Add support for querying Xterm dynamic colors and palette (#17729)

This pull request adds support for querying all of the "dynamic
resource" colors (foreground, background, cursor) as well as the entire
color palette using OSC 4, 10, 11 and 12 with the `?` color specifier.

To ease integration and to make it easier to extend later, I have
consolidated `SetDefaultForeground`, `SetDefaultBackground` and
`SetCursorColor` into one function `SetXtermColorResource`, plus its
analog `RequestXtermColorResource`.

Those functions will map xterm resource OSC numbers to color table
entries and optionally color _alias_ entries using a constant table. The
alias mappings are required to support reassigning the default
foreground and background to their indexed entries after a `DECAC`.

While there are only three real entries in the mapping table right now,
I have designs on bringing in selection background (xterm "highlight")
and foreground (xterm "highlightText").

We can also extend this to support resetting via OSC 110-119. However,
at the adapter layer we do not have the requisite information to restore
any of the colors (even the cursor color!) to the user's defaults.

`OSC 10` and `OSC 11` queries report the final values of
`DECAC`-reassigned entries, under the assumption that an application
asking for them wants to make a determination regardless of their
internal meaning to us (that is: they read through the aliased color to
its final destination in the color palette.)

I've tested this with lsix, which detects the background color before
generating sixel previews. It works great!

ConPTY does not currently pass OSC sequences received on the input
handle, so work was required to make it do so.

Closes #3718

.github/actions/spelling/patterns/patterns.txt

@@ -22,6 +22,7 @@ vcvars\w*
 ROY\sG\.\sBIV
 !(?:(?i)ESC)!\[
 !(?:(?i)CSI)!(?:\d+(?:;\d+|)m|[ABCDF])
+(?i)rgb:[a-z0-9]{2,4}/[a-z0-9]{2,4}/[a-z0-9]{2,4}
 
 # SSE intrinsics like "_mm_subs_epu16"
 \b_mm(?:|256|512)_\w+\b

src/terminal/adapter/ITermDispatch.hpp

@@ -76,9 +76,10 @@ class Microsoft::Console::VirtualTerminal::ITermDispatch
     virtual bool BackwardsTab(const VTInt numTabs) = 0; // CBT
     virtual bool TabClear(const DispatchTypes::TabClearType clearType) = 0; // TBC
     virtual bool TabSet(const VTParameter setType) = 0; // DECST8C
-    virtual bool SetColorTableEntry(const size_t tableIndex, const DWORD color) = 0; // OSCColorTable
-    virtual bool SetDefaultForeground(const DWORD color) = 0; // OSCDefaultForeground
-    virtual bool SetDefaultBackground(const DWORD color) = 0; // OSCDefaultBackground
+    virtual bool SetColorTableEntry(const size_t tableIndex, const DWORD color) = 0; // OSCSetColorTable
+    virtual bool RequestColorTableEntry(const size_t tableIndex) = 0; // OSCGetColorTable
+    virtual bool SetXtermColorResource(const size_t resource, const DWORD color) = 0; // OSCSetDefaultForeground, OSCSetDefaultBackground, OSCSetCursorColor, OSCResetCursorColor
+    virtual bool RequestXtermColorResource(const size_t resource) = 0; // OSCGetDefaultForeground, OSCGetDefaultBackground, OSCGetCursorColor
     virtual bool AssignColor(const DispatchTypes::ColorItem item, const VTInt fgIndex, const VTInt bgIndex) = 0; // DECAC
 
     virtual bool EraseInDisplay(const DispatchTypes::EraseType eraseType) = 0; // ED
@@ -128,7 +129,6 @@ class Microsoft::Console::VirtualTerminal::ITermDispatch
     virtual bool ScreenAlignmentPattern() = 0; // DECALN
 
     virtual bool SetCursorStyle(const DispatchTypes::CursorStyle cursorStyle) = 0; // DECSCUSR
-    virtual bool SetCursorColor(const COLORREF color) = 0; // OSCSetCursorColor, OSCResetCursorColor
 
     virtual bool SetClipboard(wil::zwstring_view content) = 0; // OSCSetClipboard
 

src/terminal/adapter/adaptDispatch.cpp

@@ -18,6 +18,25 @@ using namespace Microsoft::Console::VirtualTerminal;
 
 static constexpr std::wstring_view whitespace{ L" " };
 
