SeekBar Thumb position issue

问题

I'm trying to do a "labeled" thumb for my Seekbar. The objective is to customize a text above the thumb every time the Seekbar position changes.

I'm doing this:

        ...
        seekBar = (SeekBar) findViewById(R.id.bet_seek_bar);
        seekBar.setMax(10);
        setSeekBarLabel("0");
        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {

            @Override
            public void onStopTrackingTouch(SeekBar seekBar)
            {

            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar)
            {

            }

            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser)
            {
                setSeekBarLabel(String.valueOf(progress));
            }
        });
    }

    private void setSeekBarLabel(String text)
    {
        BitmapDrawable thumb = Utils.writeOnBitmap(thumbBmp, text, 0, 0, thumbLablePaint);
        seekBar.setThumb(thumb);
    }

After running it, and touch the bar, I'm getting this:

I DON'T CARE right now about any text issue (not writing one, porition, etc).

I DO CARE about thumb position relative to the bar progress.

The thumb position should be where the green bar ends. What am I missing?

Regards.

回答1:

I've ended up extending from SeekBar, and overriding the onMeasure() and onDraw methods(), that was the only way I've found to so the label/thumb thing work.

Posting it to help others:

...
    @Override
    protected synchronized void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
     {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        if (labelBackground != null)
        {

            viewWidth = getMeasuredWidth();
            barHeight = getMeasuredHeight();// returns only the bar height (without the label);
            setMeasuredDimension(viewWidth, barHeight + labelBackground.getHeight());
        }

    }



    @Override
    protected synchronized void onDraw(Canvas canvas)
    {
        if (labelBackground != null)
        {
            barBounds.left = getPaddingLeft();
            barBounds.top = labelBackground.getHeight() + getPaddingTop();
            barBounds.right = barBounds.left + viewWidth - getPaddingRight() - getPaddingLeft();
            barBounds.bottom = barBounds.top + barHeight - getPaddingBottom() - getPaddingTop();

            progressPosX = barBounds.left + ((float) this.getProgress() / (float) this.getMax()) * barBounds.width();

            labelPos.x = (int) progressPosX - labelOffset;
            labelPos.y = getPaddingTop();

            progressDrawable = getProgressDrawable();
            progressDrawable.setBounds(barBounds.left, barBounds.top, barBounds.right, barBounds.bottom);
            progressDrawable.draw(canvas);

            labelTextPaint.getTextBounds(labelText, 0, labelText.length(), labelTextRect);

            canvas.drawBitmap(labelBackground, labelPos.x, labelPos.y, labelBackgroundPaint);
            canvas.drawText(labelText, labelPos.x + labelBackground.getWidth() / 2 - labelTextRect.width() / 2, labelPos.y + labelBackground.getHeight() / 2 + labelTextRect.height() / 2, labelTextPaint);

            thumbX = (int) progressPosX - getThumbOffset();
            thumbDrawable.setBounds(thumbX, barBounds.top, thumbX + thumbDrawable.getIntrinsicWidth(), barBounds.top + thumbDrawable.getIntrinsicHeight());
            thumbDrawable.draw(canvas);
        } else
        {
            super.onDraw(canvas);
        }
    }

Result:

回答2:

Pass int progress to the method where you set drawable to the seekBar and use setProgress() method:

private void setSeekBarLabel(String text, int progress)
{
    BitmapDrawable thumb = Utils.writeOnBitmap(thumbBmp, text, 0, 0, thumbLablePaint);
    seekBar.setThumb(thumb);
    seekBar.setProgress(progress);
}

and add the second argument to the calling method:

setSeekBarLabel(String.valueOf(progress), progress);

来源：https://stackoverflow.com/questions/13887556/seekbar-thumb-position-issue