Additional fixes for drag cancellation in the node tool

(bzr r10926)

5 files changed, 45 insertions, 18 deletions

diff --git a/src/ui/tool/control-point.cpp b/src/ui/tool/control-point.cpp
index adad8611a..8ab7fe64f 100644
--- a/src/ui/tool/control-point.cpp
+++ b/src/ui/tool/control-point.cpp
@@ -21,6 +21,8 @@
 #include "event-context.h"
 #include "message-context.h"
 #include "preferences.h"
+#include "snap-preferences.h"
+#include "sp-namedview.h"
 #include "ui/tool/control-point.h"
 #include "ui/tool/event-utils.h"
 #include "ui/tool/transform-handle-set.h"
@@ -440,31 +442,32 @@ bool ControlPoint::_eventHandler(SPEventContext *event_context, GdkEvent *event)
         {
         case GDK_Escape: {
             // ignore Escape if this is not a drag
-            if (!_drag_initiated) return false;
+            if (!_drag_initiated) break;
 
-            // Do not process delayed snap events - we might snap to a different place than we were initially
-            delete _desktop->event_context->_delayed_snap_event;
-            _desktop->event_context->_delayed_snap_event = NULL;
+            // temporarily disable snapping - we might snap to a different place than we were initially
+            sp_event_context_discard_delayed_snap_event(_desktop->event_context);
+            SnapPreferences &snapprefs = _desktop->namedview->snap_manager.snapprefs;
+            bool snap_save = snapprefs.getSnapEnabledGlobally();
+            snapprefs.setSnapEnabledGlobally(false);
 
             Geom::Point new_pos = _drag_origin;
 
             // make a fake event for dragging
             // ASSUMPTION: dragging a point without modifiers will never prevent us from moving it
-            // to its original position
-            // TODO: pass correct values for x, y, x_root and y_root
+            //             to its original position
             GdkEventMotion fake;
             fake.type = GDK_MOTION_NOTIFY;
             fake.window = event->key.window;
             fake.send_event = event->key.send_event;
             fake.time = event->key.time;
-            fake.x = 0; // not used in handlers atm
-            fake.y = 0; // not used in handlers atm
+            fake.x = 0; // not used in handlers (and shouldn't be)
+            fake.y = 0; // not used in handlers (and shouldn't be)
             fake.axes = NULL;
             fake.state = 0; // unconstrained drag
             fake.is_hint = FALSE;
             fake.device = NULL;
-            fake.x_root = 0; // not used in handlers atm
-            fake.y_root = 0; // not used in handlers atm
+            fake.x_root = -1; // not used in handlers (and shouldn't be)
+            fake.y_root = -1; // can be used as a flag to check for cancelled drag
             
             dragged(new_pos, &fake);
 
@@ -475,6 +478,7 @@ bool ControlPoint::_eventHandler(SPEventContext *event_context, GdkEvent *event)
             _drag_initiated = false;
 
             ungrabbed(NULL); // ungrabbed handlers can handle a NULL event
+            snapprefs.setSnapEnabledGlobally(snap_save);
             } return true;
         case GDK_Tab:
             {// Downcast from ControlPoint to TransformHandle, if possible
@@ -624,6 +628,11 @@ void ControlPoint::_setColors(ColorEntry colors)
     g_object_set(_canvas_item, "fill_color", colors.fill, "stroke_color", colors.stroke, NULL);
 }
 
+bool ControlPoint::_is_drag_cancelled(GdkEventMotion *event)
+{
+    return !event || event->x_root == -1;
+}
+
 // dummy implementations for handlers
 // they are here to avoid unused param warnings
 bool ControlPoint::grabbed(GdkEventMotion *) { return false; }
diff --git a/src/ui/tool/control-point.h b/src/ui/tool/control-point.h
index 0719370f7..991d9123d 100644
--- a/src/ui/tool/control-point.h
+++ b/src/ui/tool/control-point.h
@@ -158,9 +158,10 @@ protected:
     ColorSet *_cset; ///< Colors used to represent the point
     State _state;
 
