[ENH] Widget Insertion

[irgolic]

Feature

Insert a widget in-between two already connected widgets by either:

• dragging it from the widget selection menu onto the link,
• right-clicking the link and selecting 'Insert Widget'

Description of changes

• Added an 'Insert Node' command for purposes of undo/redo
• Added entry to 'right-click on link' context menu
• Widget drag from menu -> insert

Includes

• Code changes
• Tests
• Documentation

[codecov-io]

Codecov Report

Merging #3179 into master will increase coverage by 0.1%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master    #3179     +/-   ##
=========================================
+ Coverage   82.54%   82.64%   +0.1%     
=========================================
  Files         337      342      +5     
  Lines       58431    59016    +585     
=========================================
+ Hits        48229    48776    +547     
- Misses      10202    10240     +38

[ales-erjavec]

This is the same as parentItem()

[ales-erjavec]

You can use self.__scene.item_at(event.scenePos(), items.LinkItem) for better and easier hit detection (you also would not need the new LinkCurveItem.parent method).

[ales-erjavec]

This logic in __init__ should be moved out of the command class. Parameterize the command with the new node, old link and new link pairs.

[ales-erjavec]

Change the command name/text to 'Insert widget on link' or something similar.

[ales-erjavec]

The test here should also be constrained on the existing link.source_channel and link.sink_channel.

E.g. If I use:

and drop an Impute widget on the link, I get a

------------------- IncompatibleChannelTypeError Exception --------------------
Traceback (most recent call last):
  File "/Users/aleserjavec/workspace/orange3/Orange/canvas/document/schemeedit.py", line 1102, in eventFilter
    self.tryInsertNode(link, desc, pos)
  File "/Users/aleserjavec/workspace/orange3/Orange/canvas/document/schemeedit.py", line 1066, in tryInsertNode
    new_node, possible_links[0][0][1]),  # first link, first entry, output
  File "/Users/aleserjavec/workspace/orange3/Orange/canvas/scheme/link.py", line 125, in __init__
    % (source_channel.type, sink_channel.type)
Orange.canvas.scheme.errors.IncompatibleChannelTypeError: Cannot connect 'Orange.base.Model' to 'Orange.base.Learner'
-------------------------------------------------------------------------------

The set of possible links below should also be filtered correspondingly.

P.S.
The same also applies to the 'Insert widget` context menu action.

[ales-erjavec]

Can you also implement drop target detection in eventFilter for GraphicsSceneDragEnter, GraphicsSceneDragMove and GraphicsSceneDragLeave events and highlight the drop target.
Something like:

diff --git a/Orange/canvas/document/schemeedit.py b/Orange/canvas/document/schemeedit.py
index 840ece304..ddf453fa6 100644
--- a/Orange/canvas/document/schemeedit.py
+++ b/Orange/canvas/document/schemeedit.py
@@ -132,6 +132,7 @@ class SchemeEditWidget(QWidget):
         self.__possibleMouseItemsMove = False
         self.__itemsMoving = {}
         self.__contextMenuTarget = None
+        self.__dropTarget = None
         self.__quickMenu = None
         self.__quickTip = ""
 
@@ -1066,18 +1067,43 @@ class SchemeEditWidget(QWidget):
 
     def eventFilter(self, obj, event):
         # Filter the scene's drag/drop events.
+        MIME_TYPE = "application/vnv.orange-canvas.registry.qualified-name"
         if obj is self.scene():
             etype = event.type()
             if etype == QEvent.GraphicsSceneDragEnter or \
                     etype == QEvent.GraphicsSceneDragMove:
                 mime_data = event.mimeData()
-                if mime_data.hasFormat(
-                        "application/vnv.orange-canvas.registry.qualified-name"
-                        ):
+                droptarget = None
+                accept = True
+                if mime_data.hasFormat(MIME_TYPE):
+                    qname = bytes(mime_data.data(MIME_TYPE)).decode("ascii")
+                    try:
+                        desc = self.__registry.widget(qname)
+                    except KeyError:
+                        pass
+                    else:
+                        item = self.__scene.item_at(event.scenePos(),
+                                                    items.LinkItem)
+                        link = self.__scene.link_for_item(item) if item else None
+                        if link is not None:
+                            droptarget = item
+                            droptarget.setHoverState(True)
+                            accept = can_insert_node(desc, link)
+                if accept:
                     event.acceptProposedAction()
                 else:
                     event.ignore()
+                if self.__dropTarget is not None and \
+                        self.__dropTarget is not droptarget:
+                    self.__dropTarget.setHoverState(False)
+                    self.__dropTarget = None
+
+                self.__dropTarget = droptarget
                 return True
+            elif etype == QEvent.GraphicsSceneDragLeave:
+                if self.__dropTarget is not None:
+                    self.__dropTarget.setHoverState(False)
+                    self.__dropTarget = None

[ajdapretnar]

Dragging the widget no longer works for me...?

[irgolic]

Are you dragging a compatible widget to the link? If the widget is incompatible, it's simply added as if dragged to empty canvas.
https://gyazo.com/bcd54f4c9279e804ed43f3629e938530

[ajdapretnar]

Yes. File - Select Columns - Data Table.

[irgolic]

Resolved.