My iOS app enables the user to toggle on and off a square grid. When the grid is enabled, a tap inside a cell toggles the color of the cell between black and blue. When the grid is disabled, one can use a pinch-zoom gesture to adjust the sizes of the cells.
(I'm not so sure that's a sensible UI but that's not the problem I'm looking into just now.) If the pitch of the gride is fine, then there are many lines on the screen. If I autorotate, redrawing the vertical lines takes hundreds of times as long as redrawing the horizontal lines. That makes sense as one can draw a horizontal line by incrementing a pointer into the image buffer. To draw a vertical line one has to draw a pixel, then calculate the memory address of the next pixel vertically downwards. I wonder if there is a better way to do this? I'm using UIRectFill to draw 1.0 point thick rectangles. I thought of using CoreGraphics directly but Instruments tells me that all the time is spent way down in the innards of CG. Before I draw the grid, I erase the whole view to blue, then draw black rectangles for my cells. A small optimization is that if two or more cells are horizontal neighbors, I draw them in one UIRectFill operation. The vertical line drawing is so slow that it is disruptive to the user when autorotating - the whole UI freezes for as long as two seconds, looks distorted during that time then very quickly renders the desired appearance. One way would be to render a single vertical line into a tall, narrow offscreen image buffer then copy that buffer into multiple locations on the screen. Another way would be for me to render the entire view in an offscreen image buffer, which I expect I could do far more efficiently than by making many calls into UIRectFill or even CoreGraphics. I've done lots of direct memory pixel manipulations over the years, that wouldn't be a problem for me to implement but before I do, do you think it would be a good idea? -- Michael David Crawford, Consulting Software Engineer mdcrawf...@gmail.com http://www.warplife.com/mdc/ Available for Software Development in the Portland, Oregon Metropolitan Area. _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
