Android 自绘TextView解决提前换行问题，支持图文混排

本文转载自：Android 自绘TextView解决提前换行问题，支持图文混排

先看下效果图：

上面是MTextView，下面是默认的TextView。

 

一、原因

用最简单的全英文句子为例，如果有一个很长的单词，这一行剩余的空间显示不下了，那么规则就是不打断单词，而是把整个单词丢到下一行开始显示。这样本来没有错。一是咱们中国人都是方块字，怎么都放得下，不存在英文的这个问题。所以不习惯那个排版。二是如果TextView里面有图片，如图，不知道判断单词的代码是怎么弄得，总之它觉得最后一个啦字和后面的一串表情应该是一个整体，不能分开，就一起丢到第二行了，也就造成了这种难看的排版。要验证这个说法也很简单，自己去QQ里试一试，在每个表情之间都加一个空格，就会发现排版一下子正常了。

二、解决方法

    最简单的就是表情之间加空格，如果不想这么做，就只有自己来画啦。

    先给初学的朋友解释一下View绘制的流程，首先是onMeasure(int widthMeasureSpec, int heightMeasureSpec),onMeasure执行的时候，就是父View在问你，小朋友，你要占多大的地儿呀？当然，问你的时候，会给你个限制条件，就是那两参数，以widthMeasureSpec为例，这参数不能直接用，得先拆开，用int widthMode = MeasureSpec.getMode(widthMeasureSpec) 和 int widthSize = MeasureSpec.getSize(widthMeasureSpec);widthMode就三种情况：

MeasureSpec.EXACTLY：你就widthSize那么宽就行了。

MeasureSpec.AT_MOST：你最多只能widthSize那么宽。

MeasureSpec.UNSPECIFIED：未指定，你爱多宽多宽。

当然，其实这只父View给你的建议，遵不遵守你自己看着办，但是自己乱来导致显示不全就不是父View的错了。

最终你听取了建议，思量了一番，觉得自己应该有width那么宽，height那么高，最后就得用setMeasuredDimension(width, height)这个函数真正确定自己的高宽。然后onMeasure()的工作就完了。

然后就是onDraw(Canvas canvas)，这个就简单了，canvas就是父View给的一块画布，爱在上面画啥都行，比如写个字drawText(String text,float x, float y, Paint paint)，

text是要写的字，paint是写字的笔，值得注意的是x,y坐标是相对于你自己这一小块画布的左上角的。最左上就是0,0右下是width,height

 

上代码

 </pre><pre>

 /**
  * @author huangwei
  * @version SocialClient 1.2.0
  * @功能 图文混排TextView，请使用{@link #setMText(CharSequence)}
  * @2014年5月27日
  * @下午5:29:27
  */
 public class MTextView extends TextView
 {
     /**
      * 缓存测量过的数据
      */
     private static HashMap<String, SoftReference<MeasuredData>> measuredData = new HashMap<String, SoftReference<MeasuredData>>();
     private static int hashIndex = 0;
     /**
      * 存储当前文本内容，每个item为一行
      */
     ArrayList<LINE> contentList = new ArrayList<LINE>();
     private Context context;
     /**
      * 用于测量字符宽度
      */
     private TextPaint paint = new TextPaint();

 //  private float lineSpacingMult = 0.5f;
     private int textColor = Color.BLACK;
     //行距
     private float lineSpacing;
     private int lineSpacingDP = 5;
     /**
      * 最大宽度
      */
     private int maxWidth;
     /**
      * 只有一行时的宽度
      */
     private int oneLineWidth = -1;
     /**
      * 已绘的行中最宽的一行的宽度
      */
     private float lineWidthMax = -1;
     /**
      * 存储当前文本内容,每个item为一个字符或者一个SpanObject
      */
     private ArrayList<Object> obList = new ArrayList<Object>();
     /**
      * 是否使用默认{@link #onMeasure(int, int)}和{@link #onDraw(Canvas)}
      */
     private boolean useDefault = false;
     private CharSequence text = "";

     private int minHeight;
     /**
      * 用以获取屏幕高宽
      */
     private DisplayMetrics displayMetrics;
     /**
      * {@link android.text.style.BackgroundColorSpan}用
      */
     private Paint textBgColorPaint = new Paint();
     /**
      * {@link android.text.style.BackgroundColorSpan}用
      */
     private Rect textBgColorRect = new Rect();

