Update ZoomBorder.cs

src/Wpf.Controls.PanAndZoom/ZoomBorder.cs

@@ -22,18 +22,18 @@ namespace Wpf.Controls.PanAndZoom
         private Point _previous;
         private Matrix _matrix;
         private bool _isPanning;
-        private static StretchMode[] _autoFitModes = (StretchMode[])Enum.GetValues(typeof(StretchMode));
-        private static ButtonName[] _buttonNames = (ButtonName[])Enum.GetValues(typeof(ButtonName));
+        private static readonly StretchMode[] s_autoFitModes = (StretchMode[])Enum.GetValues(typeof(StretchMode));
+        private static readonly ButtonName[] s_buttonNames = (ButtonName[])Enum.GetValues(typeof(ButtonName));
 
         /// <summary>
         /// Gets available stretch modes.
         /// </summary>
-        public static StretchMode[] StretchModes => _autoFitModes;
+        public static StretchMode[] StretchModes => s_autoFitModes;
 
         /// <summary>
         /// Gets available button names.
         /// </summary>
-        public static ButtonName[] ButtonNames => _buttonNames;
+        public static ButtonName[] ButtonNames => s_buttonNames;
 
         /// <inheritdoc/>
         public Action<double, double, double, double>? InvalidatedChild { get; set; }
@@ -415,14 +415,16 @@ namespace Wpf.Controls.PanAndZoom
         {
             var size = base.ArrangeOverride(finalSize);
 
-            if (_element != null && _element.IsMeasureValid)
+            if (_element == null || !_element.IsMeasureValid)
             {
+                return size;
+            }
+
             AutoFit(
                 size.Width,
                 size.Height,
                 _element.RenderSize.Width,
                 _element.RenderSize.Height);
-            }
 
             return size;
         }
@@ -441,39 +443,44 @@ namespace Wpf.Controls.PanAndZoom
 
         private void Border_PreviewMouseWheel(object sender, MouseWheelEventArgs e)
         {
-            if (EnableInput)
+            if (!EnableInput)
             {
-                Wheel(e);
+                return;
             }
+            Wheel(e);
         }
 
         private void Border_PreviewMouseDown(object sender, MouseButtonEventArgs e)
         {
-            if (EnableInput)
+            if (!EnableInput)
             {
+                return;
+            }
             var button = PanButton;
-                if ((e.ChangedButton == MouseButton.Left && button == ButtonName.Left)
-                    || (e.ChangedButton == MouseButton.Right && button == ButtonName.Right)
-                    || (e.ChangedButton == MouseButton.Middle && button == ButtonName.Middle))
+            if ((e.ChangedButton != MouseButton.Left || button != ButtonName.Left)
+                && (e.ChangedButton != MouseButton.Right || button != ButtonName.Right)
+                && (e.ChangedButton != MouseButton.Middle || button != ButtonName.Middle))
             {
+                return;
+            }
             Pressed(e);
         }
-            }
-        }
 
         private void Border_PreviewMouseUp(object sender, MouseButtonEventArgs e)
         {
-            if (EnableInput)
+            if (!EnableInput)
             {
+                return;
+            }
             var button = PanButton;
-                if ((e.ChangedButton == MouseButton.Left && button == ButtonName.Left)
-                    || (e.ChangedButton == MouseButton.Right && button == ButtonName.Right)
-                    || (e.ChangedButton == MouseButton.Middle && button == ButtonName.Middle))
+            if ((e.ChangedButton != MouseButton.Left || button != ButtonName.Left)
+                && (e.ChangedButton != MouseButton.Right || button != ButtonName.Right)
+                && (e.ChangedButton != MouseButton.Middle || button != ButtonName.Middle))
             {
+                return;
+            }
             Released(e);
         }
-            }
-        }
 
         private void Border_PreviewMouseMove(object sender, MouseEventArgs e)
         {
@@ -485,64 +492,46 @@ namespace Wpf.Controls.PanAndZoom
 
         private void Border_ManipulationStarting(object? sender, ManipulationStartingEventArgs e)
         {
-            if (EnableInput && _element != null)
+            if (!EnableInput || _element == null)
             {
-                e.ManipulationContainer = this;
+                return;
             }
+            e.ManipulationContainer = this;
         }
 
