窗体图片背景（两种方法：设置Brush.Bitmap指向图片，别的控件也可以这样）

var
  Bitmap: TBitmap;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Bitmap := TBitmap.Create;
  Bitmap.LoadFromFile('c:\temp\bg.bmp');
  Self.Brush.Bitmap := Bitmap;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  Bitmap.Free;
end;

---

//效果图:

http://www.cnblogs.com/del/archive/2008/02/10/1066596.html

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WinAPI: CreatePatternBrush - 建立位图画刷
//声明:
CreatePatternBrush(
  Bitmap: HBITMAP {位图句柄}
): HBRUSH;        {返回画刷句柄}

---

//举例:
procedure TForm1.FormPaint(Sender: TObject);
var
  Bitmap: TBitmap;
  BrushHandle: HBRUSH;
begin
  Bitmap := TBitmap.Create;
  Bitmap.LoadFromFile('c:\temp\bg.bmp');
  BrushHandle := CreatePatternBrush(Bitmap.Handle);
  FillRect(Canvas.Handle, ClientRect, BrushHandle);
  DeleteObject(BrushHandle);
end;

---

//效果图: