brightness（亮度）是window中的一個屬性
修改亮度需要取得window屬性
方法為：WindowManager.LayoutParams layoutParams = getWindow().getAttributes();
layoutParams.screenBrightness = b;// b是亮度
getWindow().setAttributes(layoutParams);
b是一個浮點數 從0~1 ，表示亮度
因此可以通過設置b的值預覽屏幕的亮度，然後通過
Settings.System.putInt(mContext.getContentResolver(), Settings.System.SCREEN_BRIGHTNESS,brightness);s設置屏幕亮度，brightness值為30-255
實現如圖所示效果代碼：
1.自定義一個SeekbarPreference繼承dialogPreference實現亮度預覽
public class SeekBarPreference extends DialogPreference implements OnSeekBarChangeListener{
private static final String TAG = "SeekBarPreference";
private static final int MINIMUM_BACKLIGHT = 30;//最低亮度
private static final int MAXIMUM_BACKLIGHT = 255;
private SeekBar bar;
private int oldBrightness;
private SharedPreferences sp;
private static String KEY="brightness";
public SeekBarPreference(Context context, AttributeSet attrs) {
super(context, attrs);
setDialogLayoutResource(R.layout.seekbar_dialog);
setPositiveButtonText(android.R.string.ok);
setNegativeButtonText(android.R.string.cancel);
setDialogIcon(R.drawable.ic_settings_display);
}
@Override
protected void onBindDialogView(View view) {
super.onBindDialogView(view);
sp=getSharedPreferences();
bar= (SeekBar) view.findViewById(R.id.seekbar);
bar.setMax(MAXIMUM_BACKLIGHT-MINIMUM_BACKLIGHT);
oldBrightness=sp.getInt(KEY, 125);
bar.setOnSeekBarChangeListener(this);//進度條改變 www.aiwalls.com
bar.setProgress(oldBrightness-MINIMUM_BACKLIGHT);//初始化進度條
}
@Override
protected void onDialogClosed(boolean positiveResult) {
// TODO Auto-generated method stub
super.onDialogClosed(positiveResult);
if(positiveResult){
/*do nothing*/
}else{
sp.edit().putInt(KEY, oldBrightness).commit();
}
}
@Override
public void onProgressChanged(SeekBar seekbar, int progress, boolean arg2) {
// TODO Auto-generated method stub
sp.edit().putInt(KEY, progress+MINIMUM_BACKLIGHT).commit(); //進度條改變時改變存儲數據，
}
@Override
public void onStartTrackingTouch(SeekBar arg0) {
// TODO Auto-generated method stub
}
@Override
public void onStopTrackingTouch(SeekBar arg0) {
// TODO Auto-generated method stub
}
}
2.調節亮度
public class ControlBrightness extends PreferenceActivity implements OnSharedPreferenceChangeListener {
private SeekBarPreference seekBarPreference;
private Button enBtn;
private Button disBtn;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.buttonbar);
addPreferencesFromResource(R.xml.custom_setting);
SharedPreferences sp= getSharedPreferences(BatteryUtils.FILE_NAME, MODE_WORLD_WRITEABLE);
sp.registerOnSharedPreferenceChangeListener(this);//監聽數據變化，調節屏幕亮度
}
@Override
public void onSharedPreferenceChanged(SharedPreferences sp, String key) {
// TODO Auto-generated method stub
if(TextUtils.equals(key, "brightness")){
int brightness=sp.getInt("brightness", 125);
LayoutParams lp= getWindow().getAttributes();
lp.screenBrightness=brightness/255.0f;
getWindow().setAttributes(lp);
}
}
}
摘自 android 開發專欄