chromeos: Add ArcInputBridge to components/arc

components/arc/input/arc_input_bridge.cc

Index: components/arc/input/arc_input_bridge.cc
diff --git a/components/arc/input/arc_input_bridge.cc b/components/arc/input/arc_input_bridge.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e9b70467f4acbd5210d80c4e9274566597a93bac
--- /dev/null
+++ b/components/arc/input/arc_input_bridge.cc
@@ -0,0 +1,301 @@
+// Copyright 2015 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 "components/arc/input/arc_input_bridge.h"
+
+#include <linux/input.h>
+
+#include "base/logging.h"
+#include "base/posix/eintr_wrapper.h"
+#include "base/time/time.h"
+#include "components/arc/arc_bridge_service.h"
+#include "ui/events/event_utils.h"
+#include "ui/events/keycodes/dom/keycode_converter.h"
+#include "ui/events/ozone/evdev/keyboard_util_evdev.h"
+
+namespace {
+// input_event values for keyboard events

[jochen (gone - plz use gerrit), 2015/12/02 13:09:02]

empty line before this one

[denniskempin, 2015/12/03 01:26:41]

Done.

+static const int kKeyReleased = 0;

[jochen (gone - plz use gerrit), 2015/12/02 13:09:02]

no static required

should those be an enum?

[denniskempin, 2015/12/03 01:26:41]

removed static. I would argue against an enum since they are the integer values
that we have to put into the struct input_event's. That's the only way in which
they are being used, so it seems to make sense to use constants instead of an
enum. 
I don't feel too strongly about this, I'm happy to change it. Let me know.

+static const int kKeyPressed = 1;
+static const int kKeyRepeated = 2;
+
+// maximum number of supported multi-touch slots (simultaneous fingers)
+static const int kMaxSlots = 64;
+
+// tracking id of an empty slot
+static const int kEmptySlot = -1;
+
+// maximum possible pressure as defined in EventHubARC.
+// todo(denniskempin): communicate maximum during initialization.
+static const int kMaxPressure = 65536;
+
+struct MouseButtonMapping {
+  int ui_flag;
+  int evdev_code;
+};
+MouseButtonMapping kMouseButtonMap[] = {

[jochen (gone - plz use gerrit), 2015/12/02 13:09:01]

empty line before this one

[denniskempin, 2015/12/03 01:26:42]

Done.

+    {ui::EF_LEFT_MOUSE_BUTTON, BTN_LEFT},
+    {ui::EF_RIGHT_MOUSE_BUTTON, BTN_RIGHT},
+    {ui::EF_MIDDLE_MOUSE_BUTTON, BTN_MIDDLE},
+};
+
+// Weak pointer.  This class is owned by ChromeBrowserMainPartsChromeos.
+arc::ArcInputBridge* g_arc_input_bridge = nullptr;
+}

[jochen (gone - plz use gerrit), 2015/12/02 13:09:01]

empty line before this one, also }  // namespace

[denniskempin, 2015/12/03 01:26:42]

Done.

+
+namespace arc {
+
+ArcInputBridge::ArcInputBridge(
+    base::WeakPtr<ArcBridgeService> arc_bridge_service)
+    : arc_bridge_service_(arc_bridge_service),
+      current_slot_(-1),
+      current_slot_tracking_ids_(kMaxSlots, kEmptySlot) {
+  if (arc_bridge_service) {
+    DCHECK(arc_bridge_service->state() == ArcBridgeService::State::STOPPED);

[jochen (gone - plz use gerrit), 2015/12/02 13:09:01]

DCHECK_EQ

[denniskempin, 2015/12/03 01:26:42]

Unfortunately DCHECK_EQ can't compare enums. Well it can compare them, but the
logging output in case of a failure throws a compiler error.

+    arc_bridge_service->AddObserver(this);
+  }
+  g_arc_input_bridge = this;

[jochen (gone - plz use gerrit), 2015/12/02 13:09:02]

using observers and weak ptrs implies some weak coupling, but there can only be
one input bridge. this is pretty confusing.

Either the bridge service should own/create the input bridge, or it should be
loosely coupled without some magic global Get()

[denniskempin, 2015/12/03 01:26:42]

I agree. I would like the bridge service to own the input bridge, however that
would create a two-way dependency. I am talking to Luis and Oshima about this
since it is not clear yet what a good approach here would be. 

+}
+
+ArcInputBridge::~ArcInputBridge() {
+  if (arc_bridge_service_) {

[jochen (gone - plz use gerrit), 2015/12/02 13:09:01]

no { } required for single line body

[denniskempin, 2015/12/03 01:26:41]

Done. In other parts of the code as well.

