wpf: fix margin calculations and resize events (#7892)

.github/actions/spell-check/dictionary/microsoft.txt

@@ -32,6 +32,7 @@ tasklist
 tdbuildteamid
 vcruntime
 visualstudio
+VSTHRD
 wlk
 wslpath
 wtl

src/cascadia/WpfTerminalControl/TerminalContainer.cs

@@ -66,7 +66,18 @@ namespace Microsoft.Terminal.Wpf
         /// Gets or sets a value indicating whether if the renderer should automatically resize to fill the control
         /// on user action.
         /// </summary>
-        public bool AutoFill { get; set; } = true;
+        internal bool AutoResize { get; set; } = true;
+
+        /// <summary>
+        /// Gets or sets the size of the parent user control that hosts the terminal hwnd.
+        /// </summary>
+        /// <remarks>Control size is in device independent units, but for simplicity all sizes should be scaled.</remarks>
+        internal Size TerminalControlSize { get; set; }
+
+        /// <summary>
+        /// Gets or sets the size of the terminal renderer.
+        /// </summary>
+        internal Size TerminalRendererSize { get; set; }
 
         /// <summary>
         /// Gets the current character rows available to the terminal.
@@ -78,18 +89,6 @@ namespace Microsoft.Terminal.Wpf
         /// </summary>
         internal int Columns { get; private set; }
 
-        /// <summary>
-        /// Gets the maximum amount of character rows that can fit in this control.
-        /// </summary>
-        /// <remarks>This will be in sync with <see cref="Rows"/> unless <see cref="AutoFill"/> is set to false.</remarks>
-        internal int MaxRows { get; private set; }
-
-        /// <summary>
-        /// Gets the maximum amount of character columns that can fit in this control.
-        /// </summary>
-        /// <remarks>This will be in sync with <see cref="Columns"/> unless <see cref="AutoFill"/> is set to false.</remarks>
-        internal int MaxColumns { get; private set; }
-
         /// <summary>
         /// Gets the window handle of the terminal.
         /// </summary>
@@ -139,7 +138,7 @@ namespace Microsoft.Terminal.Wpf
 
             NativeMethods.TerminalSetTheme(this.terminal, theme, fontFamily, fontSize, (int)dpiScale.PixelsPerInchX);
 
-            this.TriggerResize(this.RenderSize);
+            this.Resize(this.TerminalControlSize);
         }
 
         /// <summary>
@@ -157,26 +156,22 @@ namespace Microsoft.Terminal.Wpf
         }
 
         /// <summary>
-        /// Triggers a refresh of the terminal with the given size.
+        /// Triggers a resize of the terminal with the given size, redrawing the rendered text.
         /// </summary>
         /// <param name="renderSize">Size of the rendering window.</param>
-        /// <returns>Tuple with rows and columns.</returns>
+        internal void Resize(Size renderSize)
-        internal (int rows, int columns) TriggerResize(Size renderSize)
         {
-            var dpiScale = VisualTreeHelper.GetDpi(this);
-
-            NativeMethods.COORD dimensions;
             NativeMethods.TerminalTriggerResize(
                 this.terminal,
-                Convert.ToInt16(renderSize.Width * dpiScale.DpiScaleX),
+                Convert.ToInt16(renderSize.Width),
-                Convert.ToInt16(renderSize.Height * dpiScale.DpiScaleY),
+                Convert.ToInt16(renderSize.Height),
-                out dimensions);
+                out NativeMethods.COORD dimensions);
 
             this.Rows = dimensions.Y;
             this.Columns = dimensions.X;
+            this.TerminalRendererSize = renderSize;
 
             this.Connection?.Resize((uint)dimensions.Y, (uint)dimensions.X);
-            return (dimensions.Y, dimensions.X);
         }
 
