feat: Undo/Redo Feature for Mantis (#379)

* Undo/Redo Feature for Mantis

* Addressing comments in PR

* Add MantisExampleTests target back to project - somehow got deleted.

* Adressing Comments in Chante List:
- added "enableUndo" flag in Config
- undo/redo/reset logic checks the "enableUndo" flag in cropViewController to enable functionality
- abstracted the TransformRecord logic into the CropViewController class
- removed UIButtons from TransformDelegate
- moved TransformDelegate in to new file in the Protocols folder

* added logic to validate the Catalyst menus (disable undo menus when "enableUndo" is false in Config file.

* Address latest round of comments
- More private variables.
- Embedded controller uses proxy functions to communicate with CropViewController state.
- Defaults function implementations in delegate methods.

* Rename some delegate methods:
cropViewControllerDidEnableUndo -> cropViewControllerDidUpdateEnableStateForUndo
cropViewControllerDidEnableRedo -> cropViewControllerDidUpdateEnableStateForRedo
cropViewControllerDidEnableReset -> cropViewControllerDidUpdateEnableStateForReset

* TransformStack private now

* changed actionString declaration.

* removed unwanted space

* Removed some old code, that was not needed anymore when the function signature changed.

* removed  func cropViewControllerDidImageTransformed(_ cropViewController: CropViewController) from CropViewControllerDelegate

* Remove spaces

* removed public from some data types:
TransformType
TransformRecord
TransformStack

* TransformDelegate methods no longer public

* moved opening brackets up to end of function declarations

* removed public modifier in all variables and function signatures in TransformRecord

* removed public modifier from all variables and function signatures in TransformStack

* Placeholder localization strings for "Change Crop" and "Reset Changes"

* Localized "Change Crop" and "Reset Changes" using Google Translate.

* updated the README.md file to describe Undo/Redo support.

* Changed Chinese language localization strings

* Refactoring work:
- rename TransformDelegate methods
- make TransformStack init a private method

* - Fixed a localization bug
- Removed a dead deprecation directive

* cleaned up property list for TransformRecord

* made dictionary passed to TransformRecord have strong type in value field

* changed transformDelegate to an optional

* made private some variables in TransformStack

* Add new files to Mantis.xcodeproj:
- TransformStack.swift
- TransformRecord.swift
- TransformDelegate.swift

* remove dead code

* Rename delegate methods in CropViewControllerDelegate:
- cropViewControllerDidUpdateEnableStateForUndo(_ enable: Bool) -> cropViewController(_ cropViewController: CropViewController, didUpdateEnableStateForUndo enable: Bool)

- cropViewControllerDidUpdateEnableStateForRedo(_ enable: Bool) -> cropViewController(_ cropViewController: CropViewController, didUpdateEnableStateForRedo enable: Bool)

- cropViewControllerDidUpdateEnableStateForReset(_ enable: Bool) -> cropViewController(_ cropViewController: CropViewController, didUpdateEnableStateForReset enable: Bool)

* Remove blanl line

* Simplify an optional value boolean test

* Remove three unused variables from TransformStack

* Address a SwiftLint warning in TransformRecord

* Address a SwiftLint warning in TransformRecord

* Fixed Unit Tests in Mantis.xcodeproj related to new API for undo/redo feature.

* remove first call to transform() in applyCropState() and just set the viewModel's cropBoxFrame to the transform.maskFrame

* moved function "pushTransformRecordOntoStack" out of CropViewController and in to TransformStack class

* added bounds check in TransformStack.popTransformStack()

* added Unit Test for TransformStack

* Updated TransformStack Unit Test.

Example/AppDelegate.swift

@@ -40,3 +40,40 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
     // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
   }
 }
+
+extension AppDelegate {
+
+    override func buildMenu(with builder: UIMenuBuilder) {
+        super.buildMenu(with: builder)
+
+        // Ensure that the builder is modifying the menu bar system.
+        guard builder.system == UIMenuSystem.main else { return }
+
+        // remove items from Edit menu
+        builder.remove(menu: .undoRedo)
+
+        // Undo
+        let undoCommand = UIKeyCommand(title: "Undo",
+                                       action: #selector(EmbeddedCropViewController.undoButtonPressed(_:)),
+                                       input: "z",
+                                       modifierFlags: [.command])
+
+
+        // Redo
+        let redoCommand = UIKeyCommand(title: "Redo",
+                                       action: #selector(EmbeddedCropViewController.redoButtonPressed(_:)),
+                                       input: "z",
+                                       modifierFlags: [.shift, .command])
+
+        // Revert
+        let revertCommand = UIKeyCommand(title: "Revert to Original",
+                                       action: #selector(EmbeddedCropViewController.resetButtonPressed(_:)),
+                                       input: "r",
+                                         modifierFlags: [.alternate])
+
+        let undoMenu = UIMenu(title: "", identifier: .undoRedo, options: .displayInline, children: [undoCommand, redoCommand, revertCommand ])
+
+        builder.insertChild(undoMenu, atStartOfMenu: .edit)
+
+    }
+}

Example/Base.lproj/Main.storyboard

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="21507" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="BYZ-38-t0r">
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="22505" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="BYZ-38-t0r">
     <device id="retina4_7" orientation="portrait" appearance="light"/>
     <dependencies>
         <deployment identifier="iOS"/>
-        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="21505"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="22504"/>
         <capability name="Safe area layout guides" minToolsVersion="9.0"/>
         <capability name="System colors in document resources" minToolsVersion="11.0"/>
         <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
@@ -174,7 +174,7 @@
                                 </constraints>
                             </stackView>
                             <imageView userInteractionEnabled="NO" contentMode="scaleAspectFit" horizontalHuggingPriority="251" verticalHuggingPriority="251" image="sunflower" translatesAutoresizingMaskIntoConstraints="NO" id="pUS-Eo-0ui" userLabel="Cropped Image">
-                                <rect key="frame" x="32" y="16" width="311" height="342"/>
+                                <rect key="frame" x="32" y="36" width="311" height="322"/>
                             </imageView>
                         </subviews>
                         <viewLayoutGuide key="safeArea" id="6Tk-OE-BBY"/>
@@ -247,6 +247,23 @@
                                 <action selector="cancel:" destination="aIe-ND-Zfg" id="j3e-ai-8lv"/>
                             </connections>
                         </barButtonItem>
+                        <barButtonItem title="Undo" id="HSP-G5-UOE">
+                            <color key="tintColor" systemColor="systemYellowColor"/>
+                            <connections>
+                                <action selector="undoButtonPressed:" destination="aIe-ND-Zfg" id="8eI-4B-Rt7"/>
+                            </connections>
+                        </barButtonItem>
+                        <barButtonItem title="Redo" id="l1v-fT-hP5">
+                            <color key="tintColor" systemColor="systemYellowColor"/>
+                            <connections>
+                                <action selector="redoButtonPressed:" destination="aIe-ND-Zfg" id="pck-70-va2"/>
+                            </connections>
+                        </barButtonItem>
+                        <barButtonItem title="Reset" id="eee-mM-zNC">
+                            <connections>
+                                <action selector="resetButtonPressed:" destination="aIe-ND-Zfg" id="S6Q-y0-GYz"/>
+                            </connections>
+                        </barButtonItem>
                         <barButtonItem style="plain" systemItem="flexibleSpace" id="DsY-rM-AWO"/>
                         <barButtonItem systemItem="bookmarks" id="sQZ-M0-ZLt">
                             <color key="tintColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
@@ -270,7 +287,10 @@
                     <connections>
                         <outlet property="cancelButton" destination="5p4-Ob-R9b" id="kQq-ir-MSf"/>
                         <outlet property="doneButton" destination="kZP-3N-vXv" id="RPY-W3-vWu"/>
+                        <outlet property="redoButton" destination="l1v-fT-hP5" id="jYe-4F-ear"/>
+                        <outlet property="resetButton" destination="eee-mM-zNC" id="Jfu-qz-XAZ"/>
                         <outlet property="resolutionLabel" destination="NDR-Th-Zyy" id="rUQ-h6-q2i"/>
+                        <outlet property="undoButton" destination="HSP-G5-UOE" id="BLL-45-Dfn"/>
                     </connections>
                 </viewController>
                 <placeholder placeholderIdentifier="IBFirstResponder" id="xP6-ML-BEH" userLabel="First Responder" sceneMemberID="firstResponder"/>
@@ -322,5 +342,8 @@
         <systemColor name="systemGray6Color">
             <color red="0.94901960784313721" green="0.94901960784313721" blue="0.96862745098039216" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
         </systemColor>
+        <systemColor name="systemYellowColor">
+            <color red="1" green="0.80000000000000004" blue="0.0" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+        </systemColor>
     </resources>
 </document>

Example/EmbeddedCropViewController.swift

@@ -14,21 +14,47 @@ class EmbeddedCropViewController: UIViewController {
     var image: UIImage?
     var cropViewController: CropViewController?
 
+    weak var toolbarDelegate: CropToolbarDelegate?
+
     var didGetCroppedImage: ((UIImage) -> Void)?
 
     @IBOutlet weak var cancelButton: UIBarButtonItem!
     @IBOutlet weak var doneButton: UIBarButtonItem!
     @IBOutlet weak var resolutionLabel: UILabel!
 
