Confirmation popup before closing the occlusion editor

Fixes glutanimate#72.
Note that this confirmation popup is shown in some cases where I don't
think it's necessary. If the user adds occlusions, clicks on one of the
buttons to create the cards and then closes the editor dialog they are
prompted for confirmation.
The only way I can think of to prevent this is to reset the svg-edit
undo stack when the user clicks on the button, but I'm not sure if
that's acceptable.

src/image_occlusion_enhanced/add.py

@@ -21,7 +21,7 @@
 
 from aqt.qt import *
 
-from aqt import mw
+from aqt import mw, dialogs
 from aqt.utils import tooltip, showWarning
 
 from .ngen import *
@@ -189,7 +189,7 @@ def callImgOccEdit(self, width, height):
         flds = self.mflds
         deck = mw.col.decks.nameOrNone(opref["did"])
 
-        dialog = ImgOccEdit(self, self.ed.parentWindow)
+        dialog = dialogs.open('ImgOccEdit', self, self.ed.parentWindow)
         dialog.setupFields(flds)
         dialog.switchToMode(self.mode)
         self.imgoccedit = dialog
@@ -247,6 +247,11 @@ def onSvgEditLoaded():
                     ioInfo("obsolete_aa", parent=dialog)
                 dialog.showSvgEdit(True)
                 dialog.fitImageCanvas()
+                # The only thing undo does in edit mode is removing all
+                # occlusions. If the undo stack is not empty at the beginning
+                # there will always be a confirmation popup before the user
+                # can close the dialog.
+                dialog.svg_edit.eval("svgCanvas.undoMgr.resetUndoStack()")
 
         dialog.svg_edit.runOnLoaded(onSvgEditLoaded)
         dialog.visible = True

src/image_occlusion_enhanced/editor.py

@@ -20,7 +20,7 @@
 
 from aqt.qt import *
 
-from aqt import mw, webview, deckchooser, tagedit, sip
+from aqt import mw, webview, deckchooser, tagedit, sip, dialogs
 from aqt.utils import saveGeom, restoreGeom
 from anki.hooks import addHook, remHook
 
@@ -89,14 +89,42 @@ def __init__(self, imgoccadd, parent):
         restoreGeom(self, "imgoccedit")
         addHook("unloadProfile", self.onProfileUnload)
 
+    def closeWithCallback(self, callback):
+        def ifCanClose():
+            self._close()
+            callback()
+
+        self.askIfClose(ifCanClose)
+
+    def askIfClose(self, callback):
+        from aqt.utils import askUser
+        from anki.lang import _
+
+        def js_callback(size):
+            canClose = not size or size == 0 \
+                or (size > 0 and
+                    askUser(_("Close and lose current input?"),
+                            defaultno=True))
+            if canClose:
+                callback()
+
+        self.svg_edit.evalWithCallback('svgCanvas.undoMgr.getUndoStackSize()',
+                                       js_callback)
+
     def closeEvent(self, event):
+        event.ignore()
+        self.askIfClose(lambda: self._close())
+
+    def _close(self):
         if mw.pm.profile is not None:
             self.deckChooser.cleanup()
             saveGeom(self, "imgoccedit")
         self.visible = False
         self.svg_edit = None
-        del(self.svg_edit_anim)  # might not be gc'd
+        if hasattr(self, "svg_edit_anim"):
+            del(self.svg_edit_anim)  # might not be gc'd
         remHook("unloadProfile", self.onProfileUnload)
+        dialogs.markClosed("ImgOccEdit")
         QDialog.reject(self)
 
     def onProfileUnload(self):

src/image_occlusion_enhanced/main.py

@@ -23,6 +23,7 @@
 from aqt.qt import *
 
 from aqt import mw
+from aqt import dialogs
 from aqt.editor import Editor, EditorWebView
 from aqt.addcards import AddCards
 from aqt.editcurrent import EditCurrent
@@ -35,6 +36,7 @@
 from .add import ImgOccAdd
 from .options import ImgOccOpts
 from .dialogs import ioHelp, ioCritical
+from .editor import ImgOccEdit
 
 logging.basicConfig(stream=sys.stdout, level=logging.ERROR)
 
@@ -269,3 +271,6 @@ def onShowAnswer(self, _old):
     Reviewer._keyHandler = wrap(Reviewer._keyHandler, newKeyHandler, "before")
 else:
     addHook("reviewStateShortcuts", onReviewerStateShortcuts)
+
+# Set up dialog
+dialogs._dialogs['ImgOccEdit'] = [ImgOccEdit, None]