Convert from line scrolling to pixel scrolling. Increase pixel scroll amount...

webkit/glue/webinputevent_linux.cc

 // Copyright (c) 2006-2008 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 "config.h"
 
 #include "webkit/glue/webinputevent.h"
 
 #include "KeyboardCodes.h"
 #include "KeyCodeConversion.h"
@@ skipping 105 matching lines @@
   // How much should we scroll per mouse wheel event?
   // - Windows uses 3 lines by default and obeys a system setting.
   // - Mozilla has a pref that lets you either use the "system" number of lines
   //   to scroll, or lets the user override it.
   //   For the "system" number of lines, it appears they've hardcoded 3.
   //   See case NS_MOUSE_SCROLL in content/events/src/nsEventStateManager.cpp
   //   and InitMouseScrollEvent in widget/src/gtk2/nsCommonWidget.cpp .
   // - Gtk makes the scroll amount a function of the size of the scroll bar,
   //   which is not available to us here.
   // Instead, we pick a number that empirically matches Firefox's behavior.
-  static const float kWheelDelta = 4;
+  static const float kScrollbarPixelsPerTick = 160.0f / 3.0f;
 
   delta_x = 0;
   delta_y = 0;
   switch (event->direction) {
     case GDK_SCROLL_UP:
-      delta_y = kWheelDelta;
+      delta_y = kScrollbarPixelsPerTick;
       break;
     case GDK_SCROLL_DOWN:
-      delta_y = -kWheelDelta;
+      delta_y = -kScrollbarPixelsPerTick;
       break;
     case GDK_SCROLL_LEFT:
-      delta_x = kWheelDelta;
+      delta_x = kScrollbarPixelsPerTick;
       break;
     case GDK_SCROLL_RIGHT:
-      delta_x = -kWheelDelta;
+      delta_x = -kScrollbarPixelsPerTick;
       break;
     default:
       break;
   }
   scroll_by_page = false;
 }
 
 WebKeyboardEvent::WebKeyboardEvent(const GdkEventKey* event) {
   system_key = false;
   modifiers = GdkStateToWebEventModifiers(event->state);
@@ skipping 36 matching lines @@
       break;
   }
 
   std::string key_identifier_str =
       webkit_glue::GetKeyIdentifierForWindowsKeyCode(windows_key_code);
   base::strlcpy(key_identifier, key_identifier_str.c_str(),
                 kIdentifierLengthCap);
 
   // TODO(tc): Do we need to set IS_AUTO_REPEAT or IS_KEYPAD?
 }