Delphi API 之 BitBlt

var
  bit1,bit2: TBitmap;
  cvs1,cvs2,cvs3: TCanvas;
procedure TForm1.FormCreate(Sender: TObject);
begin
   with ListBox1.Items do
  begin
    Add(‘SRCCOPY    ‘);
    Add(‘SRCPAINT   ‘);
    Add(‘SRCAND     ‘);
    Add(‘SRCINVERT  ‘);
    Add(‘SRCERASE   ‘);
    Add(‘NOTSRCCOPY ‘);
    Add(‘NOTSRCERASE‘);
    Add(‘MERGECOPY  ‘);
    Add(‘MERGEPAINT ‘);
    Add(‘PATCOPY    ‘);
    Add(‘PATPAINT   ‘);
    Add(‘PATINVERT  ‘);
    Add(‘DSTINVERT  ‘);
    Add(‘BLACKNESS  ‘);
    Add(‘WHITENESS  ‘);
end;
   Panel1.Caption := ‘‘;
  Panel2.Caption := ‘‘;
  Panel3.Caption := ‘‘;

  bit1 := TBitmap.Create;
  bit1.Width := Panel1.ClientWidth;
  bit1.Height := Panel1.ClientHeight;

  bit2 := TBitmap.Create;
  bit2.Width := Panel2.ClientWidth;
  bit2.Height := Panel2.ClientHeight;


  cvs1 := TCanvas.Create;
  cvs2 := TCanvas.Create;
  cvs3 := TCanvas.Create;

  cvs1.Handle := GetDC(Panel1.Handle);
  cvs2.Handle := GetDC(Panel2.Handle);
  cvs3.Handle := GetDC(Panel3.Handle);
end;


procedure TForm1.FormPaint(Sender: TObject);
const
  ColorArr: array[0..5] of TColor = (clRed, clGreen, clBlue, clYellow, clFuchsia, clPurple);
var
  wi,hi: Integer;
  I: Integer;
begin
  wi := bit1.Width div 4;
  hi := bit1.Height div 4;

  bit1.Canvas.Pen.Width := 10;

  for I := 1 to 3 do
  begin
    bit1.Canvas.Pen.Color := ColorArr[i-1];
    bit1.Canvas.MoveTo(wi*i, 0);
    bit1.Canvas.LineTo(wi*i, bit1.Height);

    bit1.Canvas.Pen.Color := ColorArr[i+2];
    bit1.Canvas.MoveTo(0, hi*i);
    bit1.Canvas.LineTo(bit1.Width, hi*i);
  end;

  bit2.Canvas.Pen.Width := 15;
  bit2.Canvas.Ellipse(15, 15, bit2.Width-15, bit2.Height-15);

  cvs1.Draw(0, 0, bit1);
  cvs2.Draw(0, 0, bit2);
end;

procedure TForm1.ListBox1Click(Sender: TObject);
var
  Rop: Cardinal;
begin
  Repaint;
  Rop := SRCCOPY;
  case ListBox1.ItemIndex of
    0 : Rop := SRCCOPY    ;
    1 : Rop := SRCPAINT   ;
    2 : Rop := SRCAND     ;
    3 : Rop := SRCINVERT  ;
    4 : Rop := SRCERASE   ;
    5 : Rop := NOTSRCCOPY ;
    6 : Rop := NOTSRCERASE;
    7 : Rop := MERGECOPY  ;
    8 : Rop := MERGEPAINT ;
    9 : Rop := PATCOPY    ;
    10: Rop := PATPAINT   ;
    11: Rop := PATINVERT  ;
    12: Rop := DSTINVERT  ;
    13: Rop := BLACKNESS  ;
    14: Rop := WHITENESS  ;
  end;

  cvs3.Draw(0, 0, bit1);
  BitBlt(cvs3.Handle, (bit1.Width - bit2.Width) div 2, (bit1.Height - bit2.Height) div 2,
    bit2.Width, bit2.Height, bit2.Canvas.Handle, 0, 0, Rop);
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
 bit1.Free;
  bit2.Free;
  cvs1.Free;
  cvs2.Free;
  cvs3.Free;
end;

end.