     public MTextView(Context context)
     {
         super(context);
         this.context = context;
         paint.setAntiAlias(true);
         lineSpacing = dip2px(context, lineSpacingDP);
         minHeight = dip2px(context, 30);

         displayMetrics = new DisplayMetrics();
     }

     public MTextView(Context context,AttributeSet attrs)
     {
         super(context,attrs);
         this.context = context;
         paint.setAntiAlias(true);
         lineSpacing = dip2px(context, lineSpacingDP);
         minHeight = dip2px(context, 30);

         displayMetrics = new DisplayMetrics();
     }

     public static int px2sp(Context context, float pxValue)
     {
         final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;
         return (int) (pxValue / fontScale + 0.5f);
     }

     /**
      * 根据手机的分辨率从 dp 的单位 转成为 px(像素)
      */
     public static int dip2px(Context context, float dpValue)
     {
         final float scale = context.getResources().getDisplayMetrics().density;
         return (int) (dpValue * scale + 0.5f);
     }

     @Override
     public void setMaxWidth(int maxpixels)
     {
         super.setMaxWidth(maxpixels);
         maxWidth = maxpixels;
     }

     @Override
     public void setMinHeight(int minHeight)
     {
         super.setMinHeight(minHeight);
         this.minHeight = minHeight;
     }

     @Override
     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
     {
         if (useDefault)
         {
             super.onMeasure(widthMeasureSpec, heightMeasureSpec);
             return;
         }
         int width = 0, height = 0;

         int widthMode = MeasureSpec.getMode(widthMeasureSpec);
         int heightMode = MeasureSpec.getMode(heightMeasureSpec);
         int widthSize = MeasureSpec.getSize(widthMeasureSpec);
         int heightSize = MeasureSpec.getSize(heightMeasureSpec);

         switch (widthMode)
         {
         case MeasureSpec.EXACTLY:
             width = widthSize;
             break;
         case MeasureSpec.AT_MOST:
             width = widthSize;
             break;
         case MeasureSpec.UNSPECIFIED:

             ((Activity) context).getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
             width = displayMetrics.widthPixels;
             break;
         default:
             break;
         }
         if (maxWidth > 0)
             width = Math.min(width, maxWidth);

         paint.setTextSize(this.getTextSize());
         paint.setColor(textColor);
         int realHeight = measureContentHeight((int) width);

         //如果实际行宽少于预定的宽度，减少行宽以使其内容横向居中
         int leftPadding = getCompoundPaddingLeft();
         int rightPadding = getCompoundPaddingRight();
         width = Math.min(width, (int) lineWidthMax + leftPadding + rightPadding);

         if (oneLineWidth > -1)
         {
             width = oneLineWidth;
         }
         switch (heightMode)
         {
         case MeasureSpec.EXACTLY:
             height = heightSize;
             break;
         case MeasureSpec.AT_MOST:
             height = realHeight;
             break;
         case MeasureSpec.UNSPECIFIED:
             height = realHeight;
             break;
         default:
             break;
         }

         height += getCompoundPaddingTop() + getCompoundPaddingBottom();

         height = Math.max(height, minHeight);

         setMeasuredDimension(width, height);
     }

     @Override
     protected void onDraw(Canvas canvas)
     {
         if (useDefault)
         {
             super.onDraw(canvas);
             return;
         }
         if (contentList.isEmpty())
             return;
         int width;

         Object ob;

         int leftPadding = getCompoundPaddingLeft();
         int topPadding = getCompoundPaddingTop();

         float height = 0 + topPadding + lineSpacing;
         //只有一行时
         if (oneLineWidth != -1)
         {
             height = getMeasuredHeight() / 2 - contentList.get(0).height / 2;
         }

         for (LINE aContentList : contentList)
         {
             //绘制一行
             float realDrawedWidth = leftPadding;
             for (int j = 0; j < aContentList.line.size(); j++)
             {
                 ob = aContentList.line.get(j);
                 width = aContentList.widthList.get(j);

                 if (ob instanceof String)
                 {
                     canvas.drawText((String) ob, realDrawedWidth, height + aContentList.height - paint.getFontMetrics().descent, paint);
                     realDrawedWidth += width;
                 }
                 else if (ob instanceof SpanObject)
                 {
                     Object span = ((SpanObject) ob).span;
                     if(span instanceof ImageSpan)
                     {
                         ImageSpan is = (ImageSpan) span;
                         Drawable d = is.getDrawable();