         private void Border_ManipulationDelta(object? sender, ManipulationDeltaEventArgs e)
         {
-            if (EnableInput && _element != null)
+            if (!EnableInput || _element == null)
             {
-                var deltaManipulation = e.DeltaManipulation;
-                double scale = ((deltaManipulation.Scale.X - 1) * ZoomSpeed) + 1;
-                var matrix = ((MatrixTransform)_element.RenderTransform).Matrix;
-                Point center = new Point(_element.RenderSize.Width / 2, _element.RenderSize.Height / 2);
-                center = matrix.Transform(center);
-
-                if (EnableGestureZoom)
-                {
-                    matrix.ScaleAt(scale, scale, center.X, center.Y);
+                return;
             }
-
-                if (EnableGestureRotation)
-                {
-                    matrix.RotateAt(e.DeltaManipulation.Rotation, center.X, center.Y);
-                }
-
-                if (EnableGestureTranslation)
-                {
-                    matrix.Translate(e.DeltaManipulation.Translation.X, e.DeltaManipulation.Translation.Y);
-                }
-
-                 ((MatrixTransform)_element.RenderTransform).Matrix = matrix;
+            Manipulation(e.DeltaManipulation);
             e.Handled = true;
-
-                SetValue(ZoomXPropertyKey, matrix.M11);
-                SetValue(ZoomYPropertyKey, matrix.M22);
-                SetValue(OffsetXPropertyKey, matrix.OffsetX);
-                SetValue(OffsetYPropertyKey, matrix.OffsetY);
-            }
         }
 
         private void ChildChanged(UIElement element)
         {
-            if (element != null && element != _element && _element != null)
+            if (element == null || element == _element || _element == null)
+            {
+            }
+            else
             {
                 DetachElement();
             }
 
-            if (element != null && element != _element)
+            if (element == null || element == _element)
             {
-                AttachElement(element);
+                return;
             }
+            AttachElement(element);
         }
 
         private void AttachElement(UIElement element)
         {
-            if (element != null)
+            if (element == null)
             {
+                return;
+            }
             Defaults();
             _element = element;
             this.Focus();
@@ -553,12 +542,13 @@ namespace Wpf.Controls.PanAndZoom
             this.ManipulationStarting += Border_ManipulationStarting;
             this.ManipulationDelta += Border_ManipulationDelta;
         }
-        }
 
         private void DetachElement()
         {
-            if (_element != null)
+            if (_element == null)
             {
+                return;
+            }
             this.PreviewMouseWheel -= Border_PreviewMouseWheel;
             this.PreviewMouseDown -= Border_PreviewMouseDown;
             this.PreviewMouseUp -= Border_PreviewMouseUp;
@@ -569,44 +559,76 @@ namespace Wpf.Controls.PanAndZoom
             _element = null;
             Defaults();
         }
-        }
 
         private void Wheel(MouseWheelEventArgs e)
         {
-            if (_element != null && Mouse.Captured == null)
+            if (_element == null || Mouse.Captured != null)
             {
+                return;
+            }
             Point point = e.GetPosition(_element);
             ZoomDeltaTo((double)e.Delta, point.X, point.Y);
         }
-        }
 
         private void Pressed(MouseButtonEventArgs e)
         {
-            if (_element != null && Mouse.Captured == null && _isPanning == false)
+            if (_element == null || Mouse.Captured != null || _isPanning != false)
             {
+                return;
+            }
             Point point = e.GetPosition(_element);
             StartPan(point.X, point.Y);
             _element.CaptureMouse();
             _isPanning = true;
         }
-        }
 
         private void Released(MouseButtonEventArgs e)
         {
-            if (_element != null && _element.IsMouseCaptured == true && _isPanning == true)
+            if (_element == null || _element.IsMouseCaptured != true || _isPanning != true)
             {
+                return;
+            }
             _element.ReleaseMouseCapture();
             _isPanning = false;
         }
-        }
 
         private void Moved(MouseEventArgs e)
         {
-            if (_element != null && _element.IsMouseCaptured == true && _isPanning == true)
+            if (_element == null || _element.IsMouseCaptured != true || _isPanning != true)
             {
+                return;
+            }
             Point point = e.GetPosition(_element);
             PanTo(point.X, point.Y);
         }
+
+        private void Manipulation(ManipulationDelta delta)
+        {
+            if (_element == null)
+            {
+                return;
+            }
+
+            var scale = ((delta.Scale.X - 1) * ZoomSpeed) + 1;
+            var center = new Point(_element.RenderSize.Width / 2, _element.RenderSize.Height / 2);
+            center = _matrix.Transform(center);
+
+            if (EnableGestureZoom)
+            {
+                _matrix.ScaleAt(scale, scale, center.X, center.Y);
+            }
+
+            if (EnableGestureRotation)
+            {
+                _matrix.RotateAt(delta.Rotation, center.X, center.Y);
+            }
+
+            if (EnableGestureTranslation)
+            {
+                _matrix.Translate(delta.Translation.X, delta.Translation.Y);
+            }
+
+            Invalidate();
         }
 
         private double Constrain(double value, double minimum, double maximum)
@@ -632,8 +654,10 @@ namespace Wpf.Controls.PanAndZoom
         /// <inheritdoc/>
         public void Invalidate()
         {
-            if (_element != null)
+            if (_element == null)
             {
+                return;
+            }
             if (EnableConstrains == true)
             {
                 Constrain();
@@ -648,7 +672,6 @@ namespace Wpf.Controls.PanAndZoom
             _element.RenderTransform = new MatrixTransform(_matrix);
             _element.InvalidateVisual();
         }
-        }
 
