实际效果图

image

核心#代码

public FlagsPieView(Context c, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(c, attrs, defStyleAttr);

    this.context = c;
    TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.PieView);
    mRadius = typedArray.getDimension(R.styleable.PieView_radius, 150);
    mBorderLength = typedArray.getDimension(R.styleable.PieView_border_length, 15);
    mTextColor = typedArray.getColor(R.styleable.PieView_textColor, Color.BLACK);
    mTextSize = typedArray.getDimension(R.styleable.PieView_textSize, 30);
    centerTitle = typedArray.getString(R.styleable.PieView_centerTitle);
    centerHint = typedArray.getString(R.styleable.PieView_centerHint);
    typedArray.recycle();
    init();
}

/**
 * 测量文字的高度
 */
public float measureTextHeight(Paint paint) {
    float height = 0f;
    if (null == paint) {
        return height;
    }
    Paint.FontMetrics fontMetrics = paint.getFontMetrics();
    height = fontMetrics.descent - fontMetrics.ascent;
    return height;
}

private void init() {
    //外圆
    mPiePaint = new Paint();
    mPiePaint.setAntiAlias(true);
    mPiePaint.setStyle(Paint.Style.STROKE);
    mPiePaint.setStrokeWidth(mBorderLength*0.6f);

    //内圆
    mInnerPiePaint = new Paint();
    mInnerPiePaint.setAntiAlias(true);
    mInnerPiePaint.setStyle(Paint.Style.FILL);

    //绘制大圆的矩形
    preRectF = new RectF();
    //绘制内圆的矩形
    preInnerRectF = new RectF();

    //弧度小方格
    mBlockAgePaint = new Paint();
    mBlockAgePaint.setAntiAlias(true);
    mBlockAgePaint.setStyle(Paint.Style.FILL);
    mBlockAgePaint.setStrokeWidth(mTextSize);
    //右侧小方格 说明
    rectBlockage = new Rect();
    //文字画笔
    mTextPaint = new Paint();
    mTextPaint.setAntiAlias(true);
    mTextPaint.setColor(mTextColor);
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    mWidth = resolveSize(DensityUtils.getScreenWidth(context), widthMeasureSpec);
    mHeight = resolveSize((int) (DensityUtils.getScreenWidth(context) / 2), heightMeasureSpec);
    setMeasuredDimension(mWidth, mHeight);
    //TODO 最大半径
    radiusMax = (Math.min(mHeight/2, mWidth/2)-mBorderLengt);
}

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    drawPie(canvas, preRectF);
    drawCenter(canvas, preInnerRectF);
    drawBlockAge(canvas);
}

//绘制饼图
private void drawPie(Canvas canvas, RectF preRectF) {
    //兼容 短边的一半 作半径
    //得到实际半径
    float mRadiusValue = Math.min(mRadius, radiusMax);
    //避免创建对象
    preRectF.left = getPaddingLeft() + mLeft;
    preRectF.top = (mHeight - mRadiusValue * 2-getPaddingTop()*2) / 2 + getPaddingTop();
    preRectF.right = preRectF.left + mRadiusValue * 2;
    preRectF.bottom = preRectF.top + mRadiusValue * 2;
    float currentAngle = 0;//当前角度
    for (int i = 0; i < mData.size(); i++) {
        PieData pieData = mData.get(i);
        mPiePaint.setColor(Color.parseColor(mData.get(i).getGetColor()));
        canvas.drawArc(preRectF, currentAngle, pieData.getPercentage() * 360, false, mPiePaint);
        currentAngle += pieData.getPercentage() * 360;
    }
    //圆内文本
    preInnerRectF.left = preRectF.left + mBorderLength / 3;
    preInnerRectF.top = preRectF.top + mBorderLength / 3;
    preInnerRectF.right = preRectF.right - mBorderLength / 3;
    preInnerRectF.bottom = preRectF.bottom - mBorderLength / 3;
}