                         int left = (int) (realDrawedWidth);
                         int top = (int) height;
                         int right = (int) (realDrawedWidth + width);
                         int bottom = (int) (height + aContentList.height);
                         d.setBounds(left, top, right, bottom);
                         d.draw(canvas);
                         realDrawedWidth += width;
                     }
                     else if(span instanceof BackgroundColorSpan)
                     {

                         textBgColorPaint.setColor(((BackgroundColorSpan) span).getBackgroundColor());
                         textBgColorPaint.setStyle(Style.FILL);
                         textBgColorRect.left = (int) realDrawedWidth;
                         int textHeight = (int) getTextSize();
                         textBgColorRect.top = (int) (height + aContentList.height - textHeight - paint.getFontMetrics().descent);
                         textBgColorRect.right = textBgColorRect.left+width;
                         textBgColorRect.bottom = (int) (height + aContentList.height + lineSpacing  - paint.getFontMetrics().descent);
                         canvas.drawRect(textBgColorRect, textBgColorPaint);
                         canvas.drawText(((SpanObject) ob).source.toString(), realDrawedWidth, height + aContentList.height - paint.getFontMetrics().descent, paint);
                         realDrawedWidth += width;
                     }
                     else//做字符串处理
                     {
                         canvas.drawText(((SpanObject) ob).source.toString(), realDrawedWidth, height + aContentList.height - paint.getFontMetrics().descent, paint);
                         realDrawedWidth += width;
                     }
                 }

             }
             height += aContentList.height + lineSpacing;
         }

     }

     @Override
     public void setTextColor(int color)
     {
         super.setTextColor(color);
         textColor = color;
     }

     /**
      * 用于带ImageSpan的文本内容所占高度测量
      * @param width 预定的宽度
      * @return 所需的高度
      */
     private int measureContentHeight(int width)
     {
         int cachedHeight = getCachedData(text.toString(), width);

         if (cachedHeight > 0)
         {
             return cachedHeight;
         }

         // 已绘的宽度
         float obWidth = 0;
         float obHeight = 0;

         float textSize = this.getTextSize();
         FontMetrics fontMetrics = paint.getFontMetrics();
         //行高
         float lineHeight = fontMetrics.bottom - fontMetrics.top;
         //计算出的所需高度
         float height = lineSpacing;

         int leftPadding = getCompoundPaddingLeft();
         int rightPadding = getCompoundPaddingRight();

         float drawedWidth = 0;

         boolean splitFlag = false;//BackgroundColorSpan拆分用

         width = width - leftPadding - rightPadding;

         oneLineWidth = -1;

         contentList.clear();

         StringBuilder sb;

         LINE line = new LINE();

         for (int i = 0; i < obList.size(); i++)
         {
             Object ob = obList.get(i);

             if (ob instanceof String)
             {

                 obWidth = paint.measureText((String) ob);
                 obHeight = textSize;
             }
             else if (ob instanceof SpanObject)
             {
                 Object span = ((SpanObject) ob).span;
                 if(span instanceof ImageSpan)
                 {
                     Rect r = ((ImageSpan)span).getDrawable().getBounds();
                     obWidth = r.right - r.left;
                     obHeight = r.bottom - r.top;
                     if (obHeight > lineHeight)
                         lineHeight = obHeight;
                 }
                 else if(span instanceof BackgroundColorSpan)
                 {
                     String str = ((SpanObject) ob).source.toString();
                     obWidth = paint.measureText(str);
                     obHeight = textSize;

                     //如果太长,拆分
                     int k= str.length()-1;
                     while(width - drawedWidth < obWidth)
                     {
                         obWidth = paint.measureText(str.substring(0,k--));
                     }
                     if(k < str.length()-1)
                     {
                         splitFlag = true;
                         SpanObject so1 = new SpanObject();
                         so1.start = ((SpanObject) ob).start;
                         so1.end = so1.start + k;
                         so1.source = str.substring(0,k+1);
                         so1.span = ((SpanObject) ob).span;

                         SpanObject so2 = new SpanObject();
                         so2.start =  so1.end;
                         so2.end = ((SpanObject) ob).end;
                         so2.source = str.substring(k+1,str.length());
                         so2.span = ((SpanObject) ob).span;

