前言

今天客户提了个需求，因为我们的设备在正常情况下无法调节通话音量，只有在打电话过程中，按物理音量加减键才能出现调节通话音量seekBar，很不方便，于是乎需求就来了。需要优化两个地方

1、在正常情况下，按物理音量加减键都显示 通话音量调节seekBar,可方便快速调节通话音量

2、在Settings中提示音界面点击设置进入，增加通话音量调节seekBar

修改前

修改后

实现

第一个功能

先来完成第一个功能，还是通过Hierarchy View查看布局结构，查找到布局文件id为volume_dialog，通过在源码中搜索找到位于SystemUI中，volume_dialog.xml
源码位置 frameworks\base\packages\SystemUI\res\layout\volume_dialog.xml

对应的java类为 frameworks\base\packages\SystemUI\src\com\android\systemui\volume\VolumeDialog.java

修改代码

addRow(AudioManager.STREAM_VOICE_CALL,
            R.drawable.ic_volume_voice, R.drawable.ic_volume_voice, true);

原来的第四个参数为false，修改为true即可显示通话音量seekBar

为了便于说明，我们跟进addRow()中查看

private void addRow(int stream, int iconRes, int iconMuteRes, boolean important) {
    final VolumeRow row = initRow(stream, iconRes, iconMuteRes, important);
    if (!mRows.isEmpty()) {
        final View v = new View(mContext);
        v.setId(android.R.id.background);
        final int h = mContext.getResources()
                .getDimensionPixelSize(R.dimen.volume_slider_interspacing);
        final LinearLayout.LayoutParams lp =
                new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, h);
        mDialogContentView.addView(v, mDialogContentView.getChildCount() - 1, lp);
        row.space = v;
    }
    ...
}

传递的参数对应important，从字面意思理解重要对应显示，继续查看initRow都做了什么

private VolumeRow initRow(final int stream, int iconRes, int iconMuteRes, boolean important) {
    final VolumeRow row = new VolumeRow();
    row.stream = stream;
    row.iconRes = iconRes;
    row.iconMuteRes = iconMuteRes;
    row.important = important;
    row.view = mDialog.getLayoutInflater().inflate(R.layout.volume_dialog_row, null);
    row.view.setTag(row);
    row.header = (TextView) row.view.findViewById(R.id.volume_row_header);
    mSpTexts.add(row.header);
    row.slider = (SeekBar) row.view.findViewById(R.id.volume_row_slider);
    row.slider.setOnSeekBarChangeListener(new VolumeSeekBarChangeListener(row));

    // forward events above the slider into the slider
    row.view.setOnTouchListener(new OnTouchListener() {
        private final Rect mSliderHitRect = new Rect();
        private boolean mDragging;

        @SuppressLint("ClickableViewAccessibility")
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            row.slider.getHitRect(mSliderHitRect);
            if (!mDragging && event.getActionMasked() == MotionEvent.ACTION_DOWN
                    && event.getY() < mSliderHitRect.top) {
                mDragging = true;
            }
            if (mDragging) {
                event.offsetLocation(-mSliderHitRect.left, -mSliderHitRect.top);
                row.slider.dispatchTouchEvent(event);
                if (event.getActionMasked() == MotionEvent.ACTION_UP
                        || event.getActionMasked() == MotionEvent.ACTION_CANCEL) {
                    mDragging = false;
                }
                return true;
            }
            return false;
        }
    });
    row.icon = (ImageButton) row.view.findViewById(R.id.volume_row_icon);
    row.icon.setImageResource(iconRes);
    row.icon.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            Events.writeEvent(mContext, Events.EVENT_ICON_CLICK, row.stream, row.iconState);
            mController.setActiveStream(row.stream);
            if (row.stream == AudioManager.STREAM_RING) {
                final boolean hasVibrator = mController.hasVibrator();
                if (mState.ringerModeInternal == AudioManager.RINGER_MODE_NORMAL) {
                    if (hasVibrator) {
                        mController.setRingerMode(AudioManager.RINGER_MODE_VIBRATE,