怎样制作全透明的窗口
2000-08-01· -·逸仙时空
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.
