Android实现带有指示器的进度条

    //获取自定义属性
    TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.HorizontalProgressBar);
    mTextSize = ta.getDimension(R.styleable.HorizontalProgressBar_hpb_textSize, Utils.sp2px(context, 12));
    mTextColor = ta.getColor(R.styleable.HorizontalProgressBar_hpb_textColor, Color.parseColor("#FFFFFF"));
    currentProgress = ta.getFloat(R.styleable.HorizontalProgressBar_hpb_progress, 0);
    mTextLeftPadding = (int) ta.getDimension(R.styleable.HorizontalProgressBar_hpb_textLeftPadding, Utils.sp2px(context, 5));
    mTextRightPadding = (int) ta.getDimension(R.styleable.HorizontalProgressBar_hpb_textRightPadding, Utils.sp2px(context, 5));
    mTextTopPadding = (int) ta.getDimension(R.styleable.HorizontalProgressBar_hpb_textTopPadding, Utils.sp2px(context, 5));
    mTextBottomPadding = (int) ta.getDimension(R.styleable.HorizontalProgressBar_hpb_textBottomPadding, Utils.sp2px(context, 5));
    mCenterPadding = (int) ta.getDimension(R.styleable.HorizontalProgressBar_hpb_centerPadding, Utils.sp2px(context, 5));
    mProgressHeight = (int) ta.getDimension(R.styleable.HorizontalProgressBar_hpb_progressBarHeight, Utils.sp2px(context, 2));
    mBackgroundColor = ta.getColor(R.styleable.HorizontalProgressBar_hpb_progressBarBackgroundColor, Color.parseColor("#E8E8E8"));
    mForegroundColor = ta.getColor(R.styleable.HorizontalProgressBar_hpb_progressBarForegroundColor, Color.parseColor("#912CEE"));
    ta.recycle();

    //进度条条背景色画笔初始化
    mBackgroundPaint = new Paint();
    mBackgroundPaint.setColor(mBackgroundColor);
    mBackgroundPaint.setStrokeCap(Paint.Cap.ROUND);
    mBackgroundPaint.setStrokeWidth(mProgressHeight);
    mBackgroundPaint.setAntiAlias(true);

    //指示器Path画笔初始化
    mPathPaint = new Paint();
    mPathPaint.setColor(mForegroundColor);
    mPathPaint.setStrokeCap(Paint.Cap.ROUND);
    mPathPaint.setPathEffect(new CornerPathEffect(Utils.dp2px(getContext(), 2)));
    mPathPaint.setAntiAlias(true);

    //进度条前景色画笔初始化
    mProgressPaint = new Paint();
    mProgressPaint.setColor(mForegroundColor);
    mProgressPaint.setStrokeWidth(mProgressHeight);
    mProgressPaint.setStrokeCap(Paint.Cap.ROUND);
    mProgressPaint.setAntiAlias(true);

    //进度值文案画笔初始化
    mTextPaint = new Paint();
    mTextPaint.setColor(mTextColor);
    mTextPaint.setTextSize(mTextSize);
    mTextPaint.setStyle(Paint.Style.FILL);

    //指示器Path初始化
    mPath = new Path();

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    int widthMode = MeasureSpec.getMode(widthMeasureSpec);
    int width = MeasureSpec.getSize(widthMeasureSpec);

    int heightMode = MeasureSpec.getMode(heightMeasureSpec);
    int height = MeasureSpec.getSize(heightMeasureSpec);

    setMeasuredDimension(measureWidth(widthMode, width), measureHeight(heightMode, height));
}

/**
 * 测量宽度
 *
 * @param mode
 * @param width
 * @return
 */
private int measureWidth(int mode, int width) {
    switch (mode) {
        case MeasureSpec.UNSPECIFIED:
        case MeasureSpec.AT_MOST:
        case MeasureSpec.EXACTLY:
            mWidth = width;
            break;
    }
    return mWidth;
}

