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