Display part of image
lazarus / 39-Graphics

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gyts · 2011-03-20 16:31

Is it possible to load bigger (f.e. 300x300) picture into smaller
(f.e. 200x200) TImage and to order which part of picture should be
loaded into. Maybe it's possible with other TObjects?

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Marc · 2011-03-21 10:01

You can load to picture ina TBitmap (or other graphic type) ad use a
TPaintBox to draw the part of the picture yourself in an OnPaint event



PS. I split and moved your post, please don't hijack other thread to
post unrelated messages

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gyts · 2011-03-25 17:53

Can you give me an example?

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typo · 2011-03-25 18:27

Code: [Select]procedure TForm1.PaintBox1Paint(Sender: TObject);
 var
   r :TRect;
 begin
   r.Top := 0;
   r.Left := 0;
   r.Right := PaintBox1.Width;
   r.Bottom := PaintBox1.Height;
   PaintBox1.Canvas.CopyRect(r, Image1.Picture.Bitmap.Canvas, r);
 end;

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gyts · 2011-03-25 18:46

Is it possible to rotate picture?

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typo · 2011-03-25 18:55

There are some algorithms.

http://www.delphi-central.com/tutorials/RotateBitmapBitBlt.aspx

http://delphi.about.com/cs/adptips2001/a/bltip1201_4.htm

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gyts · 2011-03-26 11:55

Quote from: typo on March 25, 2011, 07:55:32
pmhttp://delphi.about.com/cs/adptips2001/a/bltip1201_4.htm

Identifier not found "TRGBTriple". What unit i should include?

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marcov · 2011-03-26 12:13

Quote from: typo on March 25, 2011, 07:55:32 pmThere are some
algorithms.

http://www.delphi-central.com/tutorials/RotateBitmapBitBlt.aspx

http://delphi.about.com/cs/adptips2001/a/bltip1201_4.htm

If you only need 90 or 270 degrees: (lot faster, think 1-4ms/MByte on
modern hardware)

http://stackoverflow.com/questions/848025/rotating-bitmaps-in-code

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gyts · 2011-03-28 10:04

http://www.delphiarea.com/products/delphi-components/rotateimage/. Is
it possible to add it in Lazarus?

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marcov · 2011-03-28 15:33

Quote from: gyts on March 28, 2011, 12:04:05
pmhttp://www.delphiarea.com/products/delphi-components/rotateimage/.
Is it possible to add it in Lazarus?

That code looks very windowsspecific, but worse, it doesn't seem to
have a compatible license.

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VTwin · 2011-03-28 20:52

I just posted rotate 90 code here:

http://lazarus.firmos.at/index.php/topic,8282.0.html

Cheers,
Frederick

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VTwin · 2011-03-28 21:04

This works:

Code: [Select]var
  fPicture: TPicture;
  fImage: TImage;

procedure CopyRect(imgX, imgY, imgWidth, imgHeight,
                              picX, picY, picWidth, picHeight:
integer);
{
  Copies a retangular portion of fPicture to fImage.
}
var
  bmp: TBitmap;
begin
  bmp := TBitmap.Create;
  bmp.Width := picWidth;
  bmp.Height := picHeight;
  // get the portion of source (fPicture) to be displayed
  bmp.Canvas.CopyRect(Rect(0, 0, picWidth, picHeight),
    fPicture.Bitmap.Canvas, Rect(picX, picY, picX+picWidth,
picY+picHeight));
  // set destination to visible area of fImage
  fImage.Picture.Bitmap.SetSize(fImage.Width, fImage.Height);
  // do the copy
  fImage.Picture.Bitmap.Canvas.StretchDraw(
    Rect(imgX, imgY, imgX+imgWidth, imgY+imgHeight), bmp);
  bmp.Free;
end;      
Cheers,
Frederick