Android仿支付宝上芝麻信用分雷达图

一、首先看下支付宝上芝麻信用分的效果图：

二、思路

     1、确定雷达图中心点坐标

     2、绘制多边形及连接线

     3、根据维度值绘制覆盖区域

     4、绘制分数

     5、绘制每个维度的标题文字和图标

三、实现

获取布局的中心坐标

在onSizeChanged(int w, int h, int oldw, int oldh)方法里面，根据View的长宽，计算出雷达图的半径（这里取布局宽高最小值的四分之一，可以自定义），获取整个布局的中心坐标。

public class CreditScoreView extends View {

 //数据个数
 private int dataCount = 5;
 //每个角的弧度
 private float radian = (float) (Math.PI * 2 / dataCount);
 //雷达图半径
 private float radius;
 //中心X坐标
 private int centerX;
 //中心Y坐标
 private int centerY;
 //各维度标题
 private String[] titles = {"履约能力", "信用历史", "人脉关系", "行为偏好", "身份特质"};
 //各维度图标
 private int[] icons = {R.mipmap.ic_performance, R.mipmap.ic_history, R.mipmap.ic_contacts,
   R.mipmap.ic_predilection, R.mipmap.ic_identity};
 //各维度分值
 private float[] data = {170, 180, 160, 170, 180};
 //数据最大值
 private float maxValue = 190;
 //雷达图与标题的间距
 private int radarMargin = DensityUtils.dp2px(getContext(), 15);
 //雷达区画笔
 private Paint mainPaint;
 //数据区画笔
 private Paint valuePaint;
 //分数画笔
 private Paint scorePaint;
 //标题画笔
 private Paint titlePaint;
 //图标画笔
 private Paint iconPaint;
 //分数大小
 private int scoreSize = DensityUtils.dp2px(getContext(), 28);
 //标题文字大小
 private int titleSize = DensityUtils.dp2px(getContext(), 13);

 ...

 @Override
 protected void onSizeChanged(int w, int h, int oldw, int oldh) {
  //雷达图半径
  radius = Math.min(h, w) / 2 * 0.5f;
  //中心坐标
  centerX = w / 2;
  centerY = h / 2;
  postInvalidate();
  super.onSizeChanged(w, h, oldw, oldh);
 }

 ...
}

绘制多边形和连接线

主要看下getPoint方法，此方法封装了获取雷达图上各个点坐标的计算逻辑。

/**
 * 绘制多边形
 *
 * @param canvas 画布
 */
private void drawPolygon(Canvas canvas) {
 Path path = new Path();
 for (int i = 0; i < dataCount; i++) {
  if (i == 0) {
   path.moveTo(getPoint(i).x, getPoint(i).y);
  } else {
   path.lineTo(getPoint(i).x, getPoint(i).y);
  }
 }

 //闭合路径
 path.close();
 canvas.drawPath(path, mainPaint);
}

/**
 * 绘制连接线
 *
 * @param canvas 画布
 */
private void drawLines(Canvas canvas) {
 Path path = new Path();
 for (int i = 0; i < dataCount; i++) {
  path.reset();
  path.moveTo(centerX, centerY);
  path.lineTo(getPoint(i).x, getPoint(i).y);
  canvas.drawPath(path, mainPaint);
 }
}

getPoint方法，参数radarMargin与percent在此步骤赋予默认值。

/**
 * 获取雷达图上各个点的坐标
 *
 * @param position 坐标位置（右上角为0，顺时针递增）
 * @return 坐标
 */
private Point getPoint(int position) {
 return getPoint(position, 0, 1);
}

/**
 * 获取雷达图上各个点的坐标（包括维度标题与图标的坐标）
 *
 * @param position 坐标位置
 * @param radarMargin 雷达图与维度标题的间距
 * @param percent  覆盖区的的百分比
 * @return 坐标
 */
private Point getPoint(int position, int radarMargin, float percent) {
 int x = 0;
 int y = 0;

 if (position == 0) {
  x = (int) (centerX + (radius + radarMargin) * Math.sin(radian) * percent);
  y = (int) (centerY - (radius + radarMargin) * Math.cos(radian) * percent);

 } else if (position == 1) {
  x = (int) (centerX + (radius + radarMargin) * Math.sin(radian / 2) * percent);
  y = (int) (centerY + (radius + radarMargin) * Math.cos(radian / 2) * percent);

 } else if (position == 2) {
  x = (int) (centerX - (radius + radarMargin) * Math.sin(radian / 2) * percent);
  y = (int) (centerY + (radius + radarMargin) * Math.cos(radian / 2) * percent);

 } else if (position == 3) {
  x = (int) (centerX - (radius + radarMargin) * Math.sin(radian) * percent);
  y = (int) (centerY - (radius + radarMargin) * Math.cos(radian) * percent);

 } else if (position == 4) {
  x = centerX;
  y = (int) (centerY - (radius + radarMargin) * percent);
 }

 return new Point(x, y);
}

多边形和连接线

绘制覆盖区域

/**
 * 绘制覆盖区域
 *
 * @param canvas 画布
 */
private void drawRegion(Canvas canvas) {
 Path path = new Path();

 for (int i = 0; i < dataCount; i++) {
  //计算百分比
  float percent = data[i] / maxValue;
  int x = getPoint(i, 0, percent).x;
  int y = getPoint(i, 0, percent).y;
  if (i == 0) {
   path.moveTo(x, y);
  } else {
   path.lineTo(x, y);
  }
 }

 //绘制填充区域的边界
 path.close();
 valuePaint.setStyle(Paint.Style.STROKE);
 canvas.drawPath(path, valuePaint);

 //绘制填充区域
 valuePaint.setStyle(Paint.Style.FILL_AND_STROKE);
 canvas.drawPath(path, valuePaint);
}

覆盖区域

绘制分数

/**
 * 绘制分数
 *
 * @param canvas 画布
 */
private void drawScore(Canvas canvas) {
 int score = 0;
 //计算总分
 for (int i = 0; i < dataCount; i++) {
  score += data[i];
 }
 canvas.drawText(score + "", centerX, centerY + scoreSize / 2, scorePaint);
}

分数

绘制标题

/**
 * 绘制标题
 *
 * @param canvas 画布
 */
private void drawTitle(Canvas canvas) {
 for (int i = 0; i < dataCount; i++) {
  int x = getPoint(i, radarMargin, 1).x;
  int y = getPoint(i, radarMargin, 1).y;

  Bitmap bitmap = BitmapFactory.decodeResource(getResources(), icons[i]);
  int iconHeight = bitmap.getHeight();
  float titleWidth = titlePaint.measureText(titles[i]);

  //底下两个角的坐标需要向下移动半个图片的位置（1、2）
  if (i == 1) {
   y += (iconHeight / 2);
  } else if (i == 2) {
   x -= titleWidth;
   y += (iconHeight / 2);
  } else if (i == 3) {
   x -= titleWidth;
  } else if (i == 4) {
   x -= titleWidth / 2;
  }
  canvas.drawText(titles[i], x, y, titlePaint);
 }
}

标题

绘制图标

/**
 * 绘制图标
 *
 * @param canvas 画布
 */
private void drawIcon(Canvas canvas) {
 for (int i = 0; i < dataCount; i++) {
  int x = getPoint(i, radarMargin, 1).x;
  int y = getPoint(i, radarMargin, 1).y;

  Bitmap bitmap = BitmapFactory.decodeResource(getResources(), icons[i]);
  int iconWidth = bitmap.getWidth();
  int iconHeight = bitmap.getHeight();
  float titleWidth = titlePaint.measureText(titles[i]);

  //上面获取到的x、y坐标是标题左下角的坐标
  //需要将图标移动到标题上方居中位置
  if (i == 0) {
   x += (titleWidth - iconWidth) / 2;
   y -= (iconHeight + getTextHeight(titlePaint));
  } else if (i == 1) {
   x += (titleWidth - iconWidth) / 2;
   y -= (iconHeight / 2 + getTextHeight(titlePaint));
  } else if (i == 2) {
   x -= (iconWidth + (titleWidth - iconWidth) / 2);
   y -= (iconHeight / 2 + getTextHeight(titlePaint));
  } else if (i == 3) {
   x -= (iconWidth + (titleWidth - iconWidth) / 2);
   y -= (iconHeight + getTextHeight(titlePaint));
  } else if (i == 4) {
   x -= iconWidth / 2;
   y -= (iconHeight + getTextHeight(titlePaint));
  }

  canvas.drawBitmap(bitmap, x, y, titlePaint);
 }
}
/**
 * 获取文本的高度
 *
 * @param paint 文本绘制的画笔
 * @return 文本高度
 */
private int getTextHeight(Paint paint) {
 Paint.FontMetrics fontMetrics = paint.getFontMetrics();
 return (int) (fontMetrics.descent - fontMetrics.ascent);
}

图标

总结

好了，到这里主要的绘制工作就完成了，有些图标实在找不到，就用相似的代替了。希望这篇文章的内容对各位Android开发者们能有所帮助，如果有疑问大家可以留言交流。