Core Text a bit smaller than NSString drawInRect:?
Asked Answered
F

1

10

In theory, these should be the same size, but they're not:

The text in blue is from Core Text, in black is from -[NSString drawInRect:]. Here is the code:

//Some formatting to get the correct frame
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);


    //Draw in rect method
    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];



    //Frame change to suit CoreText
    CGRect rect2 = CGRectMake(MESSAGE_FRAME.origin.x + 8, self.bounds.size.height - y - height, MESSAGE_FRAME.size.width - 16, height);

    //Core text method
    CTFontRef fontRef = CTFontCreateWithName((CFStringRef)@"Crimson", 15.0f, NULL);

    NSDictionary *attDictionary = [NSDictionary dictionaryWithObjectsAndKeys:
                                   (__bridge_transfer id)fontRef, (NSString *)kCTFontAttributeName,
                                   (id)[[UIColor blueColor] CGColor], (NSString *)kCTForegroundColorAttributeName,
                                   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);

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

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

The font is the same. I don't understand why one is being rendered differently.

Feldstein answered 14/5, 2012 at 16:44 Comment(3)
That looks like different line spacings, not size.Torse
#10067889Straitjacket
You're right, it is. How do i get it to be the same line spacing?Feldstein
P
4

It’s because NSLayoutManager uses some unusual heuristics to cope with certain fonts.

See How does line spacing work in Core Text? (and why is it different from NSLayoutManager?) for more detail.

Pegpega answered 17/5, 2012 at 13:14 Comment(0)

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