我正在尝试使用各种技术获取MacOS X / iOS中角色的边界框。我现在正在展示我的所有尝试。到目前为止，如果我想获得像“Ä”这样的变音符号的大小，代码就会失败。
CTFontGetBoundingRectsForGlyphs -(void) resizeLayer1:(CATextLayer *)l toString:(NSString *)string
{
// need to set CGFont explicitly to convert font property to a CGFontRef
CGFontRef layerFont = CGFontCreateWithFontName((CFStringRef)@"Helvetica");
l.font = layerFont;
string = l.string;
NSUInteger len = [string length];
// get characters from NSString
UniChar *characters = (UniChar *)malloc(sizeof(UniChar)*len);
CFStringGetCharacters((__bridge CFStringRef)l.string, CFRangeMake(0, [l.string length]), characters);
// Get CTFontRef from CGFontRef
CTFontRef coreTextFont = CTFontCreateWithGraphicsFont(layerFont, l.fontSize, NULL, NULL);
// allocate glyphs and bounding box arrays for holding the result
// assuming that each character is only one glyph, which is wrong
CGGlyph *glyphs = (CGGlyph *)malloc(sizeof(CGGlyph)*len);
CTFontGetGlyphsForCharacters(coreTextFont, characters, glyphs, len);
// get bounding boxes for glyphs
CGRect *bb = (CGRect *)malloc(sizeof(CGRect)*len);
CTFontGetBoundingRectsForGlyphs(coreTextFont, kCTFontDefaultOrientation, glyphs, bb, len);
CFRelease(coreTextFont);
l.position = CGPointMake(200.f, 100.f);
l.bounds = bb[0];
l.backgroundColor = CGColorCreateGenericRGB(0.f, .5f, .9f, 1.f);
free(characters);
free(glyphs);
free(bb);
}
结果这种方式有效，但有一些填充正在进行，因为字形由CATextLayer呈现
CTFramesetterSuggestFrameSizeWithConstraints -(void) resizeLayer2:(CATextLayer *)l toString:(NSString *)string
{
// need to set CGFont explicitly to convert font property to a CGFontRef
CGFontRef layerFont = CGFontCreateWithFontName((CFStringRef)@"Helvetica");
l.font = layerFont;
string = l.string;
NSUInteger len = [string length];
// get characters from NSString
UniChar *characters = (UniChar *)malloc(sizeof(UniChar)*len);
CFStringGetCharacters((__bridge CFStringRef)l.string, CFRangeMake(0, [l.string length]), characters);
// Get CTFontRef from CGFontRef
CTFontRef coreTextFont = CTFontCreateWithGraphicsFont(layerFont, l.fontSize, NULL, NULL);
CFMutableAttributedStringRef attrStr = CFAttributedStringCreateMutable(kCFAllocatorDefault, 0);
CFAttributedStringReplaceString(attrStr, CFRangeMake(0, 0), (__bridge CFStringRef)string);
CTTextAlignment alignment = kCTJustifiedTextAlignment;
CTParagraphStyleSetting _settings[] = { {kCTParagraphStyleSpecifierAlignment, sizeof(alignment), &alignment} };
CTParagraphStyleRef paragraphStyle = CTParagraphStyleCreate(_settings, sizeof(_settings) / sizeof(_settings[0]));
CFAttributedStringSetAttribute(attrStr, CFRangeMake(0, CFAttributedStringGetLength(attrStr)), kCTParagraphStyleAttributeName, paragraphStyle);
CFAttributedStringSetAttribute(attrStr, CFRangeMake(0, CFAttributedStringGetLength(attrStr)), kCTFontAttributeName, coreTextFont);
CFRelease(paragraphStyle);
CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(attrStr);
CFRelease(attrStr);
CFRange range;
CGFloat maxWidth = CGFLOAT_MAX;
CGFloat maxHeight = 10000.f;
CGSize constraint = CGSizeMake(maxWidth, maxHeight);
// checking frame sizes
CGSize coreTextSize = CTFramesetterSuggestFrameSizeWithConstraints(framesetter, CFRangeMake(0, len), nil, constraint, &range);
// allocate glyphs and bounding box arrays for holding the result
// assuming that each character is only one glyph, which is wrong
CGGlyph *glyphs = (CGGlyph *)malloc(sizeof(CGGlyph)*len);
CTFontGetGlyphsForCharacters(coreTextFont, characters, glyphs, len);
// get bounding boxes for glyphs
CGRect *bb = (CGRect *)malloc(sizeof(CGRect)*len);
CTFontGetBoundingRectsForGlyphs(coreTextFont, kCTFontDefaultOrientation, glyphs, bb, len);
CFRelease(coreTextFont);
bb[0].origin = l.bounds.origin;
coreTextSize.width = ceilf(coreTextSize.width);
coreTextSize.height = ceilf(coreTextSize.height);
bb[0].size = coreTextSize;
l.position = CGPointMake(200.f, 100.f);
