CoreText --- 段落样子CTParagraphStyle

在前面一篇文章中，介绍了属性文字的基本使用，本章节主要针对文字的段落样式展开演示说明。

先定义一段演示文字（文字中有中，英文）。

NSString *src = [NSString stringWithString:@"其实流程是这样的： 1、生成要绘制的NSAttributedString对象。 2、生成一个CTFramesetterRef对象，然后创建一个CGPath对象，这个Path对象用于表示可绘制区域坐标值、长宽。 3、使用上面生成的setter和path生成一个CTFrameRef对象，这个对象包含了这两个对象的信息（字体信息、坐标信息），它就可以使用CTFrameDraw方法绘制了。"];
    NSMutableAttributedString * mabstring = [[NSMutableAttributedString alloc]initWithString:src];

    long slen = [mabstring length];

<span style="font-family: Arial, Helvetica, sans-serif;">  在未设置段落样式的情况下，效果：</span>

从上面的交果来看，想必大家也看到了，英文部份换行显示了。这个一般情况下不注意，但在大的段落文章中就会出现不对齐现象。

先不管上面的，下面逐个来演示一下段落属性。
段落样式定义：

kCTParagraphStyleSpecifierAlignment = 0,                 //对齐属性
 kCTParagraphStyleSpecifierFirstLineHeadIndent = 1,       //首行缩进
 kCTParagraphStyleSpecifierHeadIndent = 2,                //段头缩进
 kCTParagraphStyleSpecifierTailIndent = 3,                //段尾缩进
 kCTParagraphStyleSpecifierTabStops = 4,                  //制表符模式
 kCTParagraphStyleSpecifierDefaultTabInterval = 5,        //默认tab间隔
 kCTParagraphStyleSpecifierLineBreakMode = 6,             //换行模式
 kCTParagraphStyleSpecifierLineHeightMultiple = 7,        //多行高
 kCTParagraphStyleSpecifierMaximumLineHeight = 8,         //最大行高
 kCTParagraphStyleSpecifierMinimumLineHeight = 9,         //最小行高
 kCTParagraphStyleSpecifierLineSpacing = 10,              //行距
 kCTParagraphStyleSpecifierParagraphSpacing = 11,         //段落间距  在段的未尾（Bottom）加上间隔，这个值为负数。
 kCTParagraphStyleSpecifierParagraphSpacingBefore = 12,   //段落前间距 在一个段落的前面加上间隔。TOP
 kCTParagraphStyleSpecifierBaseWritingDirection = 13,     //基本书写方向
 kCTParagraphStyleSpecifierMaximumLineSpacing = 14,       //最大行距
 kCTParagraphStyleSpecifierMinimumLineSpacing = 15,       //最小行距
 kCTParagraphStyleSpecifierLineSpacingAdjustment = 16,    //行距调整
 kCTParagraphStyleSpecifierCount = 17,        //

对齐属性：

kCTLeftTextAlignment = 0,                //左对齐
kCTRightTextAlignment = 1,               //右对齐
kCTCenterTextAlignment = 2,              //居中对齐
kCTJustifiedTextAlignment = 3,           //文本对齐
kCTNaturalTextAlignment = 4              //自然文本对齐

段落默认样式为

kCTNaturalTextAlignment

效果：

居中：

文本对齐Justified效果

对齐方式设置代码：

  
  
  
  
CTTextAlignment alignment = kCTJustifiedTextAlignment;
    CTParagraphStyleSetting alignmentStyle;
    alignmentStyle.spec=kCTParagraphStyleSpecifierAlignment;//指定为对齐属性
    alignmentStyle.valueSize=sizeof(alignment);
    alignmentStyle.value=&alignment;
首行缩进代码：

  
  
  
  
//首行缩进
    CGFloat fristlineindent = 24.0f;
    CTParagraphStyleSetting fristline;
    fristline.spec = kCTParagraphStyleSpecifierFirstLineHeadIndent;
    fristline.value = &fristlineindent;
    fristline.valueSize = sizeof(float);
效果：

段头缩进代码：

  
  
  
  
//段缩进
CGFloat headindent = 10.0f;
CTParagraphStyleSetting head;
head.spec = kCTParagraphStyleSpecifierHeadIndent;
head.value = &headindent;
head.valueSize = sizeof(float);
效果：

段尾缩进代码：

  
  
  
  
//段尾缩进
CGFloat tailindent = 50.0f;
CTParagraphStyleSetting tail;
tail.spec = kCTParagraphStyleSpecifierTailIndent;
tail.value = &tailindent;
tail.valueSize = sizeof(float);
效果：

制表符（tab）代码：

  
  
  
  
//tab
    CTTextAlignment tabalignment = kCTJustifiedTextAlignment;
    CTTextTabRef texttab = CTTextTabCreate(tabalignment, 24, NULL);
    CTParagraphStyleSetting tab;
    tab.spec = kCTParagraphStyleSpecifierTabStops;
    tab.value = &texttab;
    tab.valueSize = sizeof(CTTextTabRef);

