Add internal render resolution scale and fix DPI Issue (#468)

* Add internal render resolution scale and fix embedded surface DPI scaling

Adds a GUI-configurable internal resolution scale (Graphics tab) that
renders offscreen color/depth targets below native guest resolution
and upscales on present, trading image quality for GPU headroom.
Storage/UAV images and sampled asset textures are left untouched, and
texture-alias/feedback-loop lookups compare against each target's
logical (unscaled) size so scaled render targets are still found
correctly when sampled back.

Also fixes the embedded game surface not filling the window: the
isolated emulator child process had no declared DPI awareness, so
Windows silently downscaled every window-geometry query it made
against the GUI-owned surface HWND by the display's DPI factor,
leaving an unfilled black margin on scaled displays.

* Remove flaky Gen5ScalarMemoryFallbackTests

* Restore Gen5ScalarMemoryFallbackTests

---------

Co-authored-by: Spooks4576 <Spooks4576@users.noreply.github.com>

src/SharpEmu.CLI/app.manifest

@@ -13,4 +13,9 @@ SPDX-License-Identifier: GPL-2.0-or-later
       <supportedOS Id="{8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a}" />
     </application>
   </compatibility>
+  <asmv3:application xmlns:asmv3="urn:schemas-microsoft-com:asm.v3">
+    <asmv3:windowsSettings>
+      <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitorV2</dpiAwareness>
+    </asmv3:windowsSettings>
+  </asmv3:application>
 </assembly>

src/SharpEmu.GUI/GameSurfaceHost.cs

@@ -351,6 +351,13 @@ public sealed class GameSurfaceHost : NativeControlHost
         var width = Math.Max(1, (int)Math.Round(Bounds.Width * renderScale));
         var height = Math.Max(1, (int)Math.Round(Bounds.Height * renderScale));
         var sizeChanged = _surface.PixelWidth != width || _surface.PixelHeight != height;
+        if (Environment.GetEnvironmentVariable("SHARPEMU_TRACE_SURFACE_SIZE") == "1")
+        {
+            Console.Error.WriteLine(
+                $"[GUI][TRACE] GameSurfaceHost.UpdateSurfaceSize bounds={Bounds.Width}x{Bounds.Height} " +
+                $"scale={renderScale} computed={width}x{height} changed={sizeChanged} " +
+                $"prevSurface={_surface.PixelWidth}x{_surface.PixelHeight}");
+        }
         _surface.UpdatePixelSize(width, height);
 
         if (!sizeChanged)

src/SharpEmu.GUI/GuiSettings.cs

@@ -53,6 +53,9 @@ public sealed class GuiSettings
     /// <summary>Names of SHARPEMU_* switches set to "1" in the emulator's environment at launch.</summary>
     public List<string> EnvironmentToggles { get; set; } = new();
 
+    /// <summary>Internal render resolution scale (1.0 = native, 0.5 = half).</summary>
+    public double RenderResolutionScale { get; set; } = 1.0;
+
     /// <summary>
     /// Discord application ID used for Rich Presence; the default is the
     /// SharpEmu application. Override to rebrand what Discord shows as
@@ -96,6 +99,10 @@ public sealed class GuiSettings
         settings.LogLevel ??= "Info";
         settings.Language ??= "en";
         settings.DiscordClientId ??= "1525606762248540221";
+        if (settings.RenderResolutionScale <= 0 || settings.RenderResolutionScale > 2.0)
+        {
+            settings.RenderResolutionScale = 1.0;
+        }
 
         return settings;
     }

src/SharpEmu.GUI/MainWindow.axaml

@@ -400,6 +400,29 @@ SPDX-License-Identifier: GPL-2.0-or-later
                 </StackPanel>
               </ScrollViewer>
             </TabItem>
+            <TabItem x:Name="GraphicsTabItem" Header="Graphics" FontSize="15">
+              <ScrollViewer>
+                <StackPanel Margin="0,14,0,16" Spacing="16" MaxWidth="1280" HorizontalAlignment="Left">
+
+                  <Border Classes="card">
+                    <StackPanel Spacing="14">
+                      <TextBlock x:Name="RenderingSectionTitle" Classes="sectionTitle" Text="RENDERING" />
+
+                      <local:SettingRow x:Name="RenderResolutionRow" Label="Internal resolution"
+                                        Description="Render offscreen targets below native resolution and upscale on present. Lower values trade image quality for GPU headroom; takes effect on next launch.">
+                        <ComboBox x:Name="RenderResolutionBox" Width="160" SelectedIndex="0"
+                                  VerticalAlignment="Center" CornerRadius="8">
+                          <ComboBoxItem x:Name="RenderResolution100Item" Content="100% (native)" Tag="1.0" />
+                          <ComboBoxItem x:Name="RenderResolution75Item" Content="75%" Tag="0.75" />
+                          <ComboBoxItem x:Name="RenderResolution50Item" Content="50%" Tag="0.5" />
+                          <ComboBoxItem x:Name="RenderResolution25Item" Content="25%" Tag="0.25" />
+                        </ComboBox>
+                      </local:SettingRow>
+                    </StackPanel>
+                  </Border>
+                </StackPanel>
+              </ScrollViewer>
+            </TabItem>
             <TabItem x:Name="EnvTabItem" Header="Environment" FontSize="15">
               <ScrollViewer>
                 <StackPanel Margin="0,14,0,16" Spacing="16" MaxWidth="1280" HorizontalAlignment="Left">

