Simple editing image
lazarus / 39-Graphics

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xinyiman · 2012-07-20 13:16

Hello guys, how can I extract a portion of the image contained within
a TPicture? In order to save it then as I want it cut?!

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KpjComp · 2012-07-20 14:02

Something like this should do. 

Code: [Select]procedure TForm1.Button1Click(Sender: TObject);
var
  b:TBitmap;
begin
  //lets copy a 100 by 100 pixels, at offset 100,100 from a TImage
  b := TBitmap.Create;
  try
    b.Width := 100;
    b.height := 100;
    b.canvas.draw(-100,-100,image1.Picture.Graphic);
    b.SaveToFile('d:\temp.bmp');
  finally
    b.free;
  end;
end;

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xinyiman · 2012-07-21 16:00

Thanks, it works. But now I need to know one more thing. I imported
the image I have set the TImage object with Proportional:=TRUE and I
centered the image. How do I know the proportions of the image you
just loaded (which is smaller than the image file). thanks

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KpjComp · 2012-07-23 09:46

QuoteHow do I know the proportions of the image

Well the proportions of the image are always the same whatever the
size, if Proportional is set.

I assume you mean what are the dimensions on the image on screen?
If so there is a protected method called DestRect, to get at the
protected method we can use a Cracker Class.  Here is an example ->

Code: [Select]type
  TCustomImageCrack = class(TCustomImage)
  end;

{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
var
  dr:TRect;
begin
  dr := TCustomImageCrack(image1).destrect;
  showmessage(format('Width=%d, Height=%d',[dr.Right-
dr.left,dr.Bottom-dr.top]));
end;