[SOLVED] Image Transparency
lazarus / 39-Graphics

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JasonLugg · 2017-04-28 18:22

Hi All,

Not been here for ages but really could do with some help please.

I have a TImage on a form which the user draws to (like a pixel paint
program). Currently the 'background' of the TImage.Canvas is clBlack.

I wish to save this image with the clBlack (or any other colour) being
transparent so that when it is loaded into another app such as
paint.net, the 'background' is transparent.

I have tried saving it as a png and just get a totally transparent png
(no pixels shown)?

Any help to 'turn' an existing TImage.Canvas into a transparent png
would be very much appreciated.

Thanks in advance.

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RAW · 2017-04-28 19:33

You can use

BGRABitmap
or
Graphics32
or
VampyreImagingLib
or
fpGUI (AGG PAS)

to create semitransparent pics or draw semitransparent pixels...

I don't think Lazarus can do this out of the box, but I never really
tried this...

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Handoko · 2017-04-28 19:34

@JasonLugg:

I found these discussions may be useful to you:

http://forum.lazarus.freepascal.org/index.php/topic,13163.msg214640.ht
ml

http://forum.lazarus.freepascal.org/index.php/topic,2939.msg13502.html

http://forum.lazarus.freepascal.org/index.php/topic,8937.msg43394.html

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JasonLugg · 2017-04-29 08:49

Guys

Many many thanks. That is VERY helpful!

Problem solved.