This patch switches to instance methods of draw and display for
ASTextNode and ASImageNode to attempt to increase their performance.
It also fixes some thread safety issues in ASImageNode which appear
to have been regressions (though probably not hit very often).
And it sets up work for allowing modification of CGContexts before
and after a node's contents are drawn.
Currently, subnodes of nodes marked with shouldRasterizeSubnodes do not get layout calls. This adds the call to layout and changes the __layout method to reference self.bounds instead of _layer.bounds.
Also adds support for corner radius when rasterizing subnodes.
ASDISPLAYNODE_DELAY_DISPLAY unconditionally delays *all* attempts to
execute display blocks, even those that have been cancelled. Fix that.
The DELAY_DISPLAY debugging tool is intended to simulate the effect of
expensive draw calls -- it lets you test your app's behaviour under
conditions potentially even worse than an iPhone 4. Unfortunately, the
current simulation is unusably incorrect, as can be demonstrated by
repeatedly scrolling up and down in the Kittens example project.
ASRangeController enqueues asynchronous display of ASTableView cell
nodes when they enter the working range, and suspends their display when
they exit. On a slow device, this performs as desired, limiting
expensive display computation to the space of the working range. In
the DELAY_DISPLAY simulation, the suspended displays are as expensive as
the executed ones, so ASRangeController becomes unusably slow.
* Reorganise and rename `_flags` for clarity and consistency.
* Remove ambiguity between `implementsDisplay` and `hasClassDisplay`.
* Delete useless `hasWillDisplayAsyncLayer` check -- make it a simple
subclass override point, as with `didDisplayAsyncLayer:`.
* Minor comment cleanup.
Fixes:
- Usage of UIScreen in -[ASDisplayNode init]
(the offending individual will be prosecuted)
- #38: Proper teardown of nodes owned by ASTableView / ASRangeController
- #34: Fix infinite recursion in very rare subclassing scenario
- #30: Avoid animating cell and section additions to ASTableView
- #19: Set a more reasonable default for maximum display concurrency
r=nadi
