Library: Port 'CSS Gradients' to Python (#724)

* Library: Port 'CSS Gradients' to Python

* Fix string formatting

* Use snake case

* Make it work

* library: CSS Gradients, py: Explicitly init GtkSource

---------

Co-authored-by: Marco Capypara Köpcke <[email protected]>

Author: 2 people

src/Library/demos/CSS Gradients/main.py

@@ -0,0 +1,121 @@
+import gi
+
+gi.require_version("Gtk", "4.0")
+gi.require_version("Gdk", "4.0")
+gi.require_version("Adw", "1")
+gi.require_version("GtkSource", "5")
+from gi.repository import Gtk, Gdk, Adw, GtkSource
+import workbench
+
+Adw.init()
+GtkSource.init()
+
+
+combo_row_gradient_type = workbench.builder.get_object(
+    "combo_row_gradient_type",
+)
+spin_row_angle = workbench.builder.get_object("spin_row_angle")
+button_color_1 = workbench.builder.get_object("button_color_1")
+button_color_2 = workbench.builder.get_object("button_color_2")
+button_color_3 = workbench.builder.get_object("button_color_3")
+gtksource_buffer = workbench.builder.get_object("gtksource_buffer")
+button_copy_css = workbench.builder.get_object("button_copy_css")
+
+
+def generate_css():
+    angle_string = spin_row_angle.get_value()
+    first_color_string = button_color_1.get_rgba().to_string()
+    second_color_string = button_color_2.get_rgba().to_string()
+    third_color_string = button_color_3.get_rgba().to_string()
+
+    css = ""
+    if combo_row_gradient_type.get_selected() == 0:
+        css = f"""
+.background-gradient {{
+  background-image: linear-gradient(
+    {angle_string}deg,
+    {first_color_string},
+    {second_color_string},
+    {third_color_string}
+  );
+}}"""
+    elif combo_row_gradient_type.get_selected() == 1:
+        css = f"""
+.background-gradient {{
+  background-image: radial-gradient(
+    {first_color_string},
+    {second_color_string},
+    {third_color_string}
+  );
+}}"""
+    elif combo_row_gradient_type.get_selected() == 2:
+        css = f"""
+.background-gradient {{
+  background-image: conic-gradient(
+    from {angle_string}deg,
+    {first_color_string},
+    {second_color_string},
+    {third_color_string}
+  );
+}}"""
+
+    return css.lstrip()
+
+
+def update_css_provider(css):
+    display = Gdk.Display.get_default()
+
+    css_provider = Gtk.CssProvider()
+    css_provider.load_from_string(css)
+    Gtk.StyleContext.add_provider_for_display(
+        display,
+        css_provider,
+        Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION,
+    )
+
+
+def update(*args):
+    spin_row_angle.set_sensitive(combo_row_gradient_type.get_selected() != 1)
+    css = generate_css()
+    gtksource_buffer.set_text(css, -1)
+    update_css_provider(css)
+
+
+combo_row_gradient_type.connect("notify::selected", update)
+spin_row_angle.connect("notify::value", update)
+button_color_1.connect("notify::rgba", update)
+button_color_2.connect("notify::rgba", update)
+button_color_3.connect("notify::rgba", update)
+
+update()
+
+
+clipboard = Gdk.Display.get_default().get_clipboard()
+
+button_copy_css.connect(
+    "clicked",
+    lambda *args: clipboard.set(
+        gtksource_buffer.get_text(
+            gtksource_buffer.get_start_iter(), gtksource_buffer.get_end_iter(), False
+        )
+    ),
+)
+
+scheme_manager = GtkSource.StyleSchemeManager.get_default()
+
+
+def update_color_scheme():
+    scheme = scheme_manager.get_scheme(
+        "Adwaita-dark" if style_manager.get_dark() else "Adwaita"
+    )
+    gtksource_buffer.set_style_scheme(scheme)
+
+
+style_manager = Adw.StyleManager.get_default()
+style_manager.connect("notify::dark", lambda *args: update_color_scheme)
+
+update_color_scheme()
+
+language_manager = GtkSource.LanguageManager.get_default()
+css_language = language_manager.get_language("css")
+gtksource_buffer.set_language(css_language)