前两天的画线不能改变颜色问题。好几天没人能解决。再拿出来碰碰运气。

Question

procedure TForm1.Button3Click(Sender: TObject);
var hdcMem:hdc;
hPen,hOldPen,BitMap,bmpMemOld:dword;
begin
hdcMem:=CreateCompatibleDC(self.Canvas.Handle);
BitMap:=CreateCompatibleBitmap(hdcMem,100,200);
bmpMemOld:=SelectObject(hdcMem,Bitmap);
hPen:=CreatePen(PS_SOLID, 1, RGB(255, 222, 0));
hOldPen:=SelectObject(hdcMem, hPen);
windows.Rectangle(hdcMem,1,1,100,50);//Memframe);
LineTo(hdcMem,100,10);
LineTo(hdcMem,10,10);
SelectObject(hdcMem, hOldPen);
Bitblt(self.Canvas.Handle,1,1,100,100,hdcMem,0,0,SRCCOPY);
end;

Answer 1

BitMap:=CreateCompatibleBitmap(self.Canvas.Handle ,100,200);

Answer 2

procedure TForm1.Button1Click(Sender: TObject);
var hdcMem:hdc;
hPen,hOldPen,BitMap,bmpMemOld:dword;
begin
  hdcMem:=CreateCompatibleDC(self.Canvas.Handle);
  BitMap:=CreateCompatibleBitmap(self.Canvas.Handle ,100,200);
  bmpMemOld:=SelectObject(hdcMem,Bitmap);
  hPen:=CreatePen(PS_SOLID, 1, RGB(255, 0, 0));
  hOldPen:=SelectObject(hdcMem , hPen);
  windows.Rectangle(hdcMem,1,1,100,50);//Memframe);
  LineTo(hdcMem,100,10);
  LineTo(hdcMem,10,10);
  SelectObject(BitMap, hOldPen);
  Bitblt(self.Canvas.Handle,1,1,100,100,hdcMem,0,0,SRCCOPY);
end;