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。