Cache DeviceDisplayInfo data in shared structure on native side to avoid frequent JNI calls.

ui/gfx/android/shared_device_display_info.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.
+
+#include "ui/gfx/android/shared_device_display_info.h"
+
+#include "base/android/jni_android.h"
+#include "base/android/jni_string.h"
+#include "base/logging.h"
+#include "jni/DeviceDisplayInfo_jni.h"
+
+using base::android::AttachCurrentThread;
+using base::android::ScopedJavaLocalRef;
+
+namespace gfx {
+
+base::LazyInstance<SharedDeviceDisplayInfo>
+  SharedDeviceDisplayInfo::g_instance_;
+
+int SharedDeviceDisplayInfo::GetDisplayHeight() {
+  SharedDeviceDisplayInfo* instance = Instance();
+  base::AutoLock(instance->lock_);
+  return instance->display_height_;
+}
+
+int SharedDeviceDisplayInfo::GetDisplayWidth() {
+  SharedDeviceDisplayInfo* instance = Instance();
+  base::AutoLock(instance->lock_);
+  return instance->display_width_;
+}
+
+int SharedDeviceDisplayInfo::GetBitsPerPixel() {
+  SharedDeviceDisplayInfo* instance = Instance();
+  base::AutoLock(instance->lock_);
+  return instance->bits_per_pixel_;
+}
+
+int SharedDeviceDisplayInfo::GetBitsPerComponent() {
+  SharedDeviceDisplayInfo* instance = Instance();
+  base::AutoLock(instance->lock_);
+  return instance->bits_per_component_;
+}
+
+double SharedDeviceDisplayInfo::GetDIPScale() {
+  SharedDeviceDisplayInfo* instance = Instance();
+  base::AutoLock(instance->lock_);
+  return instance->dip_scale_;
+}
+
+void UpdateSharedDeviceDisplayInfo(JNIEnv* env,
+                                   jobject obj,
+                                   jint display_height,
+                                   jint display_width,
+                                   jint bits_per_pixel,
+                                   jint bits_per_component,
+                                   jdouble dip_scale) {
+  SharedDeviceDisplayInfo* instance = SharedDeviceDisplayInfo::Instance();
+  base::AutoLock(instance->lock());
+
+  instance->UpdateDisplayInfo(env, obj, display_height,
+            display_width, bits_per_pixel, bits_per_component, dip_scale);
+}
+
+void SharedDeviceDisplayInfo::UpdateDisplayInfo(JNIEnv*,
+                                                jobject,
+                                                jint display_height,
+                                                jint display_width,
+                                                jint bits_per_pixel,
+                                                jint bits_per_component,
+                                                jdouble dip_scale) {
+  display_height_ = static_cast<int>(display_height);

[Yaron, 2013/10/11 10:18:14]

Add lock_->AssertAcquired();

+  display_width_ = static_cast<int>(display_width);
+  bits_per_pixel_ = static_cast<int>(bits_per_pixel);
+  bits_per_component_ = static_cast<int>(bits_per_component);
+  dip_scale_ = static_cast<double>(dip_scale);
+}
+
+SharedDeviceDisplayInfo* SharedDeviceDisplayInfo::Instance() {
+  return g_instance_.Pointer();
+}
+
+SharedDeviceDisplayInfo::SharedDeviceDisplayInfo() {
+  JNIEnv* env = AttachCurrentThread();
+  j_device_info_.Reset(
+    Java_DeviceDisplayInfo_createWithListener(env,
+      base::android::GetApplicationContext()));
+  UpdateDisplayInfo(env, j_device_info_.obj(),
+    Java_DeviceDisplayInfo_getDisplayHeight(env, j_device_info_.obj()),
+    Java_DeviceDisplayInfo_getDisplayWidth(env, j_device_info_.obj()),
+    Java_DeviceDisplayInfo_getBitsPerPixel(env, j_device_info_.obj()),
+    Java_DeviceDisplayInfo_getBitsPerComponent(env, j_device_info_.obj()),
+    Java_DeviceDisplayInfo_getDIPScale(env, j_device_info_.obj()));
+}
+
+bool SharedDeviceDisplayInfo::RegisterSharedDeviceDisplayInfo(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+}  // namespace gfx