Resolves: rhbz#1344042 deb#826654 scale gtk3 smooth scaling events...

to give traditional amounts of scroll on a single mouse wheel event

ditch non smooth scroll events now seeing as apparently they are always
available so the other types are irrelevent now

if we get x and y scroll, then like macosx just dispatch x and y scroll events.

Note: there seems to be a bug in the stack below us where the first scroll
event after getting focus is one of a 0 x and y delta.  Because we now check x
and y against 0, we don't launch a scroll event in the case of a 0x0 scroll
which stops us occasionally appearing to go backwards on the first scroll after
getting focus. Which is the same thing I see on e.g. gedit, the first mouse
wheel scroll after getting focus doesn't actually do anything.

Change-Id: Iec8f2e4627cd84e3896270a0847a5c4907fa083f
(cherry picked from commit 0159ef4fbfd23ba97b20f97eb0677564bebd4ee7)

2 files changed, 32 insertions, 44 deletions

diff --git a/vcl/inc/unx/gtk/gtkframe.hxx b/vcl/inc/unx/gtk/gtkframe.hxx
index 14a9818d09b3..355910ca4f3e 100644
--- a/vcl/inc/unx/gtk/gtkframe.hxx
+++ b/vcl/inc/unx/gtk/gtkframe.hxx
@@ -214,7 +214,6 @@ class GtkSalFrame : public SalFrame
 #if GTK_CHECK_VERSION(3,0,0)
     OUString                        m_aTooltip;
     Rectangle                       m_aHelpArea;
-    guint32                         m_nLastScrollEventTime;
     long                            m_nWidthRequest;
     long                            m_nHeightRequest;
     cairo_region_t*                 m_pRegion;
diff --git a/vcl/unx/gtk3/gtk3gtkframe.cxx b/vcl/unx/gtk3/gtk3gtkframe.cxx
index 2c0461657dc4..83a4e8a1f425 100644
--- a/vcl/unx/gtk3/gtk3gtkframe.cxx
+++ b/vcl/unx/gtk3/gtk3gtkframe.cxx
@@ -1046,7 +1046,6 @@ void GtkSalFrame::InitCommon()
     m_bSpanMonitorsWhenFullscreen = false;
     m_nState            = GDK_WINDOW_STATE_WITHDRAWN;
     m_nVisibility       = GDK_VISIBILITY_FULLY_OBSCURED;
-    m_nLastScrollEventTime = GDK_CURRENT_TIME;
     m_bSendModChangeOnRelease = false;
     m_pIMHandler        = nullptr;
     m_hBackgroundPixmap = None;
@@ -2634,63 +2633,53 @@ gboolean GtkSalFrame::signalButton( GtkWidget*, GdkEventButton* pEvent, gpointer
 
 gboolean GtkSalFrame::signalScroll( GtkWidget*, GdkEvent* pEvent, gpointer frame )
 {
-    GtkSalFrame* pThis = static_cast<GtkSalFrame*>(frame);
     GdkEventScroll* pSEvent = reinterpret_cast<GdkEventScroll*>(pEvent);
+    if (pSEvent->direction != GDK_SCROLL_SMOOTH)
+        return false;
 
-    // gnome#726878 check for duplicate legacy scroll event
-    if (pSEvent->direction != GDK_SCROLL_SMOOTH &&
-        pThis->m_nLastScrollEventTime == pSEvent->time)
-    {
-        return true;
-    }
+    GtkSalFrame* pThis = static_cast<GtkSalFrame*>(frame);
 
     SalWheelMouseEvent aEvent;
 
     aEvent.mnTime = pSEvent->time;
     aEvent.mnX = (sal_uLong)pSEvent->x;
+    // --- RTL --- (mirror mouse pos)
+    if (AllSettings::GetLayoutRTL())
+        aEvent.mnX = pThis->maGeometry.nWidth - 1 - aEvent.mnX;
     aEvent.mnY = (sal_uLong)pSEvent->y;
     aEvent.mnCode = GetMouseModCode( pSEvent->state );
-    aEvent.mnScrollLines = 3;
 
-    switch (pSEvent->direction)
+    // rhbz#1344042 "Traditionally" in gtk3 we tool a single up/down event as
+    // equating to 3 scroll lines and a delta of 120. So scale the delta here
+    // by 120 where a single mouse wheel click is an incoming delta_x of 1
+    // and divide that by 40 to get the number of scrollines
+    if (pSEvent->delta_x != 0.0)
     {
-        case GDK_SCROLL_SMOOTH:
-        {
-            //pick the bigger one I guess
-            aEvent.mbHorz = fabs(pSEvent->delta_x) > fabs(pSEvent->delta_y);
-            if (aEvent.mbHorz)
-                aEvent.mnDelta = -pSEvent->delta_x * 40;
-            else
-                aEvent.mnDelta = -pSEvent->delta_y * 40;
+        aEvent.mnDelta = -pSEvent->delta_x * 120;
+        aEvent.mnNotchDelta = aEvent.mnDelta < 0 ? -1 : +1;
+        if (aEvent.mnDelta == 0)
+            aEvent.mnDelta = aEvent.mnNotchDelta;
+        aEvent.mbHorz = true;
+        aEvent.mnScrollLines = abs(aEvent.mnDelta) / 40;
+        if (aEvent.mnScrollLines == 0)
             aEvent.mnScrollLines = 1;
-            pThis->m_nLastScrollEventTime = pSEvent->time;
-            break;
-        }
-        case GDK_SCROLL_UP:
-            aEvent.mnDelta = 120;
-            aEvent.mbHorz = false;
-            break;
-        case GDK_SCROLL_DOWN:
-            aEvent.mnDelta = -120;
-            aEvent.mbHorz = false;
-            break;
-        case GDK_SCROLL_LEFT:
-            aEvent.mbHorz = true;
-            aEvent.mnDelta = 120;
-            break;
-        case GDK_SCROLL_RIGHT:
-            aEvent.mnDelta = -120;
-            aEvent.mbHorz = true;
-            break;
-    };
 
-    aEvent.mnNotchDelta     = aEvent.mnDelta < 0 ? -1 : 1;
+        pThis->CallCallback(SalEvent::WheelMouse, &aEvent);
+    }
 
-    // --- RTL --- (mirror mouse pos)
-    if( AllSettings::GetLayoutRTL() )
-        aEvent.mnX = pThis->maGeometry.nWidth-1-aEvent.mnX;
+    if (pSEvent->delta_y != 0.0)
+    {
+        aEvent.mnDelta = -pSEvent->delta_y * 120;
+        aEvent.mnNotchDelta = aEvent.mnDelta < 0 ? -1 : +1;
+        if (aEvent.mnDelta == 0)
+            aEvent.mnDelta = aEvent.mnNotchDelta;
+        aEvent.mbHorz = false;
+        aEvent.mnScrollLines = abs(aEvent.mnDelta) / 40;
+        if (aEvent.mnScrollLines == 0)
+            aEvent.mnScrollLines = 1;
 
-    pThis->CallCallback( SalEvent::WheelMouse, &aEvent );
+        pThis->CallCallback(SalEvent::WheelMouse, &aEvent);
+    }
 
     return true;
 }