On May 24, 2012, at 9:36 AM, Manfred Schwind wrote: >> CGContextShowTextAtPoint(contextRef, 0, 40, >> [textToDraw UTF8String], [textToDraw length]); > > One bug I see here: you're passing a wrong length parameter. > CGContextShowTextAtPoint expects the length of the char array (number of > bytes of the UTF-8 encoded string), but you'e passing the number of Unicode > characters in the string. That's not the same; one character may be > represented by multiple chars in UTF-8 encoding. > > E.g. use it this way: > > const char *myUTF8String = [textToDraw UTF8String]; > CGContextShowTextAtPoint(contextRef, 0, 40, > myUTF8String, strlen(myUTF8String)); >
Also, CGContextShowTextAtPoint is designed only to display text in MacRoman encoding (and a corresponding font that has MacRoman character data tables). If the string has anything other than ASCII text, the UTF8String won't be in MacRoman (and in general, MacRoman is a very small subset of what Unicode supports, so even if you got the string in MacRoman encoding, there is a very good chance it still won't draw correctly because somebody used a character outside of MacRoman). >From the docs: > If setting the font to a MacRoman text encoding is sufficient for your > application, use the CGContextSelectFont function. Then, when you are ready > to draw the text, you call the function CGContextShowTextAtPoint. The > function CGContextSelectFont takes as parameters a graphics context, the > PostScript name of the font to set, the size of the font (in user space > units), and a text encoding. > > To set the font to a text encoding other than MacRoman, you can use the > functions CGContextSetFont and CGContextSetFontSize. You must supply a CGFont > object to the function CGContextSetFont. You call the function > CGFontCreateWithPlatformFont to obtain a CGFont object from an ATS font. When > you are ready to draw the text, you use the function > CGContextShowGlyphsAtPoint rather thanCGContextShowTextAtPoint. > So for general case drawing, you'll need to generate glyphs from the text, which is an extremely complicated procedure to do without some sort of type-setter support (such as found in CoreText or (not available on iOS) NSTypesetter). Basically, CGContextShowTextAtPoint is designed to show simple debugging information and very limited/controlled strings, not a general purpose drawing routine. Just use NSString's drawAtPoint:withFont: and the like... Glenn Andreas gandr...@gandreas.com The most merciful thing in the world ... is the inability of the human mind to correlate all its contents - HPL _______________________________________________ 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
