modified PopupLayout

CursorLang/Services/ILayoutPopupWindow.cs

@@ -0,0 +1,21 @@
+namespace CursorLang.Services;
+
+/// <summary>
+/// The popup window as seen by whoever decides when it is shown.
+/// </summary>
+/// <remarks>
+/// The window picks its place and size itself, and only three actions are needed from
+/// it on the outside. The tests check the work of the popup service through the same
+/// interface: there is no point bringing up a real window to check a timer.
+/// </remarks>
+public interface ILayoutPopupWindow
+{
+    /// <summary>Shows the window at the place set by the settings.</summary>
+    void ShowPopup();
+
+    /// <summary>Takes the window off the screen without destroying it.</summary>
+    void Hide();
+
+    /// <summary>Closes the window for good.</summary>
+    void Close();
+}

CursorLang/Services/KeyboardLayoutService.cs

@@ -27,29 +27,54 @@ public sealed class KeyboardLayoutOptions
 public sealed class KeyboardLayoutService : IKeyboardLayoutService, IDisposable
 {
     private readonly DispatcherTimer _pollTimer;
+    private readonly Func<IntPtr> _getForegroundWindow;
+    private readonly Func<int> _getActiveLocaleId;
+    private readonly Action _requestNextLayout;
+
     private int _lastLocaleId = -1;
     private IntPtr _lastForegroundWindow;
 
     public KeyboardLayoutService(KeyboardLayoutOptions options)
+        : this(
+            options,
+            KeyboardLayoutNative.GetForegroundWindow,
+            KeyboardLayoutNative.GetActiveLocaleId,
+            KeyboardLayoutNative.RequestNextLayout)
     {
+    }
+
+    /// <summary>
+    /// Takes the sources of system information explicitly: in tests the layout and the
+    /// active window are not provided by Windows.
+    /// </summary>
+    internal KeyboardLayoutService(
+        KeyboardLayoutOptions options,
+        Func<IntPtr> getForegroundWindow,
+        Func<int> getActiveLocaleId,
+        Action requestNextLayout)
+    {
+        _getForegroundWindow = getForegroundWindow;
+        _getActiveLocaleId = getActiveLocaleId;
+        _requestNextLayout = requestNextLayout;
+
         _pollTimer = new DispatcherTimer { Interval = options.PollInterval };
         _pollTimer.Tick += OnTick;
     }
 
     public event EventHandler<LayoutChangedEventArgs>? LayoutChanged;
 
-    public KeyboardLayout Current => KeyboardLayout.FromLocaleId(KeyboardLayoutNative.GetActiveLocaleId());
+    public KeyboardLayout Current => KeyboardLayout.FromLocaleId(_getActiveLocaleId());
 
     public void Start()
     {
-        _lastForegroundWindow = KeyboardLayoutNative.GetForegroundWindow();
-        _lastLocaleId = KeyboardLayoutNative.GetActiveLocaleId();
+        _lastForegroundWindow = _getForegroundWindow();
+        _lastLocaleId = _getActiveLocaleId();
         _pollTimer.Start();
     }
 
     public void Stop() => _pollTimer.Stop();
 
-    public void SwitchToNext() => KeyboardLayoutNative.RequestNextLayout();
+    public void SwitchToNext() => _requestNextLayout();
 
     public void Dispose()
     {
@@ -57,9 +82,14 @@ public sealed class KeyboardLayoutService : IKeyboardLayoutService, IDisposable
         _pollTimer.Tick -= OnTick;
     }
 
-    private void OnTick(object? sender, EventArgs e)
+    private void OnTick(object? sender, EventArgs e) => Poll();
+
+    // A single poll step. Called by the timer, and in tests — directly:
+    // there is no point waiting for a tick to check how the reason for a layout
+    // change is decided
+    internal void Poll()
     {
-        IntPtr foreground = KeyboardLayoutNative.GetForegroundWindow();
+        IntPtr foreground = _getForegroundWindow();
         if (foreground == IntPtr.Zero)
         {
             return;
@@ -68,7 +98,7 @@ public sealed class KeyboardLayoutService : IKeyboardLayoutService, IDisposable
         bool appSwitched = foreground != _lastForegroundWindow;
         _lastForegroundWindow = foreground;
 