效果（未看出哪有变化感觉行距大了点）：

换行模式：

kCTLineBreakByWordWrapping = 0,        //出现在单词边界时起作用，如果该单词不在能在一行里显示时，整体换行。此为段的默认值。
kCTLineBreakByCharWrapping = 1,        //当一行中最后一个位置的大小不能容纳一个字符时，才进行换行。
kCTLineBreakByClipping = 2,            //超出画布边缘部份将被截除。
kCTLineBreakByTruncatingHead = 3,      //截除前面部份，只保留后面一行的数据。前部份以...代替。
kCTLineBreakByTruncatingTail = 4,      //截除后面部份，只保留前面一行的数据，后部份以...代替。
kCTLineBreakByTruncatingMiddle = 5     //在一行中显示段文字的前面和后面文字，中间文字使用...代替。
换行模式代码：

   
   
   
   
//换行模式
   CTParagraphStyleSetting lineBreakMode;
   CTLineBreakMode lineBreak = kCTLineBreakByWordWrapping;//kCTLineBreakByCharWrapping;//换行模式
   lineBreakMode.spec = kCTParagraphStyleSpecifierLineBreakMode;
   lineBreakMode.value = &lineBreak;
   lineBreakMode.valueSize = sizeof(CTLineBreakMode);

kCTLineBreakByWordWrapping
效果：

kCTLineBreakByCharWrapping
效果:


kCTLineBreakByClipping
效果：


kCTLineBreakByTruncatingHead
效果：


kCTLineBreakByTruncatingTail
效果：


kCTLineBreakByTruncatingMiddle
效果：


多行高设置代码：
         
         
         
         
//多行高
CGFloat MutiHeight = 10.0f;
CTParagraphStyleSetting Muti;
Muti.spec = kCTParagraphStyleSpecifierLineHeightMultiple;
Muti.value = &MutiHeight;
Muti.valueSize = sizeof(float);
效果：

最大行高代码：
         
         
         
         
//最大行高
    CGFloat MaxHeight = 5.0f;
    CTParagraphStyleSetting Max;
    Max.spec = kCTParagraphStyleSpecifierLineHeightMultiple;
    Max.value = &MaxHeight;
    Max.valueSize = sizeof(float);
效果：

行距代码：
         
         
         
         
//行距
CGFloat _linespace = 5.0f;
CTParagraphStyleSetting lineSpaceSetting;
lineSpaceSetting.spec = kCTParagraphStyleSpecifierLineSpacing;
lineSpaceSetting.value = &_linespace;
lineSpaceSetting.valueSize = sizeof(float);
效果：

段前间距设置代码（段与段之间）：
         
         
         
         
//段前间隔
CGFloat paragraphspace = 5.0f;
CTParagraphStyleSetting paragraph;
paragraph.spec = kCTParagraphStyleSpecifierLineSpacing;
paragraph.value = ¶graphspace;
paragraph.valueSize = sizeof(float);
效果：
kCTWritingDirectionNatural = -1,            //普通书写方向，一般习惯是从左到右写
kCTWritingDirectionLeftToRight = 0,         //从左到右写
kCTWritingDirectionRightToLeft = 1          //从右到左写


基本书写方向代码：
          
          
          
          
//书写方向
CTWritingDirection wd = kCTWritingDirectionRightToLeft;
CTParagraphStyleSetting writedic;
writedic.spec = kCTParagraphStyleSpecifierBaseWritingDirection;
writedic.value = &wd;
writedic.valueSize = sizeof(CTWritingDirection);
效果：

这个跟字体右对齐效果上类似。

好了，段落的API样式介绍到这里，里面还有很多配合设置时的效果。读者自行演示了。
下面附上draw 代码：
          
          
          
          
-(void)ParagraphStyle
{
    NSString *src = [NSString stringWithString:@"其实流程是这样的： 1、生成要绘制的NSAttributedString对象。 2、生成一个CTFramesetterRef对象，然后创建一个CGPath对象，这个Path对象用于表示可绘制区域坐标值、长宽。 3、使用上面生成的setter和path生成一个CTFrameRef对象，这个对象包含了这两个对象的信息（字体信息、坐标信息），它就可以使用CTFrameDraw方法绘制了。"];

    //修改windows回车换行为mac的回车换行
    //src = [src stringByReplacingOccurrencesOfString:@"\r\n" withString:@"\n"];

    NSMutableAttributedString * mabstring = [[NSMutableAttributedString alloc]initWithString:src];

    long slen = [mabstring length];


    //创建文本对齐方式
    CTTextAlignment alignment = kCTRightTextAlignment;//kCTNaturalTextAlignment;
    CTParagraphStyleSetting alignmentStyle;
    alignmentStyle.spec=kCTParagraphStyleSpecifierAlignment;//指定为对齐属性
    alignmentStyle.valueSize=sizeof(alignment);
    alignmentStyle.value=&alignment;

