content/browser/renderer_host/input/web_input_event_builders_gtk.cc

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/browser/renderer_host/input/web_input_event_builders_gtk.h"
   6
   7 #include <gdk/gdk.h>
   8 #include <gdk/gdkkeysyms.h>
   9 #include <gtk/gtk.h>
  10
  11 #include "base/logging.h"
  12 #include "content/browser/renderer_host/input/web_input_event_util_posix.h"
  13 #include "third_party/WebKit/public/web/WebInputEvent.h"
  14 #include "ui/events/keycodes/keyboard_code_conversion_gtk.h"
  15
  16 using blink::WebInputEvent;
  17 using blink::WebMouseEvent;
  18 using blink::WebMouseWheelEvent;
  19 using blink::WebKeyboardEvent;
  20
  21 namespace {
  22
  23 // For click count tracking.
  24 static int num_clicks = 0;
  25 static GdkWindow* last_click_event_window = 0;
  26 static gint last_click_time = 0;
  27 static gint last_click_x = 0;
  28 static gint last_click_y = 0;
  29 static WebMouseEvent::Button last_click_button = WebMouseEvent::ButtonNone;
  30
  31 bool ShouldForgetPreviousClick(GdkWindow* window, gint time, gint x, gint y) {
  32   static GtkSettings* settings = gtk_settings_get_default();
  33
  34   if (window != last_click_event_window)
  35     return true;
  36
  37   gint double_click_time = 250;
  38   gint double_click_distance = 5;
  39   g_object_get(G_OBJECT(settings),
  40                "gtk-double-click-time",
  41                &double_click_time,
  42                "gtk-double-click-distance",
  43                &double_click_distance,
  44                NULL);
  45   return (time - last_click_time) > double_click_time ||
  46          std::abs(x - last_click_x) > double_click_distance ||
  47          std::abs(y - last_click_y) > double_click_distance;
  48 }
  49
  50 void ResetClickCountState() {
  51   num_clicks = 0;
  52   last_click_event_window = 0;
  53   last_click_time = 0;
  54   last_click_x = 0;
  55   last_click_y = 0;
  56   last_click_button = blink::WebMouseEvent::ButtonNone;
  57 }
  58
  59 bool IsKeyPadKeyval(guint keyval) {
  60   // Keypad keyvals all fall into one range.
  61   return keyval >= GDK_KP_Space && keyval <= GDK_KP_9;
  62 }
  63
  64 double GdkEventTimeToWebEventTime(guint32 time) {
  65   // Convert from time in ms to time in sec.
  66   return time / 1000.0;
  67 }
  68
  69 int GdkStateToWebEventModifiers(guint state) {
  70   int modifiers = 0;
  71   if (state & GDK_SHIFT_MASK)
  72     modifiers |= WebInputEvent::ShiftKey;
  73   if (state & GDK_CONTROL_MASK)
  74     modifiers |= WebInputEvent::ControlKey;
  75   if (state & GDK_MOD1_MASK)
  76     modifiers |= WebInputEvent::AltKey;
  77   if (state & GDK_META_MASK)
  78     modifiers |= WebInputEvent::MetaKey;
  79   if (state & GDK_BUTTON1_MASK)
  80     modifiers |= WebInputEvent::LeftButtonDown;
  81   if (state & GDK_BUTTON2_MASK)
  82     modifiers |= WebInputEvent::MiddleButtonDown;
  83   if (state & GDK_BUTTON3_MASK)
  84     modifiers |= WebInputEvent::RightButtonDown;
  85   if (state & GDK_LOCK_MASK)
  86     modifiers |= WebInputEvent::CapsLockOn;
  87   if (state & GDK_MOD2_MASK)
  88     modifiers |= WebInputEvent::NumLockOn;
  89   return modifiers;
  90 }
  91
  92 ui::KeyboardCode GdkEventToWindowsKeyCode(const GdkEventKey* event) {
  93   static const unsigned int kHardwareCodeToGDKKeyval[] = {
  94     0,                 // 0x00:
