Renderer: Add link icons

GeminiRenderer/DocumentView.swift

@@ -35,7 +35,7 @@ public struct DocumentView: View {
     private var scrollBody: some View {
         MaybeLazyVStack(alignment: .leading) {
             ForEach(blocks.indices) { (index) in
-                RenderingBlockView(block: blocks[index], changeURL: changeURL)
+                RenderingBlockView(document: document, block: blocks[index], changeURL: changeURL)
             }
         }.padding([.leading, .trailing, .bottom])
     }

GeminiRenderer/RenderingBlockView.swift

@@ -9,11 +9,13 @@ import SwiftUI
 import GeminiFormat
 
 struct RenderingBlockView: View {
+    let document: Document
     let block: RenderingBlock
     let changeURL: ((URL) -> Void)?
     @State var hovering = false
     
-    init(block: RenderingBlock, changeURL: ((URL) -> Void)? = nil) {
+    init(document: Document, block: RenderingBlock, changeURL: ((URL) -> Void)? = nil) {
+        self.document = document
         self.block = block
         self.changeURL = changeURL
     }
@@ -51,25 +53,34 @@ struct RenderingBlockView: View {
             let buttonStyle = PlainButtonStyle()
         #endif
         
+        let imageName: String
+        if url.scheme != "gemini" {
+            imageName = "arrow.up.left.square"
+        } else if url.host == document.url.host {
+            imageName = "arrow.right"
+        } else {
+            imageName = "link"
+        }
+        
         let button: some View = Button {
             self.changeURL?(url)
         } label: {
+            HStack(alignment: .firstTextBaseline, spacing: 4) {
+                Image(systemName: imageName)
+                
                 Text(verbatim: text)
                     .font(.documentBody)
                     .foregroundColor(hovering ? .blue : Color.blue.opacity(0.8))
                     .underline()
                     .frame(maxWidth: .infinity, alignment: .leading)
             }
+        }
             .buttonStyle(buttonStyle)
             .onHover { hovering in
                 self.hovering = hovering
             }
         
-        if #available(macOS 10.16, iOS 14.0, *) {
-            return AnyView(button.help(url.absoluteString))
-        } else {
-            return AnyView(button)
-        }
+        return button.maybeHelp(url.absoluteString)
     }
     
     private func preformatted(_ text: String) -> some View {
@@ -109,10 +120,12 @@ struct RenderingBlockView: View {
 }
 
 struct RenderingBlockView_Previews: PreviewProvider {
+    static let doc = Document(url: URL(string: "gemini://localhost/test.gmi")!, lines: [.text("Some Text"), .quote("A Quote")])
+    
     static var previews: some View {
         Group {
-            RenderingBlockView(block: .text("Some Text"))
-            RenderingBlockView(block: .quote("A Quote"))
+            RenderingBlockView(document: doc, block: .text("Some Text"))
+            RenderingBlockView(document: doc, block: .quote("A Quote"))
         }
     }
 }

GeminiRenderer/View+Extensions.swift

@@ -0,0 +1,21 @@
+//
+//  View+Extensions.swift
+//  GeminiRenderer
+//
+//  Created by Shadowfacts on 9/29/20.
+//
+
+import SwiftUI
+
+extension View {
+    
+    @ViewBuilder
+    func maybeHelp(_ help: String) -> some View {
+        if #available(iOS 14.0, macOS 11.0, *) {
+            self.help(help)
+        } else {
+            self
+        }
+    }
+    
+}