How to use CopyRect method in Delphi

Question

I\'m loading an image from disk and want to copy (part of) it to a second TImage:

Image1.Picture.LoadFromFile(S);
with Image1.Picture.Bitmap do
  Image2.Ca         


        

Answer 1

TCanvas.CopyRect copies the rectangle by using StretchBlt. StretchBlt requires a bitmap. If you're loading any other graphic type to your image then its Picture.Bitmap is empty. In fact the bitmap gets created just when you refer to it: with Image1.Picture.Bitmap do.

You can use a temporary bitmap for the cause:

var
  Bmp: TBitmap;
begin
  Image1.Picture.LoadFromFile(S);

  Bmp := TBitmap.Create;
  try
    Bmp.Assign(Image1.Picture.Graphic);

    with Bmp do
      Image2.Canvas.CopyRect(Image2.Canvas.ClipRect, Canvas, Canvas.ClipRect);
  finally
    Bmp.Free;
  ..