scroll: replace dx + dy with dominant axis, correct sign

src/bauhaus/bauhaus.c

@@ -508,13 +508,21 @@ static gboolean _popup_scroll(GtkWidget *widget,
                               gpointer user_data)
 {
   dt_bauhaus_widget_t *w = darktable.bauhaus->current;
-  int delta_y = 0;
-  if(dt_gui_get_scroll_unit_delta(event, &delta_y))
+  if(w->type == DT_BAUHAUS_COMBOBOX)
   {
-    if(w->type == DT_BAUHAUS_COMBOBOX)
-      _combobox_next_sensitive(w, delta_y, 0, w->combobox.mute_scrolling);
-    else
-      _slider_zoom_range(w, delta_y);
+    // match keyboard: right & down -> next
+    int delta_x = 0, delta_y = 0;
+    if(dt_gui_get_scroll_unit_deltas(event, &delta_x, &delta_y))
+    {
+      int delta = abs(delta_x) > abs(delta_y) ? delta_x : delta_y;
+      _combobox_next_sensitive(w, delta, 0, w->combobox.mute_scrolling);
+    }
+  }
+  else
+  {
+    int delta = 0;
+    if(dt_gui_get_scroll_unit_delta(event, &delta))
+      _slider_zoom_range(w, delta);
   }
   return TRUE;
 }
@@ -3087,14 +3095,17 @@ static void _widget_scroll(GtkEventControllerScroll *controller,
   {
     gtk_widget_grab_focus(widget);
 
-    int delta = dx + dy;
-    if(delta != 0)
+    int magnitude_x = fabs(dx);
+    int magnitude_y = fabs(dy);
+
+    if(magnitude_x || magnitude_y)
     {
       dt_bauhaus_widget_t *w = (dt_bauhaus_widget_t *)widget;
       _request_focus(w);
 
       if(w->type == DT_BAUHAUS_SLIDER)
       {
+        int delta = magnitude_x > magnitude_y ? -dx : dy;
         const gboolean force = darktable.control->element == DT_ACTION_ELEMENT_FORCE
                             && event->scroll.window == gtk_widget_get_window(widget);
         if(force && dt_modifier_is(event->scroll.state, GDK_SHIFT_MASK | GDK_CONTROL_MASK))
@@ -3106,7 +3117,12 @@ static void _widget_scroll(GtkEventControllerScroll *controller,
           _slider_add_step(widget, - delta, event->scroll.state, force);
       }
       else
+      {
+        // match keyboard: right & down -> next
+        int delta = magnitude_x > magnitude_y ? dx : dy;
+
         _combobox_next_sensitive(w, delta, 0, FALSE);
+      }
     }
   }
   if(event) gdk_event_free(event);

src/develop/imageop.c

@@ -2368,9 +2368,13 @@ static gboolean _presets_scroll_callback(GtkWidget *widget,
 {
   if(dt_gui_ignore_scroll(event)) return FALSE;
 
-  int delta_y = 0;
-  if(dt_gui_get_scroll_unit_delta(event, &delta_y))
-    dt_gui_presets_apply_adjacent_preset(module, delta_y);
+  // preset cycling: right==down==next
+  int delta_x = 0, delta_y = 0;
+  if(dt_gui_get_scroll_unit_deltas(event, &delta_x, &delta_y))
+  {
+    const int delta = abs(delta_x) > abs(delta_y) ? delta_x : delta_y;
+    dt_gui_presets_apply_adjacent_preset(module, delta);
+  }
 