// after setting the bounds the layer gets transparent
l.bounds = bb[0];
l.opaque = YES;
return;
l.backgroundColor = CGColorCreateGenericRGB(0.f, .5f, .9f, 1.f);
free(characters);
free(glyphs);
free(bb);
}
结果字符串的边界框是正确的。变音符号会出现问题：Ä缺少点，因为边界框不够高。
CTLineGetTypographicBounds -(void) resizeLayer3:(CATextLayer *)l toString:(NSString *)string
{
// need to set CGFont explicitly to convert font property to a CGFontRef
CGFontRef layerFont = CGFontCreateWithFontName((CFStringRef)@"Helvetica");
l.font = layerFont;
string = l.string;
NSUInteger len = [string length];
// get characters from NSString
UniChar *characters = (UniChar *)malloc(sizeof(UniChar)*len);
CFStringGetCharacters((__bridge CFStringRef)l.string, CFRangeMake(0, [l.string length]), characters);
// Get CTFontRef from CGFontRef
CTFontRef coreTextFont = CTFontCreateWithGraphicsFont(layerFont, l.fontSize, NULL, NULL);
CFMutableAttributedStringRef attrStr = CFAttributedStringCreateMutable(kCFAllocatorDefault, 0);
CFAttributedStringReplaceString(attrStr, CFRangeMake(0, 0), (__bridge CFStringRef)string);
CFAttributedStringSetAttribute(attrStr, CFRangeMake(0, CFAttributedStringGetLength(attrStr)), kCTFontAttributeName, coreTextFont);
CTLineRef line = CTLineCreateWithAttributedString(attrStr);
CGFloat ascent;
CGFloat descent;
CGFloat width = CTLineGetTypographicBounds(line, &ascent, &descent, NULL);
CGFloat height = ascent+descent;
CGSize coreTextSize = CGSizeMake(width,height);
// get bounding boxes for glyphs
CGRect *bb = (CGRect *)malloc(sizeof(CGRect)*len);
CFRelease(coreTextFont);
bb[0].origin = CGPointZero;
coreTextSize.width = ceilf(coreTextSize.width);
coreTextSize.height = ceilf(coreTextSize.height);
bb[0].size = coreTextSize;
l.position = CGPointMake(200.f, 100.f);
// after setting the bounds the layer gets transparent
l.bounds = bb[0];
l.opaque = YES;
return;
l.backgroundColor = CGColorCreateGenericRGB(0.f, .5f, .9f, 1.f);
free(characters);
free(bb);
}
结果字符串的边界框是正确的。变音符号会出现问题：Ä缺少点，因为边界框不够高。
CTFontGetBoundingRectsForGlyphs -(void) resizeLayer4:(CATextLayer *)l toString:(NSString *)string
{
// need to set CGFont explicitly to convert font property to a CGFontRef
CGFontRef layerFont = CGFontCreateWithFontName((CFStringRef)@"Helvetica");
l.font = layerFont;
string = l.string;
NSUInteger len = [string length];
// get characters from NSString
UniChar *characters = (UniChar *)malloc(sizeof(UniChar)*len);
CFStringGetCharacters((__bridge CFStringRef)l.string, CFRangeMake(0, [l.string length]), characters);
// Get CTFontRef from CGFontRef
CTFontRef coreTextFont = CTFontCreateWithGraphicsFont(layerFont, l.fontSize, NULL, NULL);
// allocate glyphs and bounding box arrays for holding the result
// assuming that each character is only one glyph, which is wrong
CGGlyph *glyphs = (CGGlyph *)malloc(sizeof(CGGlyph)*len);
CTFontGetGlyphsForCharacters(coreTextFont, characters, glyphs, len);
CGPathRef glyphPath = CTFontCreatePathForGlyph(coreTextFont, glyphs[1], NULL);
CGRect rect = CGPathGetBoundingBox(glyphPath);
// get bounding boxes for glyphs
CGRect *bb = (CGRect *)malloc(sizeof(CGRect)*len);
CTFontGetBoundingRectsForGlyphs(coreTextFont, kCTFontDefaultOrientation, glyphs, bb, len);
CFRelease(coreTextFont);
l.position = CGPointMake(200.f, 100.f);
l.bounds = rect;
l.backgroundColor = CGColorCreateGenericRGB(0.f, .5f, .9f, 1.f);
free(characters);
free(glyphs);
free(bb);
}
结果字符串的边界框是正确的。由于变音符号本身是一个字形，而字符是另一个字形意味着Ä由两个字形组成，因此变音符号存在问题。怎么可以用呢？
我是否还有其他可能忽略并且值得尝试的可能性？
第三个选项CTLineGetTypographicBounds似乎有效。然而，我正在运行一个不同的问题，CATextLayer中的第一行缺少其变音符号。第一行不知何故不够高。这意味着我在这里咆哮错误的树。
答案 0 :(得分：4)
尝试CTLineGetImageBounds。但请注意，这将包括延伸到基线以下的字形部分，例如，与小写ä相关。
简要说明：圆形形状必须超出直线形状才能以相同的视觉重量显示。例如，请参见小写字母b或d，它们在基线处具有圆形和直线形状。
答案 1 :(得分：4)
在第一个例子中，你似乎忽略了这样一个事实，即字形的边界矩形很可能是负y的原点。返回的rect通常将y=0视为文本的基线。因此，您可以在bounds rect中设置偏移量，这也可能是图层在文本中具有偏移量的原因。 （没试过但是这么想）
如果您对特定文字的边界不感兴趣，但选择包含各种文字的高度，您可能还想选择CTFontGetBoundingBox。