Hmm. I would have thought there where hardware/windows support functions you could use to blit transparency... This shouldn't be complicated, since the means to do it is available already in most OSes. Mind you, the feature *is* limited, at least in one application I use, which has it, to Windows 2000 and higher, and may have the same issue (requiring DirectX) as the new sound feature.
Also, note, if you add png, you need to be careful you are using, and using correctly, the official libraries for them. A lot of applications get this wrong and end up screwing up transparency support, or otherwise introducing annoyances in how it works (including nearly 100% of them which completely mangle Gamma correction, when that data is stored in the file). In general, you can tell if the later is working by how it adjusts the colors. Bad implementations tend to.. well, get it wrong.. This usually means that if you had an image with red, green, blue and yellow, where, well, its hard to describe, but the test file is constructed so you have four outer boxes, and four inner boxes, and on a gamma that "works right", the 5 inner boxes are "corrected" down to 50% color. On wrong implementations, it corrects all the middle boxes, but also the outer yellow, so that, instead of having 8 colors, you have 7. Most of these buggy versions are not fixed in **anything**, when/if gamma is supported at all. :(
Same glitch happens in gray too:
http://entropymine.com/jason/testbed/alphagamma/
Firefox 3.0 gets this wrong, and its usually better than most of the applications out there are getting it right.
Frankly, as sad as it is, your probably better off ignoring the gamma feature in libpng, since no one seems to "ever" make it work right. Well, except for a few graphics applications, and, at one point, even Photoshop screwed it up. |
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