         /// <inheritdoc/>
         public void ZoomTo(double zoom, double x, double y)
@@ -741,6 +764,9 @@ namespace Wpf.Controls.PanAndZoom
                             return MatrixHelper.ScaleAt(zoom, zoom, cx, cy);
                         }
                     }
+
+                case StretchMode.None:
+                    break;
             }
             return Matrix.Identity;
         }
@@ -749,41 +775,46 @@ namespace Wpf.Controls.PanAndZoom
         public void Fill(double panelWidth, double panelHeight, double elementWidth, double elementHeight)
         {
             Debug.WriteLine($"Fill: {panelWidth}x{panelHeight} {elementWidth}x{elementHeight}");
-            if (_element != null)
+            if (_element == null)
             {
+                return;
+            }
             _matrix = GetMatrix(panelWidth, panelHeight, elementWidth, elementHeight, StretchMode.Fill);
             Invalidate();
         }
-        }
 
         /// <inheritdoc/>
         public void Uniform(double panelWidth, double panelHeight, double elementWidth, double elementHeight)
         {
             Debug.WriteLine($"Uniform: {panelWidth}x{panelHeight} {elementWidth}x{elementHeight}");
-            if (_element != null)
+            if (_element == null)
             {
+                return;
+            }
             _matrix = GetMatrix(panelWidth, panelHeight, elementWidth, elementHeight, StretchMode.Uniform);
             Invalidate();
         }
-        }
 
         /// <inheritdoc/>
         public void UniformToFill(double panelWidth, double panelHeight, double elementWidth, double elementHeight)
         {
             Debug.WriteLine($"UniformToFill: {panelWidth}x{panelHeight} {elementWidth}x{elementHeight}");
-            if (_element != null)
+            if (_element == null)
             {
+                return;
+            }
             _matrix = GetMatrix(panelWidth, panelHeight, elementWidth, elementHeight, StretchMode.UniformToFill);
             Invalidate();
         }
-        }
 
         /// <inheritdoc/>
         public void AutoFit(double panelWidth, double panelHeight, double elementWidth, double elementHeight)
         {
             Debug.WriteLine($"AutoFit: {panelWidth}x{panelHeight} {elementWidth}x{elementHeight}");
-            if (_element != null)
+            if (_element == null)
             {
+                return;
+            }
             switch (Stretch)
             {
                 case StretchMode.Fill:
@@ -798,7 +829,6 @@ namespace Wpf.Controls.PanAndZoom
             }
             Invalidate();
         }
-        }
 
         /// <inheritdoc/>
         public void ToggleStretchMode()
@@ -830,37 +860,41 @@ namespace Wpf.Controls.PanAndZoom
         /// <inheritdoc/>
         public void Fill()
         {
-            if (_element != null)
+            if (_element == null)
             {
-                Fill(this.RenderSize.Width, this.RenderSize.Height, _element.RenderSize.Width, _element.RenderSize.Height); 
+                return;
             }
+            Fill(this.RenderSize.Width, this.RenderSize.Height, _element.RenderSize.Width, _element.RenderSize.Height);
         }
 
         /// <inheritdoc/>
         public void Uniform()
         {
-            if (_element != null)
+            if (_element == null)
             {
-                Uniform(this.RenderSize.Width, this.RenderSize.Height, _element.RenderSize.Width, _element.RenderSize.Height); 
+                return;
             }
+            Uniform(this.RenderSize.Width, this.RenderSize.Height, _element.RenderSize.Width, _element.RenderSize.Height);
         }
 
         /// <inheritdoc/>
         public void UniformToFill()
         {
-            if (_element != null)
+            if (_element == null)
             {
-                UniformToFill(this.RenderSize.Width, this.RenderSize.Height, _element.RenderSize.Width, _element.RenderSize.Height); 
+                return;
             }
+            UniformToFill(this.RenderSize.Width, this.RenderSize.Height, _element.RenderSize.Width, _element.RenderSize.Height);
         }
 
         /// <inheritdoc/>
         public void AutoFit()
         {
-            if (_element != null)
+            if (_element == null)
             {
+                return;
+            }
             AutoFit(this.RenderSize.Width, this.RenderSize.Height, _element.RenderSize.Width, _element.RenderSize.Height);
         }
     }
-    }
 }