                         ob = so1;
                         obList.set(i,so2);
                         i--;
                     }
                 }//做字符串处理
                 else
                 {
                     String str = ((SpanObject) ob).source.toString();
                     obWidth = paint.measureText(str);
                     obHeight = textSize;
                 }
             }

             //这一行满了，存入contentList,新起一行
             if (width - drawedWidth < obWidth || splitFlag)
             {
                 splitFlag = false;
                 contentList.add(line);

                 if (drawedWidth > lineWidthMax)
                 {
                     lineWidthMax = drawedWidth;
                 }
                 drawedWidth = 0;
                 height += line.height + lineSpacing;

                 lineHeight = obHeight;

                 line = new LINE();
             }

             drawedWidth += obWidth;

             if (ob instanceof String && line.line.size() > 0 && (line.line.get(line.line.size() - 1) instanceof String))
             {
                 int size = line.line.size();
                 sb = new StringBuilder();
                 sb.append(line.line.get(size - 1));
                 sb.append(ob);
                 ob = sb.toString();
                 obWidth = obWidth + line.widthList.get(size - 1);
                 line.line.set(size - 1, ob);
                 line.widthList.set(size - 1, (int) obWidth);
                 line.height = (int) lineHeight;

             }
             else
             {
                 line.line.add(ob);
                 line.widthList.add((int) obWidth);
                 line.height = (int) lineHeight;
             }

         }

         if (drawedWidth > lineWidthMax)
         {
             lineWidthMax = drawedWidth;
         }

         if (line != null && line.line.size() > 0)
         {
             contentList.add(line);
             height += lineHeight + lineSpacing;
         }
         if (contentList.size() <= 1)
         {
             oneLineWidth = (int) drawedWidth + leftPadding + rightPadding;
             height = lineSpacing + lineHeight + lineSpacing;
         }

         cacheData(width, (int) height);
         return (int) height;
     }

     /**
      * 获取缓存的测量数据，避免多次重复测量
      * @param text
      * @param width
      * @return height
      */
     @SuppressWarnings("unchecked")
     private int getCachedData(String text, int width)
     {
         SoftReference<MeasuredData> cache = measuredData.get(text);
         if (cache == null)
             return -1;
         MeasuredData md = cache.get();
         if (md != null && md.textSize == this.getTextSize() && width == md.width)
         {
             lineWidthMax = md.lineWidthMax;
             contentList = (ArrayList<LINE>) md.contentList.clone();
             oneLineWidth = md.oneLineWidth;

             StringBuilder sb = new StringBuilder();
             for (int i = 0; i < contentList.size(); i++)
             {
                 LINE line = contentList.get(i);
                 sb.append(line.toString());
             }
             return md.measuredHeight;
         }
         else
             return -1;
     }

     /**
      * 缓存已测量的数据
      * @param width
      * @param height
      */
     @SuppressWarnings("unchecked")
     private void cacheData(int width, int height)
     {
         MeasuredData md = new MeasuredData();
         md.contentList = (ArrayList<LINE>) contentList.clone();
         md.textSize = this.getTextSize();
         md.lineWidthMax = lineWidthMax;
         md.oneLineWidth = oneLineWidth;
         md.measuredHeight = height;
         md.width = width;
         md.hashIndex = ++hashIndex;

         StringBuilder sb = new StringBuilder();
         for (int i = 0; i < contentList.size(); i++)
         {
             LINE line = contentList.get(i);
             sb.append(line.toString());
         }

         SoftReference<MeasuredData> cache = new SoftReference<MeasuredData>(md);
         measuredData.put(text.toString(), cache);
     }

     /**
      * 用本函数代替{@link #setText(CharSequence)}
      * @param cs
      */
     public void setMText(CharSequence cs)
     {
         text = cs;

         obList.clear();

         ArrayList<SpanObject> isList = new ArrayList<MTextView.SpanObject>();
         useDefault = false;
         if (cs instanceof SpannableString)
         {
             SpannableString ss = (SpannableString) cs;
             CharacterStyle[] spans = ss.getSpans(0, ss.length(), CharacterStyle.class);
             for (int i = 0; i < spans.length; i++)
             {

                 int s = ss.getSpanStart(spans[i]);
                 int e = ss.getSpanEnd(spans[i]);
                 SpanObject iS = new SpanObject();
                 iS.span = spans[i];
                 iS.start = s;
                 iS.end = e;
                 iS.source = ss.subSequence(s, e);
                 isList.add(iS);
             }
         }

