Re: [GD-DEVEL] re: Blending images with alpha (patches inside)

On Sunday 19 August 2007 20:34, patrick keshishian wrote:
> 
> What I was trying to accomplish with my patch was to provide for
> a method by which the user/programmer could change the level of
> opacity of a source image at run-time.

If I understood correctly, your watermark image is transparent
everywhere except for the watermark itself.  In this case can you
not use the function
   gdImageCopyMerge(..., pct)
where pct is the multiplier for the alpha channel value of the
watermark itself?

	Ethan



> 
> Something like this Perl code snippet:
> 
>     my $iw = GD::Image->new('circ.png'); # Watermark image
>     my $is = GD::Image->new('test_in.jpg');
>     # ... Set up vars
>     # Blend the watermark at 100%, 65%, 35% and 10% opacities.
>     $is->blend($iw, $dx, $dy, $sx, $sy, $sw, $sh, 100);
>     $is->blend($iw, $dx + $sw, $dy, $sx, $sy, $sw, $sh, 65);
>     $is->blend($iw, $dx, $dy + $sh, $sx, $sy, $sw, $sh, 35);
>     $is->blend($iw, $dx + $sw, $dy + $sh, $sx, $sy, $sw, $sh, 10);
>     # ... Write resulting image.
> 
> 
> This will blend the watermark image onto the the test_in.jpg
> four times, in four quadrants at four different opacity levels.
> 
> Here is the result from the code:
> 
> 	http://sidster.org/code/gd/gd_blend_test.jpg
> 
> Best,
> --patrick
> 

-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle 98195-7742