Support smooth scrolling (part 2)

Fix scrolling when smooth scrolling is enabled /
allow to scroll smoothly for:
- canvas palette
- node selection in path tool
- selection cycling in select tool while holding Alt key
- spraying in spray tool with mouse wheel
- adjusting color by scrolling in lower left stroke/fill fields

6 files changed, 26 insertions, 6 deletions

diff --git a/src/ui/previewholder.cpp b/src/ui/previewholder.cpp
index ae6907cc7..a39eb7ca6 100644
--- a/src/ui/previewholder.cpp
+++ b/src/ui/previewholder.cpp
@@ -76,7 +76,18 @@ bool PreviewHolder::on_scroll_event(GdkEventScroll *event)
         return FALSE;
     }
 
-    int move = (event->direction == GDK_SCROLL_DOWN) ? adj->get_page_size() : -adj->get_page_size();
+    int move;
+    switch (event->direction) {
+        case GDK_SCROLL_UP:
+            move = -adj->get_page_size();
+            break;
+        case GDK_SCROLL_DOWN:
+            move =  adj->get_page_size();
+            break;
+        case GDK_SCROLL_SMOOTH:
+            move = event->delta_y > 0 ? adj->get_page_size() : -adj->get_page_size();
+            break;
+    }
 
     double value = std::min(adj->get_upper() - move, adj->get_value() + move );
 
diff --git a/src/ui/tool/control-point.cpp b/src/ui/tool/control-point.cpp
index 85475d2d5..54fc4718f 100644
--- a/src/ui/tool/control-point.cpp
+++ b/src/ui/tool/control-point.cpp
@@ -52,7 +52,7 @@ Geom::Point ControlPoint::_drag_origin(Geom::infinity(), Geom::infinity());
 
 int const ControlPoint::_grab_event_mask = (GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK |
         GDK_POINTER_MOTION_MASK | GDK_POINTER_MOTION_HINT_MASK | GDK_KEY_PRESS_MASK |
-        GDK_KEY_RELEASE_MASK);
+        GDK_KEY_RELEASE_MASK | GDK_SCROLL_MASK | GDK_SMOOTH_SCROLL_MASK);
 
 bool ControlPoint::_drag_initiated = false;
 bool ControlPoint::_event_grab = false;
diff --git a/src/ui/tool/node.cpp b/src/ui/tool/node.cpp
index 9223b44de..49ee0cb1d 100644
--- a/src/ui/tool/node.cpp
+++ b/src/ui/tool/node.cpp
@@ -980,7 +980,11 @@ bool Node::_eventHandler(Inkscape::UI::Tools::ToolBase *event_context, GdkEvent
             dir = 1;
         } else if (event->scroll.direction == GDK_SCROLL_DOWN) {
             dir = -1;
-        } else break;
+        } else if (event->scroll.direction == GDK_SCROLL_SMOOTH) {
+            dir = event->scroll.delta_y > 0 ? -1 : 1;
+        } else {
+            break;
+        }
         if (held_control(event->scroll)) {
             _linearGrow(dir);
         } else {
diff --git a/src/ui/tools/select-tool.cpp b/src/ui/tools/select-tool.cpp
index 835bb6f94..92ae7558b 100644
--- a/src/ui/tools/select-tool.cpp
+++ b/src/ui/tools/select-tool.cpp
@@ -398,7 +398,8 @@ void SelectTool::sp_select_context_cycle_through_items(Inkscape::Selection *sele
 
     std::vector<SPItem *>::iterator next = cycling_items.end();
 
-    if (scroll_event->direction == GDK_SCROLL_UP) {
+    if ((scroll_event->direction == GDK_SCROLL_UP) ||
+        (scroll_event->direction == GDK_SCROLL_SMOOTH && scroll_event->delta_y < 0)) {
         if (! cycling_cur_item) {
             next = cycling_items.begin();
         } else {
diff --git a/src/ui/tools/spray-tool.cpp b/src/ui/tools/spray-tool.cpp
index cf677ff0c..c56bceda4 100644
--- a/src/ui/tools/spray-tool.cpp
+++ b/src/ui/tools/spray-tool.cpp
@@ -1304,7 +1304,8 @@ bool SprayTool::root_handler(GdkEvent* event) {
                 
                 switch (event->scroll.direction) {
                     case GDK_SCROLL_DOWN:
-                    case GDK_SCROLL_UP: {
+                    case GDK_SCROLL_UP:
+                    case GDK_SCROLL_SMOOTH: {
                         if (Inkscape::have_viable_layer(desktop, this->message_context) == false) {
                             return TRUE;
                         }
diff --git a/src/ui/widget/rotateable.cpp b/src/ui/widget/rotateable.cpp
index 64b37a07f..6c2056da1 100644
--- a/src/ui/widget/rotateable.cpp
+++ b/src/ui/widget/rotateable.cpp
@@ -34,7 +34,7 @@ Rotateable::Rotateable():
     signal_button_press_event().connect(sigc::mem_fun(*this, &Rotateable::on_click));
     signal_motion_notify_event().connect(sigc::mem_fun(*this, &Rotateable::on_motion));
     signal_button_release_event().connect(sigc::mem_fun(*this, &Rotateable::on_release));
-    gtk_widget_add_events(GTK_WIDGET(gobj()), GDK_SCROLL_MASK);
+    gtk_widget_add_events(GTK_WIDGET(gobj()), GDK_SCROLL_MASK | GDK_SMOOTH_SCROLL_MASK);
     signal_scroll_event().connect(sigc::mem_fun(*this, &Rotateable::on_scroll));
 
 }
@@ -139,6 +139,9 @@ bool Rotateable::on_scroll(GdkEventScroll* event)
         change = 1.0;
     } else if (event->direction == GDK_SCROLL_DOWN) {
         change = -1.0;
+    } else if (event->direction == GDK_SCROLL_SMOOTH) {
+        double delta_y_clamped = CLAMP(event->delta_y, -1.0, 1.0); // values > 1 result in excessive changes
+        change = 1.0 * -delta_y_clamped;
     } else {
         return FALSE;
     }