Share a deck or a profile as a QR code

androidApp/src/main/AndroidManifest.xml

@@ -199,6 +199,19 @@
                 <data android:pathPattern=".*\\..*\\..*\\..*\\.apkg" />
             </intent-filter>
         </activity>
+
+        <!-- The QR image the share sheet attaches. Not exported: the receiving app reads it
+             through the one-shot grant on the ACTION_SEND intent, which is what
+             FLAG_GRANT_READ_URI_PERMISSION there is for. -->
+        <provider
+            android:name="androidx.core.content.FileProvider"
+            android:authorities="${applicationId}.fileprovider"
+            android:exported="false"
+            android:grantUriPermissions="true">
+            <meta-data
+                android:name="android.support.FILE_PROVIDER_PATHS"
+                android:resource="@xml/file_paths" />
+        </provider>
     </application>
 
 </manifest>

androidApp/src/main/kotlin/com/github/jvsena42/loopky/ui/components/QrCode.kt

@@ -7,7 +7,6 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.graphics.ImageBitmap
 import androidx.compose.ui.graphics.asImageBitmap
 import androidx.compose.ui.graphics.toArgb
 import androidx.compose.ui.layout.ContentScale
@@ -44,7 +43,7 @@ fun QrCode(
 ) {
     val sizePx = with(LocalDensity.current) { size.roundToPx() }
     val bitmap = remember(content, sizePx, foreground, background) {
-        encodeQr(content, sizePx, foreground.toArgb(), background.toArgb())
+        qrBitmap(content, sizePx, foreground.toArgb(), background.toArgb())?.asImageBitmap()
     } ?: return
 
     Image(
@@ -57,7 +56,18 @@ fun QrCode(
     )
 }
 
-private fun encodeQr(content: String, sizePx: Int, fgArgb: Int, bgArgb: Int): ImageBitmap? {
+/**
+ * The same code as [QrCode], as a plain bitmap — for the callers that hand one to something other
+ * than composition, such as the share sheet attaching it to an `ACTION_SEND`.
+ *
+ * `null` when the encoder refuses [content], exactly as [QrCode] draws nothing for it.
+ */
+fun qrBitmap(
+    content: String,
+    sizePx: Int,
+    fgArgb: Int = Color.Black.toArgb(),
+    bgArgb: Int = Color.White.toArgb(),
+): Bitmap? {
     if (content.isEmpty() || sizePx <= 0) return null
     val matrix = runCatching {
         QRCodeWriter().encode(
@@ -86,7 +96,7 @@ private fun encodeQr(content: String, sizePx: Int, fgArgb: Int, bgArgb: Int): Im
     }
     return Bitmap.createBitmap(sizePx, sizePx, Bitmap.Config.ARGB_8888).apply {
         setPixels(pixels, 0, sizePx, 0, 0, sizePx, sizePx)
-    }.asImageBitmap()
+    }
 }
 
 private val DEFAULT_SIZE = 220.dp

androidApp/src/main/kotlin/com/github/jvsena42/loopky/ui/components/ShareLinkSheet.kt

