content: /*
   * Copyright (C) 2011 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.media.effect;
  
  import android.filterfw.core.CachedFrameManager;
  import android.filterfw.core.FilterContext;
  import android.filterfw.core.GLEnvironment;
  import android.opengl.GLES20;
  
  /**
   * <p>An EffectContext keeps all necessary state information to run Effects within a Open GL ES 2.0
   * context.</p>
   *
   * <p>Every EffectContext is bound to one GL context. The application is responsible for creating
   * this EGL context, and making it current before applying any effect. If your EGL context is
   * destroyed, the EffectContext becomes invalid and any effects bound to this context can no longer
   * be used. If you switch to another EGL context, you must create a new EffectContext. Each Effect
   * is bound to a single EffectContext, and can only be executed in that context.</p>
   */
  public class EffectContext {
  
      private final int GL_STATE_FBO          = 0;
      private final int GL_STATE_PROGRAM      = 1;
      private final int GL_STATE_ARRAYBUFFER  = 2;
      private final int GL_STATE_COUNT        = 3;
  
      FilterContext mFilterContext;
  
      private EffectFactory mFactory;
  
      private int[] mOldState = new int[GL_STATE_COUNT];
  
      /**
       * Creates a context within the current GL context.
       *
       * <p>Binds the EffectContext to the current OpenGL context. All subsequent calls to the
       * EffectContext must be made in the GL context that was active during creation.
       * When you have finished using a context, you must call {@link #release()}. to dispose of all
       * resources associated with this context.</p>
       */
      public static EffectContext createWithCurrentGlContext() {
          EffectContext result = new EffectContext();
          result.initInCurrentGlContext();
          return result;
      }
  
      /**
       * Returns the EffectFactory for this context.
       *
       * <p>The EffectFactory returned from this method allows instantiating new effects within this
       * context.</p>
       *
       * @return The EffectFactory instance for this context.
       */
      public EffectFactory getFactory() {
          return mFactory;
      }
  
      /**
       * Releases the context.
       *
       * <p>Releases all the resources and effects associated with the EffectContext. This renders the
       * context and all the effects bound to this context invalid. You must no longer use the context
       * or any of its bound effects after calling release().</p>
       *
       * <p>Note that this method must be called with the proper EGL context made current, as the
       * EffectContext and its effects may release internal GL resources.</p>
       */
      public void release() {
          mFilterContext.tearDown();
          mFilterContext = null;
      }
  
      private EffectContext() {
          mFilterContext = new FilterContext();
          mFilterContext.setFrameManager(new CachedFrameManager());
          mFactory = new EffectFactory(this);
      }
  
      private void initInCurrentGlContext() {
          if (!GLEnvironment.isAnyContextActive()) {
              throw new RuntimeException("Attempting to initialize EffectContext with no active "
                  + "GL context!");
          }
          GLEnvironment glEnvironment = new GLEnvironment();
          glEnvironment.initWithCurrentContext();
          mFilterContext.initGLEnvironment(glEnvironment);
      }
  
      final void assertValidGLState() {
          GLEnvironment glEnv = mFilterContext.getGLEnvironment();
          if (glEnv == null || !glEnv.isContextActive()) {
              if (GLEnvironment.isAnyContextActive()) {
                  throw new RuntimeException("Applying effect in wrong GL context!");
              } else {
                  throw new RuntimeException("Attempting to apply effect without valid GL context!");
              }
          }
      }
  
      final void saveGLState() {
          GLES20.glGetIntegerv(GLES20.GL_FRAMEBUFFER_BINDING, mOldState, GL_STATE_FBO);
          GLES20.glGetIntegerv(GLES20.GL_CURRENT_PROGRAM, mOldState, GL_STATE_PROGRAM);
          GLES20.glGetIntegerv(GLES20.GL_ARRAY_BUFFER_BINDING, mOldState, GL_STATE_ARRAYBUFFER);
      }
  
      final void restoreGLState() {
          GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, mOldState[GL_STATE_FBO]);
          GLES20.glUseProgram(mOldState[GL_STATE_PROGRAM]);
          GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, mOldState[GL_STATE_ARRAYBUFFER]);
      }
  }
  
  