TBGRABitmap Resize Image help
lazarus / 39-Graphics

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JasonLugg · 2018-02-24 21:07

Hi All

Thanks in advance!

I am coding an image placement editor and want the option to click on
a sprite {TBGRABitmap) and resize with the mouse ( as is used in most
image editors where there is a focus rectangle with mouse adjustable
corners - Can draw and detect this no issues  ).

I have used the resample option but this creates a VERY blurred image
which is not acceptable. I then saw the TBGRABitmap.Canvas.Stretchdraw
which may be useful but I cannot work out
a) could I use this?
b) how to use this
   b1) Do I create a new 'resized' TBGRABitmap and stretchdraw onto it
<HOW?>

I want the expanded image to be as clear as possible.

Any other ideas VERY welcome!

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lainz · 2018-02-24 22:49

If the source image is of bad quality when you resize it to a bigger
one of course it will be blured, doesn't matter if you use BGRABitmap
or Photoshop.

When downsizing, you must choose the right filter when using the
Resize method, to keep a good quality.

I can suggest you to keep the original image in memory and then use
resample in a new copy using a good filter

See list of filters here:
http://wiki.lazarus.freepascal.org/BGRABitmap_Miscellaneous_types#Imag
es_and_resampling

And using BGRABitmap.Canvas is discouraged (by the author of
bgrabitmap), since it is slow.

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circular · 2018-02-25 08:58

If you're stretching images on the fly and want to use no filtering,
you can use StretchPutImage function.