Added experimental.pixelShaderImagePath (#14073)

I realize I might be one of the few developers that care about custom
shader support in terminal but I thought it's worth proposing it and see
what you think.

This is to support custom shaders with custom textures.

I was thinking of exposing the background image to the shader but that
felt complicated after looking into it.

I have tested exploratively. I think the texture loader is possible to
unit test so that is a possible improvement.

The error reporting (as with other custom pixel shader code) is not very
good. That is also an area that I could improve upon.

I do think the risk of adding this is rather low as the new code is only
executed when experimental.pixelShaderImagePath is set.

### Details

Only added to the Atlas engine.

Instead I load the texture using WIC into a shader resource view. When
binding shader resources I test for presence of custom texture and bind
it to register t1.

The image loading code was found in [the D3D Texture documentation].
It's a mouthful but seems rather robust.


Tested setting: "experimental.pixelShaderImagePath"

1. Tested not specifying it.
2. Tested setting it.
3. Tested changing it (the changes are picked up)
4. Tested invalid path
5. Tested a custom shader that made use of the custom texture.

[the D3D Texture documentation]: https://learn.microsoft.com/en-us/windows/win32/direct3d11/overviews-direct3d-11-resources-textures-how-to

Co-authored-by: Mike Griese <[email protected]>
Co-authored-by: Leonard Hecker <[email protected]>

Author: 3 people

samples/PixelShaders/BackgroundImage.hlsl

@@ -0,0 +1,23 @@
+// Demo shader to show passing in an image using
+// experimental.pixelShaderImagePath. This shader simply displays the Terminal
+// contents on top of the given image.
+//
+// The image loaded by the terminal will be placed into the `image` texture.
+
+SamplerState samplerState;
+Texture2D shaderTexture : register(t0);
+Texture2D image : register(t1);
+
+cbuffer PixelShaderSettings {
+    float Time;
+    float Scale;
+    float2 Resolution;
+    float4 Background;
+};
+
+float4 main(float4 pos : SV_POSITION, float2 tex : TEXCOORD) : SV_TARGET
+{
+    float4 terminalColor = shaderTexture.Sample(samplerState, tex);
+    float4 imageColor = image.Sample(samplerState, tex);
+    return lerp(imageColor, terminalColor, terminalColor.a);
+}

src/cascadia/TerminalControl/ControlCore.cpp

@@ -387,6 +387,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
 
             _renderEngine->SetRetroTerminalEffect(_settings->RetroTerminalEffect());
             _renderEngine->SetPixelShaderPath(_settings->PixelShaderPath());
+            _renderEngine->SetPixelShaderImagePath(_settings->PixelShaderImagePath());
             _renderEngine->SetForceFullRepaintRendering(_settings->ForceFullRepaintRendering());
             _renderEngine->SetSoftwareRendering(_settings->SoftwareRendering());
 
@@ -914,6 +915,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
             _renderEngine->SetSelectionBackground(til::color{ newAppearance->SelectionBackground() });
             _renderEngine->SetRetroTerminalEffect(newAppearance->RetroTerminalEffect());
             _renderEngine->SetPixelShaderPath(newAppearance->PixelShaderPath());
+            _renderEngine->SetPixelShaderImagePath(newAppearance->PixelShaderImagePath());
 
             // Incase EnableUnfocusedAcrylic is disabled and Focused Acrylic is set to true,
             // the terminal should ignore the unfocused opacity from settings.

src/cascadia/TerminalControl/IControlAppearance.idl

@@ -18,5 +18,6 @@ namespace Microsoft.Terminal.Control
         // Experimental settings
         Boolean RetroTerminalEffect { get; };
         String PixelShaderPath { get; };
+        String PixelShaderImagePath { get; };
     };
 }

src/cascadia/TerminalCore/Terminal.cpp

@@ -1602,7 +1602,7 @@ til::point Terminal::GetViewportRelativeCursorPosition() const noexcept
 // These functions are used by TerminalInput, which must build in conhost
 // against OneCore compatible signatures. See the definitions in
 // VtApiRedirection.hpp (which we cannot include cross-project.)
-// Since we do nto run on OneCore, we can dispense with the compatibility
+// Since we don't run on OneCore, we can dispense with the compatibility
 // shims.
 extern "C" UINT OneCoreSafeMapVirtualKeyW(_In_ UINT uCode, _In_ UINT uMapType)
 {

src/cascadia/TerminalSettingsModel/IAppearanceConfig.idl

@@ -51,6 +51,7 @@ namespace Microsoft.Terminal.Settings.Model
 
         INHERITABLE_APPEARANCE_SETTING(Boolean, RetroTerminalEffect);
         INHERITABLE_APPEARANCE_SETTING(String, PixelShaderPath);
+        INHERITABLE_APPEARANCE_SETTING(String, PixelShaderImagePath);
         INHERITABLE_APPEARANCE_SETTING(IntenseStyle, IntenseTextStyle);
         INHERITABLE_APPEARANCE_SETTING(Microsoft.Terminal.Core.AdjustTextMode, AdjustIndistinguishableColors);
         INHERITABLE_APPEARANCE_SETTING(Double, Opacity);

