New option for automatically recovering session after a forced system reboot

Unavoidable system reboots will always (I assume) be a part of Windows.  PhotoDemon can now survive such a reboot.  If PD is open with one or more unsaved changes, and the system forces a reboot, PD will now auto-open after the reboot and restore your previous session, with all work intact.

Note that if you do *not* have any unsaved changes, PD will still auto-start after the reboot but will not re-load any images.  I still need to solve this (it's tied to PD's AutoSave system, which tries not to bug the user with prompts unless work risks being lost), presumably by subclassing WM_ENDSESSION and modifying PD's AutoSave triggers accordingly.

Author: tannerhelland

Forms/Dialog_AutosaveFound.frm

@@ -168,7 +168,7 @@ Public Sub ShowDialog()
 
     'Load command button images
     Dim buttonIconSize As Long
-    buttonIconSize = FixDPI(32)
+    buttonIconSize = Interface.FixDPI(32)
     cmdOK.AssignImage "generic_ok", , buttonIconSize, buttonIconSize
     cmdCancel.AssignImage "generic_cancel", , buttonIconSize, buttonIconSize
 

Forms/Tools_Options.frm

@@ -335,6 +335,28 @@ Begin VB.Form FormOptions
          FontSize        =   12
          ForeColor       =   5263440
       End
+      Begin PhotoDemon.pdLabel lblTitle 
+         Height          =   285
+         Index           =   22
+         Left            =   0
+         Top             =   5520
+         Width           =   8115
+         _ExtentX        =   14314
+         _ExtentY        =   503
+         Caption         =   "session restore"
+         FontSize        =   12
+         ForeColor       =   5263440
+      End
+      Begin PhotoDemon.pdCheckBox chkSystemReboots 
+         Height          =   330
+         Left            =   180
+         TabIndex        =   42
+         Top             =   5880
+         Width           =   7920
+         _ExtentX        =   13970
+         _ExtentY        =   582
+         Caption         =   "automatically restore sessions interrupted by system updates or reboots"
+      End
    End
    Begin PhotoDemon.pdContainer picContainer 
       Height          =   6720
@@ -1168,6 +1190,10 @@ Private Sub cmdBarMini_OKClick()
 
     UserPrefs.SetPref_Boolean "Loading", "ExifAutoRotate", chkLoadingOrientation.Value
 
+    'Restore after reboot behavior requires an immediate API to de/activate
+    UserPrefs.SetPref_Boolean "Loading", "RestoreAfterReboot", chkSystemReboots.Value
+    OS.SetRestartRestoreBehavior chkSystemReboots.Value
+    
     'Saving preferences
     SetProgBarVal 3
 
@@ -1388,6 +1414,7 @@ Private Sub LoadAllPreferences()
     chkMetadataUnknown.Value = UserPrefs.GetPref_Boolean("Loading", "Metadata Extract Unknown", False)
     chkMetadataBinary.Value = UserPrefs.GetPref_Boolean("Loading", "Metadata Extract Binary", False)
     chkLoadingOrientation.Value = UserPrefs.GetPref_Boolean("Loading", "EXIF Auto Rotate", True)
+    chkSystemReboots.Value = UserPrefs.GetPref_Boolean("Loading", "RestoreAfterReboot", False)
 
     'Saving preferences
     chkConfirmUnsaved.Value = g_ConfirmClosingUnsaved
@@ -1525,7 +1552,8 @@ Private Sub Form_Load()
     chkMetadataUnknown.AssignTooltip "Some camera manufacturers store proprietary metadata tags inside image files.  These tags are not generally useful to humans, but PhotoDemon can attempt to extract them anyway."
     chkMetadataBinary.AssignTooltip "By default, large binary tags (like image thumbnails) are not processed.  Instead, PhotoDemon simply reports the size of the embedded data.  If you require this data, PhotoDemon can manually convert it to Base64 for further analysis."
     chkLoadingOrientation.AssignTooltip "Most digital photos include rotation instructions (EXIF orientation metadata), which PhotoDemon will use to automatically rotate photos.  Some older smartphones and cameras may not write these instructions correctly, so if your photos are being imported sideways or upside-down, you can try disabling the auto-rotate feature."
-        
+    chkSystemReboots.AssignTooltip "If your PC reboots while PhotoDemon is running, PhotoDemon can automatically restore your previous session."
+    
     'Saving prefs
     chkConfirmUnsaved.AssignTooltip "By default, PhotoDemon will warn you when you attempt to close an image with unsaved changes."
 