   return TRUE;
 }

src/dtgtk/culling.c

@@ -694,10 +694,11 @@ static gboolean _event_scroll(GtkWidget *widget,
     gdouble dx = 0.0, dy = 0.0;
     if(dt_gui_get_scroll_deltas(e, &dx, &dy) && (dx != 0.0 || dy != 0.0))
     {
-    // dt_gui_get_scroll_deltas gives the raw fractional platform delta.
+      // dt_gui_get_scroll_deltas gives the raw fractional platform delta.
       // Scale so that one full unit of scroll (delta_y == 1.0) matches the
-      // 0.5 zoom_delta of a discrete mouse-wheel click.
-      const float zoom_delta = (float)(-(dx + dy) * 0.5);
+      // 0.5 zoom_delta of a discrete mouse-wheel click. right==up==zoom-in
+      const gdouble delta = fabs(dx) > fabs(dy) ? -dx : dy;
+      const float zoom_delta = (float)(-delta * 0.5);
       // convert screen to culling coordinates
       int ox = 0, oy = 0;
       GdkWindow *win = gtk_widget_get_window(table->widget);
@@ -750,12 +751,14 @@ static gboolean _event_scroll(GtkWidget *widget,
     }
   }
 
-  int delta;
-  if(dt_gui_get_scroll_unit_delta(e, &delta))
+  int delta_x = 0, delta_y = 0;
+  if(dt_gui_get_scroll_unit_deltas(e, &delta_x, &delta_y))
   {
+    const gboolean is_horizontal = abs(delta_x) > abs(delta_y);
     if(dt_modifiers_include(e->state, GDK_CONTROL_MASK))
     {
-      // zooming
+      // zooming: right==up==zoom-in
+      const int delta = is_horizontal ? -delta_x : delta_y;
       const float zoom_delta = delta < 0 ? 0.5f : -0.5f;
       // convert screen to culling coordinates
       int ox = 0, oy = 0;
@@ -775,6 +778,8 @@ static gboolean _event_scroll(GtkWidget *widget,
     }
     else
     {
+      // navigation: right==down==next
+      const int delta = is_horizontal ? delta_x : delta_y;
       const int move = delta < 0 ? -1 : 1;
       dt_print(DT_DEBUG_INPUT, "[culling scroll] navigate move=%d", move);
       _thumbs_move(table, move);

src/gui/gtk.c

@@ -603,7 +603,8 @@ gboolean dt_gui_get_scroll_delta(const GdkEventScroll *event,
   gdouble delta_x, delta_y;
   if(dt_gui_get_scroll_deltas(event, &delta_x, &delta_y))
   {
-    *delta = delta_x + delta_y;
+    // treat right like up, left like down
+    *delta = fabs(delta_x) > fabs(delta_y) ? -delta_x : delta_y;
     return TRUE;
   }
   return FALSE;
@@ -615,7 +616,8 @@ gboolean dt_gui_get_scroll_unit_delta(const GdkEventScroll *event,
   int delta_x, delta_y;
   if(dt_gui_get_scroll_unit_deltas(event, &delta_x, &delta_y))
   {
-    *delta = delta_x + delta_y;
+    // treat right like up, left like down
+    *delta = abs(delta_x) > abs(delta_y) ? -delta_x : delta_y;
     return TRUE;
   }
   return FALSE;

src/gui/gtk.h

@@ -236,7 +236,7 @@ gboolean dt_gui_get_scroll_unit_deltas(const GdkEventScroll *event, int *delta_x
  * So if Shift changes scrolling effect, both scrolls should be handled the same.
  * For this case (or if it's otherwise useful) use the following 2 functions. */
 
-/* Return sum of scroll deltas from event. Return TRUE if any deltas
+/* Return delta of larger magnitude from the event. Return TRUE if any deltas
  * can be retrieved. Handles both GDK_SCROLL_UP/DOWN/LEFT/RIGHT and
  * GDK_SCROLL_SMOOTH style scroll events. */
 gboolean dt_gui_get_scroll_delta(const GdkEventScroll *event, gdouble *delta);

src/iop/atrous.c

@@ -1523,7 +1523,7 @@ static gboolean area_scrolled(GtkWidget *widget,
   int delta_y;
   if(dt_gui_get_scroll_unit_delta(event, &delta_y))
   {
-    g->mouse_radius = CLAMP(g->mouse_radius * (1.0 + 0.1 * delta_y), 0.25 / BANDS, 1.0);
+    g->mouse_radius = CLAMP(g->mouse_radius * (1.0 - 0.1 * delta_y), 0.25 / BANDS, 1.0);
     gtk_widget_queue_draw(widget);
   }
   return TRUE;

