客户定制 音量控制 Preference
参考网上代码自己做了一个客户定制 Preference，没有使用 preference的 android:layout 属性，因为总觉得在不同版本系统上难以和其他preference的控件对齐，所以采用仅设置 android:widget_layout 的方式。
先创建自己要定制的 widget_layout 文件“preference_widget_seekbar.xml”：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center_vertical"
android:minHeight="?android:attr/listPreferredItemHeight"
android:paddingRight="?android:attr/scrollbarSize" >
<SeekBar
android:id="@+id/seekBar1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:max="60"
android:minWidth="240dip"
android:paddingRight="5dp"
android:progress="20"
android:textIsSelectable="true" >
</SeekBar>
<TextView
android:id="@+id/seekBarPrefValue"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/seekBar1"
android:layout_centerHorizontal="true"
android:textIsSelectable="true" >
</TextView>
<TextView
android:id="@+id/seekBarPrefUnitsLeft"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/seekBar1"
android:layout_toLeftOf="@id/seekBarPrefValue"
android:textIsSelectable="true" >
</TextView>
<TextView
android:id="@+id/seekBarPrefUnitsRight"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textIsSelectable="true"
android:layout_below="@id/seekBar1"
android:layout_toRightOf="@id/seekBarPrefValue" >
</TextView>
</RelativeLayout>
建立 com.sample.preference.SeekBarPreference 类，用来初始化界面，同步音量滑块表示的preference数据
package com.sample.preference; import com.sample.R;
import android.content.Context;
import android.content.res.TypedArray;
import android.preference.Preference;
import android.util.AttributeSet;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.widget.RelativeLayout;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.TextView;
public class SeekBarPreference extends Preference
implements OnSeekBarChangeListener
{
private final String TAG = "SeekBarPreference";
//private static final String ANDROIDNS="http://schemas.android.com/apk/res/android";
private static final String SEEKBAR_PREFS="SeekBarPreference";
private static final int DEFAULT_VALUE = 50;
Context mContext;
private int mMaxValue = 100;
private int mMinValue = 0;
private int mInterval = 1;
private int mCurrentValue = 50;
private String mUnitsLeft = "";
private String mUnitsRight = "";
private SeekBar mSeekBar;
private TextView mCurrentValueText;
public SeekBarPreference(Context context, AttributeSet attrs) {
super(context, attrs);
initPreference(context, attrs);
}
public SeekBarPreference(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initPreference(context, attrs);
}
private void initPreference(Context context, AttributeSet attrs) {
Log.v(TAG,"initPreference");
mContext = context;
updateValuesFromXml(attrs);
this.setWidgetLayoutResource(R.layout.preference_widget_seekbar);
}
private void updateValuesFromXml(AttributeSet attrs) {
mMaxValue = attrs.getAttributeIntValue(SEEKBAR_PREFS, "max", 100);
mMinValue = attrs.getAttributeIntValue(SEEKBAR_PREFS, "min", 0);
mUnitsLeft = getAttributeStringValue(attrs, SEEKBAR_PREFS, "unitsLeft", "");
String value = getAttributeStringValue(attrs, SEEKBAR_PREFS, "value", "");
mUnitsRight = getAttributeStringValue(attrs, SEEKBAR_PREFS, "unitsRight", "");
try {
mInterval = attrs.getAttributeIntValue(SEEKBAR_PREFS, "interval", 1);
if( mInterval <= 0 )
{
mInterval = 1;
}
}
catch(Exception e) {
Log.e(TAG, "Invalid interval value", e);
}
}
private String getAttributeStringValue(AttributeSet attrs, String namespace, String name, String defaultValue) {
String value = attrs.getAttributeValue(namespace, name);
if(value == null)
value = defaultValue;
return value;
}
@Override
protected View onCreateView(ViewGroup parent){
Log.v(TAG, "onCreateView()");
return super.onCreateView(parent);
}
@Override
public void onBindView(View view) {
super.onBindView(view);
View layout = view;
Log.v(TAG, "onBindView()");
mSeekBar = (SeekBar)view.findViewById(R.id.seekBar1);
mCurrentValueText = (TextView)view.findViewById(R.id.seekBarPrefValue);
if( null != mCurrentValueText ){
mCurrentValueText.setText(String.valueOf(mCurrentValue));
mCurrentValueText.setMinimumWidth(30);
}
if( null != mSeekBar )
{
mSeekBar.setMax(mMaxValue - mMinValue);
mSeekBar.setProgress(mCurrentValue - mMinValue);
mSeekBar.setOnSeekBarChangeListener(this);
}
TextView unitsRight = (TextView)view.findViewById(R.id.seekBarPrefUnitsRight);
if( null != unitsRight ){
unitsRight.setText(mUnitsRight);
}
TextView unitsLeft = (TextView)view.findViewById(R.id.seekBarPrefUnitsLeft);
if( null != unitsLeft ){
unitsLeft.setText(mUnitsLeft);
}
}
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
int newValue = progress + mMinValue;
if(newValue > mMaxValue)
newValue = mMaxValue;
else if(newValue < mMinValue)
newValue = mMinValue;
else if(mInterval != 1 && newValue % mInterval != 0)
newValue = Math.round(((float)newValue)/mInterval)*mInterval;
// change rejected, revert to the previous value
if(!callChangeListener(newValue)){
seekBar.setProgress(mCurrentValue - mMinValue);
return;
}
// change accepted, store it
mCurrentValue = newValue;
if( null != mCurrentValueText ){
mCurrentValueText.setText(String.valueOf(newValue));
}
persistInt(newValue);
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
notifyChanged();
}
@Override
protected Object onGetDefaultValue(TypedArray ta, int index){
int defaultValue = ta.getInt(index, DEFAULT_VALUE);
return defaultValue;
}
@Override
protected void onSetInitialValue(boolean restoreValue, Object defaultValue) {
if(restoreValue) {
mCurrentValue = getPersistedInt(mCurrentValue);
}
else {
int temp = 0;
try {
temp = (Integer)defaultValue;
}
catch(Exception ex) {
Log.e(TAG, "Invalid default value: " + defaultValue.toString());
}
persistInt(temp);
mCurrentValue = temp;
}
}
}
最后，在preference xml中加入对应项
<?xml version="1.0" encoding="utf-8"?> <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" android:title="audioSetting"> <!-- ... 其他 preference 项 --> <com.sample.preference.SeekBarPreference android:key="key_nes_volume_option" android:title="volumeSetting" android:summary="volumeSettingSummary" />
<!-- ... 其他 preference 项 -->
</PreferenceScreen>