CoreText使用介绍

2019-11-09 15:02:20

字体：大中小

来源：转载

供稿：网友

一、概述 1.CoreText是苹果创建的一个用于文字排版的框架，可以实现文字排版、图文混排等复杂的界面效果。从iOS3.2启用。2.一个开源工具类-OHAttributedLabel，就是使用CoreText框架实现的，能够实现一个Label中有不同的文字大小、文字颜色、字体以及链接等。二、一般使用步骤1.创建NSMutableAttributedStringNSMutableAttributedString *attributeString = [[NSMutableAttributedString alloc] initWithString:contentString]; 2.设置文字颜色 [attributeString addAttribute:(id)kCTForegroundColorAttributeName value:(id)[UIColor darkGrayColor].CGColor range:NSMakeRange(0, tempArticle.desc.length)];2.设置字体以及大小 CTFontRef font = CTFontCreateWithName(CFSTR("Bodoni 72"), contentFontSize, NULL);[attributeString addAttribute:(id)kCTFontAttributeName value:(id)font range:NSMakeRange(0, [attributeString length])];CFRelease(font);4.初始化段落首行缩进样式CGFloat headIndent = contentFontSize * 2;CTParagraphStyleSetting headIndentStyle;headIndentStyle.spec = kCTParagraphStyleSpecifierFirstLineHeadIndent;headIndentStyle.valueSize = sizeof(headIndent);headIndentStyle.value = &headIndent; 5.初始化文字对齐方式 CTTextAlignment alignment = kCTJustifiedTextAlignment;CTParagraphStyleSetting alignmentStyle;alignmentStyle.spec = kCTParagraphStyleSpecifierAlignment;alignmentStyle.valueSize = sizeof(alignment);alignmentStyle.value = &alignment; 6.初始化行间距CGFloat lineSpace = 12.0f;CTParagraphStyleSetting lineSpaceStyle;lineSpaceStyle.spec = kCTParagraphStyleSpecifierLineSpacing;lineSpaceStyle.valueSize = sizeof(lineSpace);lineSpaceStyle.value = &lineSpace; 7.初始化段间距CGFloat paragraphSpace = 18;CTParagraphStyleSetting paragraphSpaceStyle;paragraphSpaceStyle.spec = kCTParagraphStyleSpecifierParagraphSpacing;paragraphSpaceStyle.valueSize = sizeof(paragraphSpace);paragraphSpaceStyle.value = &paragraphSpace; 8.将段落属性设置到NSMutableAttributedStringCTParagraphStyleSetting settings[4] = {headIndentStyle,alignmentStyle,lineSpaceStyle,paragraphSpaceStyle};CTParagraphStyleRef paragraphStyle = CTParagraphStyleCreate((const CTParagraphStyleSetting*)&settings,4);[attributeString addAttribute:(id)kCTParagraphStyleAttributeName value:(id)paragraphStyle range:NSMakeRange(0, [attributeString length])];CFRelease(paragraphStyle);9.创建CTFramesetterRef CTFramesetterRef frameSetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attributeString); 10.绘制之前，翻转绘图坐标系CGContextRef context = UIGraphicsGetCurrentContext();CGContextSetTextMatrix(context, CGAffineTransformIdentity);CGContextTranslateCTM(context, 0, self.bounds.size.height);CGContextScaleCTM(context, 1.0, -1.0); 11.按照区域进行绘制 CFIndex startIndex = 0; NSInteger pathCount = 0;while (YES) { //构建绘图区域 CGMutablePathRef columnPath = CGPathCreateMutable(); CGPathAddRect(columnPath, NULL, CGRectMake(20 + (pathCount%columnNum) * ((768-(columnNum+1)*20)/columnNum + 20), 50, (768-(columnNum+1)*20)/columnNum, 904)); //构建内容窗体 CTFrameRef frame = CTFramesetterCreateFrame(frameSetter, CFRangeMake(startIndex,0), columnPath, NULL); //绘制内容窗体 CTFrameDraw(frame, context); //计算当前显示结束位置的字符索引 CFRange currRange = CTFrameGetVisibleStringRange(frame); startIndex = startIndex + currRange.length; //释放 CGPathRelease(columnPath); CFRelease(frame); //计数增加 pathCount++; //结束 if (startIndex == [attributeString length]) { break; }}12.按照行进行绘制CFIndex start = 0;while (YES) { //判断是否绘制完毕 if (start == attributeString.length) { break; } //根据内容、开始索引位置和绘制区域的宽度，返回推荐的换行位置索引 CFIndex count = CTTypesetterSuggestLineBreak(frameSetter, start, pageWidth); //创建一个新行 CTLineRef line = CTTypesetterCreateLine(frameSetter, CFRangeMake(start, count)); //获取新行的排版属性 CGFloat ascent; CGFloat descent; CGFloat leading; CTLineGetTypographicBounds(line, &ascent, &descent, &leading); //计算新行的Y值 imageY = imageY - lineSpace - ascent - descent - leading; //绘制行 CGContextSetTextPosition(currContext, 0.0f, imageY); CTLineDraw(line, currContext); //释放行对象 CFRelease(line); //更改当前绘制的位置索引 start += count;}

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