On Thu, May 20, 2010 at 1:38 PM, David Hyatt <[email protected]> wrote:
> This is all coming back to me now. > > When two cells occupy the same position in the grid, only one of them gets > stored at that position. The current code puts the first cell encountered > into the grid. This means if you ask what cell is present in row 3 and > column 2 of the above example, you'll get back cell #5. > > This actually makes the grid unsuitable for hit testing and is why I hadn't > converted nodeAtPoint over to use the grid yet. > > The grid needs to be fixed so that it records all of the cells present at a > given position. If it did that, then you could binary search as long as > there are no overflowing cells, since you'd then be able to see all the > cells that actually occupy a given grid position. > > The paint method uses the grid and actually has a repaint bug, since if you > make the repaint rect tight enough, it won't think it has to paint the > second and subsequent cells that occupy a given grid position. > It sounds like your recommended steps are: * First fix the grid to record all the cells at a given position. This fixes a repaint bug. * Then change the hit-testing to work just like painting. This makes hit testing more efficient and ensures hit testing and painting agree. * Then optimize hit-testing to binary-search if there are no overflowing cells. (And optimize painting similarly? I dunno what that would mean, though--just going off the "optimize together" comment earlier.) Is this a good summary? PK
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