+struct XtermResourceColorTableEntry
+{
+    int ColorTableIndex;
+    int AliasIndex;
+};
+
+static constexpr std::array<XtermResourceColorTableEntry, 10> XtermResourceColorTableMappings{ {
+    /* 10 */ { TextColor::DEFAULT_FOREGROUND, static_cast<int>(ColorAlias::DefaultForeground) },
+    /* 11 */ { TextColor::DEFAULT_BACKGROUND, static_cast<int>(ColorAlias::DefaultBackground) },
+    /* 12 */ { TextColor::CURSOR_COLOR, -1 },
+    /* 13 */ { -1, -1 },
+    /* 14 */ { -1, -1 },
+    /* 15 */ { -1, -1 },
+    /* 16 */ { -1, -1 },
+    /* 17 */ { -1, -1 },
+    /* 18 */ { -1, -1 },
+    /* 19 */ { -1, -1 },
+} };
+
 AdaptDispatch::AdaptDispatch(ITerminalApi& api, Renderer* renderer, RenderSettings& renderSettings, TerminalInput& terminalInput) noexcept :
     _api{ api },
     _renderer{ renderer },
@@ -3446,18 +3465,6 @@ bool AdaptDispatch::SetCursorStyle(const DispatchTypes::CursorStyle cursorStyle)
     return true;
 }
 
-// Method Description:
-// - Sets a single entry of the colortable to a new value
-// Arguments:
-// - tableIndex: The VT color table index
-// - dwColor: The new RGB color value to use.
-// Return Value:
-// True if handled successfully. False otherwise.
-bool AdaptDispatch::SetCursorColor(const COLORREF cursorColor)
-{
-    return SetColorTableEntry(TextColor::CURSOR_COLOR, cursorColor);
-}
-
 // Routine Description:
 // - OSC Copy to Clipboard
 // Arguments:
@@ -3498,28 +3505,69 @@ bool AdaptDispatch::SetColorTableEntry(const size_t tableIndex, const DWORD dwCo
     return true;
 }
 
+bool AdaptDispatch::RequestColorTableEntry(const size_t tableIndex)
+{
+    const auto color = _renderSettings.GetColorTableEntry(tableIndex);
+    if (color != INVALID_COLOR)
+    {
+        const til::color c{ color };
+        // Scale values up to match xterm's 16-bit color report format.
+        _api.ReturnResponse(fmt::format(FMT_COMPILE(L"\033]4;{};rgb:{:04x}/{:04x}/{:04x}\033\\"), tableIndex, c.r * 0x0101, c.g * 0x0101, c.b * 0x0101));
+    }
+
+    return true;
+}
+
 // Method Description:
-// - Sets the default foreground color to a new value
-// Arguments:
-// - dwColor: The new RGB color value to use, as a COLORREF, format 0x00BBGGRR.
+// - Sets one Xterm Color Resource such as Default Foreground, Background, Cursor
 // Return Value:
 // True if handled successfully. False otherwise.
-bool AdaptDispatch::SetDefaultForeground(const DWORD dwColor)
+bool AdaptDispatch::SetXtermColorResource(const size_t resource, const DWORD color)
 {
-    _renderSettings.SetColorAliasIndex(ColorAlias::DefaultForeground, TextColor::DEFAULT_FOREGROUND);
-    return SetColorTableEntry(TextColor::DEFAULT_FOREGROUND, dwColor);
+    assert(resource >= 10);
+    const auto mappingIndex = resource - 10;
+    const auto& oscMapping = XtermResourceColorTableMappings.at(mappingIndex);
+    if (oscMapping.ColorTableIndex > 0)
+    {
+        if (oscMapping.AliasIndex >= 0) [[unlikely]]
+        {
+            // If this color change applies to an aliased color, point the alias at the new color
+            _renderSettings.SetColorAliasIndex(static_cast<ColorAlias>(oscMapping.AliasIndex), oscMapping.ColorTableIndex);
+        }
+        return SetColorTableEntry(oscMapping.ColorTableIndex, color);
+    }
+
+    return true;
 }
 
 // Method Description:
-// - Sets the default background color to a new value
-// Arguments:
-// - dwColor: The new RGB color value to use, as a COLORREF, format 0x00BBGGRR.
+// - Reports the value of one Xterm Color Resource, if it is set.
 // Return Value:
 // True if handled successfully. False otherwise.
-bool AdaptDispatch::SetDefaultBackground(const DWORD dwColor)
+bool AdaptDispatch::RequestXtermColorResource(const size_t resource)
 {
-    _renderSettings.SetColorAliasIndex(ColorAlias::DefaultBackground, TextColor::DEFAULT_BACKGROUND);
-    return SetColorTableEntry(TextColor::DEFAULT_BACKGROUND, dwColor);
+    assert(resource >= 10);
+    const auto mappingIndex = resource - 10;
+    const auto& oscMapping = XtermResourceColorTableMappings.at(mappingIndex);
+    if (oscMapping.ColorTableIndex > 0)
+    {
+        size_t finalColorIndex = oscMapping.ColorTableIndex;
+
+        if (oscMapping.AliasIndex >= 0) [[unlikely]]
+        {
+            finalColorIndex = _renderSettings.GetColorAliasIndex(static_cast<ColorAlias>(oscMapping.AliasIndex));
+        }
+
+        const auto color = _renderSettings.GetColorTableEntry(finalColorIndex);
+        if (color != INVALID_COLOR)
+        {
+            const til::color c{ color };
+            // Scale values up to match xterm's 16-bit color report format.
+            _api.ReturnResponse(fmt::format(FMT_COMPILE(L"\033]{};rgb:{:04x}/{:04x}/{:04x}\033\\"), resource, c.r * 0x0101, c.g * 0x0101, c.b * 0x0101));
+        }
+    }
+
+    return true;
 }
 
