Question

Here’s the code I use to show some text in core graphics:

int y = MESSAGE_FRAME.origin.y + 8;

if (month) y = y + 27;
int height = [JHomeViewCellContentView heightOfMessage:self.entry.message];

CGRect rect = CGRectMake(MESSAGE_FRAME.origin.x + 8, y, MESSAGE_FRAME.size.width - 16, height);

UIFont *font = [UIFont fontWithName:@"Crimson" size:15.0f];

[[UIColor colorWithWhite:0.2 alpha:1.0] setFill];

[self.entry.message drawInRect:rect withFont:font lineBreakMode:UILineBreakModeWordWrap alignment:UITextAlignmentLeft];

And here’s the code if I want to show the same text in core text:

CGRect rect2 = CGRectMake(MESSAGE_FRAME.origin.x + 8, self.bounds.size.height - y - height + 2, MESSAGE_FRAME.size.width - 16, height);


    UIFont *font = [UIFont fontWithName:@"Crimson" size:15.0f];
    CGFloat lineHeight = [font lineHeight];

    CTFontRef fontRef = CTFontCreateWithName((CFStringRef)@"Crimson", 15.0f, NULL);

    CGFloat lineSpacing = 0;

    CTParagraphStyleSetting settings[] = {
        { kCTParagraphStyleSpecifierMinimumLineHeight, sizeof(lineHeight), &lineHeight },
        { kCTParagraphStyleSpecifierMaximumLineSpacing, sizeof(lineSpacing), &lineSpacing },

    };

    CTParagraphStyleRef paragraphStyle = CTParagraphStyleCreate(settings, sizeof(settings) / sizeof(settings[0]));

    NSMutableDictionary *attDictionary = [NSMutableDictionary dictionaryWithObjectsAndKeys:
                                   (__bridge_transfer id)fontRef, (NSString *)kCTFontAttributeName,
                                          (id)[[UIColor colorWithWhite:0.2 alpha:1.0] CGColor], (NSString *)kCTForegroundColorAttributeName,
                                          paragraphStyle, kCTParagraphStyleAttributeName,
                                          nil];

     NSAttributedString *attString = [[NSAttributedString alloc] initWithString:self.entry.message attributes:attDictionary];

    //Flip the coordinate system
    CGContextSetTextMatrix(context, CGAffineTransformIdentity);
    CGContextTranslateCTM(context, 0, self.bounds.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);



    CGMutablePathRef path = CGPathCreateMutable();
    CGPathAddRect(path, NULL, rect2);


    self.framesetter = CTFramesetterCreateWithAttributedString((__bridge_retained CFAttributedStringRef)attString);
    CTFrameRef theFrame = CTFramesetterCreateFrame(self.framesetter, CFRangeMake(0, [attString length]), path, NULL);

    CFRelease(path);

    CTFrameDraw(theFrame, context);
    CFRelease(theFrame);

Apparently, despite being more longwinded, core text is meant to be faster than core graphics, which is the reason I learnt how to do it. But running this code through in instruments, core graphics is achieving 5ms, while core text is doing it in 14ms. I feel like I am missing something here. drawInRect is almost 3 times faster, and I hear it should be slower. I’ve refined the code on the bottom as much as I know how to, but I am not an expert and I’d appreciate any help.

To clarify, I am drawing a block of text onto a view. That’s all I wish to do. And all the text has the same appearance.

Answer 1

I don’t use the CT stuff, but it looks to me like you’re setting up invariant font and other attributes on every draw. Try factoring out everything up to the comment “Flip the coordinate system, and cache the attString.

That should improve speed for a better head-to-head test.