HTML5-like Canvas API

It should be possible to procedurally render certain types of graphics, such as graphs, from QML. If possible, the API should be similar to the HTML5 Canvas API to help developers familiar with that migrate.

Some preliminary work has been done here:

http://qt.gitorious.org/qt-labs/qmlcanvas
http://bugreports.qt.nokia.com/browse/QTCOMPONENTS-143

Ideally this would be extended to:

• Implement the complete HTML5 context2d API (http://dev.w3.org/html5/canvas-api/canvas-2d-api.html, http://dev.w3.org/html5/2dcontext/)
• Support tiled rendering so that the element can be "infinitely large".
• Support threaded rendering for non-blocking drawing (offscreen canvas? http://lists.whatwg.org/pipermail/whatwg-whatwg.org/2010-February/025259.html)

Implementation Backlog

• Add new QSGCanvasItem class
  • Add thread rendering support to QSGCanvasItem
  • Add tiled rendering support to QSGCanvasItem
  • Add asynchronous image loading support to QSGCanvasItem
  • Add QSGContext2DNode for scengraph canvas node management
  • Add QSGContext2DTexture/QSGContext2DImageTexture/QSGContext2DFBOTexture/ canvas item texture management
  • Add QSGContext2DTile for tiled canvas painting

• Context2D API
  • QSGContext2D class for HTML5 context2d compatible API implementation
    • Add state management API (save, restore, reset) to QSGContext2D
    • Add transformation API (scale, rotate, translate, transform, shear) to QSGContext2D
    • Add stroke/fill style APIs (colors, gradients, patterns) to QSGContext2D
    • Add line style APIs (line width, cap, join. miterlimit) to QSGContext2D
    • Add shadow APIs(offsetX, offsetY, shadowColor, shadowBlur) to QSGContext2D
    • Add path APIs(rects, begin/close Path, moveTo, lineTo, arc/arcTo, quadratic/bezierCurveTo, fill/stroke/clip) to QSGContext2D
    • Add additional path APIs(ellipse, roundedrect, text path etc) to QSGContext2D
    • Add filter APIs(mirror, grayscale, threshold, mono, blur, invert, brightness, opaque, convolute, etc) to QSGContext2D
    • Add text APIs(font, strokeText, fillText, text measurement, text align/baseline) to QSGContext2D
    • Add drawimage APIs to QSGContext2D
    • Add pixel operation APIs (create/get/put image data, fast pixel access by V8 indexed array getter/setter) to QSGContext2D
  • Expose context2d APIs to V8 engine
  • Add QSGContext2DCommandBuffer for painting command streaming

• Documentations
• Demos&Examples
• Tests
  • Unit tests
  • Test on device
  • Performance tuning on device