Android SeekBarPreference

I'm currently trying to implement SeekBarPreference class using http://android-journey.blogspot.com/2010/01/for-almost-any-application-we-need-to.html tutorial with RelativeLayout. First problem is TextView preferenceText isn't showing at all. Second problem is the bar can't be slided like those in regular preferences (like media volume bar)?

public class SeekBarPreference extends Preference implements
    OnSeekBarChangeListener {

public static int maximum    = 100;
public static int interval   = 5;
private float oldValue = 25;
private TextView Indicator;

public SeekBarPreference(Context context) {
    super(context);
}

public SeekBarPreference(Context context, AttributeSet attrs) {
    super(context, attrs);
}

public SeekBarPreference(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
}

@Override
protected View onCreateView(ViewGroup parent) {

    float scale = getContext().getResources().getDisplayMetrics().density;

    RelativeLayout layout = new RelativeLayout(getContext());

    RelativeLayout.LayoutParams textParams = new RelativeLayout.LayoutParams(
            RelativeLayout.LayoutParams.WRAP_CONTENT,
            RelativeLayout.LayoutParams.WRAP_CONTENT);

    RelativeLayout.LayoutParams sbarParams = new RelativeLayout.LayoutParams(
            Math.round(scale * 160),
            RelativeLayout.LayoutParams.WRAP_CONTENT);

    RelativeLayout.LayoutParams indParams = new RelativeLayout.LayoutParams(
            RelativeLayout.LayoutParams.WRAP_CONTENT,
            RelativeLayout.LayoutParams.WRAP_CONTENT);

    TextView preferenceText = new TextView(getContext());
    preferenceText.setId(0);
    preferenceText.setText(getTitle());
    preferenceText.setTextSize(18);
    preferenceText.setTypeface(Typeface.SANS_SERIF, Typeface.BOLD);


    SeekBar sbar = new SeekBar(getContext());
    sbar.setId(1);
    sbar.setMax(maximum);
    sbar.setProgress((int)this.oldValue);
    sbar.setOnSeekBarChangeListener(this);

    this.Indicator = new TextView(getContext());
    this.Indicator.setTextSize(12);
    this.Indicator.setTypeface(Typeface.MONOSPACE, Typeface.ITALIC);
    this.Indicator.setText("" + sbar.getProgress());

    textParams.addRule(RelativeLayout.ALIGN_PARENT_LEFT);
    sbarParams.addRule(RelativeLayout.RIGHT_OF, preferenceText.getId());
    indParams.setMargins(Math.round(20*scale), 0, 0, 0);
    indParams.addRule(RelativeLayout.RIGHT_OF, sbar.getId());

    preferenceText.setLayoutParams(textParams);
    sbar.setLayoutParams(sbarParams);
    this.Indicator.setLayoutParams(indParams);
    layout.addView(preferenceText);
    layout.addView(this.Indicator);
    layout.addView(sbar);
    layout.setId(android.R.id.widget_frame);

    return layout;
}

@Override
public void onProgressChanged(SeekBar seekBar, int progress,
        boolean fromUser) {
    progress = Math.round(((float) progress)/interval) * interval;

    if(!callChangeListener(progress)) {
        seekBar.setProgress((int) this.oldValue);
        return;
    }

    seekBar.setProgress(progress);
    this.oldValue = progress;
    this.Indicator.setText("" + progress);
    updatePreference(progress);

    notifyChanged();
}

@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}

@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}

@Override
protected Object onGetDefaultValue(TypedArray ta, int index) {
    int dValue = ta.getInt(index, 25);

    return validateValue(dValue);
}

@Override
protected void onSetInitialValue(boolean restoreValue,
        Object defaultValue) {
    int temp = restoreValue ? getPersistedInt(25) : (Integer)defaultValue;
    if(!restoreValue)
        persistInt(temp);

    this.oldValue = temp;
}

private int validateValue(int value) {
    if(value > maximum) 
        value = maximum;
    else if (value < 0)
        value = 0;
    else if (value % interval != 0)
        value = Math.round(((float) value)/interval) * interval;

    return value;
}

private void updatePreference(int newValue) {
    SharedPreferences.Editor editor = getEditor();
    editor.putInt(getKey(), newValue);
    editor.commit();
}

}

回答1:

The problem with sliding here is due to notifyChange() call. That is interfering with the sliding somehow. I am also working on similar widget because I do not like the Dialog approach.

As promised here is the solution that I added to my open source project:

I have written a SeekBarPreference class that is embeded widget inside the preferences activity instead of popup dialog. You can download the jar file from:

http://aniqroid.sileria.com/

The class documentation and usage is here: http://aniqroid.sileria.com/doc/api/com/sileria/android/view/SeekBarPreference.html

Also do not forget to checkout the handy companion class to auto show a summary when you change the SeekBar: http://aniqroid.sileria.com/doc/api/com/sileria/android/event/PrefsSeekBarListener.html

回答2:

Slider works in tutorial by changing onProgressChanged to

public void onProgressChanged( SeekBar seekBar, int progress, boolean fromUser )
{
    progress = Math.round( ( (float) progress ) / interval ) * interval;
    persistInt(progress);
    callChangeListener( progress );
    seekBar.setProgress( progress );
    this.monitorBox.setText( progress + "" );
    updatePreference( progress );
}

回答3:

Regarding the inability to move the slider, this is because its width is set to 80 (see params2) which is too narrow to allow sliding. After setting a reasonable width for it, e.g. 400, and the associated text view and a few mods to get it to compile with my SDK version it worked for me. One advantage this version has over many others is that the layout is done in the code instead of XML which allows an app to easily instantiate multiple sliders.