Hi, webkit developers, I have recently faced a problem with support for translucent (i)frames in our (java) port, and tried to find how other ports (gtk, win, mac) deal with the same issue. The test is short (launch the test and try to scroll inner frames):
<html> <body> <div style="opacity:0.5;position:absolute;left:150;top:150"> <iframe src="http://java.sun.com/javase/6/docs/api"; width="600" height="450"></iframe> </div> <div style="opacity:0.2;position:absolute;left:250;top:250"> <iframe src="http://java.sun.com/javase/6/docs/api"; width="600" height="450"></iframe> </div> </body> </html> I was very surprised when found no webkit ports displayed the page correctly! I tried Safari 3.1 on Mac and Win and GTK Launcher on Linux (haven't looked at Safari 4.0, though). The only browser which 'passed' the test was Firefox: all the frames were displayed correctly and scrolled smoothly. It seems that both mac/win and gtk ports use some caches for rendered pages, however some bugs exist in the implementations. In Java port we have two different approaches for rendering: one is fast, but without any support of translucent (i)frames, another is correct (even with the test above), but slow. The second one is a kind of experimental, and what I want to do is to speed it up (by using some rendering cache) and make it default. The next two days I spent trying to implement the correct rendering cache. The idea is simple: render all the frames separately from each other to different offscreen images, and composite them to get a final image on the screen. However, I failed with this task :( The first part is simple: to render the frame contents I call Frame::paint(gc, rect) and skip all subsequent Widget::paint(gc, rect) calls. That's fine. The second part - compositing - is somewhat I couldn't implement. The problem is there is no way (or I don't know this way) for a given Frame to render all its child frames without rendering the frame itself. In other words, I have to render some part of the frame twice: first, all the dirty regions into the cache, and second, all the frame to get children painted correctly. Any ideas? Thanks, Artem _______________________________________________ webkit-dev mailing list [email protected] http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
