8
A
回答
7
终于找到它了...
CGRect boundingBox = CTFontGetBoundingBox(font);
//Get the position on the y axis
float midHeight = self.frame.size.height/2;
midHeight -= boundingBox.size.height/2;
CGPathAddRect(path, NULL, CGRectMake(0, midHeight, self.frame.size.width, boundingBox.size.height));
4
感谢尼克,这是一个伟大的片段。
只是扩大上,如果你做的顶部,中部和底部对齐枚举,例如,你可以做到这一点,像这样:
if (VerticalAlignmentTop == currentTextAlignment) {
CGPathAddRect(path, NULL, rect); // Draw normally (top)
}
else if (VerticalAlignmentMiddle == currentTextAlignment) {
CGRect boundingBox = CTFontGetBoundingBox(fontRef);
//Get the position on the y axis (middle)
float midHeight = rect.size.height/2;
midHeight -= boundingBox.size.height/2;
CGPathAddRect(path, NULL, CGRectMake(0, midHeight, rect.size.width, boundingBox.size.height));
}
else {
CGRect boundingBox = CTFontGetBoundingBox(fontRef);
CGPathAddRect(path, NULL, CGRectMake(0, 0, rect.size.width, boundingBox.size.height));
}
1
这说明了一个事实,即多字体和样式可以在一帧中使用(计算高度和文本的宽度,看在if(index == lastLineIndex)
块上看到的高度被计算):
- (CGSize) measureFrame: (CTFrameRef) frame forContext: (CGContext *) cgContext
{
CGPathRef framePath = CTFrameGetPath(frame);
CGRect frameRect = CGPathGetBoundingBox(framePath);
CFArrayRef lines = CTFrameGetLines(frame);
CFIndex numLines = CFArrayGetCount(lines);
CGFloat maxWidth = 0;
CGFloat textHeight = 0;
// Now run through each line determining the maximum width of all the lines.
// We special case the last line of text. While we've got it's descent handy,
// we'll use it to calculate the typographic height of the text as well.
CFIndex lastLineIndex = numLines - 1;
for(CFIndex index = 0; index < numLines; index++)
{
CGFloat ascent, descent, leading, width;
CTLineRef line = (CTLineRef) CFArrayGetValueAtIndex(lines, index);
width = CTLineGetTypographicBounds(line, &ascent, &descent, &leading);
if(width > maxWidth)
{
maxWidth = width;
}
if(index == lastLineIndex)
{
// Get the origin of the last line. We add the descent to this
// (below) to get the bottom edge of the last line of text.
CGPoint lastLineOrigin;
CTFrameGetLineOrigins(frame, CFRangeMake(lastLineIndex, 1), &lastLineOrigin);
// The height needed to draw the text is from the bottom of the last line
// to the top of the frame.
textHeight = CGRectGetMaxY(frameRect) - lastLineOrigin.y + descent;
}
}
// For some text the exact typographic bounds is a fraction of a point too
// small to fit the text when it is put into a context. We go ahead and round
// the returned drawing area up to the nearest point. This takes care of the
// discrepencies.
return CGSizeMake(ceil(maxWidth), ceil(textHeight));
}
参考:斯科特·汤普森(http://lists.apple.com/archives/quartz-dev/2008/Mar/msg00079.html)
3
您可以使用[NSString boundingRectWithSize:options:attributes:context:]来获取字符串边界框的矩形,这也允许使用多行文本。 在你的画文本的方法,请执行下列操作(RECT是要绘制文本的矩形):
// get the graphics context
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState(context);
// flip the context coordinate
CGContextTranslateCTM(context, 0.0f, 2*RECT.origin.y+RECT.size.height);
CGContextScaleCTM(context, 1.0f, -1.0f);
// Set the text matrix.
CGContextSetTextMatrix(context, CGAffineTransformIdentity);
// set text horizontal alignment
NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
paragraphStyle.alignment = NSTextAlignmentCenter;
NSDictionary *attributes = @{NSParagraphStyleAttributeName:paragraphStyle, NSFontAttributeName:YOUR_FONT, NSForegroundColorAttributeName:TEXT_COLOR};
NSAttributedString *attrString = [[NSAttributedString alloc] initWithString:YOUR_TEXT attributes:attributes];
CGMutablePathRef path = CGPathCreateMutable();
// set text vertical alignment
CGSize textSize = [text boundingRectWithSize:RECT.size options:NSStringDrawingUsesLineFragmentOrigin attributes:attributes context:nil].size;
CGPathAddRect(path, NULL, CGRectMake(RECT.origin.x, RECT.origin.y-(RECT.size.height-textSize.height)/2.0f, RECT.size.width, RECT.size.height));
CTFramesetterRef frameSetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attrString);
CTFrameRef frame = CTFramesetterCreateFrame(frameSetter, CFRangeMake(0, attrString.length), path, NULL);
CTFrameDraw(frame, context);
CFRelease(frame);
CFRelease(path);
CFRelease(frameSetter);
[attrString release];
[paragraphStyle release];
CGContextRestoreGState(context);
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这并不适用于某些字体。刚刚使用AcademyEngravedLetPlain字体进行了测试,并且字体没有绘制 – Coolant 2012-12-04 23:59:03
但我已经设法通过将rect尺寸高度设置为原始边界高度,而不是边界框高度 – Coolant 2012-12-05 01:26:14
并且它对于多行工作? – MatterGoal 2013-01-08 18:14:00