CoreText使用介紹

2019-11-09 15:02:20

字體：大中小

來源：轉載

供稿：網友

一、概述 1.CoreText是蘋果創建的一個用于文字排版的框架，可以實現文字排版、圖文混排等復雜的界面效果。從iOS3.2啟用。2.一個開源工具類-OHAttributedLabel，就是使用CoreText框架實現的，能夠實現一個Label中有不同的文字大小、文字顏色、字體以及鏈接等。二、一般使用步驟1.創建NSMutableAttributedStringNSMutableAttributedString *attributeString = [[NSMutableAttributedString alloc] initWithString:contentString]; 2.設置文字顏色 [attributeString addAttribute:(id)kCTForegroundColorAttributeName value:(id)[UIColor darkGrayColor].CGColor range:NSMakeRange(0, tempArticle.desc.length)];2.設置字體以及大小 CTFontRef font = CTFontCreateWithName(CFSTR("Bodoni 72"), contentFontSize, NULL);[attributeString addAttribute:(id)kCTFontAttributeName value:(id)font range:NSMakeRange(0, [attributeString length])];CFRelease(font);4.初始化段落首行縮進樣式CGFloat headIndent = contentFontSize * 2;CTParagraphStyleSetting headIndentStyle;headIndentStyle.spec = kCTParagraphStyleSpecifierFirstLineHeadIndent;headIndentStyle.valueSize = sizeof(headIndent);headIndentStyle.value = &headIndent; 5.初始化文字對齊方式 CTTextAlignment alignment = kCTJustifiedTextAlignment;CTParagraphStyleSetting alignmentStyle;alignmentStyle.spec = kCTParagraphStyleSpecifierAlignment;alignmentStyle.valueSize = sizeof(alignment);alignmentStyle.value = &alignment; 6.初始化行間距CGFloat lineSpace = 12.0f;CTParagraphStyleSetting lineSpaceStyle;lineSpaceStyle.spec = kCTParagraphStyleSpecifierLineSpacing;lineSpaceStyle.valueSize = sizeof(lineSpace);lineSpaceStyle.value = &lineSpace; 7.初始化段間距CGFloat paragraphSpace = 18;CTParagraphStyleSetting paragraphSpaceStyle;paragraphSpaceStyle.spec = kCTParagraphStyleSpecifierParagraphSpacing;paragraphSpaceStyle.valueSize = sizeof(paragraphSpace);paragraphSpaceStyle.value = &paragraphSpace; 8.將段落屬性設置到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.創建CTFramesetterRef CTFramesetterRef frameSetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attributeString); 10.繪制之前，翻轉繪圖坐標系CGContextRef context = UIGraphicsGetCurrentContext();CGContextSetTextMatrix(context, CGAffineTransformIdentity);CGContextTranslateCTM(context, 0, self.bounds.size.height);CGContextScaleCTM(context, 1.0, -1.0); 11.按照區域進行繪制 CFIndex startIndex = 0; NSInteger pathCount = 0;while (YES) { //構建繪圖區域 CGMutablePathRef columnPath = CGPathCreateMutable(); CGPathAddRect(columnPath, NULL, CGRectMake(20 + (pathCount%columnNum) * ((768-(columnNum+1)*20)/columnNum + 20), 50, (768-(columnNum+1)*20)/columnNum, 904)); //構建內容窗體 CTFrameRef frame = CTFramesetterCreateFrame(frameSetter, CFRangeMake(startIndex,0), columnPath, NULL); //繪制內容窗體 CTFrameDraw(frame, context); //計算當前顯示結束位置的字符索引 CFRange currRange = CTFrameGetVisibleStringRange(frame); startIndex = startIndex + currRange.length; //釋放 CGPathRelease(columnPath); CFRelease(frame); //計數增加 pathCount++; //結束 if (startIndex == [attributeString length]) { break; }}12.按照行進行繪制CFIndex start = 0;while (YES) { //判斷是否繪制完畢 if (start == attributeString.length) { break; } //根據內容、開始索引位置和繪制區域的寬度，返回推薦的換行位置索引 CFIndex count = CTTypesetterSuggestLineBreak(frameSetter, start, pageWidth); //創建一個新行 CTLineRef line = CTTypesetterCreateLine(frameSetter, CFRangeMake(start, count)); //獲取新行的排版屬性 CGFloat ascent; CGFloat descent; CGFloat leading; CTLineGetTypographicBounds(line, &ascent, &descent, &leading); //計算新行的Y值 imageY = imageY - lineSpace - ascent - descent - leading; //繪制行 CGContextSetTextPosition(currContext, 0.0f, imageY); CTLineDraw(line, currContext); //釋放行對象 CFRelease(line); //更改當前繪制的位置索引 start += count;}

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