An Android preference class that provides a user with the means to select an integer from a SeekBar and persist it. (License: MIT License)

attrs.xml

<resources>

    <!-- note: to re-use an existing Android attribute not already used by the superclass, name should have prefix "android:" and do not define a format -->
    <declare-styleable name="SeekBarDialogPreference">
        <attr name="android:max" />
        <attr name="min" format="integer" />
        <attr name="progressTextSuffix" format="string" />
    </declare-styleable>

</resources>

preference_seek_bar_dialog.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/text_dialog_message"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="6dip"
        android:paddingLeft="12dip"
        android:paddingRight="12dip" >
    </TextView>

    <TextView
        android:id="@+id/text_progress"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="6dip"
        android:gravity="center_horizontal" >
    </TextView>

    <SeekBar
        android:id="@+id/seek_bar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="6dip"
        android:layout_marginTop="6dip" />

</LinearLayout>

preferences.xml

<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:custom="http://schemas.android.com/apk/res-auto" >
 
    <com.lukehorvat.SeekBarDialogPreference
        android:defaultValue="20"
        android:dialogMessage="Please select a value for the target crosshair radius:"
        android:max="50"
        android:title="Target crosshair radius"
        custom:progressTextSuffix="%"
        custom:min="1" />
 
</PreferenceScreen>

SeekBarDialogPreference.java

package com.lukehorvat;

import android.content.Context;
import android.content.res.TypedArray;
import android.os.Parcel;
import android.os.Parcelable;
import android.preference.DialogPreference;
import android.util.AttributeSet;
import android.view.View;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.TextView;

/**
 * A {@link DialogPreference} that provides a user with the means to select an integer from a {@link SeekBar}, and persist it.
 * 
 * @author lukehorvat
 * 
 */
public class SeekBarDialogPreference extends DialogPreference
{
    private static final int DEFAULT_MIN_PROGRESS = 0;
    private static final int DEFAULT_MAX_PROGRESS = 100;
    private static final int DEFAULT_PROGRESS = 0;

    private int mMinProgress;
    private int mMaxProgress;
    private int mProgress;
    private CharSequence mProgressTextSuffix;
    private TextView mProgressText;
    private SeekBar mSeekBar;

    public SeekBarDialogPreference(Context context)
    {
        this(context, null);
    }

    public SeekBarDialogPreference(Context context, AttributeSet attrs)
    {
        super(context, attrs);

        // get attributes specified in XML
        TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.SeekBarDialogPreference, 0, 0);
        try
        {
            setMinProgress(a.getInteger(R.styleable.SeekBarDialogPreference_min, DEFAULT_MIN_PROGRESS));
            setMaxProgress(a.getInteger(R.styleable.SeekBarDialogPreference_android_max, DEFAULT_MAX_PROGRESS));
            setProgressTextSuffix(a.getString(R.styleable.SeekBarDialogPreference_progressTextSuffix));
        }
        finally
        {
            a.recycle();
        }

        // set layout
        setDialogLayoutResource(R.layout.preference_seek_bar_dialog);
        setPositiveButtonText(android.R.string.ok);
        setNegativeButtonText(android.R.string.cancel);
        setDialogIcon(null);
    }

    @Override
    protected void onSetInitialValue(boolean restore, Object defaultValue)
    {
        setProgress(restore ? getPersistedInt(DEFAULT_PROGRESS) : (Integer) defaultValue);
    }

    @Override
    protected Object onGetDefaultValue(TypedArray a, int index)
    {
        return a.getInt(index, DEFAULT_PROGRESS);
    }

    @Override
    protected void onBindDialogView(View view)
    {
        super.onBindDialogView(view);

        TextView dialogMessageText = (TextView) view.findViewById(R.id.text_dialog_message);
        dialogMessageText.setText(getDialogMessage());

        mProgressText = (TextView) view.findViewById(R.id.text_progress);

        mSeekBar = (SeekBar) view.findViewById(R.id.seek_bar);
        mSeekBar.setOnSeekBarChangeListener(new OnSeekBarChangeListener()
        {
            @Override
            public void onStopTrackingTouch(SeekBar seekBar)
            {
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar)
            {
            }