-        int localeId = KeyboardLayoutNative.GetActiveLocaleId();
+        int localeId = _getActiveLocaleId();
         if (localeId == _lastLocaleId)
         {
             return;

CursorLang/Services/LayoutPopupService.cs

@@ -1,7 +1,6 @@
 using System.Windows.Threading;
 using CursorLang.Models;
 using CursorLang.ViewModels;
-using CursorLang.Views;
 
 namespace CursorLang.Services;
 
@@ -11,12 +10,12 @@ namespace CursorLang.Services;
 /// </summary>
 public sealed class LayoutPopupService : ILayoutPopupService, IDisposable
 {
-    private readonly LayoutPopupWindow _window;
+    private readonly ILayoutPopupWindow _window;
     private readonly LayoutPopupViewModel _viewModel;
     private readonly AppSettings _settings;
     private readonly DispatcherTimer _hideTimer = new();
 
-    public LayoutPopupService(LayoutPopupWindow window, LayoutPopupViewModel viewModel, AppSettings settings)
+    public LayoutPopupService(ILayoutPopupWindow window, LayoutPopupViewModel viewModel, AppSettings settings)
     {
         _window = window;
         _viewModel = viewModel;

CursorLang/Services/MainWindowPlacement.cs

@@ -103,17 +103,18 @@ public sealed class MainWindowPlacement
     private static PopupWindowNative.Point? CenterOnActiveMonitor(PopupWindowNative.Rect bounds)
     {
         (PopupWindowNative.Rect work, _) = PopupWindowNative.GetActiveMonitorWorkArea();
-        if (IsEmpty(work))
-        {
-            return null;
+        return IsEmpty(work) ? null : Center(bounds, work);
     }
 
-        return new PopupWindowNative.Point
+    /// <summary>
+    /// The point at which a window with the given bounds ends up in the centre of the work area.
+    /// </summary>
+    internal static PopupWindowNative.Point Center(
+        PopupWindowNative.Rect bounds, PopupWindowNative.Rect work) => new()
         {
             X = work.Left + (((work.Right - work.Left) - Width(bounds)) / 2),
             Y = work.Top + (((work.Bottom - work.Top) - Height(bounds)) / 2),
         };
-    }
 
     /// <summary>
     /// Pulls the window into the work area of the nearest monitor.
@@ -145,6 +146,22 @@ public sealed class MainWindowPlacement
             return null;
         }
 
+        return Clamp(position, bounds, work);
+    }
+
+    /// <summary>
+    /// Pulls the point so that a window with the given bounds fits into the work area
+    /// entirely. A window taller than the work area gets its top edge: the title bar
+    /// is needed more than the lower part of the window.
+    /// </summary>
+    internal static PopupWindowNative.Point Clamp(
+        PopupWindowNative.Point position,
+        PopupWindowNative.Rect bounds,
+        PopupWindowNative.Rect work)
+    {
+        int width = Width(bounds);
+        int height = Height(bounds);
+
         return new PopupWindowNative.Point
         {
             X = Math.Clamp(position.X, work.Left, Math.Max(work.Left, work.Right - width)),
@@ -156,6 +173,6 @@ public sealed class MainWindowPlacement
 
     private static int Height(PopupWindowNative.Rect rect) => rect.Bottom - rect.Top;
 
-    private static bool IsEmpty(PopupWindowNative.Rect rect) =>
+    internal static bool IsEmpty(PopupWindowNative.Rect rect) =>
         rect.Right <= rect.Left || rect.Bottom <= rect.Top;
 }

