安卓(Android)开发之自定义饼状图

public class PieData {
 
  private String name;  // 名字
  private float value;  // 数值
  private float percentage; // 百分比
 
  private int color = 0;  // 颜色
  private float angle = 0; // 角度
 
  public PieData(@NonNull String name, @NonNull float value) {
   this.name = name;
   this.value = value;
  }
 }

 public class PieView extends View {
  // 颜色表
  private int[] mColors = {0xFFCCFF00, 0xFF6495ED, 0xFFE32636, 0xFF800000, 0xFF808000, 0xFFFF8C69, 0xFF808080,
    0xFFE6B800, 0xFF7CFC00};
  // 饼状图初始绘制角度
  private float mStartAngle = 0;
  // 数据
  private ArrayList<PieData> mData;
  // 宽高
  private int mWidth, mHeight;
  // 画笔
  private Paint mPaint = new Paint();
 
  public PieView(Context context) {
   this(context, null);
  }
 
  public PieView(Context context, AttributeSet attrs) {
   super(context, attrs);
   mPaint.setStyle(Paint.Style.FILL);
   mPaint.setAntiAlias(true);
  }
 
  @Override
  protected void onSizeChanged(int w, int h, int oldw, int oldh) {
   super.onSizeChanged(w, h, oldw, oldh);
   mWidth = w;
   mHeight = h;
  }
 
  @Override
  protected void onDraw(Canvas canvas) {
   super.onDraw(canvas);
   if (null == mData)
    return;
   float currentStartAngle = mStartAngle;     // 当前起始角度
   canvas.translate(mWidth / 2, mHeight / 2);    // 将画布坐标原点移动到中心位置
   float r = (float) (Math.min(mWidth, mHeight) / 2 * 0.8); // 饼状图半径
   RectF rect = new RectF(-r, -r, r, r);      // 饼状图绘制区域
 
   for (int i = 0; i < mData.size(); i++) {
    PieData pie = mData.get(i);
    mPaint.setColor(pie.getColor());
    canvas.drawArc(rect, currentStartAngle, pie.getAngle(), true, mPaint);
    currentStartAngle += pie.getAngle();
   }
 
  }
 
  // 设置起始角度
  public void setStartAngle(int mStartAngle) {
   this.mStartAngle = mStartAngle;
   invalidate(); // 刷新
  }
 
  // 设置数据
  public void setData(ArrayList<PieData> mData) {
   this.mData = mData;
   initDate(mData);
   invalidate(); // 刷新
  }
 
  // 初始化数据
  private void initDate(ArrayList<PieData> mData) {
   if (null == mData || mData.size() == 0) // 数据有问题 直接返回
    return;
 
   float sumValue = 0;
   for (int i = 0; i < mData.size(); i++) {
    PieData pie = mData.get(i);
 
    sumValue += pie.getValue();  //计算数值和
 
    int j = i % mColors.length;  //设置颜色
    pie.setColor(mColors[j]);
   }
 
   float sumAngle = 0;
   for (int i = 0; i < mData.size(); i++) {
    PieData pie = mData.get(i);
 
    float percentage = pie.getValue() / sumValue; // 百分比
    float angle = percentage * 360;     // 对应的角度
 
    pie.setPercentage(percentage);     // 记录百分比
    pie.setAngle(angle);       // 记录角度大小
    sumAngle += angle;
 
    Log.i("angle", "" + pie.getAngle());
   }
  }