         /// <summary>
@@ -184,8 +179,7 @@ namespace Microsoft.Terminal.Wpf
         /// </summary>
         /// <param name="rows">Number of rows to show.</param>
         /// <param name="columns">Number of columns to show.</param>
-        /// <returns><see cref="long"/> pair with the new width and height size in pixels for the renderer.</returns>
+        internal void Resize(uint rows, uint columns)
-        internal (int width, int height) Resize(uint rows, uint columns)
         {
             NativeMethods.SIZE dimensionsInPixels;
             NativeMethods.COORD dimensions = new NativeMethods.COORD
@@ -196,20 +190,41 @@ namespace Microsoft.Terminal.Wpf
 
             NativeMethods.TerminalTriggerResizeWithDimension(this.terminal, dimensions, out dimensionsInPixels);
 
-            // If AutoFill is true, keep Rows and Columns in sync with MaxRows and MaxColumns.
-            // Otherwise, MaxRows and MaxColumns will be set on startup and on control resize by the user.
-            if (this.AutoFill)
-            {
-                this.MaxColumns = dimensions.X;
-                this.MaxRows = dimensions.Y;
-            }
-
             this.Columns = dimensions.X;
             this.Rows = dimensions.Y;
 
-            this.Connection?.Resize((uint)dimensions.Y, (uint)dimensions.X);
+            this.TerminalRendererSize = new Size()
+            {
+                Width = dimensionsInPixels.cx,
+                Height = dimensionsInPixels.cy,
+            };
 
-            return (dimensionsInPixels.cx, dimensionsInPixels.cy);
+            this.Connection?.Resize((uint)dimensions.Y, (uint)dimensions.X);
+        }
+
+        /// <summary>
+        /// Calculates the rows and columns that would fit in the given size.
+        /// </summary>
+        /// <param name="size">DPI scaled size.</param>
+        /// <returns>Amount of rows and columns that would fit the given size.</returns>
+        internal (uint columns, uint rows) CalculateRowsAndColumns(Size size)
+        {
+            NativeMethods.TerminalCalculateResize(this.terminal, (short)size.Width, (short)size.Height, out NativeMethods.COORD dimensions);
+
+            return ((uint)dimensions.X, (uint)dimensions.Y);
+        }
+
+        /// <summary>
+        /// Triggers the terminal resize event if more space is available in the terminal control.
+        /// </summary>
+        internal void RaiseResizedIfDrawSpaceIncreased()
+        {
+            (var columns, var rows) = this.CalculateRowsAndColumns(this.TerminalControlSize);
+
+            if (this.Columns < columns || this.Rows < rows)
+            {
+                this.connection?.Resize(rows, columns);
+            }
         }
 
         /// <inheritdoc/>
@@ -335,21 +350,23 @@ namespace Microsoft.Terminal.Wpf
 
                         NativeMethods.COORD dimensions;
 
-                        // We only trigger a resize if we want to fill to maximum size.
+                        if (this.AutoResize)
-                        if (this.AutoFill)
                         {
                             NativeMethods.TerminalTriggerResize(this.terminal, (short)windowpos.cx, (short)windowpos.cy, out dimensions);
 
                             this.Columns = dimensions.X;
                             this.Rows = dimensions.Y;
-                            this.MaxColumns = dimensions.X;
+
-                            this.MaxRows = dimensions.Y;
+                            this.TerminalRendererSize = new Size()
+                            {
+                                Width = windowpos.cx,
+                                Height = windowpos.cy,
+                            };
                         }
                         else
                         {
-                            NativeMethods.TerminalCalculateResize(this.terminal, (short)windowpos.cx, (short)windowpos.cy, out dimensions);
+                            // Calculate the new columns and rows that fit the total control size and alert the control to redraw the margins.
-                            this.MaxColumns = dimensions.X;
+                            NativeMethods.TerminalCalculateResize(this.terminal, (short)this.TerminalControlSize.Width, (short)this.TerminalControlSize.Height, out dimensions);
-                            this.MaxRows = dimensions.Y;
                         }
 
                         this.Connection?.Resize((uint)dimensions.Y, (uint)dimensions.X);

src/cascadia/WpfTerminalControl/TerminalControl.xaml.cs

@@ -6,10 +6,12 @@
 namespace Microsoft.Terminal.Wpf
 {
     using System;
+    using System.Threading;
     using System.Windows;
     using System.Windows.Controls;
     using System.Windows.Input;
     using System.Windows.Media;
+    using Task = System.Threading.Tasks.Task;
 