+    arc_bridge_service_->RemoveObserver(this);
+  }
+}
+
+// static
+ArcInputBridge* ArcInputBridge::Get() {
+  DCHECK(g_arc_input_bridge);
+  return g_arc_input_bridge;
+}
+
+void ArcInputBridge::OnInstanceBootPhase(InstanceBootPhase phase) {
+  // todo(denniskempin): Investigate how to turn around the communication
+  // and initiate the creation of devices from the instance-side. This would
+  // reduce the amount of state-tracking necessary.
+  if (phase != InstanceBootPhase::SYSTEM_SERVICES_READY) {
+    return;
+  }
+
+  keyboard_fd_ = CreateBridgeInputDevice("ChromeOS Keyboard", "keyboard");
+  mouse_fd_ = CreateBridgeInputDevice("ChromeOS Mouse", "mouse");
+  touchscreen_fd_ =
+      CreateBridgeInputDevice("ChromeOS Touchscreen", "touchscreen");
+}
+
+void ArcInputBridge::SendInputEvent(ui::Event* event) {
+  if (event->IsKeyEvent()) {
+    SendKeyEvent(static_cast<ui::KeyEvent*>(event));
+  } else if (event->IsMouseEvent()) {
+    SendMouseEvent(static_cast<ui::MouseEvent*>(event));
+  } else if (event->IsTouchEvent()) {
+    SendTouchEvent(static_cast<ui::TouchEvent*>(event));
+  }
+}
+
+void ArcInputBridge::SendKeyEvent(ui::KeyEvent* event) {
+  if (keyboard_fd_.get() < 0) {
+    LOG(WARNING) << "No keyboard bridge device available.";
+    return;
+  }
+
+  int native_code = ui::KeycodeConverter::DomCodeToNativeKeycode(event->code());
+
+  unsigned short evdev_code = ui::NativeCodeToEvdevCode(native_code);
+  int evdev_value;
+  if (event->type() == ui::ET_KEY_PRESSED) {
+    if (event->flags() & ui::EF_IS_REPEAT) {
+      evdev_value = kKeyRepeated;
+    } else {
+      evdev_value = kKeyPressed;
+    }
+  } else if (event->type() == ui::ET_KEY_RELEASED) {
+    evdev_value = kKeyReleased;
+  }
+
+  base::TimeDelta time_stamp = event->time_stamp();
+  SendKernelEvent(keyboard_fd_, time_stamp, EV_KEY, evdev_code, evdev_value);
+  SendSynReport(keyboard_fd_, time_stamp);
+}
+
+void ArcInputBridge::SendTouchEvent(ui::TouchEvent* event) {
+  if (touchscreen_fd_.get() < 0) {
+    LOG(WARNING) << "No touchscreen bridge device available.";
+    return;
+  }
+
+  ui::PointerDetails details = event->pointer_details();
+  base::TimeDelta time_stamp = event->time_stamp();
+
+  // find or assing a slot for this tracking id
+  int slot_id = AcquireTouchSlot(event);
+  if (slot_id < 0) {
+    LOG(ERROR) << "Ran out of slot IDs.";
+    return;
+  }
+
+  // we only need to send the slot ID when it has changed.
+  if (slot_id != current_slot_) {
+    current_slot_ = slot_id;
+    SendKernelEvent(touchscreen_fd_, time_stamp, EV_ABS, ABS_MT_SLOT,
+                    current_slot_);
+  }
+
+  // update tracking id
+  if (event->type() == ui::ET_TOUCH_PRESSED) {
+    SendKernelEvent(touchscreen_fd_, time_stamp, EV_ABS, ABS_MT_TRACKING_ID,
+                    event->touch_id());
+  } else if (event->type() == ui::ET_TOUCH_RELEASED) {
+    SendKernelEvent(touchscreen_fd_, time_stamp, EV_ABS, ABS_MT_TRACKING_ID,
+                    kEmptySlot);
+  }
+
+  // update touch information
+  if (event->type() == ui::ET_TOUCH_MOVED ||
+      event->type() == ui::ET_TOUCH_PRESSED) {
+    SendKernelEvent(touchscreen_fd_, time_stamp, EV_ABS, ABS_MT_POSITION_X,
+                    event->x());
+    SendKernelEvent(touchscreen_fd_, time_stamp, EV_ABS, ABS_MT_POSITION_Y,
+                    event->y());
+    SendKernelEvent(touchscreen_fd_, time_stamp, EV_ABS, ABS_MT_TOUCH_MAJOR,
+                    details.radius_x());
+    SendKernelEvent(touchscreen_fd_, time_stamp, EV_ABS, ABS_MT_TOUCH_MINOR,
+                    details.radius_y());
+    SendKernelEvent(touchscreen_fd_, time_stamp, EV_ABS, ABS_MT_PRESSURE,
+                    details.force() * kMaxPressure);
+  }
+  SendSynReport(touchscreen_fd_, time_stamp);
+}
+
+void ArcInputBridge::SendMouseEvent(ui::MouseEvent* event) {
+  if (mouse_fd_.get() < 0) {
+    LOG(WARNING) << "No mouse bridge device available.";
+    return;
+  }
+
+  base::TimeDelta time_stamp = event->time_stamp();
+
+  // update location
+  if (event->type() == ui::ET_MOUSE_MOVED) {
+    SendKernelEvent(mouse_fd_, time_stamp, EV_ABS, ABS_X, event->x());
+    SendKernelEvent(mouse_fd_, time_stamp, EV_ABS, ABS_Y, event->y());
+  }
+
+  // update buttons
+  if (event->type() == ui::ET_MOUSE_PRESSED ||
+      event->type() == ui::ET_MOUSE_RELEASED) {
+    int evdev_value = static_cast<int>(event->type() == ui::ET_MOUSE_PRESSED);
+    for (MouseButtonMapping mapping : kMouseButtonMap) {
+      if (event->changed_button_flags() & mapping.ui_flag) {
+        SendKernelEvent(mouse_fd_, time_stamp, EV_KEY, mapping.evdev_code,
+                        evdev_value);
+      }
+    }
+  }
+
+  // update scroll wheel
+  if (event->IsMouseWheelEvent()) {
+    ui::MouseWheelEvent* wheel_event = static_cast<ui::MouseWheelEvent*>(event);
+    SendKernelEvent(mouse_fd_, time_stamp, EV_REL, REL_WHEEL,
+                    wheel_event->y_offset());
+    SendKernelEvent(mouse_fd_, time_stamp, EV_REL, REL_HWHEEL,
+                    wheel_event->x_offset());
+  }
+
+  SendSynReport(mouse_fd_, time_stamp);
+}
+
+void ArcInputBridge::SendKernelEvent(const base::ScopedFD& fd,
+                                     base::TimeDelta time_stamp,
+                                     unsigned short type,
+                                     unsigned short code,
+                                     int value) {
+  if (fd.get() < 0) {
+    LOG(ERROR) << "Invalid file descriptor";