src/iop/colorzones.c

@@ -1906,7 +1906,7 @@ static gboolean _area_scrolled_callback(GtkWidget *widget,
     if(g->edit_by_area)
     {
       const int bands = p->curve_num_nodes[g->channel];
-      g->mouse_radius = CLAMP(g->mouse_radius * (1.0 + 0.1 * delta_y), 0.2 / bands, 1.0);
+      g->mouse_radius = CLAMP(g->mouse_radius * (1.0 - 0.1 * delta_y), 0.2 / bands, 1.0);
       gtk_widget_queue_draw(widget);
     }
     else

src/iop/denoiseprofile.c

@@ -3548,7 +3548,7 @@ static gboolean denoiseprofile_scrolled(GtkWidget *widget,
   int delta_y;
   if(dt_gui_get_scroll_unit_delta(event, &delta_y))
   {
-    g->mouse_radius = CLAMP(g->mouse_radius * (1.f + 0.1f * delta_y),
+    g->mouse_radius = CLAMP(g->mouse_radius * (1.f - 0.1f * delta_y),
                             0.2f / DT_IOP_DENOISE_PROFILE_BANDS, 1.f);
     gtk_widget_queue_draw(widget);
   }

src/iop/lowlight.c

@@ -776,7 +776,7 @@ static gboolean lowlight_scrolled(GtkWidget *widget, GdkEventScroll *event, dt_i
   int delta_y;
   if(dt_gui_get_scroll_unit_delta(event, &delta_y))
   {
-    g->mouse_radius = CLAMP(g->mouse_radius * (1.0 + 0.1 * delta_y), 0.2 / DT_IOP_LOWLIGHT_BANDS, 1.0);
+    g->mouse_radius = CLAMP(g->mouse_radius * (1.0 - 0.1 * delta_y), 0.2 / DT_IOP_LOWLIGHT_BANDS, 1.0);
     gtk_widget_queue_draw(widget);
   }
 

src/iop/monochrome.c

@@ -538,7 +538,7 @@ static gboolean _monochrome_scrolled(GtkWidget *widget, GdkEventScroll *event, d
   if(dt_gui_get_scroll_unit_delta(event, &delta_y))
   {
     const float old_size = p->size;
-    p->size = CLAMP(p->size + delta_y * 0.1, 0.5f, 3.0f);
+    p->size = CLAMP(p->size - delta_y * 0.1, 0.5f, 3.0f);
     if(old_size != p->size) dt_dev_add_history_item(darktable.develop, self, TRUE);
     gtk_widget_queue_draw(widget);
   }

src/iop/rawdenoise.c

@@ -857,7 +857,7 @@ static gboolean rawdenoise_scrolled(GtkWidget *widget, GdkEventScroll *event, dt
   int delta_y;
   if(dt_gui_get_scroll_unit_delta(event, &delta_y))
   {
-    g->mouse_radius = CLAMP(g->mouse_radius * (1.0 + 0.1 * delta_y), 0.2 / DT_IOP_RAWDENOISE_BANDS, 1.0);
+    g->mouse_radius = CLAMP(g->mouse_radius * (1.0 - 0.1 * delta_y), 0.2 / DT_IOP_RAWDENOISE_BANDS, 1.0);
     gtk_widget_queue_draw(widget);
   }
 

src/libs/tools/timeline.c

@@ -1342,10 +1342,11 @@ static gboolean _lib_timeline_scroll_callback(GtkWidget *w, GdkEventScroll *e, d
   }
   else
   {
-    int delta;
-    if(dt_gui_get_scroll_unit_delta(e, &delta))
+    // timeline panning: right==down==forward
+    int delta_x = 0, delta_y = 0;
+    if(dt_gui_get_scroll_unit_deltas(e, &delta_x, &delta_y))
     {
-      int move = delta;
+      int move = abs(delta_x) > abs(delta_y) ? delta_x : delta_y;
       if(dt_modifier_is(e->state, GDK_SHIFT_MASK)) move *= 2;
 
       _time_add(&(strip->time_pos), move, strip->zoom);