Old method of getting glyph advance

glyph_advance.m

CGFloat getGlyphAdvanceForFont(NSString *ch, NSFont *font) {
    // Handle tab character width, because it's not correct to get it with
    // CTRunGetAdvances().
    if ([ch isEqualToString:@"\t"]) {
        // NOTE: (TAB) This clause will never reach because when a \t is entered,
        // We convert it into a '   '.
        // But I will leave this code her for alternative method to
        // get glyph width
        CGRect rect;
        CGFontRef cgFont = CTFontCopyGraphicsFont((CTFontRef)font, nil);
        CGGlyph g = CGFontGetGlyphWithGlyphName(cgFont, (CFStringRef)@"\t");
        CGFontGetGlyphBBoxes(cgFont, &g, 1, &rect);

        CGFloat hAdvance = rect.size.width / CGFontGetUnitsPerEm(cgFont) * font.pointSize;
        NSLog(@"*(TAB) width:%f", hAdvance);
        return hAdvance;
    }
    
    NSMutableAttributedString *s = [[NSMutableAttributedString alloc] initWithString:ch];
    [s addAttribute:NSFontAttributeName value:font range:NSMakeRange(0, 1)];
    [s addAttribute:NSForegroundColorAttributeName value:[NSColor blackColor] range:NSMakeRange(0, 1)];

    CFAttributedStringRef attrStr = (__bridge CFAttributedStringRef)(s);
    CTLineRef line = CTLineCreateWithAttributedString(attrStr);
    CFArrayRef runs = CTLineGetGlyphRuns(line);
    CTRunRef firstRun = CFArrayGetValueAtIndex(runs, 0);
    CGSize size;
    CTRunGetAdvances(firstRun, CFRangeMake(0, 1), &size);
    CFRelease(line);
    return size.width;
}

NSRect getGlyphBoundingBox(NSString *ch, NSFont *font, CGAffineTransform tm) {
    CGFloat glyphWidth = getGlyphAdvanceForFont(ch, font);
    NSMutableAttributedString *s = [[NSMutableAttributedString alloc]
                                    initWithString:ch];
    [s addAttribute:NSFontAttributeName value:font range:NSMakeRange(0, [ch length])];
    [s addAttribute:NSForegroundColorAttributeName value:[NSColor blackColor]
              range:NSMakeRange(0, [ch length])];
    CFAttributedStringRef attrStr = (__bridge CFAttributedStringRef)(s);
    CTLineRef line = CTLineCreateWithAttributedString(attrStr);
    CGFloat ascent, descent, leading;
    CTLineGetTypographicBounds(line, &ascent, &descent, &leading);
    CGRect textRect = NSMakeRect(0, 0 - descent, glyphWidth, descent + ascent);
    CGRect r = CGRectApplyAffineTransform(textRect, tm);
    CFRelease(line);
    return r;
}

NSRect getGlyphBoundingBoxGlyphSpace(NSString *ch, NSFont *font) {
    CGFloat glyphWidth = getGlyphAdvanceForFont(ch, font);
    NSMutableAttributedString *s = [[NSMutableAttributedString alloc]
                                    initWithString:ch];
    [s addAttribute:NSFontAttributeName value:font range:NSMakeRange(0, [ch length])];
    [s addAttribute:NSForegroundColorAttributeName value:[NSColor blackColor]
              range:NSMakeRange(0, [ch length])];
    CFAttributedStringRef attrStr = (__bridge CFAttributedStringRef)(s);
    CTLineRef line = CTLineCreateWithAttributedString(attrStr);
    CGFloat ascent, descent, leading;
    CTLineGetTypographicBounds(line, &ascent, &descent, &leading);
    CGRect textRect = NSMakeRect(0, 0 - descent, glyphWidth, descent + ascent);
    CFRelease(line);
    return textRect;
}