1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.opengl;
18
19import static javax.microedition.khronos.egl.EGL10.EGL_DEFAULT_DISPLAY;
20import static javax.microedition.khronos.egl.EGL10.EGL_NO_DISPLAY;
21
22import java.util.ArrayList;
23
24import javax.microedition.khronos.egl.EGL10;
25import javax.microedition.khronos.egl.EGLContext;
26import javax.microedition.khronos.egl.EGLDisplay;
27
28import android.os.Looper;
29import android.util.Log;
30
31import com.google.android.gles_jni.EGLImpl;
32
33/**
34 * The per-process memory overhead of hardware accelerated graphics can
35 * be quite large on some devices.  For small memory devices, being able to
36 * terminate all EGL contexts so that this graphics driver memory can be
37 * reclaimed can significant improve the overall behavior of the device.  This
38 * class helps app developers participate in releasing their EGL context
39 * when appropriate and possible.
40 *
41 * <p>To use, simple instantiate this class with the EGLContext you create.
42 * When you have done this, if the device is getting low on memory and all
43 * of the currently created EGL contexts in the process are being managed
44 * through this class, then they will all be asked to terminate through the
45 * call to {@link #onTerminate}.
46 *
47 * @hide
48 */
49public abstract class ManagedEGLContext {
50    static final String TAG = "ManagedEGLContext";
51
52    static final ArrayList<ManagedEGLContext> sActive = new ArrayList<ManagedEGLContext>();
53
54    final EGLContext mContext;
55
56    /**
57     * Instantiate to manage the given EGLContext.
58     */
59    public ManagedEGLContext(EGLContext context) {
60        mContext = context;
61        synchronized (sActive) {
62            sActive.add(this);
63        }
64    }
65
66    /**
67     * Retrieve the EGLContext being managed by the class.
68     */
69    public EGLContext getContext() {
70        return mContext;
71    }
72
73    /**
74     * Force-terminate the ManagedEGLContext.  This will cause
75     * {@link #onTerminate(EGLContext)} to be called.  You <em>must</em>
76     * call this when destroying the EGLContext, so that the framework
77     * knows to stop managing it.
78     */
79    public void terminate() {
80        execTerminate();
81    }
82
83    void execTerminate() {
84        onTerminate(mContext);
85    }
86
87    /**
88     * Override this method to destroy the EGLContext when appropriate.
89     * <em>Note that this method is always called on the main thread
90     * of the process.</em>  If your EGLContext was created on a different
91     * thread, you will need to implement this method to hand off the work
92     * of destroying the context to that thread.
93     */
94    public abstract void onTerminate(EGLContext context);
95
96    /** @hide */
97    public static boolean doTerminate() {
98        ArrayList<ManagedEGLContext> active;
99
100        if (Looper.getMainLooper() != Looper.myLooper()) {
101            throw new IllegalStateException("Called on wrong thread");
102        }
103
104        synchronized (sActive) {
105            // If there are no active managed contexts, we will not even
106            // try to terminate.
107            if (sActive.size() <= 0) {
108                return false;
109            }
110
111            // Need to check how many EGL contexts are actually running,
112            // to compare with how many we are managing.
113            EGL10 egl = (EGL10) EGLContext.getEGL();
114            EGLDisplay display = egl.eglGetDisplay(EGL_DEFAULT_DISPLAY);
115
116            if (display == EGL_NO_DISPLAY) {
117                Log.w(TAG, "doTerminate failed: no display");
118                return false;
119            }
120
121            if (EGLImpl.getInitCount(display) != sActive.size()) {
122                Log.w(TAG, "doTerminate failed: EGL count is " + EGLImpl.getInitCount(display)
123                        + " but managed count is " + sActive.size());
124                return false;
125            }
126
127            active = new ArrayList<ManagedEGLContext>(sActive);
128            sActive.clear();
129        }
130
131        for (int i = 0; i < active.size(); i++) {
132            active.get(i).execTerminate();
133        }
134
135        return true;
136    }
137}
138