ui/events/ozone/evdev/tablet_event_converter_evdev.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 "ui/events/ozone/evdev/tablet_event_converter_evdev.h"

#include <errno.h>
#include <linux/input.h>

#include "base/message_loop/message_loop.h"
#include "ui/events/event.h"

namespace ui {

TabletEventConverterEvdev::TabletEventConverterEvdev(
    int fd,
    base::FilePath path,
    int id,
    EventModifiersEvdev* modifiers,
    CursorDelegateEvdev* cursor,
    const EventDeviceInfo& info,
    const EventDispatchCallback& callback)
    : EventConverterEvdev(fd, path, id),
      cursor_(cursor),
      modifiers_(modifiers),
      callback_(callback),
      stylus_(0),
      abs_value_dirty_(false) {
  x_abs_min_ = info.GetAbsMinimum(ABS_X);
  x_abs_range_ = info.GetAbsMaximum(ABS_X) - x_abs_min_ + 1;
  y_abs_min_ = info.GetAbsMinimum(ABS_Y);
  y_abs_range_ = info.GetAbsMaximum(ABS_Y) - y_abs_min_ + 1;
}

TabletEventConverterEvdev::~TabletEventConverterEvdev() {
  Stop();
  close(fd_);
}

void TabletEventConverterEvdev::OnFileCanReadWithoutBlocking(int fd) {
  input_event inputs[4];
  ssize_t read_size = read(fd, inputs, sizeof(inputs));
  if (read_size < 0) {
    if (errno == EINTR || errno == EAGAIN)
      return;
    if (errno != ENODEV)
      PLOG(ERROR) << "error reading device " << path_.value();
    Stop();
    return;
  }

  DCHECK_EQ(read_size % sizeof(*inputs), 0u);
  ProcessEvents(inputs, read_size / sizeof(*inputs));
}

void TabletEventConverterEvdev::ProcessEvents(const input_event* inputs,
                                              int count) {
  for (int i = 0; i < count; ++i) {
    const input_event& input = inputs[i];
    switch (input.type) {
      case EV_KEY:
        ConvertKeyEvent(input);
        break;
      case EV_ABS:
        ConvertAbsEvent(input);
        break;
      case EV_SYN:
        FlushEvents();
        break;
    }
  }
}

void TabletEventConverterEvdev::ConvertKeyEvent(const input_event& input) {
  // Only handle other events if we have a stylus in proximity
  if (input.code >= BTN_TOOL_PEN && input.code <= BTN_TOOL_LENS) {
    if (input.value == 1)
      stylus_ = input.code;
    else if (input.value == 0)
      stylus_ = 0;
    else
      LOG(WARNING) << "Unexpected value: " << input.value
                   << " for code: " << input.code;
  }

  if (input.code >= BTN_TOUCH && input.code <= BTN_STYLUS2) {
    DispatchMouseButton(input);
    return;
  }
}

void TabletEventConverterEvdev::ConvertAbsEvent(const input_event& input) {
  if (!cursor_)
    return;

  switch (input.code) {
    case ABS_X:
      x_abs_location_ = input.value;
      abs_value_dirty_ = true;
      break;
    case ABS_Y:
      y_abs_location_ = input.value;
      abs_value_dirty_ = true;
      break;
  }
}

void TabletEventConverterEvdev::UpdateCursor() {
  gfx::Rect display_bounds = cursor_->GetCursorDisplayBounds();

  int x =
      ((x_abs_location_ - x_abs_min_) * display_bounds.width()) / x_abs_range_;
  int y =
      ((y_abs_location_ - y_abs_min_) * display_bounds.height()) / y_abs_range_;

  x += display_bounds.x();
  y += display_bounds.y();

  cursor_->MoveCursorTo(gfx::PointF(x, y));
}

void TabletEventConverterEvdev::DispatchMouseButton(const input_event& input) {
  if (!cursor_)
    return;

  unsigned int modifier;
  // These are the same as X11 behaviour
  if (input.code == BTN_TOUCH)
    modifier = EVDEV_MODIFIER_LEFT_MOUSE_BUTTON;
  else if (input.code == BTN_STYLUS2)
    modifier = EVDEV_MODIFIER_RIGHT_MOUSE_BUTTON;
  else if (input.code == BTN_STYLUS)
    modifier = EVDEV_MODIFIER_MIDDLE_MOUSE_BUTTON;
  else
    return;

  if (abs_value_dirty_) {
    UpdateCursor();
    abs_value_dirty_ = false;
  }

  int flag = modifiers_->GetEventFlagFromModifier(modifier);
  modifiers_->UpdateModifier(modifier, input.value);
  callback_.Run(make_scoped_ptr(
      new MouseEvent(input.value ? ET_MOUSE_PRESSED : ET_MOUSE_RELEASED,
                     cursor_->GetLocation(), cursor_->GetLocation(),
                     modifiers_->GetModifierFlags() | flag, flag)));
}

void TabletEventConverterEvdev::FlushEvents() {
  if (!cursor_)
    return;

  // Prevent propagation of invalid data on stylus lift off
  if (stylus_ == 0) {
    abs_value_dirty_ = false;
    return;
  }

  if (!abs_value_dirty_)
    return;

  UpdateCursor();

  callback_.Run(make_scoped_ptr(
      new MouseEvent(ui::ET_MOUSE_MOVED, cursor_->GetLocation(),
                     cursor_->GetLocation(), modifiers_->GetModifierFlags(),
                     /* changed_button_flags */ 0)));

  abs_value_dirty_ = false;
}

}  // namespace ui