+    @IBOutlet weak var undoButton: UIBarButtonItem!
+    @IBOutlet weak var redoButton: UIBarButtonItem!
+    @IBOutlet weak var resetButton: UIBarButtonItem!
+
     override func viewDidLoad() {
         super.viewDidLoad()
 
+        undoButton.title = "Undo"
+        redoButton.title = "Redo"
         cancelButton.title = "Cancel"
         doneButton.title = "Done"
+        resetButton.title = "Revert"
+
         resolutionLabel.text = "\(getResolution(image: image) ?? "unknown")"
 
         view.backgroundColor = .black
         navigationController?.toolbar.backgroundColor = .black
+
+        self.undoButton.isEnabled = false
+        self.redoButton.isEnabled = false
+        self.resetButton.isEnabled = false
+    }
+
+    @IBAction func undoButtonPressed(_ sender: Any) {
+        toolbarDelegate?.didSelectUndo()
+    }
+
+    @IBAction func redoButtonPressed(_ sender: Any) {
+        toolbarDelegate?.didSelectRedo()
+    }
+
+    @IBAction func resetButtonPressed(_ sender: Any) {
+        cropViewController?.didSelectReset()
     }
 
     @IBAction func cancel(_ sender: Any) {
@@ -48,9 +74,14 @@ class EmbeddedCropViewController: UIViewController {
 
         var config = Mantis.Config()
         config.cropToolbarConfig.mode = .embedded
+        config.enableUndoRedo = true
+
+        config.cropToolbarConfig.toolbarButtonOptions = [.counterclockwiseRotate, .clockwiseRotate, .horizontallyFlip, .verticallyFlip]
+
         Mantis.setupCropViewController(cropViewController, with: image, and: config)
 
         self.cropViewController = cropViewController
+        self.toolbarDelegate = cropViewController
     }
 
     private func getResolution(image: UIImage?) -> String? {
@@ -59,9 +90,76 @@ class EmbeddedCropViewController: UIViewController {
         }
         return nil
     }
+
+    override func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
+
+        if action == #selector(EmbeddedCropViewController.undoButtonPressed(_:)) ||
+           action == #selector(EmbeddedCropViewController.redoButtonPressed(_:))  ||
+           action == #selector(EmbeddedCropViewController.resetButtonPressed(_:)) {
+
+            guard let toolbarDelegate = toolbarDelegate else { return false }
+
+            return toolbarDelegate.isUndoSupported()
+        }
+
+        return true
+    }
+
+    override func validate(_ command: UICommand) {
+
+        guard let toolbarDelegate = toolbarDelegate else { return }
+
+        if toolbarDelegate.isUndoSupported() {
+
+            if command.action == #selector(EmbeddedCropViewController.undoButtonPressed(_:)) {
+
+                let undoString = NSLocalizedString("Undo", comment: "Undo")
+
+                command.title = self.undoButton.isEnabled ? "\(undoString) \(toolbarDelegate.undoActionName())" : undoString
+
+                if !self.undoButton.isEnabled {
+                    command.attributes = [.disabled]
+                }
+            }
+
+            if command.action == #selector(EmbeddedCropViewController.redoButtonPressed(_:)) {
+
+                let redoString = NSLocalizedString("Redo", comment: "Redo")
+
+                command.title = self.redoButton.isEnabled ? "\(redoString) \(toolbarDelegate.redoActionName())" : redoString
+
+                if !self.redoButton.isEnabled {
+                    command.attributes = [.disabled]
+                }
+            }
+
+            if command.action == #selector(EmbeddedCropViewController.resetButtonPressed(_:)) {
+
+                command.title = NSLocalizedString("Revert to Original", comment: "Revert to Original")
+
+                if !self.resetButton.isEnabled {
+                    command.attributes = [.disabled]
+                }
+            }
+        }
+    }
+
 }
 
 extension EmbeddedCropViewController: CropViewControllerDelegate {
+
+    func cropViewController(_ cropViewController: CropViewController, didUpdateEnableStateForUndo enable: Bool) {
+        self.undoButton.isEnabled = enable
+    }
+
+    func cropViewController(_ cropViewController: CropViewController, didUpdateEnableStateForRedo enable: Bool) {
+        self.redoButton.isEnabled = enable
+    }
+
+    func cropViewController(_ cropViewController: CropViewController, didUpdateEnableStateForReset enable: Bool) {
+        self.resetButton.isEnabled = enable
+    }
+
     func cropViewControllerDidCrop(_ cropViewController: CropViewController,
                                    cropped: UIImage,
                                    transformation: Transformation,
@@ -82,5 +180,5 @@ extension EmbeddedCropViewController: CropViewControllerDelegate {
         let size = cropViewController.getExpectedCropImageSize()
         self.resolutionLabel.text = "\(Int(size.width)) x \(Int(size.height)) pixels"
     }
-
 }
+