CursorLang/Services/PopupLayout.cs

@@ -0,0 +1,95 @@
+using CursorLang.Interop;
+using CursorLang.Models;
+
+namespace CursorLang.Services;
+
+/// <summary>
+/// Computes the screen point to show the popup at.
+/// </summary>
+/// <remarks>
+/// There is nothing but arithmetic here: where the cursor is, where the caret is and
+/// what the monitor bounds are is figured out by the window itself — it has a handle
+/// of its own for that. The computation is kept apart because it is exactly the place
+/// where a sign or half a size is easy to get wrong, and this way it can be checked
+/// without a single window on screen.
+///
+/// All the values are in physical pixels: monitors have different scaling, and
+/// converting to WPF units halfway would mean rounding twice.
+/// </remarks>
+internal static class PopupLayout
+{
+    /// <summary>
+    /// The popup position next to the anchor point — the cursor or the caret.
+    /// The cursor arrives here as a rectangle of zero size.
+    /// </summary>
+    internal static PopupWindowNative.Point NearAnchor(
+        PopupWindowNative.Rect anchor,
+        AnchorSide side,
+        int offset,
+        int width,
+        int height)
+    {
+        int toLeftOf = anchor.Left - offset - width;
+        int toRightOf = anchor.Right + offset;
+        int above = anchor.Top - offset - height;
+        int below = anchor.Bottom + offset;
+
+        // For the "left" and "right" sides the popup lines up with the anchor point
+        int middle = anchor.Top + (((anchor.Bottom - anchor.Top) - height) / 2);
+
+        (int x, int y) = side switch
+        {
+            AnchorSide.TopLeft => (toLeftOf, above),
+            AnchorSide.TopRight => (toRightOf, above),
+            AnchorSide.Left => (toLeftOf, middle),
+            AnchorSide.Right => (toRightOf, middle),
+            AnchorSide.BottomLeft => (toLeftOf, below),
+            _ => (toRightOf, below),
+        };
+
+        return new PopupWindowNative.Point { X = x, Y = y };
+    }
+
+    /// <summary>
+    /// The popup position in the given corner of the monitor work area.
+    /// </summary>
+    internal static PopupWindowNative.Point OnScreen(
+        PopupWindowNative.Rect work,
+        ScreenPosition position,
+        int margin,
+        int width,
+        int height)
+    {
+        int left = work.Left + margin;
+        int right = work.Right - margin - width;
+        int top = work.Top + margin;
+        int bottom = work.Bottom - margin - height;
+        int centerX = work.Left + ((work.Right - work.Left - width) / 2);
+        int centerY = work.Top + ((work.Bottom - work.Top - height) / 2);
+
+        (int x, int y) = position switch
+        {
+            ScreenPosition.TopLeft => (left, top),
+            ScreenPosition.Top => (centerX, top),
+            ScreenPosition.TopRight => (right, top),
+            ScreenPosition.BottomLeft => (left, bottom),
+            ScreenPosition.Bottom => (centerX, bottom),
+            ScreenPosition.BottomRight => (right, bottom),
+            _ => (centerX, centerY),
+        };
+
+        return new PopupWindowNative.Point { X = x, Y = y };
+    }
+
+    /// <summary>A rectangle of zero size at a point — the mouse cursor as an anchor.</summary>
+    internal static PopupWindowNative.Rect AsAnchor(PopupWindowNative.Point point) => new()
+    {
+        Left = point.X,
+        Top = point.Y,
+        Right = point.X,
+        Bottom = point.Y,
+    };
+
+    /// <summary>WPF units into physical pixels of a monitor with the given scale.</summary>
+    internal static int ToPixels(double wpfUnits, double scale) => (int)Math.Round(wpfUnits * scale);
+}

CursorLang/Views/LayoutPopupWindow.xaml.cs

@@ -2,6 +2,7 @@ using System.Windows;
 using System.Windows.Interop;
 using CursorLang.Interop;
 using CursorLang.Models;
+using CursorLang.Services;
 using CursorLang.ViewModels;
 
 namespace CursorLang.Views;
@@ -11,7 +12,7 @@ namespace CursorLang.Views;
 /// Responsible only for showing it, its size and its place on screen: when to take it
 /// down is decided by <see cref="Services.LayoutPopupService"/>.
 /// </summary>
-public partial class LayoutPopupWindow : Window
+public partial class LayoutPopupWindow : Window, ILayoutPopupWindow
 {
     private readonly AppSettings _settings;
     private Size _contentSize;
@@ -94,14 +95,7 @@ public partial class LayoutPopupWindow : Window
             return caret;
         }
 