     /// <summary>
     /// A basic terminal control. This control can receive and render standard VT100 sequences.
@@ -18,7 +20,13 @@ namespace Microsoft.Terminal.Wpf
     {
         private int accumulatedDelta = 0;
 
-        private (int width, int height) terminalRendererSize;
+        /// <summary>
+        /// Gets size of the terminal renderer.
+        /// </summary>
+        private Size TerminalRendererSize
+        {
+            get => this.termContainer.TerminalRendererSize;
+        }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="TerminalControl"/> class.
@@ -44,24 +52,14 @@ namespace Microsoft.Terminal.Wpf
         /// </summary>
         public int Columns => this.termContainer.Columns;
 
-        /// <summary>
-        /// Gets the maximum amount of character rows that can fit in this control.
-        /// </summary>
-        public int MaxRows => this.termContainer.MaxRows;
-
-        /// <summary>
-        /// Gets the maximum amount of character columns that can fit in this control.
-        /// </summary>
-        public int MaxColumns => this.termContainer.MaxColumns;
-
         /// <summary>
         /// Gets or sets a value indicating whether if the renderer should automatically resize to fill the control
         /// on user action.
         /// </summary>
-        public bool AutoFill
+        public bool AutoResize
         {
-            get => this.termContainer.AutoFill;
+            get => this.termContainer.AutoResize;
-            set => this.termContainer.AutoFill = value;
+            set => this.termContainer.AutoResize = value;
         }
 
         /// <summary>
@@ -69,10 +67,7 @@ namespace Microsoft.Terminal.Wpf
         /// </summary>
         public ITerminalConnection Connection
         {
-            set
+            set => this.termContainer.Connection = value;
-            {
-                this.termContainer.Connection = value;
-            }
         }
 
         /// <summary>
@@ -114,56 +109,100 @@ namespace Microsoft.Terminal.Wpf
         /// </summary>
         /// <param name="rows">Number of rows to display.</param>
         /// <param name="columns">Number of columns to display.</param>
-        public void Resize(uint rows, uint columns)
+        /// <param name="cancellationToken">Cancellation token for this task.</param>
+        /// <returns>A <see cref="Task"/> representing the asynchronous operation.</returns>
+        public async Task ResizeAsync(uint rows, uint columns, CancellationToken cancellationToken)
         {
-            var dpiScale = VisualTreeHelper.GetDpi(this);
+            this.termContainer.Resize(rows, columns);
 
-            this.terminalRendererSize = this.termContainer.Resize(rows, columns);
+#pragma warning disable VSTHRD001 // Avoid legacy thread switching APIs
-
+            await this.Dispatcher.BeginInvoke(
-            double marginWidth = ((this.terminalUserControl.RenderSize.Width * dpiScale.DpiScaleX) - this.terminalRendererSize.width) / dpiScale.DpiScaleX;
+                new Action(delegate() { this.terminalGrid.Margin = this.CalculateMargins(); }),
-            double marginHeight = ((this.terminalUserControl.RenderSize.Height * dpiScale.DpiScaleY) - this.terminalRendererSize.height) / dpiScale.DpiScaleY;
+                System.Windows.Threading.DispatcherPriority.Render);
-
+#pragma warning restore VSTHRD001 // Avoid legacy thread switching APIs
-            // Make space for the scrollbar.
-            marginWidth -= this.scrollbar.Width;
-
-            // Prevent negative margin size.
-            marginWidth = marginWidth < 0 ? 0 : marginWidth;
-            marginHeight = marginHeight < 0 ? 0 : marginHeight;
-
-            this.terminalGrid.Margin = new Thickness(0, 0, marginWidth, marginHeight);
         }
 
