re: ImageAntialias

Hello, > Not sure if this is best suited for the devel list or the user list, but > here goes.: > > Antialiasing is a basic requirement for generating professional-quality > pictures. Unfortunately the php-gd function imageantialias needs work. > Only a small subset of drawing primitives currently make use of > antialiasing. Yes, only a small set, the lines, ellipse and circles are coming. They were ready but not synced with the current GD. > See http://www.php.net/manual/en/function.imageantialias.php > > To quote, "This function is currently not documented; only the argument > list is available." So there is no documented expected behaviour for > imageantialias. The only hint of what it can and can't do is in a > user-contributed comment on the same page (provided by Yours Truly). > Yet at least one bug report > http://bugs.php.net/bug.php?id=24798 has > been marked as 'bogus', although it is at worst is a reasonable feature > request if not a bug. Doc can be quicly fixed, "It works only with blending mode, no alpha channel is used." > Actually I propose a new method for antialiasing: > > bool imageantialias ( resource im, bool on, int MODE ) > > where MODE is one of: > > AA_TRADITIONAL - Perform antialiasing the same way it's done now - that > is to use a different antialiasing function for each primitive, most of > which haven't yet been implemented. It is the only possible way right now. The support for the other primitives are coming (ellipse, circle soon), the problem is a bit more complex that you may think. Having the good compromise between speed and quality is not that easy. Keeping in mind that php is a web language and not a Adobe Illustrator (c) concurrent, with all the constraints brought by the web environment (server). > AA_SCALE - Draw the image to an internal buffer at 2x the requested > size, using regular non-antialiased primitives, and downscale the result > to the requested size with bilinear filtering. This produces nice > antialiased images with very little duplication of code across > primitives. Line thickness may need to be doubled to give the right effect. This is horribly slow and ugly. I'm strongly opposed to implement such thing in ext/gd. > AA_TEXT - Draw/downsample the image as above, but omit text objects > until after the image has been downsampled. This allows for clearer but > non-antialiased text. I fail to see the usage for that, can you bring some basic examples? Or are you talking about layers? Regards, --Pierre