Allow gtk modifiers to be expressed as css attributes. (#345)

Sources/TokamakGTK/Modifiers/LayoutModifiers.swift

@@ -19,15 +19,13 @@ import CGTK
 import TokamakCore
 
 extension _FrameLayout: WidgetModifier {
-  public func modify(widget: UnsafeMutablePointer<GtkWidget>) {
+  func modify(widget: UnsafeMutablePointer<GtkWidget>) {
     gtk_widget_set_size_request(widget, Int32(width ?? -1), Int32(height ?? -1))
-    // gtk_widget_set_halign(widget, alignment.horizontal.gtkValue)
-    // gtk_widget_set_valign(widget, alignment.vertical.gtkValue)
   }
 }
 
 extension _FlexFrameLayout: WidgetModifier {
-  public func modify(widget: UnsafeMutablePointer<GtkWidget>) {
+  func modify(widget: UnsafeMutablePointer<GtkWidget>) {
     gtk_widget_set_halign(widget, alignment.horizontal.gtkValue)
     gtk_widget_set_valign(widget, alignment.vertical.gtkValue)
     if maxWidth == .infinity {
@@ -44,13 +42,32 @@ extension _FlexFrameLayout: WidgetModifier {
   }
 }
 
-extension _BackgroundModifier: WidgetModifier where Background == Color {
-    public func modify(widget: UnsafeMutablePointer<GtkWidget>) {
-        let resolved = _ColorProxy(self.background).resolve(in: environment)
-        var color = GdkRGBA(red: resolved.red,
-                            green: resolved.green,
-                            blue: resolved.blue,
-                            alpha: resolved.opacity)
-        gtk_widget_override_background_color(widget, GtkStateFlags(rawValue: 0), &color)
-    }
+extension Color {
+  func cssValue(_ environment: EnvironmentValues) -> String {
+    let rgba = _ColorProxy(self).resolve(in: environment)
+    return "rgba(\(rgba.red * 255), \(rgba.green * 255), \(rgba.blue * 255), \(rgba.opacity))"
+  }
+}
+
+// Border modifier
+extension _OverlayModifier: WidgetAttributeModifier, WidgetModifier
+  where Overlay == _ShapeView<_StrokedShape<TokamakCore.Rectangle._Inset>, Color>
+{
+  var attributes: [String: String] {
+    let style = overlay.shape.style.dashPhase == 0 ? "solid" : "dashed"
+
+    return [
+      "border-style": style,
+      "border-width": "\(overlay.shape.style.lineWidth)px",
+      "border-color": overlay.style.cssValue(environment),
+      "border-radius": "inherit"
+    ]
+  }
+}
+
+extension _BackgroundModifier: WidgetAttributeModifier, WidgetModifier where Background == Color {
+  var attributes: [String: String] {
+    let cssValue = background.cssValue(environment)
+    return ["background": cssValue]
+  }
 }

Sources/TokamakGTK/Modifiers/WidgetModifier.swift

@@ -22,6 +22,30 @@ protocol WidgetModifier {
   func modify(widget: UnsafeMutablePointer<GtkWidget>)
 }
 
+protocol WidgetAttributeModifier: WidgetModifier {
+  var attributes: [String: String] { get }
+}
+
+extension WidgetAttributeModifier {
+  func modify(widget: UnsafeMutablePointer<GtkWidget>) {
+    let context = gtk_widget_get_style_context(widget)
+    let provider = gtk_css_provider_new()
+
+    let renderedStyle = attributes.reduce("", { $0 + "\($1.0):\($1.1);"})
+
+    gtk_css_provider_load_from_data(provider,
+                                    "* { \(renderedStyle) }",
+                                    -1,
+                                    nil)
+
+    gtk_style_context_add_provider(context,
+                                   OpaquePointer(provider),
+                                   1 /* GTK_STYLE_PROVIDER_PRIORITY_FALLBACK */)
+
+    g_object_unref(provider)
+  }
+}
+
 extension ModifiedContent: ViewDeferredToRenderer where Content: View {
   public var deferredBody: AnyView {
     guard let widgetModifier = modifier as? WidgetModifier else {

Sources/TokamakGTKDemo/main.swift

@@ -22,7 +22,9 @@ struct Counter: View {
   @State private var count: Int = 0
   var body: some View {
     VStack {
-      Text("\(count)").background(Color(red: 0.5, green: 1, blue: 0.5))
+      Text("\(count)")
+        .background(Color(red: 0.5, green: 1, blue: 0.5))
+        .border(Color.red, width: 1)
       HStack {
         Button("Decrement") { count -= 1 }
         Button("Increment") { count += 1 }