-    static int const _grab_event_mask;
     static Geom::Point const &_last_click_event_point() { return _drag_event_origin; }
     static Geom::Point const &_last_drag_origin() { return _drag_origin; }
+    static bool _is_drag_cancelled(GdkEventMotion *event);
+    static int const _grab_event_mask;
 
 private:
     ControlPoint(ControlPoint const &other);
diff --git a/src/ui/tool/curve-drag-point.cpp b/src/ui/tool/curve-drag-point.cpp
index 97e0ab7e7..3cc571585 100644
--- a/src/ui/tool/curve-drag-point.cpp
+++ b/src/ui/tool/curve-drag-point.cpp
@@ -34,6 +34,7 @@ namespace UI {
 // to be declared as a friend
 
 bool CurveDragPoint::_drags_stroke = false;
+bool CurveDragPoint::_segment_was_degenerate = false;
 
 CurveDragPoint::CurveDragPoint(PathManipulator &pm)
     : ControlPoint(pm._multi_path_manipulator._path_data.node_data.desktop, Geom::Point(),
@@ -61,6 +62,7 @@ bool CurveDragPoint::grabbed(GdkEventMotion */*event*/)
 
     // move the handles to 1/3 the length of the segment for line segments
     if (first->front()->isDegenerate() && second->back()->isDegenerate()) {
+        _segment_was_degenerate = true;
 
         // delta is a vector equal 1/3 of distance from first to second
         Geom::Point delta = (second->position() - first->position()) / 3.0;
@@ -68,13 +70,24 @@ bool CurveDragPoint::grabbed(GdkEventMotion */*event*/)
         second->back()->move(second->back()->position() - delta);
 
         _pm.update();
+    } else {
+        _segment_was_degenerate = false;
     }
     return false;
 }
 
-void CurveDragPoint::dragged(Geom::Point &new_pos, GdkEventMotion *)
+void CurveDragPoint::dragged(Geom::Point &new_pos, GdkEventMotion *event)
 {
     NodeList::iterator second = first.next();
+
+    // special cancel handling - retract handles when if the segment was degenerate
+    if (_is_drag_cancelled(event) && _segment_was_degenerate) {
+        first->front()->retract();
+        second->back()->retract();
+        _pm.update();
+        return;
+    }
+
     // Magic Bezier Drag Equations follow!
     // "weight" describes how the influence of the drag should be distributed
     // among the handles; 0 = front handle only, 1 = back handle only.
diff --git a/src/ui/tool/curve-drag-point.h b/src/ui/tool/curve-drag-point.h
index 819b7dbe1..939047634 100644
--- a/src/ui/tool/curve-drag-point.h
+++ b/src/ui/tool/curve-drag-point.h
@@ -42,6 +42,7 @@ private:
     PathManipulator &_pm;
     NodeList::iterator first;
     static bool _drags_stroke;
+    static bool _segment_was_degenerate;
     static Geom::Point _stroke_drag_origin;
 };
 
diff --git a/src/ui/tool/node.cpp b/src/ui/tool/node.cpp
index 2dc55e31c..4df4ba30e 100644
--- a/src/ui/tool/node.cpp
+++ b/src/ui/tool/node.cpp
@@ -351,13 +351,16 @@ void Handle::dragged(Geom::Point &new_pos, GdkEventMotion *event)
 void Handle::ungrabbed(GdkEventButton *event)
 {
     // hide the handle if it's less than dragtolerance away from the node
-    // TODO is this actually desired?
-    Inkscape::Preferences *prefs = Inkscape::Preferences::get();
-    int drag_tolerance = prefs->getIntLimited("/options/dragtolerance/value", 0, 0, 100);
+    // however, never do this for cancelled drag / broken grab
+    // TODO is this actually a good idea?
+    if (event) {
+        Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+        int drag_tolerance = prefs->getIntLimited("/options/dragtolerance/value", 0, 0, 100);
 
-    Geom::Point dist = _desktop->d2w(_parent->position()) - _desktop->d2w(position());
-    if (dist.length() <= drag_tolerance) {
-        move(_parent->position());
+        Geom::Point dist = _desktop->d2w(_parent->position()) - _desktop->d2w(position());
+        if (dist.length() <= drag_tolerance) {
+            move(_parent->position());
+        }
     }
 
     // HACK: If the handle was dragged out, call parent's ungrabbed handler,