Upstream: GL implementation on Android

ui/gfx/gl/gl_implementation_android.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/base_paths.h"
+#include "base/command_line.h"
+#include "base/file_path.h"
+#include "base/logging.h"
+#include "base/native_library.h"
+#include "base/path_service.h"
+#include "ui/gfx/gl/gl_bindings.h"
+#include "ui/gfx/gl/gl_implementation.h"
+
+namespace gfx {
+
+namespace {
+
+void GL_BINDING_CALL MarshalClearDepthToClearDepthf(GLclampd depth) {
+  glClearDepthf(static_cast<GLclampf>(depth));
+}
+
+void GL_BINDING_CALL MarshalDepthRangeToDepthRangef(GLclampd z_near,
+                                                    GLclampd z_far) {
+  glDepthRangef(static_cast<GLclampf>(z_near), static_cast<GLclampf>(z_far));
+}
+
+base::NativeLibrary LoadLibrary(const FilePath& filename) {
+  std::string error;
+  base::NativeLibrary library = base::LoadNativeLibrary(filename, &error);
+  if (!library) {
+    VLOG(1) << "Failed to load " << filename.MaybeAsASCII() << ": " << error;
+    return NULL;
+  }
+  return library;
+}
+
+base::NativeLibrary LoadLibrary(const char* filename) {
+  return LoadLibrary(FilePath(filename));
+}
+
+}  // namespace anonymous
+
+bool InitializeGLBindings(GLImplementation implementation) {
+  // Prevent reinitialization with a different implementation. Once the gpu
+  // unit tests have initialized with kGLImplementationMock, we don't want to
+  // later switch to another GL implementation.
+  if (GetGLImplementation() != kGLImplementationNone)
+    return true;
+
+  switch (implementation) {
+    case kGLImplementationEGLGLES2: {
+      base::NativeLibrary gles_library = LoadLibrary("libGLESv2.so");
+      if (!gles_library)
+        return false;
+      base::NativeLibrary egl_library = LoadLibrary("libEGL.so");
+      if (!egl_library)
+        return false;
+
+      // Note: Android is a GLES2 platform so no EXT or ARB entry points are
+      // used by Chromium on such platforms. However, gl_bindings_autogen_gl.cc
+      // code looks up the EXT entry points with eglGetProcAddress(), comparing
+      // the resulting function pointers against NULL to decide whether it
+      // should fall back to the non-EXT versions of these functions.
+      // However, this is wrong as eglGetProcAddress() is not guaranteed to
+      // return NULL if an extension is not supported. On Android, the
+      // end-result is that we end up with the wrong function pointers for
+      // many GL functions and the rendering is broken.

[jonathan.backer, 2011/11/21 18:54:45]

I see what you mean. glBlitFramebuffer for example. It's set in
InitializeGLBindingsGL, without querying the extension first.

There is some code later on InitializeGLExtensionBindingsGL that seems to be
doing something closer to what should be done (check for extension string before
loading).

Could you file a bug to keep track of this?

[michaelbai, 2011/11/21 19:29:04]

Done. Also add issue link here.

+      // TODO(andreip): Fix this properly by modifying the generate_bindings.py
+      // python script that generates the lookup code so that we give it two
+      // lists: one of function names to look up on desktop GL and one for
+      // those to look up on GLES2.
+      AddGLNativeLibrary(egl_library);
+      AddGLNativeLibrary(gles_library);
+      SetGLImplementation(kGLImplementationEGLGLES2);
+
+      InitializeGLBindingsGL();
+      InitializeGLBindingsEGL();
+
+      // These two functions take single precision float rather than double
+      // precision float parameters in GLES.
+      ::gfx::g_glClearDepth = MarshalClearDepthToClearDepthf;
+      ::gfx::g_glDepthRange = MarshalDepthRangeToDepthRangef;
+      break;
+    }
+    case kGLImplementationMockGL: {
+      SetGLGetProcAddressProc(GetMockGLProcAddress);
+      SetGLImplementation(kGLImplementationMockGL);
+      InitializeGLBindingsGL();
+      break;
+    }
+    default:
+      NOTIMPLEMENTED() << "InitializeGLBindings on Android";
+      return false;
+  }
+
+  return true;
+}
+
+void InitializeDebugGLBindings() {
+}
+
+}  // namespace gfx