Make the behavior of the snap indicator fully transparent, such that all events are sent to the items or canvas as intended

Fixed bugs:
  - https://launchpad.net/bugs/1420301

(bzr r14201)

1 files changed, 15 insertions, 0 deletions

diff --git a/src/display/snap-indicator.cpp b/src/display/snap-indicator.cpp
index 8c0c8163f..926b35599 100644
--- a/src/display/snap-indicator.cpp
+++ b/src/display/snap-indicator.cpp
@@ -258,6 +258,19 @@ SnapIndicator::set_new_snaptarget(Inkscape::SnappedPoint const &p, bool pre_snap
 
         const int timeout_val = 4000;
 
+        // The snap indicator will be deleted after some time-out, and sp_canvas_item_dispose
+        // will be called. This will set canvas->current_item to NULL if the snap indicator was
+        // the current item, after which any events will go to the root handler instead of any
+        // item handler. Dragging an object which has just snapped might therefore not be possible
+        // without selecting / repicking it again. To avoid this, we make sure here that the
+        // snap indicator will never be picked, and will therefore never be the current item.
+        // Reported bugs:
+        //   - scrolling when hovering above a pre-snap indicator won't work (for example)
+        //     (https://bugs.launchpad.net/inkscape/+bug/522335/comments/8)
+        //   - dragging doesn't work without repicking
+        //     (https://bugs.launchpad.net/inkscape/+bug/1420301/comments/15)
+        SP_CTRL(canvasitem)->pickable = false;
+
         SP_CTRL(canvasitem)->moveto(p.getPoint());
         _snaptarget = _desktop->add_temporary_canvasitem(canvasitem, timeout_val);
         _snaptarget_is_presnap = pre_snap;
@@ -282,6 +295,7 @@ SnapIndicator::set_new_snaptarget(Inkscape::SnappedPoint const &p, bool pre_snap
 
             SPCanvasItem *canvas_tooltip = sp_canvastext_new(_desktop->getTempGroup(), _desktop, tooltip_pos, tooltip_str);
             sp_canvastext_set_fontsize(SP_CANVASTEXT(canvas_tooltip), fontsize);
+            SP_CANVASTEXT(canvas_tooltip)->pickable = false; // See the extensive comment above
             SP_CANVASTEXT(canvas_tooltip)->rgba = 0xffffffff;
             SP_CANVASTEXT(canvas_tooltip)->outline = false;
             SP_CANVASTEXT(canvas_tooltip)->background = true;
@@ -306,6 +320,7 @@ SnapIndicator::set_new_snaptarget(Inkscape::SnappedPoint const &p, bool pre_snap
             SP_CTRLRECT(box)->setRectangle(*bbox);
             SP_CTRLRECT(box)->setColor(pre_snap ? 0x7f7f7fff : 0xff0000ff, 0, 0);
             SP_CTRLRECT(box)->setDashed(true);
+            SP_CTRLRECT(box)->pickable = false;  // See the extensive comment above
             sp_canvas_item_move_to_z(box, 0);
             _snaptarget_bbox = _desktop->add_temporary_canvasitem(box, timeout_val);
         }