[webkit-help] Issue with porting webkit to javascript

Trevor Linton trevor.linton at gmail.com
Sun May 11 21:34:02 PDT 2014


I’ve been in the process of porting webkit (just webcore) to javascript with emscripten.  I have the code compiling and successfully running with cairo, freetype2, egl/opengles v2/sdl as font/rendering backends.  In addition accelerated compositing and a host of other platform features as needed for the use. 

The issue i’m running into has to do with transparency, gradients and any rgba color values where the alpha is anything other than 1.  If I use any CSS/HTML inputs that need gradients or alpha > 0 including drop shadows they will not render.  I’ve traced that the values are successfully getting to the GraphicsContext and down into cairo.  This happens regardless if i’m using a hardware accelerated path or software only. 

I’m curious if there’s any suggestions or tips that may help track down this issue as i’m pretty stumped as to what the issue is.  My best guess is the cairo/egl context isn’t setup correctly and calls to cairo that require compositing with an alpha value blend are not being honored. 

Tips? Suggestions?  You can view the code here:


- Trevor

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