         //对span进行排序，以免不同种类的span位置错乱
         SpanObject[] spanArray = new SpanObject[isList.size()];
         isList.toArray(spanArray);
         Arrays.sort(spanArray,0,spanArray.length,new SpanObjectComparator());
         isList.clear();
         for(int i=0;i<spanArray.length;i++)
         {
             isList.add(spanArray[i]);
         }

         String str = cs.toString();

         for (int i = 0, j = 0; i < cs.length(); )
         {
             if (j < isList.size())
             {
                 SpanObject is = isList.get(j);
                 if (i < is.start)
                 {
                     Integer cp = str.codePointAt(i);
                     //支持增补字符
                     if (Character.isSupplementaryCodePoint(cp))
                     {
                         i += 2;
                     }
                     else
                     {
                         i++;
                     }

                     obList.add(new String(Character.toChars(cp)));

                 }
                 else if (i >= is.start)
                 {
                     obList.add(is);
                     j++;
                     i = is.end;
                 }
             }
             else
             {
                 Integer cp = str.codePointAt(i);
                 if (Character.isSupplementaryCodePoint(cp))
                 {
                     i += 2;
                 }
                 else
                 {
                     i++;
                 }

                 obList.add(new String(Character.toChars(cp)));
             }
         }

         requestLayout();
     }

     public void setUseDefault(boolean useDefault)
     {
         this.useDefault = useDefault;
         if (useDefault)
         {
             this.setText(text);
             this.setTextColor(textColor);
         }
     }
     /**
      * 设置行距
      * @param lineSpacingDP 行距，单位dp
      */
     public void setLineSpacingDP(int lineSpacingDP)
     {
         this.lineSpacingDP = lineSpacingDP;
         lineSpacing = dip2px(context, lineSpacingDP);
     }
     /**
      * 获取行距
      * @return 行距，单位dp
      */
     public int getLineSpacingDP()
     {
         return lineSpacingDP;
     }
     /**
      * @author huangwei
      * @version SocialClient 1.2.0
      * @功能: 存储Span对象及相关信息
      * @2014年5月27日
      * @下午5:21:37
      */
     class SpanObject
     {
         public Object span;
         public int start;
         public int end;
         public CharSequence source;
     }
     /**
      * @功能: 对SpanObject进行排序
      * @author huangwei
      * @2014年6月4日
      * @下午5:21:30
      * @version SocialClient 1.2.0
      */
     class SpanObjectComparator implements Comparator<SpanObject>
     {
         @Override
         public int compare(SpanObject lhs, SpanObject rhs)
         {

             return lhs.start - rhs.start;
         }

     }
     /**
      * @author huangwei
      * @version SocialClient 1.2.0
      * @功能: 存储测量好的一行数据
      * @2014年5月27日
      * @下午5:22:12
      */
     class LINE
     {
         public ArrayList<Object> line = new ArrayList<Object>();
         public ArrayList<Integer> widthList = new ArrayList<Integer>();
         public int height;

         @Override
         public String toString()
         {
             StringBuilder sb = new StringBuilder("height:" + height + "   ");
             for (int i = 0; i < line.size(); i++)
             {
                 sb.append(line.get(i) + ":" + widthList.get(i));
             }
             return sb.toString();
         }

     }

     /**
      * @author huangwei
      * @version SocialClient 1.2.0
      * @功能: 缓存的数据
      * @2014年5月27日
      * @下午5:22:25
      */
     class MeasuredData
     {
         public int measuredHeight;
         public float textSize;
         public int width;
         public float lineWidthMax;
         public int oneLineWidth;
         public int hashIndex;
         ArrayList<LINE> contentList;

     }

为方便在ListView中使用（ListView反复上下滑动会多次重新onMeasure）,加了缓存，相同的情况下可以不用重复在测量一次。

对于SpannableString，只支持了ImageSpan，有其它需要者可自行扩展

Demo：http://download.csdn.net/detail/yellowcath/7421147

或：

https://github.com/yellowcath/MTextView.git (2014/6/4 更新 添加对BackGroundColorSpan的支持，修复一个会导致最后一行最后一个图形显示不全的bug)

备注：android上的textview显示文本不换行的问题确实不美观，这篇文章可以作为参考，github上还有类似的工程：android-justifiedtextview