code: private void drawForegrounds(Point[] points, Canvas canvas) {
          Paint paint = new Paint();
          paint.setAntiAlias(true);
          paint.setStyle(Paint.Style.FILL);
          for (int i = 0; i < _corners; i++) {
              Path path = new Path();
              path.moveTo(points[i].x, points[i].y);
              path.lineTo(center.x, center.y);
              if (i + 1 >= _corners) {
                  path.lineTo(points[0].x, points[0].y);
              } else {
                  path.lineTo(points[i + 1].x, points[i + 1].y);
              }
              path.close();
              paint.setColor(_foreground_colors[i]);
              canvas.drawPath(path, paint);
          }
      }
docs: 根据前景色的顶点画前景色块