src/SharpEmu.GUI/MainWindow.axaml.cs

@@ -192,6 +192,18 @@ public partial class MainWindow : Window
         // it is open already uses the new values.
         LogLevelBox.SelectionChanged += (_, _) => _settings.LogLevel = SelectedLogLevel();
         TraceImportsBox.ValueChanged += (_, _) => _settings.ImportTraceLimit = (int)(TraceImportsBox.Value ?? 0);
+        RenderResolutionBox.SelectionChanged += (_, _) =>
+        {
+            if (RenderResolutionBox.SelectedItem is ComboBoxItem { Tag: string tag } &&
+                double.TryParse(
+                    tag,
+                    System.Globalization.NumberStyles.Float,
+                    System.Globalization.CultureInfo.InvariantCulture,
+                    out var scale))
+            {
+                _settings.RenderResolutionScale = scale;
+            }
+        };
         StrictToggle.IsCheckedChanged += (_, _) => _settings.StrictDynlibResolution = StrictToggle.IsChecked == true;
         LogToFileToggle.IsCheckedChanged += (_, _) => _settings.LogToFile = LogToFileToggle.IsChecked == true;
         OverrideLogFileToggle.IsCheckedChanged += (_, _) =>
@@ -869,6 +881,13 @@ public partial class MainWindow : Window
             _ => 2,
         };
         TraceImportsBox.Value = Math.Clamp(_settings.ImportTraceLimit, 0, 4096);
+        RenderResolutionBox.SelectedIndex = _settings.RenderResolutionScale switch
+        {
+            >= 0.875 => 0,
+            >= 0.625 => 1,
+            >= 0.375 => 2,
+            _ => 3,
+        };
         StrictToggle.IsChecked = _settings.StrictDynlibResolution;
         LogToFileToggle.IsChecked = _settings.LogToFile;
         OverrideLogFileToggle.IsChecked = _settings.OverrideLogFile;
@@ -1788,6 +1807,12 @@ public partial class MainWindow : Window
             _appliedEnvironmentVariables.Add(name);
         }
 
+        Environment.SetEnvironmentVariable(
+            "SHARPEMU_RENDER_SCALE",
+            _settings.RenderResolutionScale.ToString(
+                "0.###",
+                System.Globalization.CultureInfo.InvariantCulture));
+
         if (SharpEmuLog.TryParseLevel(effective.LogLevel, out var logLevel))
         {
             SharpEmuLog.MinimumLevel = logLevel;
@@ -2030,8 +2055,6 @@ public partial class MainWindow : Window
                 RestoreGameViewToFull();
                 GameView.Background = Brushes.Black;
                 GameView.IsHitTestVisible = true;
-                _gameSurfaceHost?.SetPresentationVisible(true);
-                _gameSurfaceHost?.SetCursorAutoHide(true);
                 LibraryPage.IsVisible = false;
                 OptionsPage.IsVisible = false;
                 LibraryToolbar.IsVisible = false;
@@ -2040,6 +2063,19 @@ public partial class MainWindow : Window
                 LaunchBar.IsVisible = false;
                 HideSessionLoading();
                 UpdateSessionBarVisibility();
+
+                // Defer so the layout pass from the margin change above settles first.
+                Dispatcher.UIThread.Post(() =>
+                {
+                    if (!_isRunning || _isStopping)
+                    {
+                        return;
+                    }
+
+                    _gameSurfaceHost?.RefreshSurfaceSize();
+                    _gameSurfaceHost?.SetPresentationVisible(true);
+                    _gameSurfaceHost?.SetCursorAutoHide(true);
+                });
             }
         });
     }

