Added the undo feature

Paint_2/DotPencil.cs

@@ -105,5 +105,21 @@ namespace Paint_2
         {
             return Name;
         }
+
+        public void Undo()
+        {
+            if (Drawings.Count > 1)
+            {
+                Drawings.RemoveAt(Drawings.Count - 1);
+                Colors.RemoveAt(Colors.Count - 1);
+                Widths.RemoveAt(Widths.Count - 1);
+            }
+            else
+            {
+                Drawings.Clear();
+                Colors.Clear();
+                Widths.Clear();
+            }
+        }
     }
 }

Paint_2/Form1.Designer.cs

@@ -73,6 +73,7 @@
             this.btnRandomColor = new System.Windows.Forms.Button();
             this.label2 = new System.Windows.Forms.Label();
             this.lsbTools = new System.Windows.Forms.ListBox();
+            this.btnUndo = new System.Windows.Forms.Button();
             ((System.ComponentModel.ISupportInitialize)(this.canvas)).BeginInit();
             this.panelFile.SuspendLayout();
             this.panelDrawing.SuspendLayout();
@@ -573,6 +574,7 @@
             // 
             this.panelTools.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Right)));
             this.panelTools.BackColor = System.Drawing.Color.FromArgb(((int)(((byte)(31)))), ((int)(((byte)(31)))), ((int)(((byte)(31)))));
+            this.panelTools.Controls.Add(this.btnUndo);
             this.panelTools.Controls.Add(this.btnRandomColor);
             this.panelTools.Controls.Add(this.label2);
             this.panelTools.Controls.Add(this.lsbTools);
@@ -632,10 +634,24 @@
             this.lsbTools.ItemHeight = 18;
             this.lsbTools.Location = new System.Drawing.Point(10, 358);
             this.lsbTools.Name = "lsbTools";
-            this.lsbTools.Size = new System.Drawing.Size(141, 200);
+            this.lsbTools.Size = new System.Drawing.Size(141, 182);
             this.lsbTools.TabIndex = 32;
             this.lsbTools.SelectedIndexChanged += new System.EventHandler(this.lsbTools_SelectedIndexChanged);
             // 
+            // btnUndo
+            // 
+            this.btnUndo.BackColor = System.Drawing.Color.FromArgb(((int)(((byte)(41)))), ((int)(((byte)(41)))), ((int)(((byte)(41)))));
+            this.btnUndo.FlatStyle = System.Windows.Forms.FlatStyle.Popup;
+            this.btnUndo.Font = new System.Drawing.Font("Cascadia Code", 9F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
+            this.btnUndo.ForeColor = System.Drawing.Color.FromArgb(((int)(((byte)(214)))), ((int)(((byte)(214)))), ((int)(((byte)(214)))));
+            this.btnUndo.Location = new System.Drawing.Point(3, 547);
+            this.btnUndo.Name = "btnUndo";
+            this.btnUndo.Size = new System.Drawing.Size(157, 43);
+            this.btnUndo.TabIndex = 35;
+            this.btnUndo.Text = "Undo";
+            this.btnUndo.UseVisualStyleBackColor = false;
+            this.btnUndo.Click += new System.EventHandler(this.btnUndo_Click);
+            // 
             // PaintForm
             // 
             this.AutoScaleDimensions = new System.Drawing.SizeF(8F, 18F);
@@ -722,6 +738,7 @@
         private System.Windows.Forms.Label lblHeight;
         private System.Windows.Forms.Label lblWidth;
         private System.Windows.Forms.Button btnRandomColor;
+        private System.Windows.Forms.Button btnUndo;
     }
 }
 

Paint_2/Form1.cs

@@ -86,6 +86,11 @@ namespace Paint_2
             result += "R:" + color.R + " G:" + color.G + " B:" + color.B;
             return result;
         }
+        private void ForceRefresh()
+        {
+            canvas.Image = sketch.ForcePaint();
+            RefreshUi();
+        }
         private void RefreshUi()
         {
             canvas.Image = sketch.Paint();
@@ -114,7 +119,6 @@ namespace Paint_2
             {
                 btnRandomColor.ForeColor = Color.Red;
             }
-           
         }
         private Color GetHoverColor()
         {
@@ -135,7 +139,7 @@ namespace Paint_2
         private void btnClear_Click(object sender, EventArgs e)
         {
             sketch.Clear();
-            RefreshUi();
+            ForceRefresh();
         }
 
         private void nupPencilWidth_ValueChanged(object sender, EventArgs e)
@@ -243,5 +247,11 @@ namespace Paint_2
             randomColor = !randomColor;
             RefreshUi();
         }
+
+        private void btnUndo_Click(object sender, EventArgs e)
+        {
+            sketch.Undo();
+            ForceRefresh();
+        }
     }
 }

Paint_2/PaintTool.cs

@@ -24,6 +24,7 @@ namespace Paint_2
         void Start(Color color,int width);
         void Stop(Point point);
         void Add(Point point);
+        void Undo();
         void Clear();
         List<Color> GetLastColors(int colorNumber); 
         void Paint(Bitmap canvas);

Paint_2/Pencil.cs

@@ -106,5 +106,21 @@ namespace Paint_2
         {
             return Name;
         }
+
+        public void Undo()
+        {
+            if (Drawings.Count > 1)
+            {
+                Drawings.RemoveAt(Drawings.Count -1);
+                Colors.RemoveAt(Colors.Count -1);
+                Widths.RemoveAt(Widths.Count -1);
+            }
+            else
+            {
+                Drawings.Clear();
+                Colors.Clear();
+                Widths.Clear();
+            }
+        }
     }
 }

Paint_2/Sketch.cs

@@ -64,6 +64,10 @@ namespace Paint_2
                 Console.WriteLine("Oooops...");
             }
         }
+        public void Undo()
+        {
+            CurrentTool.Undo();
+        }
         public void StartDrawing(Point location,Color color,int width)
         {
             CurrentTool.Start(color,width);
@@ -87,7 +91,6 @@ namespace Paint_2
         }
         public void Clear()
         {
-            Drawing = new Bitmap(SketchSize.Width, SketchSize.Height);
             foreach (PaintTool tool in ToolList)
             {
                 tool.Clear();
@@ -95,6 +98,12 @@ namespace Paint_2
         }
         public Bitmap Paint() 
         {
+            CurrentTool.Paint(Drawing);
+            return Drawing;
+        }
+        public Bitmap ForcePaint()
+        {
+            Drawing = new Bitmap(SketchSize.Width,SketchSize.Height);
             foreach (PaintTool tool in ToolList)
             {
                 tool.Paint(Drawing);