTYLE,

GetWindowLong(Self.Handle,GWL_EXSTYLE) or WS_EX_TRANSPARENT);

Application.MessageBox('你已关闭不了程序了，请从任务管理器里关闭',

'提示',MB_OK or MB_ICONINFORMATION);

end;

http://www.cnblogs.com/-clq/archive/2012/08/22/2650705.html