feat: add Share as Image (local file) and rename upload flow to Share as Image Url

Adds a second "Share as Image" entry to a note's 3-dot menu that renders
the same framed card, captures it to a PNG and hands the local file
straight to the Android share sheet — no preview, no upload. The existing
upload-and-share-URL flow is renamed to "Share as Image Url".

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JM7z36GaqCm612rjPnX2G9

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/navigation/AppNavigation.kt

@@ -59,6 +59,7 @@ import com.vitorpamplona.amethyst.ui.navigation.routes.isSameRoute
 import com.vitorpamplona.amethyst.ui.note.PayViaIntentScreen
 import com.vitorpamplona.amethyst.ui.note.UpdateReactionTypeScreen
 import com.vitorpamplona.amethyst.ui.note.nip22Comments.ReplyCommentPostScreen
+import com.vitorpamplona.amethyst.ui.note.share.ShareNoteAsImageFileScreen
 import com.vitorpamplona.amethyst.ui.note.share.ShareNoteAsImageScreen
 import com.vitorpamplona.amethyst.ui.screen.AccountSessionManager
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountSwitcherAndLeftDrawerLayout
@@ -417,6 +418,7 @@ fun BuildNavigation(
         composableFromEndArgs<Route.Profile> { ProfileScreen(it.id, accountViewModel, nav) }
         composableFromEndArgs<Route.Note> { ThreadScreen(it.id, accountViewModel, nav) }
         composableFromEndArgs<Route.ShareNoteAsImage> { ShareNoteAsImageScreen(it.id, accountViewModel, nav) }
+        composableFromEndArgs<Route.ShareNoteAsImageFile> { ShareNoteAsImageFileScreen(it.id, accountViewModel, nav) }
         composableFromEndArgs<Route.ContactListUsers> { ContactListUsersScreen(it.noteId, accountViewModel, nav) }
         composableFromEndArgs<Route.Hashtag> { HashtagScreen(it, accountViewModel, nav) }
         composableFromEndArgs<Route.Geohash> { GeoHashScreen(it, accountViewModel, nav) }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/navigation/routes/Routes.kt

@@ -436,6 +436,10 @@ sealed class Route {
         val id: String,
     ) : Route()
 
+    @Serializable data class ShareNoteAsImageFile(
+        val id: String,
+    ) : Route()
+
     @Serializable data class ContactListUsers(
         val noteId: String,
     ) : Route()

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/elements/DropDownMenu.kt

@@ -240,6 +240,11 @@ fun NoteDropDownMenu(
                     onDismiss()
                 }
                 M3ActionRow(icon = MaterialSymbols.Image, text = stringRes(R.string.share_as_image)) {
+                    val shareId = if (note is AddressableNote) note.address.toValue() else note.idHex
+                    nav.nav(Route.ShareNoteAsImageFile(shareId))
+                    onDismiss()
+                }
+                M3ActionRow(icon = MaterialSymbols.Image, text = stringRes(R.string.share_as_image_url)) {
                     val shareId = if (note is AddressableNote) note.address.toValue() else note.idHex
                     nav.nav(Route.ShareNoteAsImage(shareId))
                     onDismiss()

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/share/ShareNoteAsImageScreen.kt

@@ -120,6 +120,89 @@ fun ShareNoteAsImageScreen(
     }
 }
 
+/**
+ * Renders [id]'s note into the same framed card as [ShareNoteAsImageScreen], captures it to a
+ * bitmap, writes it to the cache as a PNG and hands the local file straight to the Android share
+ * sheet — no preview, no upload. The screen only shows a brief progress indicator while the card
+ * is being captured.
+ */
+@Composable
+fun ShareNoteAsImageFileScreen(
+    id: String,
+    accountViewModel: AccountViewModel,
+    nav: INav,
+) {
+    LoadNote(id, accountViewModel) { note ->
+        if (note != null) {
+            ShareNoteAsImageFileScreen(note, accountViewModel, nav)
+        }
+    }
+}
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun ShareNoteAsImageFileScreen(
+    note: Note,
+    accountViewModel: AccountViewModel,
+    nav: INav,
+) {
+    val context = LocalContext.current
+    val graphicsLayer = rememberGraphicsLayer()
+
+    // Guards against capturing/sharing more than once across recompositions.
+    var shared by remember { mutableStateOf(false) }
+
+    Scaffold(
+        topBar = { TopBarWithBackButton(stringRes(R.string.share_as_image), nav) },
+    ) { pad ->
+        Box(
+            modifier =
+                Modifier
+                    .padding(pad)
+                    .fillMaxSize()
+                    .background(
+                        Brush.verticalGradient(
+                            listOf(
+                                MaterialTheme.colorScheme.surface,
+                                MaterialTheme.colorScheme.surfaceVariant,
+                            ),
+                        ),
+                    ),
+            contentAlignment = Alignment.Center,
+        ) {
+            // Rendered (but unpainted) only to feed the snapshot; the user never sees this card.
+            CaptureSource(
+                note = note,
+                graphicsLayer = graphicsLayer,
+                accountViewModel = accountViewModel,
+                nav = nav,
+            )
+
+            GeneratingPreview()
+
+            LaunchedEffect(note) {
+                // Wait a couple of frames so the card is measured and drawn, then let network
+                // media settle before the final snapshot.
+                withFrameNanos {}
+                withFrameNanos {}
+                graphicsLayer.toImageBitmap()
+                delay(IMAGE_SETTLE_MS)
+                val bitmap = graphicsLayer.toImageBitmap()
+
+                if (!shared) {
+                    shared = true
+                    val uri =
+                        withContext(Dispatchers.IO) {
+                            saveBitmapToCache(context, bitmap.asAndroidBitmap())
+                        }
+                    startShareImageFileIntent(context, uri)
+                    nav.popBack()
+                }
+            }
+        }
+    }
+}
+
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
 fun ShareNoteAsImageScreen(
@@ -208,7 +291,7 @@ fun ShareNoteAsImageScreen(
     }
 
     Scaffold(
-        topBar = { TopBarWithBackButton(stringRes(R.string.share_as_image), nav) },
+        topBar = { TopBarWithBackButton(stringRes(R.string.share_as_image_url), nav) },
         bottomBar = {
             ShareBottomBar(
                 serverName = selectedServer.name,
@@ -451,6 +534,21 @@ private fun startShareUrlIntent(
             type = "text/plain"
             putExtra(Intent.EXTRA_TEXT, url)
         }
+    val shareIntent = Intent.createChooser(sendIntent, stringRes(context, R.string.share_as_image_url))
+    context.startActivity(shareIntent)
+}
+
+private fun startShareImageFileIntent(
+    context: Context,
+    uri: Uri,
+) {
+    val sendIntent =
+        Intent().apply {
+            action = Intent.ACTION_SEND
+            type = PNG_MIME
+            putExtra(Intent.EXTRA_STREAM, uri)
+            addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
+        }
     val shareIntent = Intent.createChooser(sendIntent, stringRes(context, R.string.share_as_image))
     context.startActivity(shareIntent)
 }

amethyst/src/main/res/values/strings.xml

@@ -474,6 +474,7 @@
     <string name="quick_action_share_browser_link">Share Browser Link</string>
     <string name="quick_action_share">Share</string>
     <string name="share_as_image">Share as Image</string>
+    <string name="share_as_image_url">Share as Image Url</string>
     <string name="share_as_image_generating">Generating preview…</string>
     <string name="share_as_image_watermark">Shared via Amethyst</string>
     <string name="quick_action_copy_user_id">Author ID</string>