  95     0,                 // 0x01:
  96     0,                 // 0x02:
  97     0,                 // 0x03:
  98     0,                 // 0x04:
  99     0,                 // 0x05:
 100     0,                 // 0x06:
 101     0,                 // 0x07:
 102     0,                 // 0x08:
 103     0,                 // 0x09: GDK_Escape
 104     GDK_1,             // 0x0A: GDK_1
 105     GDK_2,             // 0x0B: GDK_2
 106     GDK_3,             // 0x0C: GDK_3
 107     GDK_4,             // 0x0D: GDK_4
 108     GDK_5,             // 0x0E: GDK_5
 109     GDK_6,             // 0x0F: GDK_6
 110     GDK_7,             // 0x10: GDK_7
 111     GDK_8,             // 0x11: GDK_8
 112     GDK_9,             // 0x12: GDK_9
 113     GDK_0,             // 0x13: GDK_0
 114     GDK_minus,         // 0x14: GDK_minus
 115     GDK_equal,         // 0x15: GDK_equal
 116     0,                 // 0x16: GDK_BackSpace
 117     0,                 // 0x17: GDK_Tab
 118     GDK_q,             // 0x18: GDK_q
 119     GDK_w,             // 0x19: GDK_w
 120     GDK_e,             // 0x1A: GDK_e
 121     GDK_r,             // 0x1B: GDK_r
 122     GDK_t,             // 0x1C: GDK_t
 123     GDK_y,             // 0x1D: GDK_y
 124     GDK_u,             // 0x1E: GDK_u
 125     GDK_i,             // 0x1F: GDK_i
 126     GDK_o,             // 0x20: GDK_o
 127     GDK_p,             // 0x21: GDK_p
 128     GDK_bracketleft,   // 0x22: GDK_bracketleft
 129     GDK_bracketright,  // 0x23: GDK_bracketright
 130     0,                 // 0x24: GDK_Return
 131     0,                 // 0x25: GDK_Control_L
 132     GDK_a,             // 0x26: GDK_a
 133     GDK_s,             // 0x27: GDK_s
 134     GDK_d,             // 0x28: GDK_d
 135     GDK_f,             // 0x29: GDK_f
 136     GDK_g,             // 0x2A: GDK_g
 137     GDK_h,             // 0x2B: GDK_h
 138     GDK_j,             // 0x2C: GDK_j
 139     GDK_k,             // 0x2D: GDK_k
 140     GDK_l,             // 0x2E: GDK_l
 141     GDK_semicolon,     // 0x2F: GDK_semicolon
 142     GDK_apostrophe,    // 0x30: GDK_apostrophe
 143     GDK_grave,         // 0x31: GDK_grave
 144     0,                 // 0x32: GDK_Shift_L
 145     GDK_backslash,     // 0x33: GDK_backslash
 146     GDK_z,             // 0x34: GDK_z
 147     GDK_x,             // 0x35: GDK_x
 148     GDK_c,             // 0x36: GDK_c
 149     GDK_v,             // 0x37: GDK_v
 150     GDK_b,             // 0x38: GDK_b
 151     GDK_n,             // 0x39: GDK_n
 152     GDK_m,             // 0x3A: GDK_m
 153     GDK_comma,         // 0x3B: GDK_comma
 154     GDK_period,        // 0x3C: GDK_period
 155     GDK_slash,         // 0x3D: GDK_slash
 156     0,                 // 0x3E: GDK_Shift_R
 157     0,                 // 0x3F:
 158     0,                 // 0x40:
 159     0,                 // 0x41:
 160     0,                 // 0x42:
 161     0,                 // 0x43:
 162     0,                 // 0x44:
 163     0,                 // 0x45:
 164     0,                 // 0x46:
 165     0,                 // 0x47:
 166     0,                 // 0x48:
 167     0,                 // 0x49:
 168     0,                 // 0x4A:
 169     0,                 // 0x4B:
 170     0,                 // 0x4C:
 171     0,                 // 0x4D:
 172     0,                 // 0x4E:
 173     0,                 // 0x4F:
 174     0,                 // 0x50:
 175     0,                 // 0x51:
 176     0,                 // 0x52:
 177     0,                 // 0x53:
 178     0,                 // 0x54:
 179     0,                 // 0x55:
 180     0,                 // 0x56:
 181     0,                 // 0x57:
 182     0,                 // 0x58:
 183     0,                 // 0x59:
 184     0,                 // 0x5A:
 185     0,                 // 0x5B:
 186     0,                 // 0x5C:
 187     0,                 // 0x5D:
 188     0,                 // 0x5E:
 189     0,                 // 0x5F:
 190     0,                 // 0x60:
 191     0,                 // 0x61:
 192     0,                 // 0x62:
 193     0,                 // 0x63:
 194     0,                 // 0x64:
 195     0,                 // 0x65:
 196     0,                 // 0x66:
 197     0,                 // 0x67:
 198     0,                 // 0x68:
 199     0,                 // 0x69:
 200     0,                 // 0x6A:
 201     0,                 // 0x6B:
 202     0,                 // 0x6C:
 203     0,                 // 0x6D:
 204     0,                 // 0x6E:
 205     0,                 // 0x6F:
 206     0,                 // 0x70:
 207     0,                 // 0x71:
 208     0,                 // 0x72:
 209     GDK_Super_L,       // 0x73: GDK_Super_L
 210     GDK_Super_R,       // 0x74: GDK_Super_R
 211   };
 212
 213   // |windows_key_code| has to include a valid virtual-key code even when we
 214   // use non-US layouts, e.g. even when we type an 'A' key of a US keyboard
 215   // on the Hebrew layout, |windows_key_code| should be VK_A.
 216   // On the other hand, |event->keyval| value depends on the current
 217   // GdkKeymap object, i.e. when we type an 'A' key of a US keyboard on
 218   // the Hebrew layout, |event->keyval| becomes GDK_hebrew_shin and this
 219   // ui::WindowsKeyCodeForGdkKeyCode() call returns 0.
 220   // To improve compatibilty with Windows, we use |event->hardware_keycode|
 221   // for retrieving its Windows key-code for the keys when the
 222   // WebCore::windows_key_codeForEvent() call returns 0.
 223   // We shouldn't use |event->hardware_keycode| for keys that GdkKeymap
 224   // objects cannot change because |event->hardware_keycode| doesn't change
 225   // even when we change the layout options, e.g. when we swap a control
 226   // key and a caps-lock key, GTK doesn't swap their
 227   // |event->hardware_keycode| values but swap their |event->keyval| values.
 228   ui::KeyboardCode windows_key_code =
 229       ui::WindowsKeyCodeForGdkKeyCode(event->keyval);
 230   if (windows_key_code)
 231     return windows_key_code;
 232
 233   if (event->hardware_keycode < arraysize(kHardwareCodeToGDKKeyval)) {
 234     int keyval = kHardwareCodeToGDKKeyval[event->hardware_keycode];
 235     if (keyval)
 236       return ui::WindowsKeyCodeForGdkKeyCode(keyval);
 237   }
 238
 239   // This key is one that keyboard-layout drivers cannot change.
 240   // Use |event->keyval| to retrieve its |windows_key_code| value.
 241   return ui::WindowsKeyCodeForGdkKeyCode(event->keyval);
 242 }
 243
 244 // Normalizes event->state to make it Windows/Mac compatible. Since the way
 245 // of setting modifier mask on X is very different than Windows/Mac as shown
 246 // in http://crbug.com/127142#c8, the normalization is necessary.
