Fix allow scroll below document

src/AvaloniaEdit/Editing/Caret.cs

@@ -452,14 +452,14 @@ public Rect CalculateCaretRectangle()
         /// <summary>
         /// Minimum distance of the caret to the view border.
         /// </summary>
-        internal const double MinimumDistanceToViewBorder = 30;
+        internal const double MinimumDistanceToViewBorder = 0;
 
         /// <summary>
         /// Scrolls the text view so that the caret is visible.
         /// </summary>
         public void BringCaretToView()
         {
-            BringCaretToView(MinimumDistanceToViewBorder);
+            BringCaretToView(0);
         }
 
         public void BringCaretToView(double border)

src/AvaloniaEdit/Editing/LineNumberMargin.cs

@@ -177,7 +177,7 @@ protected override void OnPointerPressed(PointerPressedEventArgs e)
                     {
                         ExtendSelection(currentSeg);
                     }
-                    TextArea.Caret.BringCaretToView(5.0);
+                    TextArea.Caret.BringCaretToView(0);
                 }
             }
         }
@@ -223,7 +223,7 @@ protected override void OnPointerMoved(PointerEventArgs e)
                 if (currentSeg == SimpleSegment.Invalid)
                     return;
                 ExtendSelection(currentSeg);
-                TextArea.Caret.BringCaretToView(5.0);
+                TextArea.Caret.BringCaretToView(0);
             }
             base.OnPointerMoved(e);
         }

src/AvaloniaEdit/Editing/SelectionMouseHandler.cs

@@ -704,7 +704,7 @@ private void ExtendSelectionToMouse(PointerEventArgs e)
                     TextArea.Caret.Offset = newWord.Offset < _startWord.Offset ? newWord.Offset : Math.Max(newWord.EndOffset, _startWord.EndOffset);
                 }
             }
-            TextArea.Caret.BringCaretToView(5.0);
+            TextArea.Caret.BringCaretToView(0);
         }
         #endregion
 

src/AvaloniaEdit/Rendering/TextView.cs

@@ -116,7 +116,17 @@ public TextDocument Document
             set => SetValue(DocumentProperty, value);
         }
 
-        internal double FontSize => GetValue(TextBlock.FontSizeProperty);
+        internal double FontSize
+        {
+            get => GetValue(TemplatedControl.FontSizeProperty);
+            set => SetValue(TemplatedControl.FontSizeProperty, value);
+        }
+
+        internal FontFamily FontFamily
+        {
+            get => GetValue(TemplatedControl.FontFamilyProperty);
+            set => SetValue(TemplatedControl.FontFamilyProperty, value);
+        }
 
         /// <summary>
         /// Occurs when the document property has changed.
@@ -872,8 +882,6 @@ protected override Size MeasureOverride(Size availableSize)
 			foreach (var layer in Layers) {
 				layer.Measure(availableSize);
 			}
-
-			//InvalidateVisual(); // = InvalidateArrange+InvalidateRender
 
             MeasureInlineObjects();
 
@@ -904,32 +912,29 @@ protected override Size MeasureOverride(Size availableSize)
             maxWidth += AdditionalHorizontalScrollAmount;
             var heightTreeHeight = DocumentHeight;
             var options = Options;
+            double desiredHeight = Math.Min(availableSize.Height, heightTreeHeight);
+            double extraHeightToAllowScrollBelowDocument = 0;
             if (options.AllowScrollBelowDocument)
             {
                 if (!double.IsInfinity(_scrollViewport.Height))
                 {
                     // HACK: we need to keep at least Caret.MinimumDistanceToViewBorder visible so that we don't scroll back up when the user types after
                     // scrolling to the very bottom.
-                    var minVisibleDocumentHeight = Math.Max(DefaultLineHeight, Caret.MinimumDistanceToViewBorder);
-                    // scrollViewportBottom: bottom of scroll view port, but clamped so that at least minVisibleDocumentHeight of the document stays visible.
-                    var scrollViewportBottom = Math.Min(heightTreeHeight - minVisibleDocumentHeight, _scrollOffset.Y) + _scrollViewport.Height;
+                    var minVisibleDocumentHeight = DefaultLineHeight;
                     // increase the extend height to allow scrolling below the document
-                    heightTreeHeight = Math.Max(heightTreeHeight, scrollViewportBottom);
+                    extraHeightToAllowScrollBelowDocument = desiredHeight - minVisibleDocumentHeight;
                 }
             }
 
