Add styling-capability for active tab in Tabs view in statusline

docs/configuration/indicator-statusline.md

@@ -73,3 +73,13 @@ These parameters apply to all variables above.
 
 The `Command` variable is the only one that requires a special attribute, `Program` whose value
 is the command to execute.
+
+### Tabs formatting extensions
+
+The `Tabs` key allows additional styling through the following attributes:
+
+Parameter                 | Description
+--------------------------|--------------------------------------------------------------------
+`ActiveColor`             | color of the active tab
+`ActiveBackground`        | background color of the active tab
+

src/contour/Config.h

@@ -351,7 +351,7 @@ struct TerminalProfile
         statusDisplayPosition { vtbackend::StatusDisplayPosition::Bottom };
     ConfigEntry<std::string, documentation::IndicatorStatusLineLeft> indicatorStatusLineLeft {
         " {InputMode:Bold,Color=#FFFF00}"
-        "{Tabs:Left= │ }"
+        "{Tabs:ActiveColor=#FFFF00,Left= │ }"
         "{SearchPrompt:Left= │ }"
         "{TraceMode:Bold,Color=#FFFF00,Left= │ }"
         "{ProtectedMode:Bold,Left= │ }"

src/contour/TerminalSessionManager.h

@@ -64,20 +64,10 @@ class TerminalSessionManager: public QAbstractListModel
         if (!_activeSession)
             return;
 
-        _activeSession->terminal().setGuiTabInfoForStatusLine(
-            [this, currentSessionIndex = getCurrentSessionIndex()]() {
-                std::string tabInfo;
-                for (size_t i = 0; i < _sessions.size(); ++i)
-                {
-                    if (std::cmp_equal(i, currentSessionIndex))
-                        tabInfo += "[";
-                    tabInfo += std::to_string(i + 1);
-                    if (std::cmp_equal(i, currentSessionIndex))
-                        tabInfo += "]";
-                    tabInfo += " ";
-                }
-                return tabInfo;
-            }());
+        _activeSession->terminal().setGuiTabInfoForStatusLine(vtbackend::TabsInfo {
+            .tabCount = _sessions.size(),
+            .activeTabPosition = _sessions.empty() ? 0 : static_cast<size_t>(1 + getCurrentSessionIndex()),
+        });
     }
 
     bool isAllowedToChangeTabs()

src/vtbackend/StatusLineBuilder.cpp

@@ -42,6 +42,15 @@ namespace // helper functions
     }
 } // namespace
 
+std::optional<RGBColor> tryParseColorAttribute(crispy::string_interpolation const& interpolation,
+                                               std::string_view key)
+{
+    if (auto const i = interpolation.attributes.find(key); i != interpolation.attributes.end())
+        return parseColor(i->second);
+
+    return std::nullopt;
+}
+
 std::optional<StatusLineDefinitions::Item> makeStatusLineItem(
     crispy::interpolated_string_fragment const& fragment)
 {
@@ -73,17 +82,8 @@ std::optional<StatusLineDefinitions::Item> makeStatusLineItem(
         if (interpolation.flags.count(text))
             styles.flags.enable(flag);
 
-    if (auto const i = interpolation.attributes.find("Color"); i != interpolation.attributes.end())
-    {
-        if (auto const parsedColor = parseColor(i->second))
-            styles.foregroundColor = parsedColor.value();
-    }
-
-    if (auto const i = interpolation.attributes.find("BackgroundColor"); i != interpolation.attributes.end())
-    {
-        if (auto const parsedColor = parseColor(i->second))
-            styles.backgroundColor = parsedColor.value();
-    }
+    styles.foregroundColor = tryParseColorAttribute(interpolation, "Color");
+    styles.backgroundColor = tryParseColorAttribute(interpolation, "BackgroundColor");
 
     if (auto const i = interpolation.attributes.find("Left"); i != interpolation.attributes.end())
         styles.textLeft = i->second;
@@ -147,7 +147,16 @@ std::optional<StatusLineDefinitions::Item> makeStatusLineItem(
         return StatusLineDefinitions::VTType { styles };
 
     if (interpolation.name == "Tabs")
-        return StatusLineDefinitions::Tabs { styles };
+    {
+        std::optional<RGBColor> activeColor = tryParseColorAttribute(interpolation, "ActiveColor");
+        std::optional<RGBColor> activeBackground = tryParseColorAttribute(interpolation, "ActiveBackground");
+
+        return StatusLineDefinitions::Tabs {
+            styles,
+            activeColor,
+            activeBackground,
+        };
+    }
 
     return std::nullopt;
 }
@@ -194,22 +203,30 @@ struct VTSerializer
     StatusLineStyling styling;
     std::string result {};
 