 247 guint NormalizeEventState(const GdkEventKey* event) {
 248   guint mask = 0;
 249   switch (GdkEventToWindowsKeyCode(event)) {
 250     case ui::VKEY_CONTROL:
 251     case ui::VKEY_LCONTROL:
 252     case ui::VKEY_RCONTROL:
 253       mask = GDK_CONTROL_MASK;
 254       break;
 255     case ui::VKEY_SHIFT:
 256     case ui::VKEY_LSHIFT:
 257     case ui::VKEY_RSHIFT:
 258       mask = GDK_SHIFT_MASK;
 259       break;
 260     case ui::VKEY_MENU:
 261     case ui::VKEY_LMENU:
 262     case ui::VKEY_RMENU:
 263       mask = GDK_MOD1_MASK;
 264       break;
 265     case ui::VKEY_CAPITAL:
 266       mask = GDK_LOCK_MASK;
 267       break;
 268     default:
 269       return event->state;
 270   }
 271   if (event->type == GDK_KEY_PRESS)
 272     return event->state | mask;
 273   return event->state & ~mask;
 274 }
 275
 276 // Gets the corresponding control character of a specified key code. See:
 277 // http://en.wikipedia.org/wiki/Control_characters
 278 // We emulate Windows behavior here.
 279 int GetControlCharacter(ui::KeyboardCode windows_key_code, bool shift) {
 280   if (windows_key_code >= ui::VKEY_A && windows_key_code <= ui::VKEY_Z) {
 281     // ctrl-A ~ ctrl-Z map to \x01 ~ \x1A
 282     return windows_key_code - ui::VKEY_A + 1;
 283   }
 284   if (shift) {
 285     // following graphics chars require shift key to input.
 286     switch (windows_key_code) {
 287       // ctrl-@ maps to \x00 (Null byte)
 288       case ui::VKEY_2:
 289         return 0;
 290       // ctrl-^ maps to \x1E (Record separator, Information separator two)
 291       case ui::VKEY_6:
 292         return 0x1E;
 293       // ctrl-_ maps to \x1F (Unit separator, Information separator one)
 294       case ui::VKEY_OEM_MINUS:
 295         return 0x1F;
 296       // Returns 0 for all other keys to avoid inputting unexpected chars.
 297       default:
 298         return 0;
 299     }
 300   } else {
 301     switch (windows_key_code) {
 302       // ctrl-[ maps to \x1B (Escape)
 303       case ui::VKEY_OEM_4:
 304         return 0x1B;
 305       // ctrl-\ maps to \x1C (File separator, Information separator four)
 306       case ui::VKEY_OEM_5:
 307         return 0x1C;
 308       // ctrl-] maps to \x1D (Group separator, Information separator three)
 309       case ui::VKEY_OEM_6:
 310         return 0x1D;
 311       // ctrl-Enter maps to \x0A (Line feed)
 312       case ui::VKEY_RETURN:
 313         return 0x0A;
 314       // Returns 0 for all other keys to avoid inputting unexpected chars.
 315       default:
 316         return 0;
 317     }
 318   }
 319 }
 320
 321 }  // namespace
 322
 323 namespace content {
 324
 325 // WebKeyboardEvent -----------------------------------------------------------
 326
 327 WebKeyboardEvent WebKeyboardEventBuilder::Build(const GdkEventKey* event) {
 328   WebKeyboardEvent result;
 329
 330   result.timeStampSeconds = GdkEventTimeToWebEventTime(event->time);
 331   result.modifiers = GdkStateToWebEventModifiers(NormalizeEventState(event));
 332
 333   switch (event->type) {
 334     case GDK_KEY_RELEASE:
 335       result.type = WebInputEvent::KeyUp;
 336       break;
 337     case GDK_KEY_PRESS:
 338       result.type = WebInputEvent::RawKeyDown;
 339       break;
 340     default:
 341       NOTREACHED();
 342   }
 343
 344   // According to MSDN:
 345   // http://msdn.microsoft.com/en-us/library/ms646286(VS.85).aspx
 346   // Key events with Alt modifier and F10 are system key events.
