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xi4t6w3x
7年前发布

Android Path 最佳实践之绘制雷达图

   <h2>第一步:绘制蜘蛛网络</h2>    <pre>  <code class="language-java">private void init() {      mainPaint=new Paint();      mainPaint.setColor(Color.BLACK);      mainPaint.setAntiAlias(true);      mainPaint.setStrokeWidth(1);      mainPaint.setStyle(Paint.Style.STROKE);  }    @Override  protected void onSizeChanged(int w, int h, int oldw, int oldh) {      radius=Math.min(w,h)/2*0.9f;      centerX=w/2;      centerY=h/2;      //一旦size发生改变,重新绘制      postInvalidate();      super.onSizeChanged(w, h, oldw, oldh);  }    @Override  protected void onDraw(Canvas canvas) {      drawPolygon(canvas);  }    /**   * 绘制多边形   * @param canvas   */  private void drawPolygon(Canvas canvas){      Path path=new Path();      //1度=1*PI/180   360度=2*PI   那么我们每旋转一次的角度为2*PI/内角个数      //中心与相邻两个内角相连的夹角角度      angle= (float) (2*Math.PI/count);      //每个蛛丝之间的间距      float r= radius/(count-1);      for (int i = 0; i < count; i++) {          //当前半径          float curR=r*i;          path.reset();          for (int j = 0; j < count; j++) {              if(j==0){                  path.moveTo(centerX+curR,centerY);              }else {                  //对于直角三角形sin(x)是对边比斜边,cos(x)是底边比斜边,tan(x)是对边比底边                  //因此可以推导出:底边(x坐标)=斜边(半径)*cos(夹角角度)                  //               对边(y坐标)=斜边(半径)*sin(夹角角度)                  float x = (float) (centerX+curR*Math.cos(angle*j));                  float y = (float) (centerY+curR*Math.sin(angle*j));                  path.lineTo(x,y);              }          }          path.close();          canvas.drawPath(path,mainPaint);      }</code></pre>    <p>绘制蜘蛛网络其实就是绘制指定边数的正多边形,这一步比较简单,比较难的可能就是每个顶点的算法,相关注释我都写了,还有一张来自互联网的图以助于思考,如下:</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/237f326ca5f17d18bfbefdbcc2f2ea0a.jpg"></p>    <p>多边形夹角示意图</p>    <p>绘制出的多边形成品如下:</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/c25915ca11ad9d7fabe474b37681ef83.gif"></p>    <p>多边形效果.gif</p>    <p>动画效果只是写了 set 方法,用 handler 实现,代码如下:</p>    <pre>  <code class="language-java">//设置数值种类  public void setCount(int count) {      this.count = count;      postInvalidate();  }    //设置蜘蛛网颜色  public void setMainPaint(Paint mainPaint) {      this.mainPaint = mainPaint;      postInvalidate();  }</code></pre>    <p>调用方法:</p>    <pre>  <code class="language-java">mainPaint=new Paint();  mainPaint.setAntiAlias(true);  mainPaint.setStrokeWidth(1);  mainPaint.setStyle(Paint.Style.STROKE);  Handler handler=new Handler();  for (int i = 3; i < 20; i++) {  final int finalI = i;  handler.postDelayed(new Runnable() {      @Override      public void run() {          mRdv.setCount(finalI);          mainPaint.setStrokeWidth(finalI);          mRdv.setMainPaint(mainPaint);      }  },i*300);  }</code></pre>    <h2>第二步:绘制对角线</h2>    <pre>  <code class="language-java">/**   * 绘制直线   */  private void drawLines(Canvas canvas){      Path path=new Path();      for (int i = 0; i < count; i++) {          path.reset();          path.moveTo(centerX,centerY);          float x = (float) (centerX+radius*Math.cos(angle*i));          float y = (float) (centerY+radius*Math.sin(angle*i));          path.lineTo(x,y);          canvas.drawPath(path,mainPaint);      }  }</code></pre>    <p>这一步比较简单,就是将中心点和各个顶点连接起来,效果如下:</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/4464cdf2bbee7e5ef2bcbe1ce94b5b1f.gif"></p>    <p>多边形效果.gif</p>    <h2>第三步:绘制标题文字</h2>    <pre>  <code class="language-java">/**   * 绘制标题文字   *   * @param canvas   */  private void drawTitle(Canvas canvas) {      if (count != titles.size()) {          return;      }      //相关知识点:http://mikewang.blog.51cto.com/3826268/871765/      Paint.FontMetrics fontMetrics = textPaint.getFontMetrics();      float fontHeight = fontMetrics.descent - fontMetrics.ascent;      //绘制文字时不让文字和雷达图形交叉,加大绘制半径      float textRadius = radius + fontHeight;      double pi = Math.PI;      for (int i = 0; i < count; i++) {          float x = (float) (centerX + textRadius * Math.cos(angle * i));          float y = (float) (centerY + textRadius * Math.sin(angle * i));          //当前绘制标题所在顶点角度          float degrees = angle * i;          //从右下角开始顺时针画起,与真实坐标系相反          if (degrees >= 0 && degrees < pi / 2) {//第四象限              float dis=textPaint.measureText(titles.get(i))/(titles.get(i).length()-1);              canvas.drawText(titles.get(i), x+dis, y, textPaint);          } else if (degrees >= pi / 2 && degrees < pi) {//第三象限              float dis=textPaint.measureText(titles.get(i))/(titles.get(i).length()-1);              canvas.drawText(titles.get(i), x-dis, y, textPaint);          } else if (degrees >= pi && degrees < 3 * pi / 2) {//第二象限              float dis=textPaint.measureText(titles.get(i))/(titles.get(i).length());              canvas.drawText(titles.get(i), x-dis, y, textPaint);          } else if (degrees >= 3 * pi / 2 && degrees <= 2 * pi) {//第一象限              canvas.drawText(titles.get(i), x, y, textPaint);          }        }    }</code></pre>    <p>效果如下:</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/90bdbca949ef9940c96ecd152b677484.png"></p>    <p>image.png</p>    <h2>第四步:绘制覆盖区域</h2>    <p>要绘制覆盖区域,首先要指定最大值和每个分类的具体数值,有了这些数值之后,就可以绘制了。</p>    <p>代码如下:</p>    <pre>  <code class="language-java">/**   * 绘制覆盖区域   */  private void drawRegion(Canvas canvas){      valuePaint.setAlpha(255);      Path path=new Path();      for (int i = 0; i < count; i++) {          //计算该数值与最大值比例          Double perCenter = data.get(i)/maxValue;          //小圆点所在位置距离圆心的距离          double perRadius=perCenter*radius;          float x = (float) (centerX + perRadius * Math.cos(angle * i));          float y = (float) (centerY + perRadius * Math.sin(angle * i));          if(i==0){              path.moveTo(x,y);          }else {              path.lineTo(x,y);          }          //绘制小圆点          canvas.drawCircle(x,y,10,valuePaint);      }      //闭合覆盖区域      path.close();      valuePaint.setStyle(Paint.Style.STROKE);      //绘制覆盖区域外的连线      canvas.drawPath(path, valuePaint);      //填充覆盖区域      valuePaint.setAlpha(128);      valuePaint.setStyle(Paint.Style.FILL);      canvas.drawPath(path,valuePaint);  }</code></pre>    <p>看一下效果:</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/2af8472ae3ac09e792739129a9ed5650.png"></p>    <p>image.png</p>    <p>再来看一下动态的效果吧:</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/23bdeecc8d4a00519d634bbb67986aff.gif"></p>    <p>多边形效果.gif</p>    <h2>总结</h2>    <p>终于完成了,全部代码在下面:</p>    <p><a href="/misc/goto?guid=4959747846465631610" rel="nofollow,noindex">Android雷达图全部代码</a></p>    <p>主要是参考 crazy__chen 大神的博客,链接贴在下面,做了一遍其实还蛮简单的,这个控件还有很多不完善的,如果实际使用需要改善的地方还有很多,如果有不足希望大家可以告诉我,谢谢!!</p>    <p>参考资料</p>    <p><a href="/misc/goto?guid=4959657767360445048" rel="nofollow,noindex">Android雷达图(蜘蛛网图)绘制</a></p>    <p><a href="/misc/goto?guid=4959747846595334007" rel="nofollow,noindex">Path之基本操作</a></p>    <p> </p>    <p>来自:http://www.jianshu.com/p/afe7bfe7a3ee</p>    <p> </p>    
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