Add 16-bit support for browser compositor surface

ui/gl/gl_surface_egl.cc

 // Copyright (c) 2012 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.
 
 // This include must be here so that the includes provided transitively
 // by gl_surface_egl.h don't make it impossible to compile this code.
 #include "third_party/mesa/src/include/GL/osmesa.h"
 
 #include "ui/gl/gl_surface_egl.h"
 
 #if defined(OS_ANDROID)
 #include <android/native_window_jni.h>
+#include "base/android/sys_utils.h"
 #endif
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "build/build_config.h"
 #include "ui/gl/egl_util.h"
 #include "ui/gl/gl_context.h"
@@ skipping 107 matching lines @@
     return false;
   }
 
   if (!eglInitialize(g_display, NULL, NULL)) {
     LOG(ERROR) << "eglInitialize failed with error " << GetLastEGLErrorString();
     return false;
   }
 
   // Choose an EGL configuration.
   // On X this is only used for PBuffer surfaces.
-  static const EGLint kConfigAttribs[] = {
+  static EGLint config_attribs_8888[] = {
     EGL_BUFFER_SIZE, 32,
     EGL_ALPHA_SIZE, 8,
     EGL_BLUE_SIZE, 8,
     EGL_GREEN_SIZE, 8,
     EGL_RED_SIZE, 8,
     EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
     EGL_SURFACE_TYPE, EGL_WINDOW_BIT | EGL_PBUFFER_BIT,
     EGL_NONE
   };
 
+#if defined(OS_ANDROID)
+  static EGLint config_attribs_565[] = {
+    EGL_BUFFER_SIZE, 16,
+    EGL_BLUE_SIZE, 5,
+    EGL_GREEN_SIZE, 6,
+    EGL_RED_SIZE, 5,
+    EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
+    EGL_SURFACE_TYPE, EGL_WINDOW_BIT | EGL_PBUFFER_BIT,
+    EGL_NONE
+  };
+#endif
+
+  EGLint* choose_attributes = 0;

[kalyank, 2014/01/20 14:48:31]

choose_attributes could point to config_attribs_8888 here, which would avoid the
else case below and also #else case.

[sivag, 2014/01/21 07:44:05]

Done.

+#if defined(OS_ANDROID)
+  if (base::android::SysUtils::IsLowEndDevice()) {
+    choose_attributes = config_attribs_565;
+  } else {
+    choose_attributes = config_attribs_8888;
+  }
+#else
+  choose_attributes = config_attribs_8888;
+#endif
+
 #if defined(USE_OZONE)
   const EGLint* config_attribs =
-      surface_factory->GetEGLSurfaceProperties(kConfigAttribs);
+      surface_factory->GetEGLSurfaceProperties(choose_attributes);
 #else
-  const EGLint* config_attribs = kConfigAttribs;
+  const EGLint* config_attribs = choose_attributes;
 #endif
 
   EGLint num_configs;
   if (!eglChooseConfig(g_display,
                        config_attribs,
                        NULL,
                        0,
                        &num_configs)) {
     LOG(ERROR) << "eglChooseConfig failed with error "
                << GetLastEGLErrorString();
     return false;
   }
 
   if (num_configs == 0) {
     LOG(ERROR) << "No suitable EGL configs found.";
     return false;
   }
 
+  int config_size = 1;
+  scoped_ptr<EGLConfig[]> matching_configs(new EGLConfig[num_configs]);

[kalyank, 2014/01/20 14:48:31]

matching_configs could be defined under #if defined(OS_ANDROID) perhaps ?
(Atleast it's not used otherwise)

[sivag, 2014/01/21 07:44:05]

Done.

+  EGLConfig *config_data = NULL;

[kalyank, 2014/01/20 14:48:31]

config_data could point to g_config here ? This would avoid the else case below
and #else too.

[kalyank, 2014/01/20 14:48:31]

nit: asterisk to left i.e. EGLConfig* config_data as in rest of the code.

