在播放器中，我们常常可以看到这么一个设计，就是用户通过在屏幕的某个部分上下滑动就可以调节屏幕的亮度，在某个部分上下滑动就可以调节播放的音量。而左右滑动就可以调节播放的进度。
今天，我要说一下亮度的调节。其实主要是通过设置View的属性实现的。
public void onLightChange(float delta, int distance, Window window) {
WindowManager.LayoutParams params = window.getAttributes();
mCurrentDeltaBrintness = mCurrentDeltaBrintness + delta;
if (params.screenBrightness == WindowManager.LayoutParams.BRIGHTNESS_OVERRIDE_NONE) {
params.screenBrightness = getScreenBrightness(getContext());
}
if (Math.abs(mCurrentDeltaBrintness) >= mScrolledPixPerBringhtness) {
float deltaBrightness = mCurrentDeltaBrintness / (mScrolledPixPerBringhtness * MAX_BRINTNESS);
params.screenBrightness = params.screenBrightness + deltaBrightness;
<pre name="code" class="java"> private void performLightChange(float brightness) {
int resId = R.drawable.light_0;
if (brightness <= 0.01f) {
resId = R.drawable.light_0;
} else if (brightness <= 0.25f) {
resId = R.drawable.light_25;
} else if (brightness <= 0.5f) {
resId = R.drawable.light_50;
} else if (brightness < 1.0f) {
resId = R.drawable.light_75;
} else {
resId = R.drawable.light_100;
}
updateViews(resId, (int) (brightness * 100));
}
if (params.screenBrightness <= 0.01f) { params.screenBrightness = 0.01f; } window.setAttributes(params); mCurrentDeltaBrintness = 0; } performLightChange(params.screenBrightness); } 上述代码就是在左边部分上下滑动的时候会被调用。
另附performLigthChange的代码。
private void performLightChange(float brightness) {
int resId = R.drawable.light_0;
if (brightness <= 0.01f) {
resId = R.drawable.light_0;
} else if (brightness <= 0.25f) {
resId = R.drawable.light_25;
} else if (brightness <= 0.5f) {
resId = R.drawable.light_50;
} else if (brightness < 1.0f) {
resId = R.drawable.light_75;
} else {
resId = R.drawable.light_100;
}
updateViews(resId, (int) (brightness * 100));
}
我们在举一个相对好切入的例子。
复制代码
1 package android.lekko.tools;
2
3 import android.app.Activity;
4 import android.content.ContentResolver;
5 import android.provider.Settings;
6 import android.provider.Settings.System;
7 import android.view.WindowManager;
8 import android.widget.Toast;
9
10 public class LightnessControl {
11 // 判断是否开启了自动亮度调节
12 public static boolean isAutoBrightness(Activity act) {
13 boolean automicBrightness = false;
14 ContentResolver aContentResolver = act.getContentResolver();
15 try {
16 automicBrightness = Settings.System.getInt(aContentResolver,
17 Settings.System.SCREEN_BRIGHTNESS_MODE) == Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC;
18 } catch (Exception e) {
19 Toast.makeText(act,"无法获取亮度",Toast.LENGTH_SHORT).show();
20 }
21 return automicBrightness;
22 }
23 // 改变亮度
24 public static void SetLightness(Activity act,int value)
25 {
26 try {
27 System.putInt(act.getContentResolver(),System.SCREEN_BRIGHTNESS,value);
28 WindowManager.LayoutParams lp = act.getWindow().getAttributes();
29 lp.screenBrightness = (value<=0?1:value) / 255f;
30 act.getWindow().setAttributes(lp);
31 } catch (Exception e) {
32 Toast.makeText(act,"无法改变亮度",Toast.LENGTH_SHORT).show();
33 }
34 }
35 // 获取亮度
36 public static int GetLightness(Activity act)
37 {
38 return System.getInt(act.getContentResolver(),System.SCREEN_BRIGHTNESS,-1);
39 }
40 // 停止自动亮度调节
41 public static void stopAutoBrightness(Activity activity) {
42 Settings.System.putInt(activity.getContentResolver(),
43 Settings.System.SCREEN_BRIGHTNESS_MODE,
44 Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL);
45 }
46 // 开启亮度自动调节
47 public static void startAutoBrightness(Activity activity) {
48 Settings.System.putInt(activity.getContentResolver(),
49 Settings.System.SCREEN_BRIGHTNESS_MODE,
50 Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC);
51 }
52 }
复制代码
这是一个单独可工作的类，主要用于调节屏幕亮度，有部分注释了，解释几个概念，不标准，供参考：
ContentResolver类，为访问其它应用程序的对外共享数据提供方法，如上面获取、设置亮度时使用的System.getInt()，System.setInt()。
Activity类，android程序的主要类，一个界面必有此类提供后台支持，需要继承此类。
Settings类，android程序系统相关的设置类，各种设置都可在此找。
LayoutParams类，android界面相关的参数，如高度、宽度、亮度等。
Toast类，一个可自动消失的提示框，轻型控件。
