On Mon, Jan 3, 2011 at 1:47 PM, Wim Lewis <w...@omnigroup.com> wrote: > > On 2 Jan 2011, at 1:23 PM, George Nachman wrote: >> I'm using CGContextShowGlyphsWithAdvances to render fixed-width text >> because it is very fast. If a glyph is missing, I use >> CTFontCreateForString() to pick a better font, and that usually works. >> I ran into a case that I just can't solve with this technique [...] > > Do you need layout+rendering to be fast, or just rendering? If the latter, > for example if you're drawing a fixed string multiple times, you could use a > higher level routine to do the layout (e.g. CTTypesetterCreateLine() or > CTLineCreateWithAttributedString()) and then extract the glyphs, offsets, so > on from the typeset line to draw with CGContextShowGlyphsWithAdvances(). > > (Actually I'd be surprised if CGContextShowGlyphsWithAdvances() is much > faster than CTLineDraw() --- I'd guess that simply caching the typeset line > will get you most of the available speedup.)
It's rare that I have text that requires layout. 99% is plain old ASCII. It's not fixed text but I don't mind having a slower code path for more complex text. I tried using CTLineCreateWithAttributedString() and then rendering it with CTLineDraw() but it still fails to draw certain glyphs. For example, U+23B7: RADICAL SYMBOL BOTTOM appears as a box (the missing glyph symbol). It exists in the "Apple Symbols" font, but I guess it's just using the font I requested. If I use -[NSAttributedString drawInRect:], it can render the glyph, despite my specifying AndaleMono as the font. I wish I could do all my text drawing with -[NSAttributedString drawInRect:], but it is very slow. I tried using that call for only "problem" characters and CGContextShowGlyphsWithAdvances for "normal" characters, but I can't get the baselines to line up correctly (the attributed string draws a few pixels lower for some reason). If I could get the baselines to match up, this would be an ideal solution. Another smaller issue is that CTLineCreateWithAttributedString() + CTLineDraw() doesn't perform layout as nicely as -[NSAttributedString drawInRect:] in some edge cases. For instance, the sequence U+0061 U+20D1 (where the latter is COMBINING RIGHT HARPOON ABOVE) draws the diacritic through the top of the letter, while -[NSAttributedString drawInRect:] places it just above the letter. _______________________________________________ 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: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
