How to resize proportionally an image in canvas form
lazarus / 39-Graphics

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Christian_uy · 2013-06-23 16:54

Hello evrebody
I have this code take from the tutorial nº 2

procedure TForm1.FormPaint(Sender: TObject);
var stretched: TBGRABitmap;
begin
    stretched := image.Resample(ClientWidth, ClientHeight) as
TBGRABitmap;
    stretched.Draw(Canvas,0,0,True);
    stretched.Free;

    //image.Draw(Canvas,0,0,True);
end;

but loose proportions.
I don't care if image does not cover the entire form in both width and
length directions.
¿ Anyone know if there is a property similar to the property Stretch
in the TImage class or a method that can do that ?
Thanks Christian.

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exdatis · 2013-06-23 18:13

See:
http://forum.lazarus.freepascal.org/index.php/topic,20709.msg120369.ht
ml#msg120369
Regards
p.s. set: original_with * rescaleVal, original_height * rescaleVal
(e.g rescaleValue = 1.2 //20%)

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exdatis · 2013-06-23 18:28

You can find in examples, this procedure(very useful):
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procedure TForm1.RescaleImage(newScale: Double);
var
  OrgWidth, OrgHeight: integer;
  Rect: TRect;
begin
  OrgWidth := Image1.Picture.Bitmap.Width;
  OrgHeight := Image1.Picture.Bitmap.Height;
  FImageScale := FImageScale * NewScale; //FImageScale-> private 1.0
on start(original)
  Rect := Image1.BoundsRect;
  Rect.Right := Rect.Left + Round(OrgWidth * FImageScale);
  Rect.Bottom := Rect.Top + Round(OrgHeight * FImageScale);
  Image1.Align := AlNone;
  Image1.BoundsRect := Rect;
  Image1.Stretch:= true;   //strech
end;

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Christian_uy · 2013-06-25 03:12

Thanks for the fast reply Exdatis!. I'll be trying this as soon as
possible.