Gamepad API support for chrome on android

content/browser/gamepad/gamepad_platform_data_fetcher_android.cc

+// Copyright 2014 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 "content/browser/gamepad/gamepad_platform_data_fetcher_android.h"
+
+#include "base/android/jni_android.h"
+#include "base/android/jni_array.h"
+#include "base/android/jni_string.h"
+#include "base/debug/trace_event.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
+#include "base/strings/utf_string_conversions.h"
+
+#include "jni/GamepadList_jni.h"
+
+#include "third_party/WebKit/public/platform/WebGamepads.h"
+
+using base::android::AttachCurrentThread;
+using base::android::CheckException;
+using base::android::ClearException;
+using base::android::ConvertJavaStringToUTF8;
+using base::android::ScopedJavaLocalRef;
+using blink::WebGamepad;
+using blink::WebGamepads;
+
+namespace content {
+
+bool
+GamepadPlatformDataFetcherAndroid::RegisterGamepadPlatformDataFetcherAndroid(
+    JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+GamepadPlatformDataFetcherAndroid::GamepadPlatformDataFetcherAndroid() {
+  PauseHint(false);
+}
+
+GamepadPlatformDataFetcherAndroid::~GamepadPlatformDataFetcherAndroid() {
+  PauseHint(true);
+}
+
+void GamepadPlatformDataFetcherAndroid::GetGamepadData(
+    blink::WebGamepads* pads,
+    bool devices_changed_hint) {
+  TRACE_EVENT0("GAMEPAD", "GetGamepadData");
+
+  pads->length = 0;
+
+  JNIEnv* env = AttachCurrentThread();
+  if (!env)
+    return;
+
+  Java_GamepadList_updateGamepadData(env, reinterpret_cast<intptr_t>(pads));
+}
+
+void GamepadPlatformDataFetcherAndroid::PauseHint(bool paused) {
+  JNIEnv* env = AttachCurrentThread();
+  if (!env)
+    return;
+
+  Java_GamepadList_notifyForGamepadsAccess(env, paused);
+}
+
+static void SetGamepadData(JNIEnv* env,
+                           jobject obj,
+                           jlong gamepads,
+                           jint index,
+                           jboolean mapping,
+                           jboolean connected,
+                           jstring devicename,
+                           jlong timestamp,
+                           jfloatArray jaxes,
+                           jfloatArray jbuttons) {
+  DCHECK(gamepads);
+  blink::WebGamepads* pads = reinterpret_cast<WebGamepads*>(gamepads);
+  DCHECK_EQ(pads->length, unsigned(index));
+  DCHECK_LT(index, static_cast<int>(blink::WebGamepads::itemsLengthCap));
+
+  ++pads->length;
+
+  blink::WebGamepad& pad = pads->items[index];
+
+  pad.connected = connected;
+
+  pad.timestamp = timestamp;
+
+  // Do not set gamepad parameters for all the gamepad devices that are not
+  // attached.
+  if (!connected)
+    return;
+
+  // Map the Gamepad DeviceName String to the WebGamepad Id. Ideally it should
+  // be mapped to vendor and product information but it is only available at
+  // kernel level and it can not be queried using class
+  // android.hardware.input.InputManager.
+  // TODO(SaurabhK): Store a cached WebGamePad object in
+  // GamepadPlatformDataFetcherAndroid and only update constant WebGamepad
+  // values when a device has changed.
+  base::string16 device_name;
+  base::android::ConvertJavaStringToUTF16(env, devicename, &device_name);
+  const size_t name_to_copy =
+      std::min(device_name.size(), WebGamepad::idLengthCap - 1);
+  memcpy(pad.id,
+         device_name.data(),
+         name_to_copy * sizeof(base::string16::value_type));
+  pad.id[name_to_copy] = 0;
+
+  base::string16 mapping_name = base::UTF8ToUTF16(mapping ? "standard" : "");
+  const size_t mapping_to_copy =
+      std::min(mapping_name.size(), WebGamepad::mappingLengthCap - 1);
+  memcpy(pad.mapping,
+         mapping_name.data(),
+         mapping_to_copy * sizeof(base::string16::value_type));
+  pad.mapping[mapping_to_copy] = 0;
+
+  pad.timestamp = timestamp;
+
+  std::vector<float> axes;
+  base::android::JavaFloatArrayToFloatVector(env, jaxes, &axes);
+
+  // Set WebGamepad axeslength to total number of axes on the gamepad device.
+  // Only return the first axesLengthCap if axeslength captured by GamepadList
+  // is larger than axesLengthCap.
+  pad.axesLength = std::min(static_cast<int>(axes.size()),
+                            static_cast<int>(WebGamepad::axesLengthCap));
+
+  // Copy axes state to the WebGamepad axes[].
+  for (unsigned int i = 0; i < pad.axesLength; i++) {
+    pad.axes[i] = static_cast<double>(axes[i]);
+  }
+
+  std::vector<float> buttons;
+  base::android::JavaFloatArrayToFloatVector(env, jbuttons, &buttons);
+
+  // Set WebGamepad buttonslength to total number of axes on the gamepad
+  // device. Only return the first buttonsLengthCap if axeslength captured by
+  // GamepadList is larger than buttonsLengthCap.
+  pad.buttonsLength = std::min(static_cast<int>(buttons.size()),
+                               static_cast<int>(WebGamepad::buttonsLengthCap));
+
+  // Copy buttons state to the WebGamepad buttons[].
+  for (unsigned int j = 0; j < pad.buttonsLength; j++) {
+    pad.buttons[j].pressed = buttons[j];
+    pad.buttons[j].value = buttons[j];
+  }
+}
+
+}  // namespace content