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/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.media;
import android.annotation.IntDef;
import android.media.session.MediaSession;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
/**
* Handles requests to adjust or set the volume on a session. This is also used
* to push volume updates back to the session. The provider must call
* {@link #setCurrentVolume(int)} each time the volume being provided changes.
* <p>
* You can set a volume provider on a session by calling
* {@link MediaSession#setPlaybackToRemote}.
*/
public abstract class VolumeProvider {
/**
* @hide
*/
@IntDef({VOLUME_CONTROL_FIXED, VOLUME_CONTROL_RELATIVE, VOLUME_CONTROL_ABSOLUTE})
@Retention(RetentionPolicy.SOURCE)
public @interface ControlType {}
/**
* The volume is fixed and can not be modified. Requests to change volume
* should be ignored.
*/
public static final int VOLUME_CONTROL_FIXED = 0;
/**
* The volume control uses relative adjustment via
* {@link #onAdjustVolume(int)}. Attempts to set the volume to a specific
* value should be ignored.
*/
public static final int VOLUME_CONTROL_RELATIVE = 1;
/**
* The volume control uses an absolute value. It may be adjusted using
* {@link #onAdjustVolume(int)} or set directly using
* {@link #onSetVolumeTo(int)}.
*/
public static final int VOLUME_CONTROL_ABSOLUTE = 2;
private final int mControlType;
private final int mMaxVolume;
private int mCurrentVolume;
private Callback mCallback;
/**
* Create a new volume provider for handling volume events. You must specify
* the type of volume control, the maximum volume that can be used, and the
* current volume on the output.
*
* @param volumeControl The method for controlling volume that is used by
* this provider.
* @param maxVolume The maximum allowed volume.
* @param currentVolume The current volume on the output.
*/
public VolumeProvider(@ControlType int volumeControl, int maxVolume, int currentVolume) {
mControlType = volumeControl;
mMaxVolume = maxVolume;
mCurrentVolume = currentVolume;
}
/**
* Get the volume control type that this volume provider uses.
*
* @return The volume control type for this volume provider
*/
@ControlType
public final int getVolumeControl() {
return mControlType;
}
/**
* Get the maximum volume this provider allows.
*
* @return The max allowed volume.
*/
public final int getMaxVolume() {
return mMaxVolume;
}
/**
* Gets the current volume. This will be the last value set by
* {@link #setCurrentVolume(int)}.
*
* @return The current volume.
*/
public final int getCurrentVolume() {
return mCurrentVolume;
}
/**
* Notify the system that the current volume has been changed. This must be
* called every time the volume changes to ensure it is displayed properly.
*
* @param currentVolume The current volume on the output.
*/
public final void setCurrentVolume(int currentVolume) {
mCurrentVolume = currentVolume;
if (mCallback != null) {
mCallback.onVolumeChanged(this);
}
}
/**
* Override to handle requests to set the volume of the current output.
* After the volume has been modified {@link #setCurrentVolume} must be
* called to notify the system.
*
* @param volume The volume to set the output to.
*/
public void onSetVolumeTo(int volume) {
}
/**
* Override to handle requests to adjust the volume of the current output.
* Direction will be one of {@link AudioManager#ADJUST_LOWER},
* {@link AudioManager#ADJUST_RAISE}, {@link AudioManager#ADJUST_SAME}.
* After the volume has been modified {@link #setCurrentVolume} must be
* called to notify the system.
*
* @param direction The direction to change the volume in.
*/
public void onAdjustVolume(int direction) {
}
/**
* Sets a callback to receive volume changes.
* @hide
*/
public void setCallback(Callback callback) {
mCallback = callback;
}
/**
* Listens for changes to the volume.
* @hide
*/
public abstract static class Callback {
/**
* Called when volume changed.
*/
public abstract void onVolumeChanged(VolumeProvider volumeProvider);
}
}
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