Merge pull request #61 from PureSwift/feature/link

Add Link

Author: colemancda

AndroidSwiftUICore/Sources/AndroidSwiftUICore/Primitives/Link.swift

@@ -0,0 +1,40 @@
+//
+//  Link.swift
+//  AndroidSwiftUICore
+//
+//  Opens a URL outside the app. Nothing crosses back into Swift: the
+//  interpreter hands the address to Compose's UriHandler, so the platform
+//  decides which app answers it and no callback or bridge entry is involved.
+//
+
+import Foundation
+
+public struct Link<Label: View>: View {
+
+    internal let destination: URL
+    internal let label: Label
+
+    public init(destination: URL, @ViewBuilder label: () -> Label) {
+        self.destination = destination
+        self.label = label()
+    }
+
+    public typealias Body = Never
+}
+
+public extension Link where Label == Text {
+    init<S: StringProtocol>(_ title: S, destination: URL) {
+        self.init(destination: destination) { Text(title) }
+    }
+}
+
+extension Link: PrimitiveView {
+    public func _render(in context: ResolveContext) -> RenderNode {
+        RenderNode(
+            type: "Link",
+            id: context.path,
+            props: ["url": .string(destination.absoluteString)],
+            children: Evaluator.resolveChildren(label, context.descending("label"))
+        )
+    }
+}

AndroidSwiftUICore/Tests/AndroidSwiftUICoreTests/EvaluatorTests.swift

@@ -282,6 +282,29 @@ struct ModifierTests {
         #expect(empty.props["url"] == nil)
     }
 
+    @Test("Link carries its destination and its label")
+    func link() {
+        let node = ViewHost(
+            Link("Swift.org", destination: URL(string: "https://swift.org")!)
+        ).evaluate()
+        #expect(node.type == "Link")
+        #expect(node.props["url"] == .string("https://swift.org"))
+        #expect(firstTextString(node) == "Swift.org")
+        // no callback: the interpreter opens the address itself
+        #expect(node.props["onTap"] == nil)
+    }
+
+    @Test("Link accepts an arbitrary label")
+    func linkCustomLabel() {
+        let node = ViewHost(
+            Link(destination: URL(string: "https://example.com/docs")!) {
+                HStack { Text("Read"); Text("the docs") }
+            }
+        ).evaluate()
+        #expect(node.props["url"] == .string("https://example.com/docs"))
+        #expect(node.children.first?.type == "HStack")
+    }
+
     @Test("onAppear and onDisappear emit distinct callback kinds")
     func appearDisappear() {
         let node = ViewHost(Text("x").onAppear {}.onDisappear {}).evaluate()

Demo/App.swiftpm/Sources/Catalog.swift

@@ -42,6 +42,7 @@ struct CatalogEntry: Identifiable {
         CatalogEntry(id: "color", title: "Color", screen: AnyCatalogScreen(ColorPlayground())),
         CatalogEntry(id: "image", title: "Images", screen: AnyCatalogScreen(ImagePlayground())),
         CatalogEntry(id: "graphics", title: "Graphics", screen: AnyCatalogScreen(GraphicsPlayground())),
+        CatalogEntry(id: "link", title: "Link", screen: AnyCatalogScreen(LinkPlayground())),
         CatalogEntry(id: "map", title: "Map", screen: AnyCatalogScreen(MapPlayground())),
         CatalogEntry(id: "video", title: "Video", screen: AnyCatalogScreen(VideoPlayground())),
         CatalogEntry(id: "scroll", title: "ScrollView", screen: AnyCatalogScreen(ScrollViewPlayground())),

Demo/App.swiftpm/Sources/LinkPlaygrounds.swift

@@ -0,0 +1,33 @@
+#if canImport(AndroidSwiftUI)
+import AndroidSwiftUI
+#else
+import SwiftUI
+#endif
+import Foundation
+
+struct LinkPlayground: View {
+    var body: some View {
+        ScrollView {
+            VStack(alignment: .leading, spacing: 0) {
+                Example("Link with a title") {
+                    Link("Open swift.org", destination: URL(string: "https://swift.org")!)
+                }
+                Example("Link with a custom label") {
+                    Link(destination: URL(string: "https://developer.apple.com/documentation/swiftui")!) {
+                        HStack(spacing: 6) {
+                            Image(systemName: "star.fill")
+                            Text("SwiftUI documentation")
+                        }
+                    }
+                }
+                Example("Link inside a sentence") {
+                    VStack(alignment: .leading, spacing: 6) {
+                        Text("Questions? The forums are a good place to start.")
+                        Link("forums.swift.org", destination: URL(string: "https://forums.swift.org")!)
+                    }
+                }
+            }
+        }
+        .navigationTitle("Link")
+    }
+}

Demo/swiftui/src/commonMain/kotlin/com/pureswift/swiftui/Render.kt

@@ -158,6 +158,7 @@ import androidx.compose.ui.semantics.selected
 import androidx.compose.ui.semantics.Role
 import androidx.compose.ui.semantics.role
 import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.platform.LocalUriHandler
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.layout.ContentScale
 import androidx.compose.ui.graphics.ImageBitmap
@@ -342,6 +343,8 @@ private fun RenderResolved(node: ViewNode) {
                 }
             }
 
+            "Link" -> RenderLink(node)
+
             "GeometryReader" -> RenderGeometryReader(node)
 
             "LazyVStack" -> RenderLazyStack(node, vertical = true)
@@ -577,6 +580,27 @@ private fun RenderGeometryReader(node: ViewNode) {
     }
 }
 
+// Handing the address to the platform's UriHandler keeps the whole hop out of
+// Swift — no callback, no bridge entry. The label takes the accent colour so it
+// reads as a link, unless something upstream already tinted it.
+@Composable
+private fun RenderLink(node: ViewNode) {
+    val url = node.string("url")
+    val handler = LocalUriHandler.current
+    val accent = LocalTint.current ?: MaterialTheme.colorScheme.primary
+    Row(
+        verticalAlignment = Alignment.CenterVertically,
+        modifier = node.composeModifiers().clickable(enabled = url != null && node.isEnabled()) {
+            // a malformed or unhandled address must not take the app down
+            url?.let { runCatching { handler.openUri(it) } }
+        },
+    ) {
+        CompositionLocalProvider(LocalInheritedColor provides accent) {
+            RenderChildren(node)
+        }
+    }
+}
+
 private fun ViewNode.isPresentation(): Boolean =
     type == "Sheet" || type == "Alert" || type == "ConfirmationDialog" || type == "ToolbarItem"