Fix accuracy bugs around float/double/int conversions (#15098)

I noticed this bug while resizing my window on my 150% scale display.
Every 3 "snaps" of the window size, it would fail to resize the text
buffer. I found that this occurs, because we convert the swap chain
size from a float into a double, which converts my 597.333313 height
into 597.33331298828125, which then multiplied by 1.5 results in
895.999969482421875. If you just cast this to an integer, it'll
result in a height of 895px instead of the expected 896px.

This PR addresses the issue in two ways:
* Replace casts to integers with `lrint` or `floor`, etc.
* Remove many of the redundant double <> float conversions.

## PR Checklist
* Resizing my window always resizes the text buffer ✅

src/cascadia/TerminalControl/ControlCore.cpp

@@ -256,9 +256,9 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         _AttachedHandlers(*this, nullptr);
     }
 
-    bool ControlCore::Initialize(const double actualWidth,
-                                 const double actualHeight,
-                                 const double compositionScale)
+    bool ControlCore::Initialize(const float actualWidth,
+                                 const float actualHeight,
+                                 const float compositionScale)
     {
         assert(_settings);
 
@@ -298,8 +298,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
             // and react accordingly.
             _updateFont(true);
 
-            const til::size windowSize{ static_cast<til::CoordType>(windowWidth),
-                                        static_cast<til::CoordType>(windowHeight) };
+            const til::size windowSize{ til::math::rounding, windowWidth, windowHeight };
 
             // First set up the dx engine with the window size in pixels.
             // Then, using the font, get the number of characters that can fit.
@@ -853,8 +852,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
     //   concerned with initialization process. Value forwarded to event handler.
     void ControlCore::_updateFont(const bool initialUpdate)
     {
-        const auto newDpi = static_cast<int>(static_cast<double>(USER_DEFAULT_SCREEN_DPI) *
-                                             _compositionScale);
+        const auto newDpi = static_cast<int>(lrint(_compositionScale * USER_DEFAULT_SCREEN_DPI));
 
         _terminal->SetFontInfo(_actualFont);
 
@@ -975,8 +973,8 @@ namespace winrt::Microsoft::Terminal::Control::implementation
             return;
         }
 
-        auto cx = gsl::narrow_cast<til::CoordType>(_panelWidth * _compositionScale);
-        auto cy = gsl::narrow_cast<til::CoordType>(_panelHeight * _compositionScale);
+        auto cx = gsl::narrow_cast<til::CoordType>(lrint(_panelWidth * _compositionScale));
+        auto cy = gsl::narrow_cast<til::CoordType>(lrint(_panelHeight * _compositionScale));
 
         // Don't actually resize so small that a single character wouldn't fit
         // in either dimension. The buffer really doesn't like being size 0.
@@ -986,7 +984,6 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         // Convert our new dimensions to characters
         const auto viewInPixels = Viewport::FromDimensions({ 0, 0 }, { cx, cy });
         const auto vp = _renderEngine->GetViewportInCharacters(viewInPixels);
-        const auto currentVP = _terminal->GetViewport();
 
         _terminal->ClearSelection();
 
@@ -1005,13 +1002,13 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         }
     }
 
-    void ControlCore::SizeChanged(const double width,
-                                  const double height)
+    void ControlCore::SizeChanged(const float width,
+                                  const float height)
     {
         SizeOrScaleChanged(width, height, _compositionScale);
     }
 
-    void ControlCore::ScaleChanged(const double scale)
+    void ControlCore::ScaleChanged(const float scale)
     {
         if (!_renderEngine)
         {
@@ -1020,24 +1017,24 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         SizeOrScaleChanged(_panelWidth, _panelHeight, scale);
     }
 
-    void ControlCore::SizeOrScaleChanged(const double width,
-                                         const double height,
-                                         const double scale)
+    void ControlCore::SizeOrScaleChanged(const float width,
+                                         const float height,
+                                         const float scale)
     {
+        const auto scaleChanged = _compositionScale != scale;
         // _refreshSizeUnderLock redraws the entire terminal.
         // Don't call it if we don't have to.
-        if (_panelWidth == width && _panelHeight == height && _compositionScale == scale)
+        if (_panelWidth == width && _panelHeight == height && !scaleChanged)
         {
             return;
         }
-        const auto oldScale = _compositionScale;
 