 347   // We just emulate this behavior. It's necessary to prevent webkit from
 348   // processing keypress event generated by alt-d, etc.
 349   // F10 is not special on Linux, so don't treat it as system key.
 350   if (result.modifiers & WebInputEvent::AltKey)
 351     result.isSystemKey = true;
 352
 353   // The key code tells us which physical key was pressed (for example, the
 354   // A key went down or up).  It does not determine whether A should be lower
 355   // or upper case.  This is what text does, which should be the keyval.
 356   ui::KeyboardCode windows_key_code = GdkEventToWindowsKeyCode(event);
 357   result.windowsKeyCode = GetWindowsKeyCodeWithoutLocation(windows_key_code);
 358   result.modifiers |= GetLocationModifiersFromWindowsKeyCode(windows_key_code);
 359   result.nativeKeyCode = event->hardware_keycode;
 360
 361   if (result.windowsKeyCode == ui::VKEY_RETURN) {
 362     // We need to treat the enter key as a key press of character \r.  This
 363     // is apparently just how webkit handles it and what it expects.
 364     result.unmodifiedText[0] = '\r';
 365   } else {
 366     // FIXME: fix for non BMP chars
 367     result.unmodifiedText[0] =
 368         static_cast<int>(gdk_keyval_to_unicode(event->keyval));
 369   }
 370
 371   // If ctrl key is pressed down, then control character shall be input.
 372   if (result.modifiers & WebInputEvent::ControlKey) {
 373     result.text[0] =
 374       GetControlCharacter(ui::KeyboardCode(result.windowsKeyCode),
 375                           result.modifiers & WebInputEvent::ShiftKey);
 376   } else {
 377     result.text[0] = result.unmodifiedText[0];
 378   }
 379
 380   result.setKeyIdentifierFromWindowsKeyCode();
 381
 382   // FIXME: Do we need to set IsAutoRepeat?
 383   if (IsKeyPadKeyval(event->keyval))
 384     result.modifiers |= WebInputEvent::IsKeyPad;
 385
 386   return result;
 387 }
 388
 389 WebKeyboardEvent WebKeyboardEventBuilder::Build(wchar_t character,
 390                                                      int state,
 391                                                      double timeStampSeconds) {
 392   // keyboardEvent(const GdkEventKey*) depends on the GdkEventKey object and
 393   // it is hard to use/ it from signal handlers which don't use GdkEventKey
 394   // objects (e.g. GtkIMContext signal handlers.) For such handlers, this
 395   // function creates a WebInputEvent::Char event without using a
 396   // GdkEventKey object.
 397   WebKeyboardEvent result;
 398   result.type = blink::WebInputEvent::Char;
 399   result.timeStampSeconds = timeStampSeconds;
 400   result.modifiers = GdkStateToWebEventModifiers(state);
 401   result.windowsKeyCode = character;
 402   result.nativeKeyCode = character;
 403   result.text[0] = character;
 404   result.unmodifiedText[0] = character;
 405
 406   // According to MSDN:
 407   // http://msdn.microsoft.com/en-us/library/ms646286(VS.85).aspx
 408   // Key events with Alt modifier and F10 are system key events.
 409   // We just emulate this behavior. It's necessary to prevent webkit from
 410   // processing keypress event generated by alt-d, etc.
 411   // F10 is not special on Linux, so don't treat it as system key.
