Android自定义seekbar:无法在OnDraw方法中获得拇指的准确位置

我试图通过扩展AppCompatSeekBar来实现自定义SeekBar。我的意图是在拇指上画一些元素。我试图得到这个拇指的界限，但在第一次抽签时它是不准确的

以下是我对onDraw方法的操作：

protected void onDraw(Canvas canvas) {
    /*Rotates the seekbar, as I need it to be vertical*/
    canvas.rotate(-90);
    canvas.translate(-getHeight(), 0);
    super.onDraw(canvas);
    canvas.save();

    Paint paint = new Paint();
    paint.setColor(ContextCompat.getColor(getContext(),R.color.accent));
    paint.setStrokeWidth(2);
    paint.setStyle(Paint.Style.STROKE);

    Rect thumbBounds = this.getThumb().getBounds();
    int offset = getThumbOffset();
    Log.d(TAG,"ThumbOffset:"+offset+ " RectX:" + thumbBounds.centerX());
    thumbBounds.offset(offset,0);

    canvas.drawRect(thumbBounds, paint);        
    canvas.drawText(Integer.toString(getProgress()),thumbBounds.centerY(),-thumbBounds.centerX(),textPaint);
    canvas.restore();
}

    //Calculating the size of the text
    text = String.valueOf(getProgress() - maxValue);
    textPaint.getTextBounds(text,0,text.length(),textBounds);

    //The height of the displacement area of our bar (the height - the padding - the thumb size)
    int bottomPadding = getPaddingLeft() - getThumbOffset();
    int topPadding = getPaddingRight() - getThumbOffset();
    int height = getHeight() - bottomPadding - topPadding;

    float progressRatio = (float) getProgress() / getMax();
    float thumbOffset = getThumb().getIntrinsicWidth() * (.5f - progressRatio);

    // In our rotated canvas, positive x is higher, positive Y is more to the left
    float thumbX = progressRatio * height + bottomPadding + thumbOffset;
    float thumbY = getWidth() / 2f;
    //Since we rotate the canvas again when drawing the text, we need to translate the coords for the text
    float textX = thumbY - textBounds.width() / 2f;
    float textY = -(thumbX - textBounds.height() / 2f);

第一次加载时，看起来是这样的（不正确）

在我拖动拇指后，看起来像这样（正确）：

此外，如果我将活动最小化几次，边界就会变得疯狂：

因此，我假设我在动画中得到了几帧的拇指边界。我的问题是，我如何补偿这一点

---

谢谢

虽然我找不到一种直接从拇指获得位置的好方法，但我找到了一种间接获得位置的好方法。我只需要调整垂直条的测量值。将此代码放入onDraw方法中：

protected void onDraw(Canvas canvas) {
    /*Rotates the seekbar, as I need it to be vertical*/
    canvas.rotate(-90);
    canvas.translate(-getHeight(), 0);
    super.onDraw(canvas);
    canvas.save();

    Paint paint = new Paint();
    paint.setColor(ContextCompat.getColor(getContext(),R.color.accent));
    paint.setStrokeWidth(2);
    paint.setStyle(Paint.Style.STROKE);

    Rect thumbBounds = this.getThumb().getBounds();
    int offset = getThumbOffset();
    Log.d(TAG,"ThumbOffset:"+offset+ " RectX:" + thumbBounds.centerX());
    thumbBounds.offset(offset,0);

    canvas.drawRect(thumbBounds, paint);        
    canvas.drawText(Integer.toString(getProgress()),thumbBounds.centerY(),-thumbBounds.centerX(),textPaint);
    canvas.restore();
}

    //Calculating the size of the text
    text = String.valueOf(getProgress() - maxValue);
    textPaint.getTextBounds(text,0,text.length(),textBounds);

    //The height of the displacement area of our bar (the height - the padding - the thumb size)
    int bottomPadding = getPaddingLeft() - getThumbOffset();
    int topPadding = getPaddingRight() - getThumbOffset();
    int height = getHeight() - bottomPadding - topPadding;

    float progressRatio = (float) getProgress() / getMax();
    float thumbOffset = getThumb().getIntrinsicWidth() * (.5f - progressRatio);

    // In our rotated canvas, positive x is higher, positive Y is more to the left
    float thumbX = progressRatio * height + bottomPadding + thumbOffset;
    float thumbY = getWidth() / 2f;
    //Since we rotate the canvas again when drawing the text, we need to translate the coords for the text
    float textX = thumbY - textBounds.width() / 2f;
    float textY = -(thumbX - textBounds.height() / 2f);

---

虽然我找不到一种直接从拇指得到位置的好方法，但我找到了一种间接得到位置的好方法。我只需要调整垂直条的测量值。将此代码放入onDraw方法中：

protected void onDraw(Canvas canvas) {
    /*Rotates the seekbar, as I need it to be vertical*/
    canvas.rotate(-90);
    canvas.translate(-getHeight(), 0);
    super.onDraw(canvas);
    canvas.save();

    Paint paint = new Paint();
    paint.setColor(ContextCompat.getColor(getContext(),R.color.accent));
    paint.setStrokeWidth(2);
    paint.setStyle(Paint.Style.STROKE);

    Rect thumbBounds = this.getThumb().getBounds();
    int offset = getThumbOffset();
    Log.d(TAG,"ThumbOffset:"+offset+ " RectX:" + thumbBounds.centerX());
    thumbBounds.offset(offset,0);

    canvas.drawRect(thumbBounds, paint);        
    canvas.drawText(Integer.toString(getProgress()),thumbBounds.centerY(),-thumbBounds.centerX(),textPaint);
    canvas.restore();
}

    //Calculating the size of the text
    text = String.valueOf(getProgress() - maxValue);
    textPaint.getTextBounds(text,0,text.length(),textBounds);

    //The height of the displacement area of our bar (the height - the padding - the thumb size)
    int bottomPadding = getPaddingLeft() - getThumbOffset();
    int topPadding = getPaddingRight() - getThumbOffset();
    int height = getHeight() - bottomPadding - topPadding;

    float progressRatio = (float) getProgress() / getMax();
    float thumbOffset = getThumb().getIntrinsicWidth() * (.5f - progressRatio);

    // In our rotated canvas, positive x is higher, positive Y is more to the left
    float thumbX = progressRatio * height + bottomPadding + thumbOffset;
    float thumbY = getWidth() / 2f;
    //Since we rotate the canvas again when drawing the text, we need to translate the coords for the text
    float textX = thumbY - textBounds.width() / 2f;
    float textY = -(thumbX - textBounds.height() / 2f);