         _panelWidth = width;
         _panelHeight = height;
         _compositionScale = scale;
 
         auto lock = _terminal->LockForWriting();
-        if (oldScale != scale)
+        if (scaleChanged)
         {
             // _updateFont relies on the new _compositionScale set above
             _updateFont();
@@ -1267,7 +1264,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
     winrt::Windows::Foundation::Size ControlCore::FontSizeInDips() const
     {
         const auto fontSize = _actualFont.GetSize();
-        const auto scale = 1.0f / static_cast<float>(_compositionScale);
+        const auto scale = 1.0f / _compositionScale;
         return {
             fontSize.width * scale,
             fontSize.height * scale,

src/cascadia/TerminalControl/ControlCore.h

@@ -58,9 +58,9 @@ namespace winrt::Microsoft::Terminal::Control::implementation
                     TerminalConnection::ITerminalConnection connection);
         ~ControlCore();
 
-        bool Initialize(const double actualWidth,
-                        const double actualHeight,
-                        const double compositionScale);
+        bool Initialize(const float actualWidth,
+                        const float actualHeight,
+                        const float compositionScale);
         void EnablePainting();
 
         void Detach();
@@ -78,9 +78,9 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         uint64_t SwapChainHandle() const;
         void AttachToNewControl(const Microsoft::Terminal::Control::IKeyBindings& keyBindings);
 
-        void SizeChanged(const double width, const double height);
-        void ScaleChanged(const double scale);
-        void SizeOrScaleChanged(const double width, const double height, const double scale);
+        void SizeChanged(const float width, const float height);
+        void ScaleChanged(const float scale);
+        void SizeOrScaleChanged(const float width, const float height, const float scale);
 
         void AdjustFontSize(float fontSizeDelta);
         void ResetFontSize();
@@ -286,9 +286,9 @@ namespace winrt::Microsoft::Terminal::Control::implementation
 
         // These members represent the size of the surface that we should be
         // rendering to.
-        double _panelWidth{ 0 };
-        double _panelHeight{ 0 };
-        double _compositionScale{ 0 };
+        float _panelWidth{ 0 };
+        float _panelHeight{ 0 };
+        float _compositionScale{ 0 };
 
         uint64_t _owningHwnd{ 0 };
 

src/cascadia/TerminalControl/ControlCore.idl

@@ -64,9 +64,9 @@ namespace Microsoft.Terminal.Control
                     IControlAppearance unfocusedAppearance,
                     Microsoft.Terminal.TerminalConnection.ITerminalConnection connection);
 
-        Boolean Initialize(Double actualWidth,
-                           Double actualHeight,
-                           Double compositionScale);
+        Boolean Initialize(Single actualWidth,
+                           Single actualHeight,
+                           Single compositionScale);
 
         void UpdateSettings(IControlSettings settings, IControlAppearance appearance);
         void ApplyAppearance(Boolean focused);
@@ -108,9 +108,9 @@ namespace Microsoft.Terminal.Control
 
         void ResetFontSize();
         void AdjustFontSize(Single fontSizeDelta);
-        void SizeChanged(Double width, Double height);
-        void ScaleChanged(Double scale);
-        void SizeOrScaleChanged(Double width, Double height, Double scale);
+        void SizeChanged(Single width, Single height);
+        void ScaleChanged(Single scale);
+        void SizeOrScaleChanged(Single width, Single height, Single scale);
 
         void ToggleShaderEffects();
         void ToggleReadOnlyMode();

src/cascadia/TerminalControl/TermControl.cpp

@@ -927,8 +927,8 @@ namespace winrt::Microsoft::Terminal::Control::implementation
             return false;
         }
 
-        const auto panelWidth = SwapChainPanel().ActualWidth();
-        const auto panelHeight = SwapChainPanel().ActualHeight();
+        const auto panelWidth = static_cast<float>(SwapChainPanel().ActualWidth());
+        const auto panelHeight = static_cast<float>(SwapChainPanel().ActualHeight());
         const auto panelScaleX = SwapChainPanel().CompositionScaleX();
         const auto panelScaleY = SwapChainPanel().CompositionScaleY();
 
@@ -2245,7 +2245,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         // instantiating a DxEngine/AtlasEngine.
         // GH#10211 - UNDER NO CIRCUMSTANCE should this fail. If it does, the
         // whole app will crash instantaneously on launch, which is no good.
-        double scale;
+        float scale;
         if (settings.UseAtlasEngine())
         {
             auto engine = std::make_unique<::Microsoft::Console::Render::AtlasEngine>();
@@ -2267,21 +2267,21 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         // ComCtl scrollbars, but it's certainly close enough.
         const auto scrollbarSize = GetSystemMetricsForDpi(SM_CXVSCROLL, dpi);
 
-        double width = cols * actualFontSize.width;
+        float width = cols * static_cast<float>(actualFontSize.width);
 
         // Reserve additional space if scrollbar is intended to be visible
         if (scrollState != ScrollbarState::Hidden)
         {
             width += scrollbarSize;
         }
 
