From cf1763e79d596371d8883e8786f378d11c9502d7 Mon Sep 17 00:00:00 2001
From: Matthew Chen <matthew@signal.org>
Date: Tue, 18 Dec 2018 09:16:32 -0500
Subject: [PATCH] Suppress undo during strokes.

---
 .../Views/ImageEditor/ImageEditorModel.swift  | 51 ++-----------------
 .../Views/ImageEditor/ImageEditorView.swift   |  6 +--
 2 files changed, 5 insertions(+), 52 deletions(-)

diff --git a/SignalMessaging/Views/ImageEditor/ImageEditorModel.swift b/SignalMessaging/Views/ImageEditor/ImageEditorModel.swift
index 81fdb756e..a79eecee4 100644
--- a/SignalMessaging/Views/ImageEditor/ImageEditorModel.swift
+++ b/SignalMessaging/Views/ImageEditor/ImageEditorModel.swift
@@ -320,13 +320,6 @@ public class ImageEditorModel: NSObject {
     private var undoStack = [ImageEditorOperation]()
     private var redoStack = [ImageEditorOperation]()
 
-    // In some cases, we want to suppress changes to undo state.
-    // e.g. drawing a stroke will modify the model many times (once
-    // for each touch event/stroke sample), but we only want that
-    // to add a single undo operation.
-    private var isUndoSuppressed = false
-    private var suppressedUndoContents: ImageEditorContents?
-
     // We don't want to allow editing of images if:
     //
     // * They are invalid.
@@ -372,28 +365,6 @@ public class ImageEditorModel: NSObject {
         return !undoStack.isEmpty
     }
 
-    @objc
-    public func setIsUndoSuppressed(isUndoSuppressed: Bool) {
-        if isUndoSuppressed {
-            if self.isUndoSuppressed {
-                owsFailDebug("Undo already suppressed.")
-            }
-            if suppressedUndoContents != nil {
-                owsFailDebug("Unexpected suppressed undo contents.")
-            }
-            suppressedUndoContents = contents.clone()
-        } else {
-            if self.isUndoSuppressed {
-                if suppressedUndoContents == nil {
-                    owsFailDebug("Missing suppressed undo contents.")
-                }
-            }
-            suppressedUndoContents = nil
-        }
-
-        self.isUndoSuppressed = isUndoSuppressed
-    }
-
     @objc
     public func canRedo() -> Bool {
         return !redoStack.isEmpty
@@ -438,10 +409,10 @@ public class ImageEditorModel: NSObject {
 
     @objc
     public func replace(item: ImageEditorItem,
-                        shouldRemoveUndoSuppression: Bool = false) {
+                        suppressUndo: Bool = false) {
         performAction({ (newContents) in
             newContents.replace(item: item)
-        }, shouldRemoveUndoSuppression: shouldRemoveUndoSuppression)
+        }, suppressUndo: suppressUndo)
     }
 
     @objc
@@ -452,22 +423,8 @@ public class ImageEditorModel: NSObject {
     }
 
     private func performAction(_ action: (ImageEditorContents) -> Void,
-                               shouldRemoveUndoSuppression: Bool = false) {
-        if shouldRemoveUndoSuppression {
-            if !isUndoSuppressed {
-                owsFailDebug("Can't remove undo suppression, not suppressed.")
-            }
-            if let suppressedUndoContents = self.suppressedUndoContents {
-                let undoOperation = ImageEditorOperation(contents: suppressedUndoContents)
-                undoStack.append(undoOperation)
-                redoStack.removeAll()
-            } else {
-                owsFailDebug("Missing suppressed undo contents.")
-            }
-            self.isUndoSuppressed = false
-
-            setIsUndoSuppressed(isUndoSuppressed: false)
-        } else if !isUndoSuppressed {
+                               suppressUndo: Bool = false) {
+        if !suppressUndo {
             let undoOperation = ImageEditorOperation(contents: contents)
             undoStack.append(undoOperation)
             redoStack.removeAll()
diff --git a/SignalMessaging/Views/ImageEditor/ImageEditorView.swift b/SignalMessaging/Views/ImageEditor/ImageEditorView.swift
index d460c8834..1465bc34b 100644
--- a/SignalMessaging/Views/ImageEditor/ImageEditorView.swift
+++ b/SignalMessaging/Views/ImageEditor/ImageEditorView.swift
@@ -107,7 +107,6 @@ public class ImageEditorView: UIView, ImageEditorModelDelegate {
             if let stroke = self.currentStroke {
                 self.model.remove(item: stroke)
             }
-            self.model.setIsUndoSuppressed(isUndoSuppressed: false)
             self.currentStroke = nil
             self.currentStrokeSamples.removeAll()
         }
@@ -132,8 +131,6 @@ public class ImageEditorView: UIView, ImageEditorModelDelegate {
 
             currentStrokeSamples.append(unitSampleForGestureLocation())
 
-            model.setIsUndoSuppressed(isUndoSuppressed: true)
-
             let stroke = ImageEditorStrokeItem(color: strokeColor, unitSamples: currentStrokeSamples, unitStrokeWidth: unitStrokeWidth)
             model.append(item: stroke)
             currentStroke = stroke
@@ -150,13 +147,12 @@ public class ImageEditorView: UIView, ImageEditorModelDelegate {
             // Model items are immutable; we _replace_ the
             // stroke item rather than modify it.
             let stroke = ImageEditorStrokeItem(itemId: lastStroke.itemId, color: strokeColor, unitSamples: currentStrokeSamples, unitStrokeWidth: unitStrokeWidth)
+            model.replace(item: stroke, suppressUndo: true)
 
             if gestureRecognizer.state == .ended {
-                model.replace(item: stroke, shouldRemoveUndoSuppression: true)
                 currentStroke = nil
                 currentStrokeSamples.removeAll()
             } else {
-                model.replace(item: stroke)
                 currentStroke = stroke
             }
         default: