1/*
2 * Copyright (C) 2011 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
17
18package android.media.effect;
19
20import android.filterfw.core.CachedFrameManager;
21import android.filterfw.core.FilterContext;
22import android.filterfw.core.FilterFactory;
23import android.filterfw.core.GLEnvironment;
24import android.filterfw.core.GLFrame;
25import android.filterfw.core.FrameManager;
26import android.opengl.GLES20;
27
28/**
29 * <p>An EffectContext keeps all necessary state information to run Effects within a Open GL ES 2.0
30 * context.</p>
31 *
32 * <p>Every EffectContext is bound to one GL context. The application is responsible for creating
33 * this EGL context, and making it current before applying any effect. If your EGL context is
34 * destroyed, the EffectContext becomes invalid and any effects bound to this context can no longer
35 * be used. If you switch to another EGL context, you must create a new EffectContext. Each Effect
36 * is bound to a single EffectContext, and can only be executed in that context.</p>
37 */
38public class EffectContext {
39
40    private final int GL_STATE_FBO          = 0;
41    private final int GL_STATE_PROGRAM      = 1;
42    private final int GL_STATE_ARRAYBUFFER  = 2;
43    private final int GL_STATE_COUNT        = 3;
44
45    FilterContext mFilterContext;
46
47    private EffectFactory mFactory;
48
49    private int[] mOldState = new int[GL_STATE_COUNT];
50
51    /**
52     * Creates a context within the current GL context.
53     *
54     * <p>Binds the EffectContext to the current OpenGL context. All subsequent calls to the
55     * EffectContext must be made in the GL context that was active during creation.
56     * When you have finished using a context, you must call {@link #release()}. to dispose of all
57     * resources associated with this context.</p>
58     */
59    public static EffectContext createWithCurrentGlContext() {
60        EffectContext result = new EffectContext();
61        result.initInCurrentGlContext();
62        return result;
63    }
64
65    /**
66     * Returns the EffectFactory for this context.
67     *
68     * <p>The EffectFactory returned from this method allows instantiating new effects within this
69     * context.</p>
70     *
71     * @return The EffectFactory instance for this context.
72     */
73    public EffectFactory getFactory() {
74        return mFactory;
75    }
76
77    /**
78     * Releases the context.
79     *
80     * <p>Releases all the resources and effects associated with the EffectContext. This renders the
81     * context and all the effects bound to this context invalid. You must no longer use the context
82     * or any of its bound effects after calling release().</p>
83     *
84     * <p>Note that this method must be called with the proper EGL context made current, as the
85     * EffectContext and its effects may release internal GL resources.</p>
86     */
87    public void release() {
88        mFilterContext.tearDown();
89        mFilterContext = null;
90    }
91
92    private EffectContext() {
93        mFilterContext = new FilterContext();
94        mFilterContext.setFrameManager(new CachedFrameManager());
95        mFactory = new EffectFactory(this);
96    }
97
98    private void initInCurrentGlContext() {
99        if (!GLEnvironment.isAnyContextActive()) {
100            throw new RuntimeException("Attempting to initialize EffectContext with no active "
101                + "GL context!");
102        }
103        GLEnvironment glEnvironment = new GLEnvironment();
104        glEnvironment.initWithCurrentContext();
105        mFilterContext.initGLEnvironment(glEnvironment);
106    }
107
108    final void assertValidGLState() {
109        GLEnvironment glEnv = mFilterContext.getGLEnvironment();
110        if (glEnv == null || !glEnv.isContextActive()) {
111            if (GLEnvironment.isAnyContextActive()) {
112                throw new RuntimeException("Applying effect in wrong GL context!");
113            } else {
114                throw new RuntimeException("Attempting to apply effect without valid GL context!");
115            }
116        }
117    }
118
119    final void saveGLState() {
120        GLES20.glGetIntegerv(GLES20.GL_FRAMEBUFFER_BINDING, mOldState, GL_STATE_FBO);
121        GLES20.glGetIntegerv(GLES20.GL_CURRENT_PROGRAM, mOldState, GL_STATE_PROGRAM);
122        GLES20.glGetIntegerv(GLES20.GL_ARRAY_BUFFER_BINDING, mOldState, GL_STATE_ARRAYBUFFER);
123    }
124
125    final void restoreGLState() {
126        GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, mOldState[GL_STATE_FBO]);
127        GLES20.glUseProgram(mOldState[GL_STATE_PROGRAM]);
128        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, mOldState[GL_STATE_ARRAYBUFFER]);
129    }
130}
131
132