Gamepad API support for chrome on android

content/browser/gamepad/gamepad_platform_data_fetcher_android.cc

+// Copyright (c) 2014 The Chromium Authors. All rights reserved.

[Ted C, 2014/04/16 23:36:53]

no (c) here either

[SaurabhK, 2014/04/18 14:51:57]

On 2014/04/16 23:36:53, Ted C wrote:

Again, i have seen similar copyright in other files like
gamepad_platform_data_fetcher_linux.cc)

+// 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) {

[Ted C, 2014/04/16 23:36:53]

include the paramater name even if unused.

[SaurabhK, 2014/04/18 14:51:57]

On 2014/04/16 23:36:53, Ted C wrote:

Done.

+  TRACE_EVENT0("GAMEPAD", "GetGamepadData");
+
+  pads->length = 0;
+
+  JNIEnv* env = AttachCurrentThread();
+  if (!env)
+    return;
+
+  Java_GamepadList_getGamepadData(env, reinterpret_cast<intptr_t>(pads));
+}
+
+void GamepadPlatformDataFetcherAndroid::PauseHint(bool isaccesspaused) {

[Ted C, 2014/04/16 23:36:53]

variable name should match the header

[SaurabhK, 2014/04/18 14:51:57]

On 2014/04/16 23:36:53, Ted C wrote:

Done.

+  JNIEnv* env = AttachCurrentThread();
+  if (!env)
+    return;
+
+  Java_GamepadList_notifyForGamepadsAccess(env, isaccesspaused);
+}
+
+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(unsigned(index), 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.
+  base::string16 device_name;
+  base::android::ConvertJavaStringToUTF16(env, devicename, &device_name);

[jdduke (slow), 2014/04/16 23:23:44]

It's a shame to have to do this conversion every frame, but it's probably not a
big deal for now.  Could you write a "TODO: Store a cached WebGamePad object in
GamepadPlatformDataFetcherAndroid and only update constant WebGamepad values
when a device has changed."

[SaurabhK, 2014/04/18 14:51:57]

On 2014/04/16 23:23:44, jdduke wrote:

Done.

[jdduke (slow), 2014/04/21 19:53:58]

Hmm, is the "Done." part in a patch that hasn't been uploaded?

[SaurabhK, 2014/04/22 09:33:52]

On 2014/04/21 19:53:58, jdduke wrote:

I meant that i have introduced a TODO in the next patch-set (patch-set 20).

+  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(axes.size(), WebGamepad::axesLengthCap);
+
+  memcpy(pad.axes, axes.begin(), pad.axesLength * sizeof(float));
+
+  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(buttons.size(), 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];

[jdduke (slow), 2014/04/16 23:23:44]

Should this be |pad.buttons[j].value = buttons[j] ? 0.f : 1.f|?  Looking at the
implementations for all other platforms, they do something like that.

[SaurabhK, 2014/04/18 14:51:57]

On 2014/04/16 23:23:44, jdduke wrote:

We already store buttons data in either 1.0f or 0.0f format upon getting key
event.
Also for the conversion of axes to buttons value we have already put the check
in form of |negativeAxisValueAsButton/positiveAxisValueAsButton| which maps to
the expected values in GamepadMapping.java.
So it is not needed here.

+  }
+}
+
+}  // namespace content