-        PopupWindowNative.Point cursor = PopupWindowNative.GetCursorPosition();
-        return new PopupWindowNative.Rect
-        {
-            Left = cursor.X,
-            Top = cursor.Y,
-            Right = cursor.X,
-            Bottom = cursor.Y,
-        };
+        return PopupLayout.AsAnchor(PopupWindowNative.GetCursorPosition());
     }
 
     private void ApplyBoundsNearAnchor(IntPtr handle, PopupWindowNative.Rect anchor)
@@ -112,59 +106,27 @@ public partial class LayoutPopupWindow : Window
         // Every anchor mode has a side and an offset of its own
         bool atCaret = _settings.PlacementMode == PopupPlacementMode.AtCaret;
         AnchorSide side = atCaret ? _settings.CaretSide : _settings.CursorSide;
-        int offset = ToPixels(atCaret ? _settings.CaretOffset : _settings.CursorOffset, scale);
+        int offset = PopupLayout.ToPixels(atCaret ? _settings.CaretOffset : _settings.CursorOffset, scale);
 
-        int width = ToPixels(_contentSize.Width, scale);
-        int height = ToPixels(_contentSize.Height, scale);
+        int width = PopupLayout.ToPixels(_contentSize.Width, scale);
+        int height = PopupLayout.ToPixels(_contentSize.Height, scale);
 
-        int toLeftOf = anchor.Left - offset - width;
-        int toRightOf = anchor.Right + offset;
-        int above = anchor.Top - offset - height;
-        int below = anchor.Bottom + offset;
-        // Для сторон «слева» и «справа» подсказка встаёт вровень с точкой привязки
-        int middle = anchor.Top + (((anchor.Bottom - anchor.Top) - height) / 2);
+        PopupWindowNative.Point position = PopupLayout.NearAnchor(anchor, side, offset, width, height);
 
-        (int x, int y) = side switch
-        {
-            AnchorSide.TopLeft => (toLeftOf, above),
-            AnchorSide.TopRight => (toRightOf, above),
-            AnchorSide.Left => (toLeftOf, middle),
-            AnchorSide.Right => (toRightOf, middle),
-            AnchorSide.BottomLeft => (toLeftOf, below),
-            _ => (toRightOf, below),
-        };
-
-        PopupWindowNative.SetBounds(handle, x, y, width, height);
+        PopupWindowNative.SetBounds(handle, position.X, position.Y, width, height);
     }
 
     private void ApplyBoundsOnScreen(IntPtr handle)
     {
         (PopupWindowNative.Rect work, double scale) = PopupWindowNative.GetActiveMonitorWorkArea();
 
-        int width = ToPixels(_contentSize.Width, scale);
-        int height = ToPixels(_contentSize.Height, scale);
-        int margin = ToPixels(_settings.ScreenMargin, scale);
+        int width = PopupLayout.ToPixels(_contentSize.Width, scale);
+        int height = PopupLayout.ToPixels(_contentSize.Height, scale);
+        int margin = PopupLayout.ToPixels(_settings.ScreenMargin, scale);
 
-        int left = work.Left + margin;
-        int right = work.Right - margin - width;
-        int top = work.Top + margin;
-        int bottom = work.Bottom - margin - height;
-        int centerX = work.Left + ((work.Right - work.Left - width) / 2);
-        int centerY = work.Top + ((work.Bottom - work.Top - height) / 2);
+        PopupWindowNative.Point position =
+            PopupLayout.OnScreen(work, _settings.ScreenPosition, margin, width, height);
 
-        (int x, int y) = _settings.ScreenPosition switch
-        {
-            ScreenPosition.TopLeft => (left, top),
-            ScreenPosition.Top => (centerX, top),
-            ScreenPosition.TopRight => (right, top),
-            ScreenPosition.BottomLeft => (left, bottom),
-            ScreenPosition.Bottom => (centerX, bottom),
-            ScreenPosition.BottomRight => (right, bottom),
-            _ => (centerX, centerY),
-        };
-
-        PopupWindowNative.SetBounds(handle, x, y, width, height);
+        PopupWindowNative.SetBounds(handle, position.X, position.Y, width, height);
     }
-
-    private static int ToPixels(double wpfUnits, double scale) => (int)Math.Round(wpfUnits * scale);
 }