content: /*
   * Copyright (C) 2019 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 com.android.server.wallpaper;
  
  import static android.opengl.EGL14.EGL_ALPHA_SIZE;
  import static android.opengl.EGL14.EGL_BLUE_SIZE;
  import static android.opengl.EGL14.EGL_CONFIG_CAVEAT;
  import static android.opengl.EGL14.EGL_CONTEXT_CLIENT_VERSION;
  import static android.opengl.EGL14.EGL_DEFAULT_DISPLAY;
  import static android.opengl.EGL14.EGL_DEPTH_SIZE;
  import static android.opengl.EGL14.EGL_GREEN_SIZE;
  import static android.opengl.EGL14.EGL_HEIGHT;
  import static android.opengl.EGL14.EGL_NONE;
  import static android.opengl.EGL14.EGL_NO_CONTEXT;
  import static android.opengl.EGL14.EGL_NO_DISPLAY;
  import static android.opengl.EGL14.EGL_NO_SURFACE;
  import static android.opengl.EGL14.EGL_OPENGL_ES2_BIT;
  import static android.opengl.EGL14.EGL_RED_SIZE;
  import static android.opengl.EGL14.EGL_RENDERABLE_TYPE;
  import static android.opengl.EGL14.EGL_STENCIL_SIZE;
  import static android.opengl.EGL14.EGL_WIDTH;
  import static android.opengl.EGL14.eglChooseConfig;
  import static android.opengl.EGL14.eglCreateContext;
  import static android.opengl.EGL14.eglCreatePbufferSurface;
  import static android.opengl.EGL14.eglDestroyContext;
  import static android.opengl.EGL14.eglDestroySurface;
  import static android.opengl.EGL14.eglGetDisplay;
  import static android.opengl.EGL14.eglGetError;
  import static android.opengl.EGL14.eglInitialize;
  import static android.opengl.EGL14.eglMakeCurrent;
  import static android.opengl.EGL14.eglTerminate;
  import static android.opengl.GLES20.GL_MAX_TEXTURE_SIZE;
  import static android.opengl.GLES20.glGetIntegerv;
  
  import android.opengl.EGLConfig;
  import android.opengl.EGLContext;
  import android.opengl.EGLDisplay;
  import android.opengl.EGLSurface;
  import android.opengl.GLUtils;
  import android.os.SystemProperties;
  import android.util.Log;
  
  class GLHelper {
      private static final String TAG = GLHelper.class.getSimpleName();
      private static final int sMaxTextureSize;
  
      static {
          int maxTextureSize = SystemProperties.getInt("sys.max_texture_size", 0);
          sMaxTextureSize = maxTextureSize > 0 ? maxTextureSize : retrieveTextureSizeFromGL();
      }
  
      private static int retrieveTextureSizeFromGL() {
          try {
              String err;
  
              // Before we can retrieve info from GL,
              // we have to create EGLContext, EGLConfig and EGLDisplay first.
              // We will fail at querying info from GL once one of above failed.
              // When this happens, we will use defValue instead.
              EGLDisplay eglDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY);
              if (eglDisplay == null || eglDisplay == EGL_NO_DISPLAY) {
                  err = "eglGetDisplay failed: " + GLUtils.getEGLErrorString(eglGetError());
                  throw new RuntimeException(err);
              }
  
              if (!eglInitialize(eglDisplay, null, 0 /* majorOffset */, null, 1 /* minorOffset */)) {
                  err = "eglInitialize failed: " + GLUtils.getEGLErrorString(eglGetError());
                  throw new RuntimeException(err);
              }
  
              EGLConfig eglConfig = null;
              int[] configsCount = new int[1];
              EGLConfig[] configs = new EGLConfig[1];
              int[] configSpec = new int[] {
                      EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
                      EGL_RED_SIZE, 8,
                      EGL_GREEN_SIZE, 8,
                      EGL_BLUE_SIZE, 8,
                      EGL_ALPHA_SIZE, 0,
                      EGL_DEPTH_SIZE, 0,
                      EGL_STENCIL_SIZE, 0,
                      EGL_CONFIG_CAVEAT, EGL_NONE,
                      EGL_NONE
              };
  
              if (!eglChooseConfig(eglDisplay, configSpec, 0 /* attrib_listOffset */,
                      configs, 0  /* configOffset */, 1 /* config_size */,
                      configsCount, 0 /* num_configOffset */)) {
                  err = "eglChooseConfig failed: " + GLUtils.getEGLErrorString(eglGetError());
                  throw new RuntimeException(err);
              } else if (configsCount[0] > 0) {
                  eglConfig = configs[0];
              }
  
              if (eglConfig == null) {
                  throw new RuntimeException("eglConfig not initialized!");
              }
  
              int[] attr_list = new int[] {EGL_CONTEXT_CLIENT_VERSION, 2, EGL_NONE};
              EGLContext eglContext = eglCreateContext(
                      eglDisplay, eglConfig, EGL_NO_CONTEXT, attr_list, 0 /* offset */);
  
              if (eglContext == null || eglContext == EGL_NO_CONTEXT) {
                  err = "eglCreateContext failed: " + GLUtils.getEGLErrorString(eglGetError());
                  throw new RuntimeException(err);
              }
  
              // We create a push buffer temporarily for querying info from GL.
              int[] attrs = {EGL_WIDTH, 1, EGL_HEIGHT, 1, EGL_NONE};
              EGLSurface eglSurface =
                      eglCreatePbufferSurface(eglDisplay, eglConfig, attrs, 0 /* offset */);
              eglMakeCurrent(eglDisplay, eglSurface, eglSurface, eglContext);
  
              // Now, we are ready to query the info from GL.
              int[] maxSize = new int[1];
              glGetIntegerv(GL_MAX_TEXTURE_SIZE, maxSize, 0 /* offset */);
  
              // We have got the info we want, release all egl resources.
              eglMakeCurrent(eglDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
              eglDestroySurface(eglDisplay, eglSurface);
              eglDestroyContext(eglDisplay, eglContext);
              eglTerminate(eglDisplay);
              return maxSize[0];
          } catch (RuntimeException e) {
              Log.w(TAG, "Retrieve from GL failed", e);
              return Integer.MAX_VALUE;
          }
      }
  
      static int getMaxTextureSize() {
          return sMaxTextureSize;
      }
  }
  
  