CTRunGetImageBounds返回不准确的结果 [英] CTRunGetImageBounds returning inaccurate results
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问题描述
我正在使用Core Text绘制一些文字。我想获得各种运行边界,但是当我调用 CTRunGetImageBounds
时,返回的rect是正确的大小,但位置错误。具体来说,行原点位于整个文本的末尾。
I am using Core Text to draw some text. I would like to get the various run bounds, but when I call CTRunGetImageBounds
, the rect that is returned is the correct size, but in the wrong location. Specifically, the line origin is at the end of the text as a whole.
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
self.transform = CGAffineTransformMakeScale(1.0, -1.0);
CGContextSetTextMatrix(context, CGAffineTransformIdentity);
[[UIColor whiteColor] set];
CGContextFillRect(context, self.bounds);
NSMutableAttributedString* attrString = [[NSMutableAttributedString alloc] initWithString:@"Blue should be underlined."];
NSRange blueRange = NSMakeRange(0, 4);
[attrString beginEditing];
//make all text size 20.0
[attrString addAttribute:(NSString *)kCTFontAttributeName value:(id)CTFontCreateWithName((CFStringRef)@"Helvetica", 20.0, NULL) range:NSMakeRange(0, [attrString length])];
//make the text appear in blue
[attrString addAttribute:(NSString *)kCTForegroundColorAttributeName value:(id)[[UIColor blueColor] CGColor] range:blueRange];
//next make the text appear with an underline
[attrString addAttribute:(NSString *)kCTUnderlineStyleAttributeName value:[NSNumber numberWithInt:1] range:blueRange];
[attrString endEditing];
CGMutablePathRef path = CGPathCreateMutable();
CGRect bounds = CGRectMake(10.0, 10.0, 200.0, 200.0);
[[UIColor redColor] set];
CGContextFillRect(context, bounds);
CGPathAddRect(path, NULL, bounds);
CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attrString);
CTFrameRef frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, 0), path, NULL);
CTFrameDraw(frame, context);
for (id lineObj in (NSArray *)CTFrameGetLines(frame)) {
CTLineRef line = (CTLineRef)lineObj;
for (id runObj in (NSArray *)CTLineGetGlyphRuns(line)) {
CTRunRef run = (CTRunRef)runObj;
CGRect runBounds = CTRunGetImageBounds(run, context, CFRangeMake(0, 0));
NSLog(@"bounds: %@", NSStringFromCGRect(runBounds));
[[UIColor greenColor] set];
CGContextFillRect(context, runBounds);
}
}
CFRelease(framesetter);
CFRelease(frame);
[attrString release];
}
产生:
推荐答案
这是我想出的。这是完全准确的。
Here is what I came up with. This is completely accurate.
CTFrameRef frame = [self _frameWithRect:rect];
NSArray *lines = (NSArray *)CTFrameGetLines(frame);
CGPoint origins[[lines count]];//the origins of each line at the baseline
CTFrameGetLineOrigins(frame, CFRangeMake(0, 0), origins);
NSUInteger lineIndex = 0;
for (id lineObj in lines) {
CTLineRef line = (CTLineRef)lineObj;
for (id runObj in (NSArray *)CTLineGetGlyphRuns(line)) {
CTRunRef run = (CTRunRef)runObj;
CFRange runRange = CTRunGetStringRange(run);
CGRect runBounds;
CGFloat ascent;//height above the baseline
CGFloat descent;//height below the baseline
runBounds.size.width = CTRunGetTypographicBounds(run, CFRangeMake(0, 0), &ascent, &descent, NULL);
runBounds.size.height = ascent + descent;
CGFloat xOffset = CTLineGetOffsetForStringIndex(line, CTRunGetStringRange(run).location, NULL);
runBounds.origin.x = origins[lineIndex].x + rect.origin.x + xOffset;
runBounds.origin.y = origins[lineIndex].y + rect.origin.y;
runBounds.origin.y -= descent;
//do something with runBounds
}
lineIndex++;
}
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