android12 屏幕亮度控制修改为线性变化

由于高版本的亮度调节不是线性变化了，有客户反馈在Android11或者12上使用代码获取亮度不对，比如我们在设置中查看屏幕亮度是80%，读出来的亮度值是100，客户认为亮度值是39%。

• 获取屏幕亮度

adb shell settings get system screen_brightness 
或者
adb shell 
cat /sys/class/backlight/backlight/brightness

• 修改屏幕亮度设置为线性变化
• /frameworks/base/packages/SettingsLib/src/com/android/settingslib/display/BrightnessUtils.java

     public static final int GAMMA_SPACE_MAX = 65535;
+    public static final boolean ENABLE_GAMMA = false;...public static final float convertGammaToLinearFloat(int val, float min, float max) {
+        if(!ENABLE_GAMMA){
+            float ratio = (float)val / GAMMA_SPACE_MAX;
+            return min + (float)(ratio * (max - min));
+        }
+final float normalizedVal = MathUtils.norm(GAMMA_SPACE_MIN, GAMMA_SPACE_MAX, val);final float ret;}...public static final int convertLinearToGammaFloat(float val, float min, float max) {
+        if (!ENABLE_GAMMA){
+            float ratio = (float)(val - min)/ (max - min);
+            return (int)(ratio * GAMMA_SPACE_MAX);
+        }
+// For some reason, HLG normalizes to the range [0, 12] rather than [0, 1]final float normalizedVal = MathUtils.norm(min, max, val) * 12;