UILabel’s font property accepts UIFonts – but strange enough there’s no way to get a custom loaded CGFont (from a ttf or otf file) converted into such an UIFont. You’re stuck with the iPhone’s pre-installed fonts – at least when you have to support iOS 3.0 devices.
After googling a bit and searching Stackoverflow I found the solutions presented there not ideal or great, but too heavy weight.
So I inherited UILabel with a very lean custom class UILabelWithCGFont and overloaded it’s drawTextInRect: method like this:
1-(void)drawTextInRect:(CGRect)rect
2{
3 MRLogD(@"(%f,%f) (%f,%f)", rect.origin.x, rect.origin.y, rect.size.width, rect.size.height);
4 if ( _CGFont == NULL ) {
5 [super drawTextInRect:rect];
6 return;
7 }
8 NSAssert(_mapping != NULL, @"Mapping function pointer not set.");
9
10 // prepare the target graphics context.
11 const CGContextRef ctx = UIGraphicsGetCurrentContext();
12 CGContextSaveGState(ctx);
13 {
14 // prepare the glyphs array to draw
15 const NSString *txt = self.text;
16 const size_t glyphCount = txt.length;
17 CGGlyph glyphs[glyphCount];
18 {
19 // turn the string txt into glyphs (indices into the font):
20 // give non-allocating unicode character retrieval a try:
21 const UniChar *raw_unichars = CFStringGetCharactersPtr( (CFStringRef)txt );
22 const UniChar *unichars = raw_unichars == NULL ? malloc( glyphCount * sizeof(UniChar) ) : raw_unichars;
23 NSAssert(unichars != NULL, @"unichars not allocated");
24 if ( raw_unichars == NULL )
25 CFStringGetCharacters( (CFStringRef)txt, CFRangeMake(0, txt.length), (UniChar *)unichars );
26 for ( int i = glyphCount - 1; i >= 0; i-- )
27 glyphs[i] = _mapping(unichars[i]);
28 if ( raw_unichars == NULL )
29 free( (void *)unichars );
30 }
31
32 CGContextSetFont(ctx, _CGFont);
33 CGContextSetFontSize(ctx, self.font.pointSize);
34 CGContextSetTextMatrix( ctx, CGAffineTransformMake(1.0, 0.0, 0.0, -1.0, 0.0, 0.0) );
35
36 // first print 'invisible' to measure size:
37 CGContextSetTextDrawingMode(ctx, kCGTextInvisible);
38 const CGPoint pre = CGContextGetTextPosition(ctx);
39 CGContextShowGlyphs(ctx, glyphs, glyphCount);
40 const CGPoint post = CGContextGetTextPosition(ctx);
41 // restore text position
42 CGContextSetTextPosition(ctx, pre.x, pre.y);
43
44 // centered horizontal + vertical:
45 NSAssert( (int)rect.origin.x == 0, @"origin.x not zero" );
46 NSAssert( (int)rect.origin.y == 0, @"origin.y not zero" );
47 NSAssert(self.baselineAdjustment == UIBaselineAdjustmentAlignCenters, @"vertical alignment not 'center'");
48 NSAssert(self.textAlignment == UITextAlignmentCenter, @"horizontal alignment not 'center'");
49 const CGPoint p = CGPointMake( ( rect.size.width - (post.x - pre.x) ) / 2, (rect.size.height + self.font.pointSize + pre.y) / 2 );
50
51 // finally render it to the graphics context:
52 CGContextSetTextDrawingMode(ctx, kCGTextFill);
53 CGContextSetFillColorWithColor(ctx, self.textColor.CGColor);
54 CGContextShowGlyphsAtPoint(ctx, p.x, p.y, glyphs, glyphCount);
55 }
56 CGContextRestoreGState(ctx);
57}Usage: Just turn the UILabel instances in Interface Builder into UILabelWithCGFont and implement the UIViewController::viewDidLoad method like this:
1CGGlyph unicode2glyphDeutscheDruckschrift(UniChar c)
2{
3 if ( '0' < = c && c <= '9' )
4 return c + (16 - '0');
5 if ( 'A' <= c && c <= 'Z' )
6 return c + (32 - 'A');
7 if ( 'a' <= c && c <= 'z' )
8 return c + (58 - 'a');
9 return 0;
10}
11
12-(void)viewDidLoad
13{
14 [super viewDidLoad];
15 ...
16 [fontLabel setFontFromFile:@"DeutscheDruckschrift" ofType:@"ttf" mapping:unicode2glyphDeutscheDruckschrift];
17 ...
18}See this github gist for the complete implementation.
The mapping from Unicode character codes to glyph indices (inside the font description) currently is done via a C mapping function you have to provide a function pointer for. A later implementation could map the unicode character code to the glyph name and leverage CGFontGetGlyphWithGlyphName and render the custom mapping function obsolete.