+    std::string makeTextColor(std::optional<RGBColor> const& color, std::string_view defaultSequence = {})
+    {
+        if (!color)
+            return std::string(defaultSequence);
+
+        return std::format("\033[38:2:{}:{}:{}m", color->red, color->green, color->blue);
+    }
+
+    std::string makeBackgroundColor(std::optional<RGBColor> const& color,
+                                    std::string_view defaultSequence = {})
+    {
+        if (!color)
+            return std::string(defaultSequence);
+
+        return std::format("\033[48:2:{}:{}:{}m", color->red, color->green, color->blue);
+    }
+
     void applyStyles(StatusLineDefinitions::Styles const& styles) // {{{
     {
         if (styling == StatusLineStyling::Disabled)
             return;
 
-        if (styles.foregroundColor)
-            result += std::format("\033[38:2:{}:{}:{}m",
-                                  styles.foregroundColor->red,
-                                  styles.foregroundColor->green,
-                                  styles.foregroundColor->blue);
-
-        if (styles.backgroundColor)
-            result += std::format("\033[48:2:{}:{}:{}m",
-                                  styles.backgroundColor->red,
-                                  styles.backgroundColor->green,
-                                  styles.backgroundColor->blue);
+        result += makeTextColor(styles.foregroundColor);
+        result += makeBackgroundColor(styles.backgroundColor);
 
         result += styles.flags.reduce(std::string {}, [](std::string&& result, CellFlag flag) -> std::string {
             switch (flag)
@@ -420,9 +437,33 @@ struct VTSerializer
 
     std::string visit(StatusLineDefinitions::VTType const&) { return std::format("{}", vt.terminalId()); }
 
-    std::string visit(StatusLineDefinitions::Tabs const&)
+    std::string visit(StatusLineDefinitions::Tabs const& tabs)
     {
-        return std::format("{}", vt.guiTabInfoForStatusLine());
+        auto const tabsInfo = vt.guiTabsInfoForStatusLine();
+
+        std::string fragment;
+        for (size_t position: std::views::iota(1u, tabsInfo.tabCount + 1))
+        {
+            if (!fragment.empty())
+                fragment += ' ';
+
+            auto const isActivePosition = position == tabsInfo.activeTabPosition;
+            auto const activePositionStylized =
+                isActivePosition && (tabs.activeColor || tabs.activeBackground);
+
+            if (activePositionStylized)
+            {
+                fragment += SGRSAVE();
+                fragment += makeTextColor(tabs.activeColor);
+                fragment += makeBackgroundColor(tabs.activeBackground);
+            }
+
+            fragment += std::to_string(position);
+
+            if (activePositionStylized)
+                fragment += SGRRESTORE();
+        }
+        return fragment;
     }
     // }}}
 };

src/vtbackend/StatusLineBuilder.h

@@ -38,7 +38,12 @@ namespace StatusLineDefinitions
     struct Text: Styles { std::string text; };
     struct TraceMode: Styles {};
     struct VTType: Styles {};
-    struct Tabs: Styles {};
+
+    struct Tabs: Styles
+    {
+        std::optional<RGBColor> activeColor;
+        std::optional<RGBColor> activeBackground;
+    };
 
     using Item = std::variant<
         CellSGR,

src/vtbackend/Terminal.h

@@ -207,6 +207,12 @@ class TraceHandler: public SequenceHandler
     PendingSequenceQueue _pendingSequences = {};
 };
 
+struct TabsInfo
+{
+    size_t tabCount = 1;
+    size_t activeTabPosition = 1;
+};
+
 /// Terminal API to manage input and output devices of a pseudo terminal, such as keyboard, mouse, and screen.
 ///
 /// With a terminal being attached to a Process, the terminal's screen
@@ -955,8 +961,8 @@ class Terminal
     void setStatusLineDefinition(StatusLineDefinition&& definition);
     void resetStatusLineDefinition();
 
-    std::string_view guiTabInfoForStatusLine() const noexcept { return _guiTabInfoForStatusLine; }
-    void setGuiTabInfoForStatusLine(std::string value) { _guiTabInfoForStatusLine = std::move(value); }
+    TabsInfo guiTabsInfoForStatusLine() const noexcept { return _guiTabInfoForStatusLine; }
+    void setGuiTabInfoForStatusLine(TabsInfo info) { _guiTabInfoForStatusLine = info; }
 
   private:
     void mainLoop();
@@ -1070,7 +1076,7 @@ class Terminal
     Viewport _viewport;
     StatusLineDefinition _indicatorStatusLineDefinition;
 
-    std::string _guiTabInfoForStatusLine;
+    TabsInfo _guiTabInfoForStatusLine;
 
     // {{{ selection states
     std::unique_ptr<Selection> _selection;