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| #pragma mark - 一行一行绘制，行高确定，高度不够时加上省略号
- (void)drawRectWithLineByLineAlignmentAndEllipses
{
// 1.创建需要绘制的文字
NSMutableAttributedString *attributed = [[NSMutableAttributedString alloc] initWithString:self.text];
// 2.设置行距等样式
[[self class] addGlobalAttributeWithContent:attributed font:self.font];
self.textHeight = [[self class] textHeightWithText:self.text width:CGRectGetWidth(self.bounds) font:self.font type:self.drawType];
// 3.创建绘制区域，path的高度对绘制有直接影响，如果高度不够，则计算出来的CTLine的数量会少一行或者少多行
CGMutablePathRef path = CGPathCreateMutable();
CGPathAddRect(path, NULL, CGRectMake(0, 0, CGRectGetWidth(self.bounds), self.textHeight*2));
// 4.根据NSAttributedString生成CTFramesetterRef
CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attributed);
CTFrameRef ctFrame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, attributed.length), path, NULL);
// 重置高度
CGFloat realHeight = self.textHeight;
// 绘制全部文本需要的高度大于实际高度则调整，并加上省略号
if (realHeight > CGRectGetHeight(self.frame))
{
realHeight = CGRectGetHeight(self.frame);
}
NSLog(@"realHeight = %f",realHeight);
// 获取上下文
CGContextRef contextRef = UIGraphicsGetCurrentContext();
// 转换坐标系
CGContextSetTextMatrix(contextRef, CGAffineTransformIdentity);
CGContextTranslateCTM(contextRef, 0, realHeight); // 这里跟着调整
CGContextScaleCTM(contextRef, 1.0, -1.0);
// 这里可调整可不调整
CGPathAddRect(path, NULL, CGRectMake(0, 0, CGRectGetWidth(self.bounds), realHeight));
// 一行一行绘制
CFArrayRef lines = CTFrameGetLines(ctFrame);
CFIndex lineCount = CFArrayGetCount(lines);
CGPoint lineOrigins[lineCount];
// 把ctFrame里每一行的初始坐标写到数组里，注意CoreText的坐标是左下角为原点
CTFrameGetLineOrigins(ctFrame, CFRangeMake(0, 0), lineOrigins);
CGFloat frameY = 0;
for (CFIndex i = 0; i < lineCount; i++)
{
// 遍历每一行CTLine
CTLineRef line = CFArrayGetValueAtIndex(lines, i);
CGFloat lineAscent;
CGFloat lineDescent;
CGFloat lineLeading; // 行距
// 该函数除了会设置好ascent,descent,leading之外，还会返回这行的宽度
CTLineGetTypographicBounds(line, &lineAscent, &lineDescent, &lineLeading);
CGPoint lineOrigin = lineOrigins[i];
// 微调Y值，需要注意的是CoreText的origin的Y值是在baseLine处，而不是下方的descent。
CGFloat lineHeight = self.font.pointSize * kPerLineRatio;
// 调节self.font.descender该值可改变文字排版的上下间距，此处下间距为0
frameY = realHeight - (i + 1)*lineHeight - self.font.descender;
NSLog(@"frameY = %f",frameY);
lineOrigin.y = frameY;
// 调整坐标
CGContextSetTextPosition(contextRef, lineOrigin.x, lineOrigin.y);
// 反转坐标系
frameY = realHeight - frameY;
NSLog(@"realHeight = %f,font.descender = %f",realHeight,self.font.descender);
NSLog(@"反转后的坐标 y = %f",frameY);
// 行高
CGFloat heightPerLine = self.font.pointSize * kPerLineRatio;
if (realHeight - frameY > heightPerLine)
{
CTLineDraw(line, contextRef);
NSLog(@"一行一行的画 i = %ld",i);
} else
{
NSLog(@"最后一行");
// 最后一行，加上省略号
static NSString* const kEllipsesCharacter = @"\u2026";
CFRange lastLineRange = CTLineGetStringRange(line);
// 一个emoji表情占用两个长度单位
NSLog(@"range.location = %ld,range.length = %ld,总长度 = %ld",lastLineRange.location,lastLineRange.length,attributed.length);
if (lastLineRange.location + lastLineRange.length < (CFIndex)attributed.length)
{
// 这一行放不下所有的字符（下一行还有字符），则把此行后面的回车、空格符去掉后，再把最后一个字符替换成省略号
CTLineTruncationType truncationType = kCTLineTruncationEnd;
NSUInteger truncationAttributePosition = lastLineRange.location + lastLineRange.length - 1;
// 拿到最后一个字符的属性字典
NSDictionary *tokenAttributes = [attributed attributesAtIndex:truncationAttributePosition
effectiveRange:NULL];
// 给省略号字符设置字体大小、颜色等属性
NSAttributedString *tokenString = [[NSAttributedString alloc] initWithString:kEllipsesCharacter
attributes:tokenAttributes];
// 用省略号单独创建一个CTLine，下面在截断重新生成CTLine的时候会用到
CTLineRef truncationToken = CTLineCreateWithAttributedString((__bridge CFAttributedStringRef)tokenString);
// 把这一行的属性字符串复制一份，如果要把省略号放到中间或其他位置，只需指定复制的长度即可
NSUInteger copyLength = lastLineRange.length/3;
NSMutableAttributedString *truncationString = [[attributed attributedSubstringFromRange:NSMakeRange(lastLineRange.location, copyLength)] mutableCopy];
if (lastLineRange.length > 0)
{
// Remove any whitespace at the end of the line.
unichar lastCharacter = [[truncationString string] characterAtIndex:copyLength - 1];
// 如果复制字符串的最后一个字符是换行、空格符，则删掉
if ([[NSCharacterSet whitespaceAndNewlineCharacterSet] characterIsMember:lastCharacter])
{
[truncationString deleteCharactersInRange:NSMakeRange(copyLength - 1, 1)];
}
}
// 拼接省略号到复制字符串的最后
[truncationString appendAttributedString:tokenString];
// 把新的字符串创建成CTLine
CTLineRef truncationLine = CTLineCreateWithAttributedString((__bridge CFAttributedStringRef)truncationString);
// 创建一个截断的CTLine，该方法不能少，具体作用还有待研究
CTLineRef truncatedLine = CTLineCreateTruncatedLine(truncationLine, self.frame.size.width, truncationType, truncationToken);
if (!truncatedLine)
{
// If the line is not as wide as the truncationToken, truncatedLine is NULL
truncatedLine = CFRetain(truncationToken);
}
CFRelease(truncationLine);
CFRelease(truncationToken);
CTLineDraw(truncatedLine, contextRef);
CFRelease(truncatedLine);
} else
{
// 这一行刚好是最后一行，且最后一行的字符可以完全绘制出来
CTLineDraw(line, contextRef);
}
// 跳出循环，避免绘制剩下的多余的CTLine
break;
}
}
CFRelease(path);
CFRelease(framesetter);
CFRelease(ctFrame);
}
|
