Make Share work.

Diffusion-macOS/ContentView.swift

@@ -20,8 +20,13 @@ struct ContentView: View {
                 .frame(width: 512, height: 512)
                 .cornerRadius(15)
                 .toolbar {
-                    Button(action: {}) {
+                    if case .complete(let prompt, let cgImage, _) = generation.state, let cgImage = cgImage {
-                        Label("share", systemImage: "square.and.arrow.up")
+                        let image = Image(cgImage, scale: 1, label: Text(prompt))
+                        ShareLink(prompt, item: image, preview: SharePreview(prompt, image: image))
+                    } else {
+                        let prompt = DEFAULT_PROMPT
+                        let image = Image("placeholder")
+                        ShareLink(prompt, item: image, preview: SharePreview(prompt, image: image))
                     }
                 }
 

Diffusion/State.swift

@@ -10,6 +10,7 @@ import SwiftUI
 import StableDiffusion
 
 let DEFAULT_MODEL = ModelInfo.v2Base
+let DEFAULT_PROMPT = "Labrador in the style of Vermeer"
 
 enum GenerationState {
     case startup
@@ -35,7 +36,7 @@ class GenerationContext: ObservableObject {
     }
     @Published var state: GenerationState = .startup
     
-    @Published var positivePrompt = "Labrador in the style of Vermeer"
+    @Published var positivePrompt = DEFAULT_PROMPT
     @Published var negativePrompt = ""
     
     // FIXME: Double to support the slider component