allow surface to be resized

(cherry picked from commit b936c1004d542c5033c4a721f412588c316a1134)

src/Greenshot.Base/Interfaces/ISurface.cs

@@ -40,6 +40,7 @@ namespace Greenshot.Base.Interfaces
         event SurfaceMessageEventHandler SurfaceMessage;
         event SurfaceDrawingModeEventHandler DrawingModeChanged;
         event SurfaceElementEventHandler MovingElementChanged;
+        event SurfaceExpandedEventHandler SurfaceExpanded;
         event SurfaceForegroundColorEventHandler ForegroundColorChanged;
         event SurfaceBackgroundColorEventHandler BackgroundColorChanged;
         event SurfaceLineThicknessEventHandler LineThicknessChanged;
@@ -203,6 +204,7 @@ namespace Greenshot.Base.Interfaces
         void RemoveElement(IDrawableContainer elementToRemove, bool makeUndoable = true, bool invalidate = true, bool generateEvents = true);
 
         void SendMessageEvent(object source, SurfaceMessageTyp messageType, string message);
+        void ResizeCanvas(int left, int right, int top, int bottom);
         void ApplyBitmapEffect(IEffect effect);
         void RemoveCursor();
         bool HasCursor { get; }

src/Greenshot.Base/Interfaces/SurfaceExpandedEventHandler.cs

@@ -0,0 +1,27 @@
+/*
+ * Greenshot - a free and open source screenshot tool
+ * Copyright (C) 2007-2021 Thomas Braun, Jens Klingen, Robin Krom
+ *
+ * For more information see: https://getgreenshot.org/
+ * The Greenshot project is hosted on GitHub https://github.com/greenshot/greenshot
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+using System;
+
+namespace Greenshot.Base.Interfaces
+{
+    public delegate void SurfaceExpandedEventHandler(object sender, EventArgs e);
+}

src/Greenshot.Editor/Drawing/Surface.cs

@@ -105,6 +105,14 @@ namespace Greenshot.Editor.Drawing
             remove => _surfaceSizeChanged -= value;
         }
 
+        [NonSerialized] private SurfaceExpandedEventHandler _surfaceExpanded;
+
+        public event SurfaceExpandedEventHandler SurfaceExpanded
+        {
+            add => _surfaceExpanded += value;
+            remove => _surfaceExpanded -= value;
+        }
+
         [NonSerialized] private SurfaceMessageEventHandler _surfaceMessage;
 
         public event SurfaceMessageEventHandler SurfaceMessage
@@ -1032,6 +1040,20 @@ namespace Greenshot.Editor.Drawing
             Invalidate();
         }
 
+        /// <summary>
+        /// Set the canvas to a new size using the given bounds.
+        /// </summary>
+        /// <param name="left"></param>
+        /// <param name="right"></param>
+        /// <param name="top"></param>
+        /// <param name="bottom"></param>
+        public void ResizeCanvas(int left, int right, int top, int bottom)
+        {
+            var resizeEffect = new ResizeCanvasEffect(left, right, top, bottom);
+            ApplyBitmapEffect(resizeEffect);
+            _surfaceExpanded(this, null);
+        }
+
         /// <summary>
         /// Apply a bitmap effect to the surface
         /// </summary>

src/Greenshot.Editor/Forms/ImageEditorForm.cs

@@ -246,6 +246,7 @@ namespace Greenshot.Editor.Forms
                 _surface.MovingElementChanged += delegate { RefreshEditorControls(); };
                 _surface.DrawingModeChanged += Surface_DrawingModeChanged;
                 _surface.SurfaceSizeChanged += SurfaceSizeChanged;
+                _surface.SurfaceExpanded += SurfaceExpanded;
                 _surface.SurfaceMessage += SurfaceMessageReceived;
                 _surface.ForegroundColorChanged += ForegroundColorChanged;
                 _surface.BackgroundColorChanged += BackgroundColorChanged;
@@ -566,6 +567,14 @@ namespace Greenshot.Editor.Forms
             AlignCanvasPositionAfterResize();
         }
 
+        /// <summary>
+        /// Used when expanding the surface in one direction to accomodate shifting an object to one side.
+        /// </summary>
+        private void SurfaceExpanded(object sender, EventArgs e)
+        {
+            UpdateUndoRedoSurfaceDependencies();
+        }
+
         public ISurface Surface
         {
             get { return _surface; }