src/cascadia/TerminalSettingsModel/MTSMSettings.h

@@ -124,6 +124,7 @@ Author(s):
     X(winrt::Windows::UI::Xaml::Media::Stretch, BackgroundImageStretchMode, "backgroundImageStretchMode", winrt::Windows::UI::Xaml::Media::Stretch::UniformToFill) \
     X(bool, RetroTerminalEffect, "experimental.retroTerminalEffect", false)                                                                                        \
     X(hstring, PixelShaderPath, "experimental.pixelShaderPath")                                                                                                    \
+    X(hstring, PixelShaderImagePath, "experimental.pixelShaderImagePath")                                                                                          \
     X(ConvergedAlignment, BackgroundImageAlignment, "backgroundImageAlignment", ConvergedAlignment::Horizontal_Center | ConvergedAlignment::Vertical_Center)       \
     X(hstring, BackgroundImagePath, "backgroundImage")                                                                                                             \
     X(Model::IntenseStyle, IntenseTextStyle, "intenseTextStyle", Model::IntenseStyle::Bright)                                                                      \

src/cascadia/TerminalSettingsModel/TerminalSettings.cpp

@@ -256,6 +256,7 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
 
         _RetroTerminalEffect = appearance.RetroTerminalEffect();
         _PixelShaderPath = winrt::hstring{ wil::ExpandEnvironmentStringsW<std::wstring>(appearance.PixelShaderPath().c_str()) };
+        _PixelShaderImagePath = winrt::hstring{ wil::ExpandEnvironmentStringsW<std::wstring>(appearance.PixelShaderImagePath().c_str()) };
 
         _IntenseIsBold = WI_IsFlagSet(appearance.IntenseTextStyle(), Microsoft::Terminal::Settings::Model::IntenseStyle::Bold);
         _IntenseIsBright = WI_IsFlagSet(appearance.IntenseTextStyle(), Microsoft::Terminal::Settings::Model::IntenseStyle::Bright);

src/cascadia/TerminalSettingsModel/TerminalSettings.h

@@ -160,6 +160,7 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
         INHERITABLE_SETTING(Model::TerminalSettings, bool, ForceVTInput, false);
 
         INHERITABLE_SETTING(Model::TerminalSettings, hstring, PixelShaderPath);
+        INHERITABLE_SETTING(Model::TerminalSettings, hstring, PixelShaderImagePath);
 
         INHERITABLE_SETTING(Model::TerminalSettings, bool, Elevate, false);
 

src/cascadia/inc/ControlProperties.h

@@ -27,7 +27,8 @@
     X(winrt::Windows::UI::Xaml::HorizontalAlignment, BackgroundImageHorizontalAlignment, winrt::Windows::UI::Xaml::HorizontalAlignment::Center) \
     X(winrt::Windows::UI::Xaml::VerticalAlignment, BackgroundImageVerticalAlignment, winrt::Windows::UI::Xaml::VerticalAlignment::Center)       \
     X(bool, RetroTerminalEffect, false)                                                                                                         \
-    X(winrt::hstring, PixelShaderPath)
+    X(winrt::hstring, PixelShaderPath)                                                                                                          \
+    X(winrt::hstring, PixelShaderImagePath)
 
 // --------------------------- Core Settings ---------------------------
 //  All of these settings are defined in ICoreSettings.

src/renderer/atlas/AtlasEngine.api.cpp

@@ -328,6 +328,11 @@ HRESULT AtlasEngine::Enable() noexcept
     return _api.s->misc->customPixelShaderPath;
 }
 
+[[nodiscard]] std::wstring_view AtlasEngine::GetPixelShaderImagePath() noexcept
+{
+    return _api.s->misc->customPixelShaderImagePath;
+}
+
 [[nodiscard]] bool AtlasEngine::GetRetroTerminalEffect() const noexcept
 {
     return _api.s->misc->useRetroTerminalEffect;
@@ -400,6 +405,17 @@ try
 }
 CATCH_LOG()
 
+void AtlasEngine::SetPixelShaderImagePath(std::wstring_view value) noexcept
+try
+{
+    if (_api.s->misc->customPixelShaderImagePath != value)
+    {
+        _api.s.write()->misc.write()->customPixelShaderImagePath = value;
+        _resolveTransparencySettings();
+    }
+}
+CATCH_LOG()
+
 void AtlasEngine::SetRetroTerminalEffect(bool enable) noexcept
 {
     if (_api.s->misc->useRetroTerminalEffect != enable)