 412   if (result.modifiers & WebInputEvent::AltKey)
 413     result.isSystemKey = true;
 414
 415   return result;
 416 }
 417
 418 // WebMouseEvent --------------------------------------------------------------
 419
 420 WebMouseEvent WebMouseEventBuilder::Build(const GdkEventButton* event) {
 421   WebMouseEvent result;
 422
 423   result.timeStampSeconds = GdkEventTimeToWebEventTime(event->time);
 424
 425   result.modifiers = GdkStateToWebEventModifiers(event->state);
 426   result.x = static_cast<int>(event->x);
 427   result.y = static_cast<int>(event->y);
 428   result.windowX = result.x;
 429   result.windowY = result.y;
 430   result.globalX = static_cast<int>(event->x_root);
 431   result.globalY = static_cast<int>(event->y_root);
 432   result.clickCount = 0;
 433
 434   switch (event->type) {
 435     case GDK_BUTTON_PRESS:
 436       result.type = WebInputEvent::MouseDown;
 437       break;
 438     case GDK_BUTTON_RELEASE:
 439       result.type = WebInputEvent::MouseUp;
 440       break;
 441     case GDK_3BUTTON_PRESS:
 442     case GDK_2BUTTON_PRESS:
 443     default:
 444       NOTREACHED();
 445   }
 446
 447   result.button = WebMouseEvent::ButtonNone;
 448   if (event->button == 1)
 449     result.button = WebMouseEvent::ButtonLeft;
 450   else if (event->button == 2)
 451     result.button = WebMouseEvent::ButtonMiddle;
 452   else if (event->button == 3)
 453     result.button = WebMouseEvent::ButtonRight;
 454
 455   if (result.type == WebInputEvent::MouseDown) {
 456     bool forgetPreviousClick = ShouldForgetPreviousClick(
 457         event->window, event->time, event->x, event->y);
 458
 459     if (!forgetPreviousClick && result.button == last_click_button) {
 460       ++num_clicks;
 461     } else {
 462       num_clicks = 1;
 463
 464       last_click_event_window = event->window;
 465       last_click_x = event->x;
 466       last_click_y = event->y;
 467       last_click_button = result.button;
 468     }
 469     last_click_time = event->time;
 470   }
 471   result.clickCount = num_clicks;
 472
 473   return result;
 474 }
 475
 476 WebMouseEvent WebMouseEventBuilder::Build(const GdkEventMotion* event) {
 477   WebMouseEvent result;
 478
 479   result.timeStampSeconds = GdkEventTimeToWebEventTime(event->time);
 480   result.modifiers = GdkStateToWebEventModifiers(event->state);
 481   result.x = static_cast<int>(event->x);
 482   result.y = static_cast<int>(event->y);
 483   result.windowX = result.x;
 484   result.windowY = result.y;
 485   result.globalX = static_cast<int>(event->x_root);
 486   result.globalY = static_cast<int>(event->y_root);
 487
 488   switch (event->type) {
 489     case GDK_MOTION_NOTIFY:
 490       result.type = WebInputEvent::MouseMove;
 491       break;
 492     default:
 493       NOTREACHED();
 494   }
 495
 496   result.button = WebMouseEvent::ButtonNone;
 497   if (event->state & GDK_BUTTON1_MASK)
 498     result.button = WebMouseEvent::ButtonLeft;
 499   else if (event->state & GDK_BUTTON2_MASK)
 500     result.button = WebMouseEvent::ButtonMiddle;
 501   else if (event->state & GDK_BUTTON3_MASK)
 502     result.button = WebMouseEvent::ButtonRight;
 503
 504   if (ShouldForgetPreviousClick(event->window, event->time, event->x, event->y))
 505     ResetClickCountState();
 506
 507   return result;
 508 }
 509
 510 WebMouseEvent WebMouseEventBuilder::Build(const GdkEventCrossing* event) {
 511   WebMouseEvent result;
 512
 513   result.timeStampSeconds = GdkEventTimeToWebEventTime(event->time);
 514   result.modifiers = GdkStateToWebEventModifiers(event->state);
 515   result.x = static_cast<int>(event->x);
 516   result.y = static_cast<int>(event->y);
 517   result.windowX = result.x;
 518   result.windowY = result.y;
 519   result.globalX = static_cast<int>(event->x_root);
 520   result.globalY = static_cast<int>(event->y_root);
 521
 522   switch (event->type) {
 523     case GDK_ENTER_NOTIFY:
 524     case GDK_LEAVE_NOTIFY:
 525       // Note that if we sent MouseEnter or MouseLeave to WebKit, it
 526       // wouldn't work - they don't result in the proper JavaScript events.