[sivag, 2014/01/21 07:44:05]

Done.

[sivag, 2014/01/21 08:41:30]

Done.

+
+#if defined(OS_ANDROID)
+  if (base::android::SysUtils::IsLowEndDevice()) {
+    config_size = num_configs;
+    config_data = matching_configs.get();
+  } else {
+    config_size = 1;
+    config_data = &g_config;
+  }
+#else
+  config_size = 1;
+  config_data = &g_config;
+#endif
+
   if (!eglChooseConfig(g_display,
                        config_attribs,
-                       &g_config,
-                       1,
+                       config_data,
+                       config_size,
                        &num_configs)) {
     LOG(ERROR) << "eglChooseConfig failed with error "
                << GetLastEGLErrorString();
     return false;
   }
 
+#if defined(OS_ANDROID)
+  if (base::android::SysUtils::IsLowEndDevice()) {
+    // Because of the EGL config sort order, we have to iterate
+    // through all of them (it'll put higher sum(R,G,B) bits
+    // first with the above attribs).
+    bool match_found = false;
+    int default_format = 0;
+    for (int i = 0; i < num_configs; i++) {
+      EGLBoolean success;
+      EGLint red, green, blue, alpha;
+      // Read the relevent attributes of the EGLConfig.
+      success = eglGetConfigAttrib(g_display, matching_configs[i],
+                                   EGL_RED_SIZE, &red);
+      success &= eglGetConfigAttrib(g_display, matching_configs[i],
+                                    EGL_BLUE_SIZE, &blue);
+      success &= eglGetConfigAttrib(g_display, matching_configs[i],
+                                    EGL_GREEN_SIZE, &green);
+      success &= eglGetConfigAttrib(g_display, matching_configs[i],
+                                    EGL_ALPHA_SIZE, &alpha);
+      if ((success == EGL_TRUE) && (red == 8) &&
+        (green == 8) && (blue == 8) && (alpha == 8)) {
+         // Fallback to default format when the device fails to support 565.
+         default_format = i;
+      }
+      // Check that no error occurred and the attributes match.
+      if ((success == EGL_TRUE) && (red == 5) &&

[kalyank, 2014/01/20 14:48:31]

nit: as we are trying to find an exact match, we could use else here ? 

[sivag, 2014/01/21 07:44:05]

We dont know whether we found the exact match or not until we break the loop.so
else condition here will not work.

[kalyank, 2014/01/21 08:10:02]

Sorry, I probably wasn't clear enough. I meant something like this:

if (success == EGL_TRUE) {
  if ((red == 8) && (green == 8) other checks) {
   default_format = i;
  } else if ((red == 5) and other checks) {
    g_config = matching_configs[i];
    match_found = true;
    break;
  }
}

We cannot have a config which matches both criteria at the same time.

[sivag, 2014/01/21 08:41:30]

Done.

+          (green == 6) && (blue == 5)) {
+        g_config = matching_configs[i];
+        match_found = true;
+        break;
+      }
+    }
+    if (!match_found) {
+      LOG (ERROR) << "Falling back to default 32 bit format";
+      g_config = matching_configs[default_format];
+    }
+  }
+#endif
+
   g_egl_extensions = eglQueryString(g_display, EGL_EXTENSIONS);
   g_egl_create_context_robustness_supported =
       HasEGLExtension("EGL_EXT_create_context_robustness");
   g_egl_sync_control_supported =
       HasEGLExtension("EGL_CHROMIUM_sync_control");
 
   // Check if SurfacelessEGL is supported.
   g_egl_surfaceless_context_supported =
       HasEGLExtension("EGL_KHR_surfaceless_context");
   if (g_egl_surfaceless_context_supported) {
@@ skipping 572 matching lines @@
     }
     default:
       NOTREACHED();
       return NULL;
   }
 }
 
 #endif
 
 }  // namespace gfx