    //首行缩进
    CGFloat fristlineindent = 24.0f;
    CTParagraphStyleSetting fristline;
    fristline.spec = kCTParagraphStyleSpecifierFirstLineHeadIndent;
    fristline.value = &fristlineindent;
    fristline.valueSize = sizeof(float);

    //段缩进
    CGFloat headindent = 10.0f;
    CTParagraphStyleSetting head;
    head.spec = kCTParagraphStyleSpecifierHeadIndent;
    head.value = &headindent;
    head.valueSize = sizeof(float);

    //段尾缩进
    CGFloat tailindent = 50.0f;
    CTParagraphStyleSetting tail;
    tail.spec = kCTParagraphStyleSpecifierTailIndent;
    tail.value = &tailindent;
    tail.valueSize = sizeof(float);

    //tab
    CTTextAlignment tabalignment = kCTJustifiedTextAlignment;
    CTTextTabRef texttab = CTTextTabCreate(tabalignment, 24, NULL);
    CTParagraphStyleSetting tab;
    tab.spec = kCTParagraphStyleSpecifierTabStops;
    tab.value = &texttab;
    tab.valueSize = sizeof(CTTextTabRef);

    //换行模式
    CTParagraphStyleSetting lineBreakMode;
    CTLineBreakMode lineBreak = kCTLineBreakByTruncatingMiddle;//kCTLineBreakByWordWrapping;//换行模式
    lineBreakMode.spec = kCTParagraphStyleSpecifierLineBreakMode;
    lineBreakMode.value = &lineBreak;
    lineBreakMode.valueSize = sizeof(CTLineBreakMode);

    //多行高
    CGFloat MutiHeight = 10.0f;
    CTParagraphStyleSetting Muti;
    Muti.spec = kCTParagraphStyleSpecifierLineHeightMultiple;
    Muti.value = &MutiHeight;
    Muti.valueSize = sizeof(float);

    //最大行高
    CGFloat MaxHeight = 5.0f;
    CTParagraphStyleSetting Max;
    Max.spec = kCTParagraphStyleSpecifierLineHeightMultiple;
    Max.value = &MaxHeight;
    Max.valueSize = sizeof(float);

    //行距
    CGFloat _linespace = 5.0f;
    CTParagraphStyleSetting lineSpaceSetting;
    lineSpaceSetting.spec = kCTParagraphStyleSpecifierLineSpacing;
    lineSpaceSetting.value = &_linespace;
    lineSpaceSetting.valueSize = sizeof(float);

    //段前间隔
    CGFloat paragraphspace = 5.0f;
    CTParagraphStyleSetting paragraph;
    paragraph.spec = kCTParagraphStyleSpecifierLineSpacing;
    paragraph.value = ¶graphspace;
    paragraph.valueSize = sizeof(float);

    //书写方向
    CTWritingDirection wd = kCTWritingDirectionRightToLeft;
    CTParagraphStyleSetting writedic;
    writedic.spec = kCTParagraphStyleSpecifierBaseWritingDirection;
    writedic.value = &wd;
    writedic.valueSize = sizeof(CTWritingDirection);

    //组合设置
    CTParagraphStyleSetting settings[] = {
        alignmentStyle
        fristline,
        head,
        tail,
        tab,
        lineBreakMode,
        Muti,
        Max,
        lineSpaceSetting,
        writedic
        indentSetting

    };

    //通过设置项产生段落样式对象
    CTParagraphStyleRef style = CTParagraphStyleCreate(settings, 11);

    // build attributes
    NSMutableDictionary *attributes = [NSMutableDictionary dictionaryWithObject:(id)style forKey:(id)kCTParagraphStyleAttributeName ];

    // set attributes to attributed string
    [mabstring addAttributes:attributes range:NSMakeRange(0, slen)];


    CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)mabstring);

    CGMutablePathRef Path = CGPathCreateMutable();

    //坐标点在左下角
    CGPathAddRect(Path, NULL ,CGRectMake(10 , 10 ,self.bounds.size.width-20 , self.bounds.size.height-20));

    CTFrameRef frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, 0), Path, NULL);



    //获取当前(View)上下文以便于之后的绘画，这个是一个离屏。
    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetTextMatrix(context , CGAffineTransformIdentity);

    //压栈，压入图形状态栈中.每个图形上下文维护一个图形状态栈，并不是所有的当前绘画环境的图形状态的元素都被保存。图形状态中不考虑当前路径，所以不保存
    //保存现在得上下文图形状态。不管后续对context上绘制什么都不会影响真正得屏幕。
    CGContextSaveGState(context);

    //x，y轴方向移动
    CGContextTranslateCTM(context , 0 ,self.bounds.size.height);

    //缩放x，y轴方向缩放，－1.0为反向1.0倍,坐标系转换,沿x轴翻转180度
    CGContextScaleCTM(context, 1.0 ,-1.0);

    CTFrameDraw(frame,context);

    CGPathRelease(Path);
    CFRelease(framesetter);
}
-（void）drawRect:(CGRect)rect
{
   [self ParagraphStyle];
}