pdImage handler: fix issues with circular references

This solves a number of problematic memory leaks during batch processing

Classes/pdImage.cls

@@ -780,16 +780,17 @@ End Function
 'When this DIB is no longer being used, we can deactivate it to save on resources.
 Public Sub DeactivateImage()
 
-    'Erase the composite buffer
+    'Erase any internal image buffers
     If Not (compositeBuffer Is Nothing) Then Set compositeBuffer = Nothing
-
-    'Erase the canvas buffer
     If Not (canvasBuffer Is Nothing) Then Set canvasBuffer = Nothing
 
-    'If a selection exists, wipe it
-    If Not (mainSelection Is Nothing) Then Set mainSelection = Nothing
+    'Erase the selection manager (*very* important because of circular references)
+    If Not (mainSelection Is Nothing) Then
+        Set mainSelection.containingPDImage = Nothing
+        Set mainSelection = Nothing
+    End If
 
-    'Deactivate the Undo/Redo handler
+    'Deactivate the Undo/Redo handler (*very* important because of circular references)
     If Not (undoManager Is Nothing) Then
         undoManager.ClearUndos
         Set undoManager.parentPDImage = Nothing
@@ -804,17 +805,15 @@ Public Sub DeactivateImage()
 
     'Release all layers
     Dim i As Long
-    If m_numOfLayers > 0 Then
+    If (m_numOfLayers > 0) Then
         For i = 0 To UBound(imgLayers)
             Set imgLayers(i) = Nothing
         Next i
         m_numOfLayers = 0
     End If
 
     'It doesn't make a big difference, but we can also empty out this image's String-type variables to save a bit of space.
-    imgStorage.DeleteEntry "OriginalFileName"
-    imgStorage.DeleteEntry "OriginalFileExtension"
-    imgStorage.DeleteEntry "CurrentLocationOnDisk"
+    Set imgStorage = Nothing
 
     'Mark this image as inactive
     IsActive = False

Modules/Main.bas

@@ -668,7 +668,10 @@ Public Sub FinalShutdown()
 
     Dim i As Long
     For i = LBound(pdImages) To UBound(pdImages)
-        Set pdImages(i) = Nothing
+        If (Not pdImages(i) Is Nothing) Then
+            pdImages(i).DeactivateImage
+            Set pdImages(i) = Nothing
+        End If
     Next i
 
     'Delete any remaining temp files in the cache

Modules/VBP_LoadModule.bas

@@ -618,8 +618,12 @@ Public Function QuickLoadImageToDIB(ByVal imagePath As String, ByRef targetDIB A
             End If
         End If
 
-        'Deactivate the (now useless) DIB
-        If (Not tmpPDImage Is Nothing) Then Set tmpPDImage = Nothing
+        'Deactivate the (now useless) DIB and parent object
+        If (Not tmpPDImage Is Nothing) Then
+            tmpPDImage.DeactivateImage
+            Set tmpPDImage = Nothing
+        End If
+
         If (Not targetDIB Is Nothing) Then Set targetDIB = Nothing
 
         'Re-enable the main interface

Modules/VBP_MiscInterface.bas

@@ -529,7 +529,7 @@ Private Sub SetUIMode_NoImages()
 
     'If no images are currently open, but images were previously opened during this session, release any memory associated
     ' with those images.  This helps minimize PD's memory usage at idle.
-    If g_NumOfImagesLoaded >= 1 Then
+    If (g_NumOfImagesLoaded >= 1) Then
 
         'Loop through all pdImage objects and make sure they've been deactivated
         Dim i As Long
@@ -1839,15 +1839,15 @@ Public Function GetRuntimeUIDIB(ByVal dibType As PD_RUNTIME_UI_DIB, Optional ByV
 End Function
 
 'New test functions to (hopefully) help address high-DPI issues where VB's internal scale properties report false values
-Public Function APIWidth(ByVal srcHWnd As Long) As Long
+Public Function APIWidth(ByVal srcHwnd As Long) As Long
     Dim tmpRect As winRect
-    GetWindowRect srcHWnd, tmpRect
+    GetWindowRect srcHwnd, tmpRect
     APIWidth = tmpRect.x2 - tmpRect.x1
 End Function
 
-Public Function APIHeight(ByVal srcHWnd As Long) As Long
+Public Function APIHeight(ByVal srcHwnd As Long) As Long
     Dim tmpRect As winRect
-    GetWindowRect srcHWnd, tmpRect
+    GetWindowRect srcHwnd, tmpRect
     APIHeight = tmpRect.y2 - tmpRect.y1
 End Function