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

/*
 * Copyright (C) 2012 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.hardware.display;

import android.content.Context;
import android.os.Handler;
import android.util.SparseArray;
import android.view.Display;

/**
 * Manages the properties of attached displays.
 * <p>
 * Get an instance of this class by calling
 * {@link android.content.Context#getSystemService(java.lang.String)
 * Context.getSystemService()} with the argument
 * {@link android.content.Context#DISPLAY_SERVICE}.
 * </p>
 */
public final class DisplayManager {
    private static final String TAG = "DisplayManager";
    private static final boolean DEBUG = false;

    private final Context mContext;
    private final DisplayManagerGlobal mGlobal;

    private final Object mLock = new Object();
    private final SparseArray<Display> mDisplays = new SparseArray<Display>();

    /**
     * Broadcast receiver that indicates when the Wifi display status changes.
     * <p>
     * The status is provided as a {@link WifiDisplayStatus} object in the
     * {@link #EXTRA_WIFI_DISPLAY_STATUS} extra.
     * </p><p>
     * This broadcast is only sent to registered receivers with the
     * {@link android.Manifest.permission#CONFIGURE_WIFI_DISPLAY} permission and can
     * only be sent by the system.
     * </p>
     * @hide
     */
    public static final String ACTION_WIFI_DISPLAY_STATUS_CHANGED =
            "android.hardware.display.action.WIFI_DISPLAY_STATUS_CHANGED";

    /**
     * Contains a {@link WifiDisplayStatus} object.
     * @hide
     */
    public static final String EXTRA_WIFI_DISPLAY_STATUS =
            "android.hardware.display.extra.WIFI_DISPLAY_STATUS";

    /** @hide */
    public DisplayManager(Context context) {
        mContext = context;
        mGlobal = DisplayManagerGlobal.getInstance();
    }

    /**
     * Gets information about a logical display.
     *
     * The display metrics may be adjusted to provide compatibility
     * for legacy applications.
     *
     * @param displayId The logical display id.
     * @return The display object, or null if there is no valid display with the given id.
     */
    public Display getDisplay(int displayId) {
        synchronized (mLock) {
            return getOrCreateDisplayLocked(displayId, false /*assumeValid*/);
        }
    }

    /**
     * Gets all currently valid logical displays.
     *
     * @return An array containing all displays.
     */
    public Display[] getDisplays() {
        int[] displayIds = mGlobal.getDisplayIds();
        int expectedCount = displayIds.length;
        Display[] displays = new Display[expectedCount];
        synchronized (mLock) {
            int actualCount = 0;
            for (int i = 0; i < expectedCount; i++) {
                Display display = getOrCreateDisplayLocked(displayIds[i], true /*assumeValid*/);
                if (display != null) {
                    displays[actualCount++] = display;
                }
            }
            if (actualCount != expectedCount) {
                Display[] oldDisplays = displays;
                displays = new Display[actualCount];
                System.arraycopy(oldDisplays, 0, displays, 0, actualCount);
            }
        }
        return displays;
    }

    private Display getOrCreateDisplayLocked(int displayId, boolean assumeValid) {
        Display display = mDisplays.get(displayId);
        if (display == null) {
            display = mGlobal.getCompatibleDisplay(displayId,
                    mContext.getCompatibilityInfo(displayId));
            if (display != null) {
                mDisplays.put(displayId, display);
            }
        } else if (!assumeValid && !display.isValid()) {
            display = null;
        }
        return display;
    }

    /**
     * Registers an display listener to receive notifications about when
     * displays are added, removed or changed.
     *
     * @param listener The listener to register.
     * @param handler The handler on which the listener should be invoked, or null
     * if the listener should be invoked on the calling thread's looper.
     *
     * @see #unregisterDisplayListener
     */
    public void registerDisplayListener(DisplayListener listener, Handler handler) {
        mGlobal.registerDisplayListener(listener, handler);
    }

    /**
     * Unregisters an input device listener.
     *
     * @param listener The listener to unregister.
     *
     * @see #registerDisplayListener
     */
    public void unregisterDisplayListener(DisplayListener listener) {
        mGlobal.unregisterDisplayListener(listener);
    }

    /**
     * Initiates a fresh scan of availble Wifi displays.
     * The results are sent as a {@link #ACTION_WIFI_DISPLAY_STATUS_CHANGED} broadcast.
     * @hide
     */
    public void scanWifiDisplays() {
        mGlobal.scanWifiDisplays();
    }

    /**
     * Connects to a Wifi display.
     * The results are sent as a {@link #ACTION_WIFI_DISPLAY_STATUS_CHANGED} broadcast.
     *
     * @param deviceAddress The MAC address of the device to which we should connect.
     * @hide
     */
    public void connectWifiDisplay(String deviceAddress) {
        mGlobal.connectWifiDisplay(deviceAddress);
    }

    /**
     * Disconnects from the current Wifi display.
     * The results are sent as a {@link #ACTION_WIFI_DISPLAY_STATUS_CHANGED} broadcast.
     * @hide
     */
    public void disconnectWifiDisplay() {
        mGlobal.disconnectWifiDisplay();
    }

    /**
     * Gets the current Wifi display status.
     * Watch for changes in the status by registering a broadcast receiver for
     * {@link #ACTION_WIFI_DISPLAY_STATUS_CHANGED}.
     *
     * @return The current Wifi display status.
     * @hide
     */
    public WifiDisplayStatus getWifiDisplayStatus() {
        return mGlobal.getWifiDisplayStatus();
    }

    /**
     * Listens for changes in available display devices.
     */
    public interface DisplayListener {
        /**
         * Called whenever a logical display has been added to the system.
         * Use {@link DisplayManager#getDisplay} to get more information about
         * the display.
         *
         * @param displayId The id of the logical display that was added.
         */
        void onDisplayAdded(int displayId);

        /**
         * Called whenever a logical display has been removed from the system.
         *
         * @param displayId The id of the logical display that was removed.
         */
        void onDisplayRemoved(int displayId);

        /**
         * Called whenever the properties of a logical display have changed.
         *
         * @param displayId The id of the logical display that changed.
         */
        void onDisplayChanged(int displayId);
    }
}