Modules/AutosaveEngine.bas

@@ -3,8 +3,8 @@ Attribute VB_Name = "Autosaves"
 'Image Autosave Handler
 'Copyright 2014-2021 by Tanner Helland
 'Created: 18/January/14
-'Last updated: 14/September/20
-'Last update: rely on new Mutex class for detecting parallel sessions and modifying behavior accordingly
+'Last updated: 18/October/21
+'Last update: use autosave engine to (silently) restore previous sessions after forced system reboot
 '
 'PhotoDemon's Autosave engine is closely tied to the pdUndo class, so some understanding of that class is necessary
 ' to appreciate how this module operates.
@@ -134,20 +134,46 @@ Public Sub InitializeAutosave()
                 Dim userWantsAutosaves As VbMsgBoxResult
                 Dim listOfFilesToSave() As AutosaveXML
 
-                userWantsAutosaves = DisplayAutosaveWarning(listOfFilesToSave)
+                'If this is an auto-recovery session after a forced system reboot, and the user allows
+                ' us to auto-recover their previous session, skip displaying any UI and just jump
+                ' right to restoration.
+                Dim cmdParams As pdStringStack, showUI As Boolean
+                showUI = True
+                
+                If OS.CommandW(cmdParams, True) Then
+                    
+                    Dim i As Long
+                    For i = 0 To cmdParams.GetNumOfStrings - 1
+                        If Strings.StringsEqual(cmdParams.GetString(i), "/system-reboot", True) Then
+                            showUI = False
+                            Exit For
+                        End If
+                    Next i
+                    
+                    'If the autosave data comes from a perfectly good session interrupted by a forced system reboot,
+                    ' restore all work silently.
+                    If (Not showUI) Then
+                        Dim tmpXMLCount As Long
+                        Autosaves.GetXMLAutosaveEntries listOfFilesToSave, tmpXMLCount
+                        userWantsAutosaves = vbYes
+                    End If
+                    
+                End If
+                
+                If showUI Then userWantsAutosaves = DisplayAutosaveWarning(listOfFilesToSave)
 
                 'If the user wants to restore old Autosave data, do so now.
                 If (userWantsAutosaves = vbYes) Then
 
                     'listOfFilesToSave contains the list of Autosave files the user wants restored.
                     ' Hand them off to the autosave handler, which will load and restore each file in turn.
                     Autosaves.LoadTheseAutosaveFiles listOfFilesToSave
-                    SyncInterfaceToCurrentImage
+                    Interface.SyncInterfaceToCurrentImage
 
                 Else
 
-                    'The user has no interest in recovering AutoSave data.  Purge all the entries we found, so they don't show
-                    ' up in future AutoSave searches.
+                    'The user has no interest in recovering AutoSave data.  Purge all the entries we found,
+                    ' so they don't show up in future AutoSave checks.
                     Autosaves.PurgeOldAutosaveData
 
                 End If

Modules/Loading.bas

@@ -823,14 +823,22 @@ Public Function LoadMultipleImageFiles(ByRef srcList As pdStringStack, Optional
 
         Dim tmpFilename As String
         Do While srcList.PopString(tmpFilename)
-            If LoadFileAsNewImage(tmpFilename, , updateRecentFileList, True, False) Then
-                numSuccesses = numSuccesses + 1
-            Else
-                If (Len(tmpFilename) <> 0) Then
-                    numFailures = numFailures + 1
-                    brokenFiles = brokenFiles & Files.FileGetName(tmpFilename) & vbCrLf
+            
+            'The command-line may include other switches besides just filenames.  Ensure target file
+            ' exists before forwarding it to the loader.
+            If Files.FileExists(tmpFilename) Then
+                
+                If LoadFileAsNewImage(tmpFilename, , updateRecentFileList, True, False) Then
+                    numSuccesses = numSuccesses + 1
+                Else
+                    If (LenB(tmpFilename) <> 0) Then
+                        numFailures = numFailures + 1
+                        brokenFiles = brokenFiles & Files.FileGetName(tmpFilename) & vbCrLf
+                    End If
                 End If
+                
             End If
+            
         Loop
 
         'Make sure we loaded at least one image from the original list

Modules/Main.bas

@@ -288,6 +288,11 @@ Public Function ContinueLoadingProgram(Optional ByRef suspendAdditionalMessages
         PDDebug.LogAction "(Note: this PD instance is unique; no other instances discovered.)"
     End If
 
+    'While here, check another start-up related user perference.  Forced system reboots are
+    ' an ever-more-annoying issue on modern versions of Window.  PhotoDemon can automatically
+    ' recover sessions interrupted by reboots.
+    If UserPrefs.GetPref_Boolean("Loading", "RestoreAfterReboot", False) Then OS.SetRestartRestoreBehavior True
+    
 
     '*************************************************************************************************************************************
     ' Initialize the plugin manager and load any high-priority plugins (e.g. those required to start the program successfully)

Modules/OS.bas

@@ -3,8 +3,8 @@ Attribute VB_Name = "OS"
 'OS-specific specific features
 'Copyright 2013-2021 by Tanner Helland
 'Created: 21/November/13
-'Last updated: 18/July/17
-'Last update: migrate various OS-specific bits to this module
+'Last updated: 18/October/21
+'Last update: new helper function for requesting app restart after forced system reboots
 '
 'Newer Windows versions expose some neat features (like progress bars overlaying the taskbar), and PhotoDemon
 ' tries to make use of them when relevant.  Similarly, some OS-level features are not easily mimicked from within VB
@@ -287,6 +287,7 @@ Private Declare Function LocalFree Lib "kernel32" (ByVal hMem As Long) As Long
 Private Declare Function OpenProcess Lib "kernel32" (ByVal dwDesiredAccessas As Long, ByVal bInheritHandle As Long, ByVal dwProcId As Long) As Long
 Private Declare Function ProcessFirst Lib "kernel32" Alias "Process32FirstW" (ByVal hSnapShot As Long, ByVal ptrToUProcess As Long) As Long
 Private Declare Function ProcessNext Lib "kernel32" Alias "Process32NextW" (ByVal hSnapShot As Long, ByVal ptrToUProcess As Long) As Long
+Private Declare Function RegisterApplicationRestart Lib "kernel32" (ByVal pwzCommandline As Long, ByVal dwFlags As Long) As Long
 Private Declare Function VirtualAlloc Lib "kernel32" (ByVal lpAddress As Long, ByVal dwSize As Long, ByVal flAllocationType As Long, ByVal flProtect As Long) As Long
 Private Declare Function VirtualFree Lib "kernel32" (ByVal lpAddress As Long, ByVal dwSize As Long, ByVal dwFreeType As Long) As Long
 
@@ -909,6 +910,39 @@ Public Function RAM_SystemTotal() As String
 
 End Function
 
+'PhotoDemon can automatically recover sessions interrupted by forced system reboots.  This function
+' can be called to enable or disable this behavior (but note that there are some restrictions;
+' for example, the app must be running for ~60 seconds before it's eligible for recovery.  This is
+' an OS-level restriction.)  Note also that this is only available on Vista+, but PD actually limits
+' it to Win 7+ due to a lack of testing on Vista.
+Public Sub SetRestartRestoreBehavior(ByVal allowToRestore As Boolean)
+    
+    'Not available on XP.  Possibly available on Vista but I no longer maintain a Vista VM, so I'm
+    ' not enabling until someone can test for me.
+    If OS.IsWin7OrLater Then
+        
+        'Possible flags for this API; not all are used by PD
+        Const RESTART_NO_CRASH As Long = 1  'Do not restart the process if it terminates due to an unhandled exception.
+        Const RESTART_NO_HANG As Long = 2   'Do not restart the process if it terminates due to the application not responding.
+        'Const RESTART_NO_PATCH As Long = 4  'Do not restart the process if it terminates due to the installation of an update.
+        'Const RESTART_NO_REBOOT As Long = 8 'Do not restart the process if the computer is restarted as the result of an update.
+        Const RESTART_NONE As Long = &HF&   'All the above; used to disable restarts completely after previously requesting them
+        
+        'This function can also pass command-line parameters; we use an internal flag that bypasses
+        ' the AutoSave Recovery prompt.
+        Dim cmdParams As String
+        cmdParams = " /system-reboot"
+        
+        If allowToRestore Then
+            RegisterApplicationRestart StrPtr(cmdParams), RESTART_NO_CRASH Or RESTART_NO_HANG
+        Else
+            RegisterApplicationRestart ByVal 0&, RESTART_NONE
+        End If
+        
+    End If
+    
+End Sub
+
 'If desired, a custom state can be set for the taskbar.  (Normally this is handled by the SetTaskbarProgressValue function.)
 Public Function SetTaskbarProgressState(ByVal tbpFlags As PD_TaskBarProgress) As Long
     If WIN7_FEATURES_ALLOWED Then SetTaskbarProgressState = CallInterface(m_taskbarObjHandle, SetProgressState_, 2, FormMain.hWnd, tbpFlags)

PhotoDemon.vbp

@@ -488,7 +488,7 @@ Description="PhotoDemon Photo Editor"
 CompatibleMode="0"
 MajorVer=8
 MinorVer=9
-RevisionVer=925
+RevisionVer=929
 AutoIncrementVer=1
 ServerSupportFiles=0
 VersionComments="Copyright 2000-2021 Tanner Helland - photodemon.org"