Platform/GFX/InternProjects

Intern Projects

Ideally, we'd like to have a set of intern projects from which prospective or new interns can pick and choose. These tasks should be relatively self-contained, challenging but not impossible, and well-defined.

Please link to bugs where appropriate.

Name	Description	Bugs	Mentor
Implement the rest of ICCv4 in qcms	Benoit Girard has a patch to significantly improve qcms's ICCv4 support, but even after his patches we don't fully support ICCv4. (CMYK support, for example, is entirely absent.)	TBD	BenWa/jrmuizel
Split imgIContainer into two interfaces	imgIContainer should be split into two separate interfaces, one for decoders and libpr0n itself to use, and one for external users who just want to draw or get information about the current image.	bug 503973	joe/bholley
Don't allocate memory for unused areas in animated GIF files when compositing	Huge GIF files can be mostly empty space, but we currently allocate the full size of these images when we're compositing the frames together and drawing them to screen. (Other browsers are smarter.) We should emulate other browsers, and only allocate the parts of the frame that need to change.	bug 289763	joe/bholley
Enable proper decode-on-draw on desktop	We have the ability to throw away an image when it hasn't been drawn for a while, but we currently don't to eliminate flicker on the currently-displayed tab. We can probably get better heuristics for this, but doing so will also probably involve making asynchronous decoding more responsive, either by tweaking the way we asynchronously decode or the amount of data we asynchronously decode. This will greatly reduce the amount of memory we use on image-heavy pages.	TBD	joe/bholley
Do YCbCr/YUV->RGB conversion of JPEGs on the GPU	When we're using hardware-accelerated layers, we can reduce the amount of work we need to do on the CPU by decoding JPEGs to YUV only, uploading those channels to the GPU, and then converting the YUV to RGB in a shader. Note: This is likely not a good project to start before we have a fully colour-managed pipeline or Emerald is complete.	TBD	joe/jrmuizel/mattwoodrow
Use ARB_robustness/ARB_robustness2 in our WebGL implementation where it's available	Currently, even if a graphics driver implements and exports the ARB_robustness extension to make it less likely for shaders to DoS a computer, we don't use it. We should.	bug 656824	bjacob
Use OpenGL for WebGL, instead of ANGLE, on "good enough" drivers	ANGLE lets us support drivers with poor OpenGL implementations by rendering to Direct3D 9, but using it incurs a performance penalty. We should define what drivers are good enough, which will necessarily include Direct3D/OpenGL texture interop, and measure how good performance is on these drivers with OpenGL vs using ANGLE.	TBD	bjacob/joe
Subpixel positioning of glyphs in the Cairo image surface	Currently we snap glyphs to pixel boundaries in the image surface, which is good for performance because we can rasterize glyphs only once (in glyph space) and then re-use those rasterized glyphs as a glyph cache. We should change this to rasterize glyphs at (for example) third-pixel boundaries, and then snap our glyph positions to these third-pixel boundaries.	TBD	jrmuizel
Write a new scanline rasterizer for Cairo	The current approach is fast and high quality, but complicated, and has problems with clipping invariance. We can probably serve our needs better with something simpler, lower quality, and hopefully very fast, like skia.	TBD	jrmuizel
Speed up gradient rendering in Cairo	Rendering gradients is slower than it should be, especially on ARM. The current performance needs to be measured and the current rendering methods worked out, then it needs to be sped up significantly. This can be through better rendering methods, parallelization (e.g. SIMD instruction use), or other methods.	TBD	jrmuizel
GPU SVG filters	SVG filters are currently implemented through software rendering on the CPU, even when Firefox is using hardware for its general 2D rendering (i.e., when using Direct2D). These should be reimplemented using HLSL shaders to avoid readback. The biggest challenges here will be allowing arbitrary chaining of filters, as well as making it possible to avoid reimplementation once we need to support OpenGL shaders too.	TBD	roc
GPU Clipping	Our current GPU layer clipping code requires the clip to be an axis-aligned rectangle, and in other cases we are allocating an intermediate surface and rendering to that (transformations), or handling the render in software (SVG). We should be able to handle this using the stencil buffer or similar.	TBD	mattwoodrow/roc
Store Images as textures	When we separate an image into it's own dedicated layer we have two copies of the data, one in system memory (owned by imglib) and one as a texture. We can teach imglib about this second copy and free the system memory one in some cases to save memory usage. This is particularly useful for mobile where image scaling is much cheaper on the GPU, but the memory cost of two copies will hurt. Note: This would also be a good stepping stone towards decoding JPEGs on the GPU.	bug 650988 for mobile's usage of this.	mattwoodrow/joe/roc