－－-===制作全透明的窗口===－－-

　　我不知道全透明的窗口有什么用，但毕竟作为一种技巧，还是拿出来说说吧。下面这个例子演示如何显示透明的窗口.同时也介绍了如何捕获屏幕.必须把Form1的BorderStyle属性置为bsNone

　　C++ Builder

　　请参照Delphi的例子

　
Delphi

unit homepage_coolform;interfaceuses

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

ExtCtrls, StdCtrls, Buttons;

type TForm1 = class(TForm)

procedure FormPaint(Sender: TObject);

procedure FormShow(Sender: TObject);

procedure FormDestroy(Sender: TObject);

private { Private declarations }

public { Public declarations }

hbmp:integer;

end;

var Form1: TForm1;

implementation

{$R *.DFM}

function CopyScreenToBitmap(Rect:TREct):integer;

var

hScrDC, hMemDC, hBitmap, hOldBitmap:integer;

nX, nY, nX2, nY2: integer;

nWidth, nHeight:integer;

xScrn, yScrn:integer;

begin

if (IsRectEmpty(Rect)) then

begin

result:= 0;

exit;

end; // 获得屏幕缓冲区的句柄.

// a memory DC compatible to screen DC

hScrDC:= CreateDC('DISPLAY', pchar(0), pchar(0), PDeviceModeA(0));

hMemDC:= CreateCompatibleDC(hScrDC);

// get points of rectangle to grab

nX := rect.left;

nY := rect.top;

nX2 := rect.right;

nY2 := rect.bottom;

// get screen resolution

xScrn:= GetDeviceCaps(hScrDC, HORZRES);

yScrn := GetDeviceCaps(hScrDC, VERTRES);

//make sure bitmap rectangle is visible

if (nX <0) then

nX :="0;"

if (nY < 0) then

nY :="0;"

if (nX2> xScrn) then

nX2 := xScrn;

if (nY2 > yScrn) then

nY2 := yScrn;

nWidth := nX2 - nX;

nHeight := nY2 - nY;

// create a bitmap compatible with the screen DC

hBitmap := CreateCompatibleBitmap(hScrDC, nWidth, nHeight);

// select new bitmap into memory DC

hOldBitmap := SelectObject(hMemDC, hBitmap);

// bitblt screen DC to memory DC

BitBlt(hMemDC, 0, 0, nWidth, nHeight, hScrDC, nX, nY, SRCCOPY);

// select old bitmap back into memory DC and get handle to

// bitmap of the screen

hBitmap := SelectObject(hMemDC, hOldBitmap);

// clean up

DeleteDC(hScrDC);

DeleteDC(hMemDC);

result:= hBitmap;

end;

procedure TForm1.FormShow(Sender: TObject);

Var

rect:TRect;

p:TPoint;

begin

rect:=ClientRect;

p:=ClientOrigin;

rect.left:=p.x;

rect.top:=p.y;

rect.bottom:=rect.bottom+p.y;

rect.right:=rect.right+p.x;

hbmp:=copyScreenToBitmap(rect);

inherited;

end;

procedure TForm1.FormPaint(Sender: TObject);

var

bitmap:TBitmap;

rect:TRect;

begin

bitmap:=TBitmap.create;

bitmap.handle:=hbmp;

rect:=ClientRect;

canvas.draw(rect.left,rect.top,bitmap);

bitmap.handle:=0;

bitmap.free;

end;

procedure TForm1.FormDestroy(Sender: TObject);

begin

DeleteObject(hbmp);

end;

end.