android ScrollView 与SeekBar结合使用

要实现用SeekBar控制ScrollView滚动的位置，并且ScrollView滚动时也更新SeekBar的角度，需要继承ScrollView，实现一个新的类。可以使这个类实现 SeekBar.OnSeekBarChangeListener接口。

覆盖ScrollView的onScrollChanged方法并修改SeekBar.OnSeekBarChangeListener接口中的onProgressChanged方法。关键代码如下

 int heightMeasure;        @Override        protected void onSizeChanged(int w, int h, int oldw, int oldh) {            super.onSizeChanged(w, h, oldw, oldh);            heightMeasure = getMeasuredHeight();        }        @Override        protected void onScrollChanged(int l, int t, int oldl, int oldt) {            super.onScrollChanged(l, t, oldl, oldt);            // When the user scrolls, we hide navigation elements.            if (heightMeasure == 0) {                Toast.makeText(getContext(), "heightMeansu = 0", Toast.LENGTH_SHORT).show();            } else {                //获取ScrollView的第一个子View的高度，也就是ScorllView要展示的内容的高度                View firstChildView = getChildAt(0);                int firstChildViewHeight = firstChildView.getHeight();                if(firstChildViewHeight==0){                    Toast.makeText(getContext(), "firstChildViewHeight = 0", Toast.LENGTH_SHORT).show();                }else{                    //计算出ScrollView所处位置占整体的百分比并设置为SeekBar mSeekView的值                    int progress = (int) (t * 100.0f / (firstChildViewHeight- heightMeasure));                    mSeekView.setOnSeekBarChangeListener(null);                    mSeekView.setProgress(progress);                    mSeekView.setOnSeekBarChangeListener(this);                }//                setNavVisibility(false);            }        }        /**         * SeakBar值改变时修改ScrollView位置         * @param seekBar         * @param progress         * @param fromUser         */        @Override        public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {            if (heightMeasure == 0) {                Toast.makeText(getContext(), "heightMeansu = 0", Toast.LENGTH_SHORT).show();            } else {                View firstChildView = getChildAt(0);                int firstChildViewHeight = firstChildView.getHeight();                int y = (int) ((firstChildViewHeight - heightMeasure) * progress / 100.0f);                scrollTo(0, y);            }        }

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