src/SharpEmu.Libs/VideoOut/VulkanVideoPresenter.cs

@@ -3088,6 +3088,9 @@ internal static unsafe class VulkanVideoPresenter
             public ulong WriteAddress;
             public uint Width;
             public uint Height;
+            // Unscaled guest-requested size; Width/Height are the physical (scaled) backing size.
+            public uint LogicalWidth;
+            public uint LogicalHeight;
             public uint GuestFormat;
             public uint SwizzleMode;
             public Image Image;
@@ -3117,6 +3120,9 @@ internal static unsafe class VulkanVideoPresenter
             public long FlipVersion;
             public uint Width;
             public uint Height;
+            // Unscaled guest-requested size; Width/Height are the physical (scaled) backing size.
+            public uint LogicalWidth;
+            public uint LogicalHeight;
             public uint MipLevels;
             public uint GuestFormat;
             public Format Format;
@@ -7116,8 +7122,8 @@ internal static unsafe class VulkanVideoPresenter
                 // but it must not make a differently sized alias outrank the image
                 // that the texture descriptor actually names.
                 var score = 0;
-                if (candidate.Width == texture.Width &&
+                if (candidate.LogicalWidth == texture.Width &&
-                    candidate.Height == texture.Height)
+                    candidate.LogicalHeight == texture.Height)
                 {
                     score += 32;
                 }
@@ -7202,7 +7208,7 @@ internal static unsafe class VulkanVideoPresenter
                     continue;
                 }
 
-                if (texture.Width > depth.Width || texture.Height > depth.Height)
+                if (texture.Width > depth.LogicalWidth || texture.Height > depth.LogicalHeight)
                 {
                     continue;
                 }
@@ -7412,8 +7418,8 @@ internal static unsafe class VulkanVideoPresenter
             GuestDrawTexture texture,
             GuestImageResource guestImage)
         {
-            if (guestImage.Width == texture.Width &&
+            if (guestImage.LogicalWidth == texture.Width &&
-                guestImage.Height == texture.Height)
+                guestImage.LogicalHeight == texture.Height)
             {
                 return true;
             }
@@ -7425,8 +7431,8 @@ internal static unsafe class VulkanVideoPresenter
                 return false;
             }
 
-            return texture.Width <= guestImage.Width &&
+            return texture.Width <= guestImage.LogicalWidth &&
-                texture.Height <= guestImage.Height;
+                texture.Height <= guestImage.LogicalHeight;
         }
 
         [MethodImpl(MethodImplOptions.NoInlining)]
@@ -9161,11 +9167,19 @@ internal static unsafe class VulkanVideoPresenter
 
         private static GuestRect ClampScissor(GuestRect? scissor, Extent2D extent)
         {
-            if (scissor is not { } rect)
+            if (scissor is not { } guestRect)
             {
                 return new GuestRect(0, 0, extent.Width, extent.Height);
             }
 
+            var rect = _renderResolutionScale == 1.0
+                ? guestRect
+                : new GuestRect(
+                    (int)Math.Round(guestRect.X * _renderResolutionScale),
+                    (int)Math.Round(guestRect.Y * _renderResolutionScale),
+                    Math.Max(1u, (uint)Math.Round(guestRect.Width * _renderResolutionScale)),
+                    Math.Max(1u, (uint)Math.Round(guestRect.Height * _renderResolutionScale)));
+
             var left = Math.Clamp(rect.X, 0, checked((int)extent.Width));
             var top = Math.Clamp(rect.Y, 0, checked((int)extent.Height));
             var right = Math.Clamp(
@@ -9193,11 +9207,22 @@ internal static unsafe class VulkanVideoPresenter
 
         private static Viewport ClampViewport(GuestViewport? viewport, Extent2D extent)
         {
-            if (viewport is not { } rect)
+            if (viewport is not { } guestRect)
             {
                 return new Viewport(0, 0, extent.Width, extent.Height, 0, 1);
             }
 
+            var scale = (float)_renderResolutionScale;
+            var rect = scale == 1f
+                ? guestRect
+                : guestRect with
+                {
+                    X = guestRect.X * scale,
+                    Y = guestRect.Y * scale,
+                    Width = guestRect.Width * scale,
+                    Height = guestRect.Height * scale,
+                };
+
             // Do NOT trim the rectangle to the render target: Vulkan allows
             // viewports that extend beyond the framebuffer (rendering is
             // confined by the scissor), and trimming changes the guest's
@@ -10513,10 +10538,11 @@ internal static unsafe class VulkanVideoPresenter
                         draw.RenderState.Depth) &&
                     work.DepthTarget is { } depthTarget)
                 {
+                    // Logical dims: GetOrCreateGuestDepth below scales itself.
                     var resolution = GuestDepthExtentResolver.Resolve(
                         depthTarget,
-                        firstTarget.Width,
+                        firstTarget.LogicalWidth,
-                        firstTarget.Height,
+                        firstTarget.LogicalHeight,
                         draw.Textures);
                     var effectiveDepthTarget = resolution.IsUsable &&
                         (resolution.Width != depthTarget.Width ||
@@ -11216,7 +11242,14 @@ internal static unsafe class VulkanVideoPresenter
                     $"address 0x{target.Address:X16}.");
             }
 
