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win32: Don't multiply the scroll event deltas by the Windows scroll lines setting. See #1408

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GTK widgets expect the scroll deltas to be 1 or -1 and calculate a scroll value from that.
Multiplying the delta by the Windows scroll line setting (which defaults to 3) results
in a much larger delta and vastly different behaviour for running a GTK app on Windows
vs on Linux. For example text view and tree view scroll by 9 lines per scroll wheel tick
per default this way while on Linux it is around 3.

Remove the multiplication for now.
This commit is contained in:
Christoph Reiter 2018-11-21 20:34:29 +01:00
parent 91129be95c
commit 83204dd882
1 changed files with 0 additions and 14 deletions
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14
gdk/win32/gdkevents-win32.c
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@ -3095,25 +3095,11 @@ gdk_event_translate (MSG *msg,
if (msg->message == WM_MOUSEWHEEL)
{
UINT lines_multiplier = 3;
event->scroll.delta_y = (gdouble) GET_WHEEL_DELTA_WPARAM (msg->wParam) / (gdouble) WHEEL_DELTA;
/* -1 means that we should scroll in screens, not lines.
* Right now GDK doesn't support that.
*/
if (SystemParametersInfo (SPI_GETWHEELSCROLLLINES, 0, &lines_multiplier, 0) &&
lines_multiplier != (UINT) -1)
event->scroll.delta_y *= (gdouble) lines_multiplier;
}
else if (msg->message == WM_MOUSEHWHEEL)
{
UINT chars_multiplier = 3;
event->scroll.delta_x = (gdouble) GET_WHEEL_DELTA_WPARAM (msg->wParam) / (gdouble) WHEEL_DELTA;
/* There doesn't seem to be any indication that
* h-scroll has an equivalent of the "screen" mode,
* indicated by multiplier being (UINT) -1.
*/
if (SystemParametersInfo (SPI_GETWHEELSCROLLCHARS, 0, &chars_multiplier, 0))
event->scroll.delta_x *= (gdouble) chars_multiplier;
}
/* Positive delta scrolls up, not down,
see API documentation for WM_MOUSEWHEEL message.