         /// <summary>
         /// Resizes the terminal to the specified dimensions.
         /// </summary>
-        /// <param name="rendersize">Rendering size for the terminal.</param>
+        /// <param name="rendersize">Rendering size for the terminal in device independent units.</param>
         /// <returns>A tuple of (int, int) representing the number of rows and columns in the terminal.</returns>
         public (int rows, int columns) TriggerResize(Size rendersize)
         {
-            return this.termContainer.TriggerResize(rendersize);
+            var dpiScale = VisualTreeHelper.GetDpi(this);
+            rendersize.Width *= dpiScale.DpiScaleX;
+            rendersize.Height *= dpiScale.DpiScaleY;
+
+            this.termContainer.Resize(rendersize);
+
+            return (this.Rows, this.Columns);
         }
 
         /// <inheritdoc/>
         protected override void OnRenderSizeChanged(SizeChangedInfo sizeInfo)
         {
-            // Renderer will not resize on control resize. We have to manually recalculate the margin to fill in the space.
+            var dpiScale = VisualTreeHelper.GetDpi(this);
-            if (this.AutoFill == false && this.terminalRendererSize.width != 0 && this.terminalRendererSize.height != 0)
+
+            // termContainer requires scaled sizes.
+            this.termContainer.TerminalControlSize = new Size()
             {
-                var dpiScale = VisualTreeHelper.GetDpi(this);
+                Width = (sizeInfo.NewSize.Width - this.scrollbar.ActualWidth) * dpiScale.DpiScaleX,
+                Height = sizeInfo.NewSize.Height * dpiScale.DpiScaleY,
+            };
 
-                double width = ((sizeInfo.NewSize.Width * dpiScale.DpiScaleX) - this.terminalRendererSize.width) / dpiScale.DpiScaleX;
+            if (!this.AutoResize)
-                double height = ((sizeInfo.NewSize.Height * dpiScale.DpiScaleY) - this.terminalRendererSize.height) / dpiScale.DpiScaleY;
+            {
+                // Renderer will not resize on control resize. We have to manually calculate the margin to fill in the space.
+                this.terminalGrid.Margin = this.CalculateMargins(sizeInfo.NewSize);
 
-                // Prevent negative margin size.
+                // Margins stop resize events, therefore we have to manually check if more space is available and raise
-                width = width < 0 ? 0 : width;
+                //  a resize event if needed.
-                height = height < 0 ? 0 : height;
+                this.termContainer.RaiseResizedIfDrawSpaceIncreased();
-
-                this.terminalGrid.Margin = new Thickness(0, 0, width, height);
             }
 
             base.OnRenderSizeChanged(sizeInfo);
         }
 
+        /// <summary>
+        /// Calculates the margins that should surround the terminal renderer, if any.
+        /// </summary>
+        /// <param name="controlSize">New size of the control. Uses the control's current size if not provided.</param>
+        /// <returns>The new terminal control margin thickness in device independent units.</returns>
+        private Thickness CalculateMargins(Size controlSize = default)
+        {
+            var dpiScale = VisualTreeHelper.GetDpi(this);
+            double width = 0, height = 0;
+
+            if (controlSize == default)
+            {
+                controlSize = new Size()
+                {
+                    Width = this.terminalUserControl.ActualWidth,
+                    Height = this.terminalUserControl.ActualHeight,
+                };
+            }
+
+            // During initialization, the terminal renderer size will be 0 and the terminal renderer
+            // draws on all available space. Therefore no margins are needed until resized.
+            if (this.TerminalRendererSize.Width != 0)
+            {
+                width = controlSize.Width - (this.TerminalRendererSize.Width / dpiScale.DpiScaleX);
+            }
+
+            if (this.TerminalRendererSize.Height != 0)
+            {
+                height = controlSize.Height - (this.TerminalRendererSize.Height / dpiScale.DpiScaleX);
+            }
+
+            width -= this.scrollbar.ActualWidth;
+
+            // Prevent negative margin size.
+            width = width < 0 ? 0 : width;
+            height = height < 0 ? 0 : height;
+
+            return new Thickness(0, 0, width, height);
+        }
+
         private void TerminalControl_GotFocus(object sender, RoutedEventArgs e)
         {
             e.Handled = true;