Add method to register theme as a textual theme, and update picker example.

Author: carmiac

examples/textual_demo.py

@@ -103,6 +103,12 @@ def load_current_theme(self) -> None:
         _, theme = self.themes[self.current_index]
         self.current_theme_data = theme
 
+        # Register and apply the TCA theme as a Textual theme so that all
+        # CSS design tokens ($background, $surface, $border, etc.) update.
+        textual_theme = theme.to_textual_theme()
+        self.register_theme(textual_theme)
+        self.theme = textual_theme.name
+
         # Force refresh content
         content = self.query_one("#content")
         content.remove_children()
@@ -148,28 +154,6 @@ def build_content(self) -> list[Vertical]:
         # Left column widgets
         left_widgets.append(Label(f"Theme: {theme.meta.name}", classes="section-title"))
 
-        # Palette ramps
-        if theme.palette and isinstance(theme.palette, dict):
-            left_widgets.append(Label("Palette:", classes="section-title"))
-
-            # Show neutral ramp first
-            colors = [c for c in theme.palette["neutral"] if c]
-            if colors:
-                left_widgets.append(
-                    ColorRampDisplay("neutral", colors, classes="color-line")
-                )
-
-            # Show other ramps
-            for name in sorted(theme.palette.keys()):
-                if name != "neutral":
-                    ramp = theme.palette[name]
-                    if isinstance(ramp, ColorRamp):
-                        colors = [c for c in ramp if c]
-                        if colors:
-                            left_widgets.append(
-                                ColorRampDisplay(name, colors, classes="color-line")
-                            )
-
         # ANSI colors
         left_widgets.append(Label("ANSI Colors:", classes="section-title"))
         ansi_colors = [
@@ -196,6 +180,28 @@ def build_content(self) -> list[Vertical]:
                 label.styles.color = color
                 left_widgets.append(label)
 
+        # Palette ramps
+        if theme.palette and isinstance(theme.palette, dict):
+            left_widgets.append(Label("Palette:", classes="section-title"))
+
+            # Show neutral ramp first
+            colors = [c for c in theme.palette["neutral"] if c]
+            if colors:
+                left_widgets.append(
+                    ColorRampDisplay("neutral", colors, classes="color-line")
+                )
+
+            # Show other ramps
+            for name in sorted(theme.palette.keys()):
+                if name != "neutral":
+                    ramp = theme.palette[name]
+                    if isinstance(ramp, ColorRamp):
+                        colors = [c for c in ramp if c]
+                        if colors:
+                            left_widgets.append(
+                                ColorRampDisplay(name, colors, classes="color-line")
+                            )
+
         # Right column widgets
 
         # Semantic colors

src/tca/textual.py

@@ -53,6 +53,24 @@ def color_system(self) -> ColorSystem:
             dark=self.meta.is_dark,
         )
 
+    def to_textual_theme(self) -> Any:
+        """Build a textual.theme.Theme that can be registered with App.register_theme()."""
+        from textual.theme import Theme as _TTextualTheme
+        return _TTextualTheme(
+            name=self.meta.slug,
+            primary=self.semantic.info,
+            secondary=self.ui.fg_secondary,
+            warning=self.semantic.warning,
+            error=self.semantic.error,
+            success=self.semantic.success,
+            accent=self.semantic.highlight,
+            foreground=self.ui.fg_primary,
+            background=self.ui.bg_primary,
+            surface=self.ui.bg_secondary,
+            panel=self.ui.bg_secondary,
+            dark=self.meta.is_dark,
+        )
+
     def ansi_color(self, name: str) -> Color:
         """Get ANSI color by name as Textual Color."""
         return _color(getattr(self.ansi, name))