WebWheelEvent WebEventFactory::createWebWheelEvent(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
// Taken from WebCore
static const float cScrollbarPixelsPerLine = 100.0f / 3.0f;
POINT globalPosition = point(lParam);
POINT position = globalPosition;
::ScreenToClient(hWnd, &position);
WebWheelEvent::Granularity granularity = WebWheelEvent::ScrollByPixelWheelEvent;
WebEvent::Modifiers modifiers = modifiersForEvent(wParam);
double timestamp = ::GetTickCount() * 0.001; // ::GetTickCount returns milliseconds (Chrome uses GetMessageTime() / 1000.0)
int deltaX = 0;
int deltaY = 0;
int wheelTicksX = 0;
int wheelTicksY = 0;
float delta = GET_WHEEL_DELTA_WPARAM(wParam) / static_cast<float>(WHEEL_DELTA);
bool isMouseHWheel = (message == WM_VISTA_MOUSEHWHEEL);
if (isMouseHWheel) {
wheelTicksX = delta;
wheelTicksY = 0;
delta = -delta;
} else {
wheelTicksX = 0;
wheelTicksY = delta;
}
if (isMouseHWheel || (modifiers & WebEvent::ShiftKey)) {
deltaX = delta * static_cast<float>(horizontalScrollChars()) * cScrollbarPixelsPerLine;
deltaY = 0;
granularity = WebWheelEvent::ScrollByPixelWheelEvent;
} else {
deltaX = 0;
deltaY = delta;
int verticalMultiplier = verticalScrollLines();
if (verticalMultiplier == WHEEL_PAGESCROLL)
granularity = WebWheelEvent::ScrollByPageWheelEvent;
else {
granularity = WebWheelEvent::ScrollByPixelWheelEvent;
deltaY *= static_cast<float>(verticalMultiplier) * cScrollbarPixelsPerLine;
}
}
return WebWheelEvent(WebEvent::Wheel, position, globalPosition, FloatSize(deltaX, deltaY), FloatSize(wheelTicksX, wheelTicksY), granularity, modifiers, timestamp);
}
PlatformWheelEvent::PlatformWheelEvent(HWND hWnd, WPARAM wParam, LPARAM lParam, bool isMouseHWheel)
: PlatformEvent(PlatformEvent::Wheel, wParam & MK_SHIFT, wParam & MK_CONTROL, GetKeyState(VK_MENU) & HIGH_BIT_MASK_SHORT, GetKeyState(VK_MENU) & HIGH_BIT_MASK_SHORT, ::GetTickCount() * 0.001)
, m_position(positionForEvent(hWnd, lParam))
, m_globalPosition(globalPositionForEvent(hWnd, lParam))
, m_directionInvertedFromDevice(false)
{
float scaleFactor = deviceScaleFactorForWindow(hWnd);
// How many pixels should we scroll per line? Gecko uses the height of the
// current line, which means scroll distance changes as you go through the
// page or go to different pages. IE 7 is ~50 px/line, although the value
// seems to vary slightly by page and zoom level. Since IE 7 has a
// smoothing algorithm on scrolling, it can get away with slightly larger
// scroll values without feeling jerky. Here we use 100 px per three lines
// (the default scroll amount on Windows is three lines per wheel tick).
static const float cScrollbarPixelsPerLine = scaleFactor * 100.0f / 3.0f;
float delta = GET_WHEEL_DELTA_WPARAM(wParam) / (scaleFactor * static_cast<float>(WHEEL_DELTA));
if (isMouseHWheel) {
// Windows is <-- -/+ -->, WebKit wants <-- +/- -->, so we negate
// |delta| after saving the original value on the wheel tick member.
m_wheelTicksX = delta;
m_wheelTicksY = 0;
delta = -delta;
} else {
// Even though we use shift + vertical wheel to scroll horizontally in
// WebKit, we still note it as a vertical scroll on the wheel tick
// member, so that the DOM event we later construct will match the real
// hardware event better.
m_wheelTicksX = 0;
m_wheelTicksY = delta;
}
if (isMouseHWheel || shiftKey()) {
m_deltaX = delta * static_cast<float>(horizontalScrollChars()) * cScrollbarPixelsPerLine;
m_deltaY = 0;
m_granularity = ScrollByPixelWheelEvent;
} else {
m_deltaX = 0;
m_deltaY = delta;
int verticalMultiplier = verticalScrollLines();
m_granularity = (verticalMultiplier == WHEEL_PAGESCROLL) ? ScrollByPageWheelEvent : ScrollByPixelWheelEvent;
if (m_granularity == ScrollByPixelWheelEvent)
m_deltaY *= static_cast<float>(verticalMultiplier) * cScrollbarPixelsPerLine;
}
}