            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser)
            {
                // update text that displays the current SeekBar progress value
                // note: this does not persist the progress value. that is only ever done in setProgress()
                String progressStr = String.valueOf(progress + mMinProgress);
                mProgressText.setText(mProgressTextSuffix == null ? progressStr : progressStr.concat(mProgressTextSuffix.toString()));
            }
        });
        mSeekBar.setMax(mMaxProgress - mMinProgress);
        mSeekBar.setProgress(mProgress - mMinProgress);
    }

    public int getMinProgress()
    {
        return mMinProgress;
    }

    public void setMinProgress(int minProgress)
    {
        mMinProgress = minProgress;
        setProgress(Math.max(mProgress, mMinProgress));
    }

    public int getMaxProgress()
    {
        return mMaxProgress;
    }

    public void setMaxProgress(int maxProgress)
    {
        mMaxProgress = maxProgress;
        setProgress(Math.min(mProgress, mMaxProgress));
    }

    public int getProgress()
    {
        return mProgress;
    }

    public void setProgress(int progress)
    {
        progress = Math.max(Math.min(progress, mMaxProgress), mMinProgress);

        if (progress != mProgress)
        {
            mProgress = progress;
            persistInt(progress);
            notifyChanged();
        }
    }

    public CharSequence getProgressTextSuffix()
    {
        return mProgressTextSuffix;
    }

    public void setProgressTextSuffix(CharSequence progressTextSuffix)
    {
        mProgressTextSuffix = progressTextSuffix;
    }

    @Override
    protected void onDialogClosed(boolean positiveResult)
    {
        super.onDialogClosed(positiveResult);

        // when the user selects "OK", persist the new value
        if (positiveResult)
        {
            int seekBarProgress = mSeekBar.getProgress() + mMinProgress;
            if (callChangeListener(seekBarProgress))
            {
                setProgress(seekBarProgress);
            }
        }
    }

    @Override
    protected Parcelable onSaveInstanceState()
    {
        // save the instance state so that it will survive screen orientation changes and other events that may temporarily destroy it
        final Parcelable superState = super.onSaveInstanceState();

        // set the state's value with the class member that holds current setting value
        final SavedState myState = new SavedState(superState);
        myState.minProgress = getMinProgress();
        myState.maxProgress = getMaxProgress();
        myState.progress = getProgress();

        return myState;
    }

    @Override
    protected void onRestoreInstanceState(Parcelable state)
    {
        // check whether we saved the state in onSaveInstanceState()
        if (state == null || !state.getClass().equals(SavedState.class))
        {
            // didn't save the state, so call superclass
            super.onRestoreInstanceState(state);
            return;
        }

        // restore the state
        SavedState myState = (SavedState) state;
        setMinProgress(myState.minProgress);
        setMaxProgress(myState.maxProgress);
        setProgress(myState.progress);

        super.onRestoreInstanceState(myState.getSuperState());
    }

    private static class SavedState extends BaseSavedState
    {
        int minProgress;
        int maxProgress;
        int progress;

        public SavedState(Parcelable superState)
        {
            super(superState);
        }

        public SavedState(Parcel source)
        {
            super(source);

            minProgress = source.readInt();
            maxProgress = source.readInt();
            progress = source.readInt();
        }

        @Override
        public void writeToParcel(Parcel dest, int flags)
        {
            super.writeToParcel(dest, flags);

            dest.writeInt(minProgress);
            dest.writeInt(maxProgress);
            dest.writeInt(progress);
        }

        @SuppressWarnings("unused")
        public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>()
        {
            @Override
            public SavedState createFromParcel(Parcel in)
            {
                return new SavedState(in);
            }

            @Override
            public SavedState[] newArray(int size)
            {
                return new SavedState[size];
            }
        };
    }
}