 // Method Description:

src/terminal/adapter/adaptDispatch.hpp

@@ -126,14 +126,14 @@ namespace Microsoft::Console::VirtualTerminal
         bool HardReset() override; // RIS
         bool ScreenAlignmentPattern() override; // DECALN
         bool SetCursorStyle(const DispatchTypes::CursorStyle cursorStyle) override; // DECSCUSR
-        bool SetCursorColor(const COLORREF cursorColor) override;
 
         bool SetClipboard(const wil::zwstring_view content) override; // OSCSetClipboard
 
         bool SetColorTableEntry(const size_t tableIndex,
-                                const DWORD color) override; // OSCColorTable
-        bool SetDefaultForeground(const DWORD color) override; // OSCDefaultForeground
-        bool SetDefaultBackground(const DWORD color) override; // OSCDefaultBackground
+                                const DWORD color) override; // OSCSetColorTable
+        bool RequestColorTableEntry(const size_t tableIndex) override; // OSCGetColorTable
+        bool SetXtermColorResource(const size_t resource, const DWORD color) override; // OSCSetDefaultForeground, OSCSetDefaultBackground, OSCSetCursorColor, OSCResetCursorColor
+        bool RequestXtermColorResource(const size_t resource) override; // OSCGetDefaultForeground, OSCGetDefaultBackground, OSCGetCursorColor
         bool AssignColor(const DispatchTypes::ColorItem item, const VTInt fgIndex, const VTInt bgIndex) override; // DECAC
 
         bool WindowManipulation(const DispatchTypes::WindowManipulationType function,

src/terminal/adapter/termDispatch.hpp

@@ -69,9 +69,10 @@ class Microsoft::Console::VirtualTerminal::TermDispatch : public Microsoft::Cons
     bool BackwardsTab(const VTInt /*numTabs*/) override { return false; } // CBT
     bool TabClear(const DispatchTypes::TabClearType /*clearType*/) override { return false; } // TBC
     bool TabSet(const VTParameter /*setType*/) override { return false; } // DECST8C
-    bool SetColorTableEntry(const size_t /*tableIndex*/, const DWORD /*color*/) override { return false; } // OSCColorTable
-    bool SetDefaultForeground(const DWORD /*color*/) override { return false; } // OSCDefaultForeground
-    bool SetDefaultBackground(const DWORD /*color*/) override { return false; } // OSCDefaultBackground
+    bool SetColorTableEntry(const size_t /*tableIndex*/, const DWORD /*color*/) override { return false; } // OSCSetColorTable
+    bool RequestColorTableEntry(const size_t /*tableIndex*/) override { return false; } // OSCGetColorTable
+    bool SetXtermColorResource(const size_t /*resource*/, const DWORD /*color*/) override { return false; } // OSCSetDefaultForeground, OSCSetDefaultBackground, OSCSetCursorColor, OSCResetCursorColor
+    bool RequestXtermColorResource(const size_t /*resource*/) override { return false; } // OSCGetDefaultForeground, OSCGetDefaultBackground, OSCGetCursorColor
     bool AssignColor(const DispatchTypes::ColorItem /*item*/, const VTInt /*fgIndex*/, const VTInt /*bgIndex*/) override { return false; } // DECAC
 
     bool EraseInDisplay(const DispatchTypes::EraseType /* eraseType*/) override { return false; } // ED
@@ -121,7 +122,6 @@ class Microsoft::Console::VirtualTerminal::TermDispatch : public Microsoft::Cons
     bool ScreenAlignmentPattern() override { return false; } // DECALN
 
     bool SetCursorStyle(const DispatchTypes::CursorStyle /*cursorStyle*/) override { return false; } // DECSCUSR
-    bool SetCursorColor(const COLORREF /*color*/) override { return false; } // OSCSetCursorColor, OSCResetCursorColor
 
     bool SetClipboard(wil::zwstring_view /*content*/) override { return false; } // OscSetClipboard