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 
18 package android.media.effect;
19 
20 import android.filterfw.core.CachedFrameManager;
21 import android.filterfw.core.FilterContext;
22 import android.filterfw.core.GLEnvironment;
23 import 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  */
35 public 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      */
createWithCurrentGlContext()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      */
getFactory()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      */
release()84     public void release() {
85         mFilterContext.tearDown();
86         mFilterContext = null;
87     }
88 
EffectContext()89     private EffectContext() {
90         mFilterContext = new FilterContext();
91         mFilterContext.setFrameManager(new CachedFrameManager());
92         mFactory = new EffectFactory(this);
93     }
94 
initInCurrentGlContext()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 
assertValidGLState()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 
saveGLState()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 
restoreGLState()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