-        double height = rows * actualFontSize.height;
+        float height = rows * static_cast<float>(actualFontSize.height);
         const auto thickness = ParseThicknessFromPadding(padding);
         // GH#2061 - make sure to account for the size the padding _will be_ scaled to
-        width += scale * (thickness.Left + thickness.Right);
-        height += scale * (thickness.Top + thickness.Bottom);
+        width += scale * static_cast<float>(thickness.Left + thickness.Right);
+        height += scale * static_cast<float>(thickness.Top + thickness.Bottom);
 
-        return { gsl::narrow_cast<float>(width), gsl::narrow_cast<float>(height) };
+        return { width, height };
     }
 
     // Method Description:
@@ -2311,20 +2311,20 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         if (_initializedTerminal)
         {
             const auto fontSize = _core.FontSize();
-            double width = fontSize.Width;
-            double height = fontSize.Height;
+            auto width = fontSize.Width;
+            auto height = fontSize.Height;
             // Reserve additional space if scrollbar is intended to be visible
             if (_core.Settings().ScrollState() != ScrollbarState::Hidden)
             {
-                width += ScrollBar().ActualWidth();
+                width += static_cast<float>(ScrollBar().ActualWidth());
             }
 
             // Account for the size of any padding
             const auto padding = GetPadding();
-            width += padding.Left + padding.Right;
-            height += padding.Top + padding.Bottom;
+            width += static_cast<float>(padding.Left + padding.Right);
+            height += static_cast<float>(padding.Top + padding.Bottom);
 
-            return { gsl::narrow_cast<float>(width), gsl::narrow_cast<float>(height) };
+            return { width, height };
         }
         else
         {
@@ -2363,7 +2363,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         }
 
         const auto gridSize = dimension - nonTerminalArea;
-        const auto cells = static_cast<int>(gridSize / fontDimension);
+        const auto cells = floor(gridSize / fontDimension);
         return cells * fontDimension + nonTerminalArea;
     }
 

src/cascadia/UnitTests_Control/ControlInteractivityTests.cpp

@@ -1033,8 +1033,9 @@ namespace ControlUnitTests
                                       cursorPosition1.to_core_point());
 
         Log::Comment(L" --- Resize the terminal to be 10 columns wider ---");
-        const auto newSizeInDips{ til::size{ 40, 20 } * fontSize };
-        core->SizeChanged(newSizeInDips.width, newSizeInDips.height);
+        const auto newWidth = 40.0f * fontSize.width;
+        const auto newHeight = 20.0f * fontSize.height;
+        core->SizeChanged(newWidth, newHeight);
 
         Log::Comment(L" --- Click on a spot that's NOW INSIDE the buffer ---");
         // (32 + 35 + 1) = 68 = 'D'

src/cascadia/WindowsTerminal/AppHost.cpp

@@ -579,10 +579,8 @@ void AppHost::_HandleCreateWindow(const HWND hwnd, til::rect proposedRect, Launc
 
     auto initialSize = _windowLogic.GetLaunchDimensions(dpix);
 
-    const auto islandWidth = Utils::ClampToShortMax(
-        static_cast<long>(ceil(initialSize.Width)), 1);
-    const auto islandHeight = Utils::ClampToShortMax(
-        static_cast<long>(ceil(initialSize.Height)), 1);
+    const auto islandWidth = Utils::ClampToShortMax(lrintf(initialSize.Width), 1);
+    const auto islandHeight = Utils::ClampToShortMax(lrintf(initialSize.Height), 1);
 
     // Get the size of a window we'd need to host that client rect. This will
     // add the titlebar space.
@@ -1260,8 +1258,8 @@ void AppHost::_handleMoveContent(const winrt::Windows::Foundation::IInspectable&
         {
             const auto initialSize = _windowLogic.GetLaunchDimensions(dpi);
 
-            const auto islandWidth = Utils::ClampToShortMax(static_cast<long>(ceil(initialSize.Width)), 1);
-            const auto islandHeight = Utils::ClampToShortMax(static_cast<long>(ceil(initialSize.Height)), 1);
+            const auto islandWidth = Utils::ClampToShortMax(lrintf(initialSize.Width), 1);
+            const auto islandHeight = Utils::ClampToShortMax(lrintf(initialSize.Height), 1);
 
             // Get the size of a window we'd need to host that client rect. This will
             // add the titlebar space.

src/inc/til/math.h

@@ -17,7 +17,7 @@ namespace til
             constexpr O narrow_float(T val)
             {
                 const auto o = gsl::narrow_cast<O>(val);
-                if (std::isnan(val) || static_cast<T>(o) != val)
+                if (static_cast<T>(o) != val)
                 {
                     throw gsl::narrowing_error{};
                 }