-            var mipLevels = ClampMipLevels(target.Width, target.Height, target.MipLevels);
+            // Storage/UAV images keep native guest dimensions (compute shaders index them directly).
+            var physicalWidth = requiresStorage
+                ? target.Width
+                : ScaleGuestDimension(target.Width);
+            var physicalHeight = requiresStorage
+                ? target.Height
+                : ScaleGuestDimension(target.Height);
+            var mipLevels = ClampMipLevels(physicalWidth, physicalHeight, target.MipLevels);
             var guestFormat = GetGuestTextureFormat(target.Format, target.NumberType);
             var requestedKey = new GuestImageVariantKey(
                 target.Address,
@@ -11227,8 +11260,8 @@ internal static unsafe class VulkanVideoPresenter
                 format);
             if (_guestImages.TryGetValue(target.Address, out var existing))
             {
-                if (existing.Width == target.Width &&
+                if (existing.LogicalWidth == target.Width &&
-                    existing.Height == target.Height &&
+                    existing.LogicalHeight == target.Height &&
                     existing.MipLevels == mipLevels &&
                     existing.GuestFormat == guestFormat &&
                     existing.Format == format)
@@ -11278,8 +11311,8 @@ internal static unsafe class VulkanVideoPresenter
                 _guestImageVariants.Add(
                     new GuestImageVariantKey(
                         existing.Address,
-                        existing.Width,
+                        existing.LogicalWidth,
-                        existing.Height,
+                        existing.LogicalHeight,
                         existing.MipLevels,
                     existing.GuestFormat,
                     existing.Format),
@@ -11348,7 +11381,7 @@ internal static unsafe class VulkanVideoPresenter
                     ImageCreateFlags.CreateExtendedUsageBit,
                 ImageType = ImageType.Type2D,
                 Format = format,
-                Extent = new Extent3D(target.Width, target.Height, 1),
+                Extent = new Extent3D(physicalWidth, physicalHeight, 1),
                 MipLevels = mipLevels,
                 ArrayLayers = 1,
                 Samples = SampleCountFlags.Count1Bit,
@@ -11421,15 +11454,17 @@ internal static unsafe class VulkanVideoPresenter
                     CreateRenderPassAndFramebuffer(
                         format,
                         mipViews[0],
-                        target.Width,
+                        physicalWidth,
-                        target.Height);
+                        physicalHeight);
             }
 
             var resource = new GuestImageResource
             {
                 Address = target.Address,
-                Width = target.Width,
+                Width = physicalWidth,
-                Height = target.Height,
+                Height = physicalHeight,
+                LogicalWidth = target.Width,
+                LogicalHeight = target.Height,
                 MipLevels = mipLevels,
                 GuestFormat = guestFormat,
                 Format = format,
@@ -11685,15 +11720,19 @@ internal static unsafe class VulkanVideoPresenter
                 return existing;
             }
 
-            var (image, memory, view) = CreateDepthAttachment(target.Width, target.Height);
+            var physicalWidth = ScaleGuestDimension(target.Width);
+            var physicalHeight = ScaleGuestDimension(target.Height);
+            var (image, memory, view) = CreateDepthAttachment(physicalWidth, physicalHeight);
             var resource = new GuestDepthResource
             {
                 Key = key,
                 Address = target.Address,
                 ReadAddress = target.ReadAddress,
                 WriteAddress = target.WriteAddress,
-                Width = target.Width,
+                Width = physicalWidth,
-                Height = target.Height,
+                Height = physicalHeight,
+                LogicalWidth = target.Width,
+                LogicalHeight = target.Height,
                 GuestFormat = target.GuestFormat,
                 SwizzleMode = target.SwizzleMode,
                 Image = image,
@@ -14153,6 +14192,22 @@ internal static unsafe class VulkanVideoPresenter
             !string.IsNullOrWhiteSpace(
                 Environment.GetEnvironmentVariable(
                     "SHARPEMU_TRACE_GUEST_IMAGE_ADDRS"));
+        private static readonly double _renderResolutionScale =
+            double.TryParse(
+                Environment.GetEnvironmentVariable("SHARPEMU_RENDER_SCALE"),
+                System.Globalization.NumberStyles.Float,
+                System.Globalization.CultureInfo.InvariantCulture,
+                out var renderResolutionScale) &&
+            renderResolutionScale > 0 &&
+            renderResolutionScale <= 2.0
+                ? renderResolutionScale
+                : 1.0;
+
+        private static uint ScaleGuestDimension(uint value) =>
+            _renderResolutionScale == 1.0
+                ? value
+                : Math.Max(1u, (uint)Math.Round(value * _renderResolutionScale));
+
         private static readonly bool _forceFullscreenPipeline =
             Environment.GetEnvironmentVariable("SHARPEMU_FORCE_FULLSCREEN_PIPELINE") == "1";
         private static readonly bool _forceFullscreenVertex =