ozone: Interpret absolute events for graphics tablets

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() {
+  int width = cursor_->GetCursorDisplayBounds().width();
+  int height = cursor_->GetCursorDisplayBounds().height();
+  int x = ((x_abs_location_ - x_abs_min_) * width) / x_abs_range_;
+  int y = ((y_abs_location_ - y_abs_min_) * height) / y_abs_range_;
+
+  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_->location(),
+      cursor_->location(), 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_->location(),
+                     cursor_->location(), modifiers_->GetModifierFlags(),
+                     /* changed_button_flags */ 0)));
+
+  abs_value_dirty_ = false;
+}
+
+}  // namespace ui