/**
 * 测量高度
 *
 * @param mode
 * @param height
 * @return
 */
private int measureHeight(int mode, int height) {
    switch (mode) {
        case MeasureSpec.UNSPECIFIED:
        case MeasureSpec.AT_MOST:
        case MeasureSpec.EXACTLY:
            mHeight = height;
            break;
    }
    return mHeight;
}

//文字测量
private void measureText(String text) {
    Rect rect = new Rect();
    mTextPaint.getTextBounds(text, 0, text.length(), rect);
    mTextWidth = rect.width();
    mTextHeight = rect.height();
}

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    mIndicatorWidth = mTextLeftPadding   mTextWidth   mTextRightPadding;
    mIndicatorHeight = mTextTopPadding   mTextHeight   mTextBottomPadding;

    float backgroundProgressBarStartX = (float) (1.0 * mIndicatorWidth / 2);
    float backgroundProgressBarEndX = mWidth - mIndicatorWidth / 2;

    float foregroundProgress = (float) (1.0 * (mWidth - mIndicatorWidth) * currentProgress / 100);

    float foregroundProgressBarStartX = (float) (1.0 * mIndicatorWidth / 2);
    float foregroundProgressBarEndX = foregroundProgressBarStartX   foregroundProgress;

    Log.e(TAG, "backgroundProgressBarStartX----"   backgroundProgressBarStartX
              "----backgroundProgressBarEndX----"   backgroundProgressBarEndX
              "----foregroundProgress----"   foregroundProgress
              "----foregroundProgressBarStartX----"   foregroundProgressBarStartX
              "----foregroundProgressBarEndX----"   foregroundProgressBarEndX
    );

    float progressX = foregroundProgress;
    float progressY = (float) (mCenterPadding   mIndicatorHeight * 1.5);


    //进度背景
    canvas.drawLine(backgroundProgressBarStartX, progressY, backgroundProgressBarEndX, progressY, mBackgroundPaint);

    //进度前景色
    canvas.drawLine(foregroundProgressBarStartX, progressY, foregroundProgressBarEndX, progressY, mProgressPaint);

    //指示器
    drawPath(canvas, progressX, 45);

    //文字
    drawText(canvas, mTextProgress, progressX);
}

/**
 * 绘制指示器
 *
 * @param canvas
 * @param progressX
 */
private void drawPath(Canvas canvas, float progressX, float rotateAngle) {
    mPath.reset();

    mPath.moveTo(progressX, 0); //1
    mPath.lineTo(progressX   mIndicatorWidth, 0); //2
    mPath.lineTo(progressX   mIndicatorWidth, mIndicatorHeight); //3
    mPath.lineTo((float) (progressX   mIndicatorWidth * 0.75), mIndicatorHeight); //4
    mPath.lineTo((float) (progressX   mIndicatorWidth * 0.5), (float) (mIndicatorHeight * 1.5)); //5
    mPath.lineTo((float) (progressX   mIndicatorWidth * 0.25), mIndicatorHeight); //6
    mPath.lineTo(progressX, mIndicatorHeight);//7
    mPath.close();

    canvas.drawPath(mPath, mPathPaint);
}

/**
 * 计算绘制文字时的基线到中轴线的距离
 *
 * @param p
 * @return 基线和centerY的距离
 */
public float getBaseline(Paint p) {
    Paint.FontMetrics fontMetrics = p.getFontMetrics();
    return (fontMetrics.descent - fontMetrics.ascent) / 2 - fontMetrics.descent;
}

/**
 * 绘制文字
 *
 * @param canvas
 * @param text
 * @param progressX
 */
private void drawText(Canvas canvas, String text, float progressX) {
    float baseline = getBaseline(mTextPaint);
    float textY = mTextTopPadding   mTextHeight / 2   baseline;
    canvas.drawText(text, progressX   mTextTopPadding, textY, mTextPaint);
}