[jochen (gone - plz use gerrit), 2015/12/02 13:09:01]

please use LOG or VLOG.

Can this happen it all? Should that be a DCHECK()?

[denniskempin, 2015/12/03 01:26:41]

Done.

+    return;
+  }
+  // Chrome does not always use the monotonic system time for event times.
+  // For now always force the event time to the current system time.
+  // todo(denniskempin): To enable performance tracing of events we will want
+  // to use the kernel-provided monotonic time stamps of events.
+  time_stamp = ui::EventTimeForNow();
+
+  struct input_event event;
+  event.time.tv_sec = time_stamp.InSeconds();
+  base::TimeDelta remainder =
+      time_stamp - base::TimeDelta::FromSeconds(event.time.tv_sec);
+  event.time.tv_usec = remainder.InMicroseconds();
+  event.type = type;
+  event.code = code;
+  event.value = value;
+
+  // Write event to file descriptor
+  int num_written = write(fd.get(), reinterpret_cast<void*>(&event),
+                          sizeof(struct input_event));
+  if (num_written != sizeof(struct input_event)) {
+    LOG(ERROR) << "Can't write to file descriptor";
+  }
+}
+
+void ArcInputBridge::SendSynReport(const base::ScopedFD& fd,
+                                   base::TimeDelta time) {
+  SendKernelEvent(fd, time, EV_SYN, SYN_REPORT, 0);
+}
+
+int ArcInputBridge::AcquireTouchSlot(ui::TouchEvent* event) {
+  int slot_id;
+  if (event->type() == ui::ET_TOUCH_PRESSED) {
+    slot_id = FindTouchSlot(kEmptySlot);
+  } else {
+    slot_id = FindTouchSlot(event->touch_id());
+  }
+  if (slot_id < 0) {
+    return -1;
+  }
+
+  if (event->type() == ui::ET_TOUCH_RELEASED) {
+    current_slot_tracking_ids_[slot_id] = kEmptySlot;
+  } else if (event->type() == ui::ET_TOUCH_PRESSED) {
+    current_slot_tracking_ids_[slot_id] = event->touch_id();
+  }
+  return slot_id;
+}
+
+int ArcInputBridge::FindTouchSlot(int tracking_id) {
+  for (int i = 0; i < kMaxSlots; ++i) {
+    if (current_slot_tracking_ids_[i] == tracking_id) {
+      return i;
+    }
+  }
+  return -1;
+}
+
+base::ScopedFD ArcInputBridge::CreateBridgeInputDevice(
+    const std::string& name,
+    const std::string& device_type) {
+  if (!arc_bridge_service_) {
+    LOG(ERROR) << "ArcBridgeService disappeared.";
+    return base::ScopedFD();
+  }
+
+  // Create file descriptor pair for communication
+  int fd[2];
+  int res = HANDLE_EINTR(pipe(fd));
+  if (res < 0) {
+    PLOG(ERROR) << "Cannot create pipe";
+  }
+
+  // The read end is sent to the instance, ownership of fd transfers.
+  if (!arc_bridge_service_->RegisterInputDevice(name, device_type,
+                                                base::ScopedFD(fd[0]))) {
+    close(fd[1]);  // close write end.
+    LOG(ERROR) << "Cannot create bridge input device";
+    return base::ScopedFD();
+  }
+
+  // return the write end
+  return base::ScopedFD(fd[1]).Pass();
+}
+
+}  // namespace arc