             TextLayer.SetVisualLines(_visibleVisualLines);
 
             SetScrollData(availableSize,
-                          new Size(maxWidth, heightTreeHeight),
+                          new Size(maxWidth, heightTreeHeight + extraHeightToAllowScrollBelowDocument),
                           _scrollOffset);
 
-            // Size of control (scorll viewport) might be changed during ArrageOverride. We only need document size for now.
-            _documentSize = new Size(maxWidth, heightTreeHeight);
-
             VisualLinesChanged?.Invoke(this, EventArgs.Empty);
 
-            return new Size(Math.Min(availableSize.Width, maxWidth), Math.Min(availableSize.Height, heightTreeHeight));
+            return new Size(Math.Min(availableSize.Width, maxWidth), desiredHeight);
         }
 
 		/// <summary>
@@ -1152,13 +1157,13 @@ protected override Size ArrangeOverride(Size finalSize)
             // validate scroll position
             var newScrollOffsetX = _scrollOffset.X;
             var newScrollOffsetY = _scrollOffset.Y;
-            if (_scrollOffset.X + finalSize.Width > _documentSize.Width)
+            if (_scrollOffset.X + finalSize.Width > _scrollExtent.Width)
             {
-                newScrollOffsetX = Math.Max(0, _documentSize.Width - finalSize.Width);
+                newScrollOffsetX = Math.Max(0, _scrollExtent.Width - finalSize.Width);
             }
-            if (_scrollOffset.Y + finalSize.Height > _documentSize.Height)
+            if (_scrollOffset.Y + finalSize.Height > _scrollExtent.Height)
             {
-                newScrollOffsetY = Math.Max(0, _documentSize.Height - finalSize.Height);
+                newScrollOffsetY = Math.Max(0, _scrollExtent.Height - finalSize.Height);
             }
 
             // Apply final view port and offset
@@ -1317,11 +1322,6 @@ internal void ArrangeTextLayer(IList<VisualLineDrawingVisual> visuals)
         /// </summary>
         private Size _scrollExtent;
 
-        /// <summary>
-        /// Size of the document, in pixels.
-        /// </summary>
-        private Size _documentSize;
-
         /// <summary>
         /// Offset of the scroll position.
         /// </summary>
@@ -2052,7 +2052,7 @@ bool ILogicalScrollable.CanVerticallyScroll
             }
         }
 
-        bool ILogicalScrollable.IsLogicalScrollEnabled => true;        
+        bool ILogicalScrollable.IsLogicalScrollEnabled => true;
 
         Size ILogicalScrollable.ScrollSize => new Size(10, 50);
 

src/AvaloniaEdit/TextEditor.cs

@@ -59,6 +59,8 @@ static TextEditor()
             IsModifiedProperty.Changed.Subscribe(OnIsModifiedChanged);
             ShowLineNumbersProperty.Changed.Subscribe(OnShowLineNumbersChanged);
             LineNumbersForegroundProperty.Changed.Subscribe(OnLineNumbersForegroundChanged);
+            FontFamilyProperty.Changed.Subscribe(OnFontFamilyPropertyChanged);
+            FontSizeProperty.Changed.Subscribe(OnFontSizePropertyChanged);
         }
 
         /// <summary>
@@ -562,6 +564,21 @@ private static void OnLineNumbersForegroundChanged(AvaloniaPropertyChangedEventA
 
             lineNumberMargin?.SetValue(ForegroundProperty, e.NewValue);
         }
+
+        private static void OnFontFamilyPropertyChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            var editor = e.Sender as TextEditor;
+
+            editor?.TextArea.TextView.SetValue(FontFamilyProperty, e.NewValue);
+        }
+
+        private static void OnFontSizePropertyChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            var editor = e.Sender as TextEditor;
+
+            editor?.TextArea.TextView.SetValue(FontSizeProperty, e.NewValue);
+        }
+
         #endregion
 
         #region TextBoxBase-like methods