 527       // MouseMove does the right thing.
 528       result.type = WebInputEvent::MouseMove;
 529       break;
 530     default:
 531       NOTREACHED();
 532   }
 533
 534   result.button = WebMouseEvent::ButtonNone;
 535   if (event->state & GDK_BUTTON1_MASK)
 536     result.button = WebMouseEvent::ButtonLeft;
 537   else if (event->state & GDK_BUTTON2_MASK)
 538     result.button = WebMouseEvent::ButtonMiddle;
 539   else if (event->state & GDK_BUTTON3_MASK)
 540     result.button = WebMouseEvent::ButtonRight;
 541
 542   if (ShouldForgetPreviousClick(event->window, event->time, event->x, event->y))
 543     ResetClickCountState();
 544
 545   return result;
 546 }
 547
 548 // WebMouseWheelEvent ---------------------------------------------------------
 549
 550 float WebMouseWheelEventBuilder::ScrollbarPixelsPerTick() {
 551   // How much should we scroll per mouse wheel event?
 552   // - Windows uses 3 lines by default and obeys a system setting.
 553   // - Mozilla has a pref that lets you either use the "system" number of lines
 554   //   to scroll, or lets the user override it.
 555   //   For the "system" number of lines, it appears they've hardcoded 3.
 556   //   See case NS_MOUSE_SCROLL in content/events/src/nsEventStateManager.cpp
 557   //   and InitMouseScrollEvent in widget/src/gtk2/nsCommonWidget.cpp .
 558   // - Gtk makes the scroll amount a function of the size of the scroll bar,
 559   //   which is not available to us here.
 560   // Instead, we pick a number that empirically matches Firefox's behavior.
 561   return 160.0f / 3.0f;
 562 }
 563
 564 WebMouseWheelEvent WebMouseWheelEventBuilder::Build(
 565     const GdkEventScroll* event) {
 566   WebMouseWheelEvent result;
 567
 568   result.type = WebInputEvent::MouseWheel;
 569   result.button = WebMouseEvent::ButtonNone;
 570
 571   result.timeStampSeconds = GdkEventTimeToWebEventTime(event->time);
 572   result.modifiers = GdkStateToWebEventModifiers(event->state);
 573   result.x = static_cast<int>(event->x);
 574   result.y = static_cast<int>(event->y);
 575   result.windowX = result.x;
 576   result.windowY = result.y;
 577   result.globalX = static_cast<int>(event->x_root);
 578   result.globalY = static_cast<int>(event->y_root);
 579
 580   static const float scrollbarPixelsPerTick = ScrollbarPixelsPerTick();
 581   switch (event->direction) {
 582     case GDK_SCROLL_UP:
 583       result.deltaY = scrollbarPixelsPerTick;
 584       result.wheelTicksY = 1;
 585       break;
 586     case GDK_SCROLL_DOWN:
 587       result.deltaY = -scrollbarPixelsPerTick;
 588       result.wheelTicksY = -1;
 589       break;
 590     case GDK_SCROLL_LEFT:
 591       result.deltaX = scrollbarPixelsPerTick;
 592       result.wheelTicksX = 1;
 593       break;
 594     case GDK_SCROLL_RIGHT:
 595       result.deltaX = -scrollbarPixelsPerTick;
 596       result.wheelTicksX = -1;
 597       break;
 598   }
 599
 600   return result;
 601 }
 602
 603 }  // namespace content