Lazarus

Programming => Graphics => Graphics and Multimedia => BGRABitmap and LazPaint => Topic started by: zxandris on December 21, 2024, 03:46:09 pm

Title: Drawing text with opacity - [Solved]
Post by: zxandris on December 21, 2024, 03:46:09 pm
This is probably a really simple question, but i can't find a way to do it, at least seting the alpha what have you.  In short I am writing text to a bgra bitmap, and I would like to write the text with opacity, in other words, slightly see through.  How would I do that please?

Thanks in advance,

CJ
Title: Re: Drawing text with opacity
Post by: lainz on December 21, 2024, 05:30:50 pm
Specify the color like this BGRA(255,255,255,100) where 100 is the opacity from 0 (fully transparent) to 255 (fully opaque).
Title: Re: Drawing text with opacity
Post by: zxandris on December 21, 2024, 05:50:08 pm
I am trying that, but it doesn't appear to be working, here's my code for setting the font stuff

Code: Pascal  [Select][+][-]
  1.         // Set the font options, need this for calculations
  2.         BgraOutput.Canvas.Font.Name := lbl.FontFace;
  3.         BgraOutput.Canvas.Font.Size := lbl.FontSize;
  4.         BgraOutput.Canvas.Font.color := ColorToBgra(lbl.FontColor, lbl.Alpha);
  5.         BgraOutput.FontHeight := lbl.FontSize;
  6.         BgraOutput.FontName := lbl.FontFace;
  7.         BgraOutput.FontStyle := [];
  8.         if lbl.Bold then BgraOutput.FontStyle := BgraOutput.FontStyle + [fsBold];
  9.         if lbl.Italic then BgraOutput.FontStyle := BgraOutput.FontStyle + [fsItalic];
  10.         if lbl.Underlined then BgraOutput.FontStyle := BgraOutput.FontStyle + [fsUnderline];
  11.  

And it doesn't appear to work.

I imagine this
Code: Pascal  [Select][+][-]
  1.  ColorToBgra(lbl.FontColor, lbl.Alpha);
  2.  

Is the problem, and I optionally render the text I'm writing with a renderer but not when I'm trying this out and the text doesn't appeaer to change the alpha at all which is stored in the record there,.

Quote from: lainz on December 21, 2024, 05:30:50 pm
Specify the color like this BGRA(255,255,255,100) where 100 is the opacity from 0 (fully transparent) to 255 (fully opaque).
Title: Re: Drawing text with opacity
Post by: lainz on December 21, 2024, 05:54:18 pm
Your code looks wrong...

Please follow the tutorial here:
https://wiki.freepascal.org/BGRABitmap_tutorial_12

And change for example BGRABlack with BGRA(0,0,0,100)
Title: Re: Drawing text with opacity
Post by: zxandris on December 21, 2024, 05:58:43 pm
Yeah I didn't actually set the color on TextOut, my bad,but thanks to that reminder I checked the relevant area of code and now it works!  sorry about that, that was me being blind and a little silly!

Code: Pascal  [Select][+][-]
  1.                
  2. BgraOutput.TextOut(intX, intY, strOutput, ColorToBgra(lbl.FontColor, lbl.Alpha));
  3.  

Was what I needed to change, thanks for all your help!

CJ

Quote from: lainz on December 21, 2024, 05:54:18 pm
Your code looks wrong...

Please follow the tutorial here:
https://wiki.freepascal.org/BGRABitmap_tutorial_12

And change for example BGRABlack with BGRA(0,0,0,100)
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