//绘制小矩形和文字
private void drawBlockAge(Canvas canvas) {
    int areaHeight = DensityUtils.dip2px(context, 8);
    int currentX = (int) (preRectF.right + mBorderLength * 3);
    float textHeight = measureTextHeight(mTextPaint);
    //每一份
    int count = mData.size();
    //内容高度
    float contenHeight = count * (textHeight + areaHeight) - areaHeight;
    float centerYResult = (mHeight - contenHeight) / 2;
    float currentY = centerYResult + 2;
    //测量文本的高度  0,1,2
    for (int i = 0; i < count; i++) {
        PieData pieData = mData.get(i);
        float diff = i > 0 ? (textHeight + areaHeight) : 0;
        currentY += diff;
        mBlockAgePaint.setColor(Color.parseColor(mData.get(i).getGetColor()));
        rectBlockage.left = currentX;
        rectBlockage.top = (int) (currentY + 2);
        rectBlockage.right = (int) (currentX + textHeight / 1.5);
        rectBlockage.bottom = (int) (currentY + areaHeight);
        canvas.drawRect(rectBlockage, mBlockAgePaint);

        DecimalFormat fNum = new DecimalFormat("#0.0");
        String percentage = fNum.format(pieData.getPercentage() * 100);
        String title = pieData.getTitle() + " (" + percentage + "%)";
       //mTextPaint.setColor(Color.parseColor(mData.get(i).getGetColor()));
        canvas.drawText(title, currentX + mBorderLength * 1.4f,
                currentY + rectBlockage.bottom - rectBlockage.top, mTextPaint);
    }
}

/**
 * 绘制圆中心文字
 *
 * @param rectF 基于圆环处理内圆
 */
private void drawCenter(Canvas canvas, RectF rectF) {
    mInnerPiePaint.setColor(Color.WHITE);
    canvas.drawArc(rectF, 0, 360, true, mInnerPiePaint);
    mTextPaint.setColor(Color.parseColor("#333333"));
    mTextPaint.setFakeBoldText(true);
    mTextPaint.setTextSize(DensityUtils.sp2px(context, 12));
    //中心title
    textWidth = mTextPaint.measureText(centerTitle);
    textHeight = measureTextHeight(mTextPaint);
    int textX = (int) (rectF.left + (rectF.right - rectF.left) / 2);
    canvas.drawText(centerTitle, textX - textWidth / 2, mHeight / 2, mTextPaint);
    //hint title
    mTextPaint.setFakeBoldText(false);
    mTextPaint.setTextSize(DensityUtils.sp2px(context, 9));
    mTextPaint.setColor(Color.parseColor("#777777"));
    //hint
    textHintWidth = mTextPaint.measureText(centerHint);
    canvas.drawText(centerHint, textX - textHintWidth / 2, mHeight / 2 + textHeight, mTextPaint);
}

public void setData(List<PieData> data) {
    mData = data;
    postInvalidate();
}

How Use

//xml
<com.lib_custom_view.view.FlagsPieView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/assets_pie_chart_now"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="15dp"
    android:background="@drawable/module_view_bg_color"
    app:border_length="10dp"
    app:centerHint="Android技术栈"
    app:centerTitle="2021，牛气冲天"
    app:radius="60dp"
    app:textSize="13dp" />

    //Activity
    val pieDataList: ArrayList<PieData> = ArrayList()
    pieDataList.add(PieData("HotFix热修复", 0.15.toFloat(), "#F83130"))
    pieDataList.add(PieData("Kotlin", 0.15.toFloat(), "#FC6E1E"))
    pieDataList.add(PieData("ExecutorService", 0.30.toFloat(), "#FEC01D"))
    pieDataList.add(PieData("Okhttp", 0.20.toFloat(), "#62D54E"))
    pieDataList.add(PieData("IntentService", 0.20.toFloat(), "#34DFC4"))
    assets_pie_chart_now.setData(pieDataList)

小技巧

   1.圆右边的内容（方块+文本）相对于圆进行偏移
   2.多个方块统一居中公式：第一个方块的top值=（View总高度-多个方块总高度）/2，其他依次+自身+间隔
   3.最大半径限制，不可超过View总高度的一半
   4.初始化的时候创建好对象容器
   5.不可变得文本信息放到自定义属性中去
   ………