1. Android 9.0 之前的亮度控制介面

import android.os.IPowerManager;
import android.provider.Settings;
import android.content.Context;


    /**
     * Used by the settings application and brightness control widgets to
     * temporarily override the current screen brightness setting so that the
     * user can observe the effect of an intended settings change without
     * applying it immediately.
     * <p>
     * The override will be canceled when the setting value is next updated.
     *
     * brightness The overridden brightness.
     * @see android.provider.Settings.System#SCREEN_BRIGHTNESS
     */
    public static void setBrightnessValue(Context mContext, int value) {
        try {
            IPowerManager power = IPowerManager.Stub.asInterface(ServiceManager.getService(Context.POWER_SERVICE));
            if (power != null) {
                power.setTemporaryScreenBrightnessSettingOverride(value);
            }
        } catch (RemoteException doe) {
            Log.w(TAG, doe);
        }
        Settings.System.putInt(mContext.getContentResolver(), Settings.System.SCREEN_BRIGHTNESS, value);
    }

    public static void setBrightnessValueBg(Context mContext, int value) {
        try {
            IPowerManager power = IPowerManager.Stub.asInterface(ServiceManager.getService(Context.POWER_SERVICE));
            if (power != null) {
                power.setTemporaryScreenBrightnessSettingOverride(value);
            }
        } catch (RemoteException doe) {
            Log.w(TAG, doe);
        }
    }
 

1.1 參見Android 8.0的SystemUI程式碼

frameworks/base/packages/SystemUI/src/com/android/systemui/settings/BrightnessController.java:419: mPower.setTemporaryScreenBrightnessSettingOverride(brightness);

package com.android.systemui.settings;

public class BrightnessController implements ToggleSlider.Listener {

    private void setBrightness(int brightness) {
        try {
            mPower.setTemporaryScreenBrightnessSettingOverride(brightness);
        } catch (RemoteException ex) {
        }
    }
 

2. Android 9.0 的亮度控制介面

2.1 參考Android 9.0的SystemUI程式碼

package com.android.systemui.settings;

import android.hardware.display.DisplayManager;


public class BrightnessController implements ToggleSlider.Listener {

    private final DisplayManager mDisplayManager;


    private void setBrightness(int brightness) {
        mDisplayManager.setTemporaryBrightness(brightness);
    }
 

2.2 檢視 DisplayManager.setTemporaryBrightness原始碼

• 原始碼路徑

frameworks/base/core/java/android/hardware/display/DisplayManager.java

[email protected]:/home/suhuazhi/9.1# find frameworks/ -name  "DisplayManager.java"
frameworks/base/core/java/android/hardware/display/DisplayManager.java

• 檢視實現方式 -DisplayManager.setTemporaryBrightness

package android.hardware.display;

@SystemService(Context.DISPLAY_SERVICE)
public final class DisplayManager {

    private final DisplayManagerGlobal mGlobal;


    /**
     * Temporarily sets the brightness of the display.
     * <p>
     * Requires the {@link android.Manifest.permission#CONTROL_DISPLAY_BRIGHTNESS} permission.
     * </p>
     *
     * @param brightness The brightness value from 0 to 255.
     *
     * @hide Requires signature permission.
     */
    public void setTemporaryBrightness(int brightness) {
        mGlobal.setTemporaryBrightness(brightness);
    }

• 原始碼路徑
  frameworks/base/core/java/android/hardware/display/DisplayManagerGlobal.java

[email protected]:/home/suhuazhi/9.1# find frameworks/ -name  "DisplayManagerGlobal.java"
frameworks/base/core/java/android/hardware/display/DisplayManagerGlobal.java

• 檢視實現方式 -DisplayManagerGlobal.setTemporaryBrightness

package android.hardware.display;


public final class DisplayManagerGlobal {

    private final IDisplayManager mDm;


    /**
     * Temporarily sets the brightness of the display.
     * <p>
     * Requires the {@link android.Manifest.permission#CONTROL_DISPLAY_BRIGHTNESS} permission.
     * </p>
     *
     * @param brightness The brightness value from 0 to 255.
     *
     * @hide Requires signature permission.
     */
    public void setTemporaryBrightness(int brightness) {
        try {
            mDm.setTemporaryBrightness(brightness);
        } catch (RemoteException ex) {
            throw ex.rethrowFromSystemServer();
        }
    }

• 檢視實現方式 -DisplayManagerService.setTemporaryBrightness
• ./frameworks/base/services/core/java/com/android/server/display/DisplayManagerService.java

上述 IDisplayManager 是一個aidl介面，對應找DisplayManagerService即可

package com.android.server.display;

public final class DisplayManagerService extends SystemService {


        @Override // Binder call
        public void setTemporaryBrightness(int brightness) {
            mContext.enforceCallingOrSelfPermission(
                    Manifest.permission.CONTROL_DISPLAY_BRIGHTNESS,
                    "Permission required to set the display's brightness");
            final long token = Binder.clearCallingIdentity();
            try {
                synchronized (mSyncRoot) {
                    mDisplayPowerController.setTemporaryBrightness(brightness);
                }
            } finally {
                Binder.restoreCallingIdentity(token);
            }
        }

上述需要許可權

    <!-- DisplayManager.setTemporaryBrightness -->
    <uses-permission android:name="android.permission.CONTROL_DISPLAY_BRIGHTNESS" />

3. 綜合上述Android 9.0 的亮度控制介面

• 許可權

    <!-- DisplayManager.setTemporaryBrightness -->
    <uses-permission android:name="android.permission.CONTROL_DISPLAY_BRIGHTNESS" />

• 軟體介面

import android.hardware.display.DisplayManager;
import android.content.Context;
import android.os.ServiceManager;
import android.os.IPowerManager;

    /**
     * Used by the settings application and brightness control widgets to
     * temporarily override the current screen brightness setting so that the
     * user can observe the effect of an intended settings change without
     * applying it immediately.
     * <p>
     * The override will be canceled when the setting value is next updated.
     *
     * brightness The overridden brightness.
     * @see android.provider.Settings.System#SCREEN_BRIGHTNESS
     */
    public static void setBrightnessValue(Context mContext, int value) {
        setBrightnessValueBg(mContext, value);
        Settings.System.putInt(mContext.getContentResolver(), Settings.System.SCREEN_BRIGHTNESS, value);
    }

    public static void setBrightnessValueBg(Context mContext, int value) {
        if (android.os.Build.VERSION.SDK_INT >= 27) {
            // <uses-permission android:name="android.permission.CONTROL_DISPLAY_BRIGHTNESS" />
            DisplayManager mDisplayManager = mContext.getSystemService(DisplayManager.class);
            mDisplayManager.setTemporaryBrightness(value);
        } else {
            /*try {
                IPowerManager power = IPowerManager.Stub.asInterface(ServiceManager.getService(Context.POWER_SERVICE));
                if (power != null) {
                    power.setTemporaryScreenBrightnessSettingOverride(value);
                }
            } catch (RemoteException doe) {
                Log.w(TAG, doe);
            }*/
        }
    }