@@ -0,0 +1,213 @@
+package com.github.jvsena42.loopky.ui.components
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.ModalBottomSheet
+import androidx.compose.material3.Text
+import androidx.compose.material3.rememberModalBottomSheetState
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.platform.LocalClipboardManager
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.semantics.semantics
+import androidx.compose.ui.semantics.testTagsAsResourceId
+import androidx.compose.ui.text.AnnotatedString
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+import com.github.jvsena42.loopky.R
+import com.github.jvsena42.loopky.ui.layout.PaneWidth
+import com.github.jvsena42.loopky.ui.layout.contentPane
+import com.github.jvsena42.loopky.ui.theme.LoopkyTheme
+import com.github.jvsena42.loopky.ui.util.shareLinkWithQr
+import kotlinx.coroutines.delay
+
+/**
+ * [ShareLinkSheet] for [target], or nothing when there is none.
+ *
+ * The copy and share behaviour is the same wherever a share button is, so it lives here rather
+ * than in each screen that raises one.
+ */
+@Composable
+fun ShareLinkSheetHost(target: ShareLinkTarget?, onDismiss: () -> Unit) {
+    if (target == null) return
+    val context = LocalContext.current
+    val clipboard = LocalClipboardManager.current
+    // On the button rather than in a toast: Android 13 raises its own clipboard confirmation, and
+    // a toast lands on top of it — two notices, both over the buttons that just moved out of reach.
+    var copied by remember(target.link) { mutableStateOf(false) }
+    LaunchedEffect(copied) {
+        if (copied) {
+            delay(COPIED_LABEL_MS)
+            copied = false
+        }
+    }
+    ShareLinkSheet(
+        title = target.title,
+        link = target.link,
+        copied = copied,
+        onCopy = {
+            clipboard.setText(AnnotatedString(target.link))
+            copied = true
+        },
+        onShare = {
+            context.shareLinkWithQr(
+                text = target.message,
+                link = target.link,
+                chooserTitle = context.getString(target.chooserTitle),
+            )
+            onDismiss()
+        },
+        onDismiss = onDismiss,
+    )
+}
+
+/**
+ * What a share button raises: the link as a QR code, with the ways out of the app underneath.
+ *
+ * The code is the point of the sheet. Sharing used to go straight to the system chooser, which
+ * only ever helps someone who already has the recipient in a messaging app — the person sitting
+ * across the table had no way to take the link off the screen. A code they can point a camera at
+ * needs no channel at all, and the same picture is what [onShare] attaches.
+ */
+@OptIn(ExperimentalMaterial3Api::class, ExperimentalComposeUiApi::class)
+@Composable
+fun ShareLinkSheet(
+    title: String,
+    link: String,
+    copied: Boolean,
+    onCopy: () -> Unit,
+    onShare: () -> Unit,
+    onDismiss: () -> Unit,
+) {
+    val colors = LoopkyTheme.colors
+    ModalBottomSheet(
+        onDismissRequest = onDismiss,
+        sheetState = rememberModalBottomSheetState(skipPartiallyExpanded = true),
+        // A raised surface cannot take the ground's colour, or in dark mode the sheet has no edge.
+        containerColor = colors.surfaceSecondary,
+    ) {
+        Column(
+            modifier = Modifier
+                // A sheet spans the window, so on a tablet the buttons would otherwise sit a
+                // thousand dp apart with the code stranded between them.
+                .contentPane(PaneWidth.Focused)
+                .semantics { testTagsAsResourceId = true }
+                .testTag("share_link_sheet")
+                .padding(horizontal = 24.dp)
+                .padding(bottom = 32.dp),
+            horizontalAlignment = Alignment.CenterHorizontally,
+            verticalArrangement = Arrangement.spacedBy(16.dp),
+        ) {
+            Text(
+                text = title,
+                color = colors.foregroundPrimary,
+                fontSize = 20.sp,
+                fontWeight = FontWeight.ExtraBold,
+                textAlign = TextAlign.Center,
+                maxLines = 2,
+                overflow = TextOverflow.Ellipsis,
+            )
+            Text(
+                text = stringResource(R.string.share_sheet_hint),
+                color = colors.foregroundSecondary,
+                fontSize = 14.sp,
+                textAlign = TextAlign.Center,
+            )
+            // White in both themes: a QR inverted for dark mode is not one any scanner will read,
+            // and this padding is the quiet zone the encoder is only asked for one module of.
+            Box(
+                modifier = Modifier
+                    .clip(RoundedCornerShape(20.dp))
+                    .background(Color.White)
+                    .padding(16.dp),
+            ) {
+                QrCode(
+                    content = link,
+                    contentDescription = stringResource(R.string.share_sheet_qr_content_description),
+                )
+            }
+            Text(
+                text = link,
+                color = colors.foregroundMuted,
+                fontSize = 12.sp,
+                textAlign = TextAlign.Center,
+                // Middle, not tail: a pubky URI's two ends are what identify it — the account at
+                // the front, the deck id at the back — and eliding the back leaves 60 characters
+                // of key saying nothing. One line, since a wrapped address never elides at all.
+                maxLines = 1,
+                overflow = TextOverflow.MiddleEllipsis,
+                softWrap = false,
+                modifier = Modifier.testTag("share_link_uri"),
+            )
+            Row(
+                modifier = Modifier.fillMaxWidth(),
+                horizontalArrangement = Arrangement.spacedBy(12.dp),
+            ) {
+                LoopkyOutlinedButton(
+                    label = stringResource(
+                        if (copied) R.string.share_sheet_copied else R.string.share_sheet_copy,
+                    ),
+                    onClick = onCopy,
+                    modifier = Modifier
+                        .weight(1f)
+                        .testTag("share_link_copy"),
+                )
+                LoopkyPrimaryButton(
+                    label = stringResource(R.string.share_sheet_send),
+                    onClick = onShare,
+                    modifier = Modifier
+                        .weight(1f)
+                        .testTag("share_link_send"),
+                )
+            }
+        }
+    }
+}
+
+@Preview
+@Composable
+private fun ShareLinkSheetPreview() {
+    LoopkyTheme {
+        Column(
+            modifier = Modifier
+                .background(LoopkyTheme.colors.surfaceSecondary)
+                .padding(24.dp),
+            horizontalAlignment = Alignment.CenterHorizontally,
+            verticalArrangement = Arrangement.spacedBy(16.dp),
+        ) {
+            Text(text = "Spanish Verbs", fontWeight = FontWeight.ExtraBold, fontSize = 20.sp)
+            Box(
+                modifier = Modifier
+                    .clip(RoundedCornerShape(20.dp))
+                    .background(Color.White)
+                    .padding(16.dp),
+            ) {
+                QrCode(content = "pubky://abc/pub/loopky/decks/deck1/manifest.json")
+            }
+        }
+    }
+}
+
+private const val COPIED_LABEL_MS = 2000L

androidApp/src/main/kotlin/com/github/jvsena42/loopky/ui/components/ShareLinkTarget.kt

@@ -0,0 +1,17 @@
+package com.github.jvsena42.loopky.ui.components
+
+import androidx.annotation.StringRes
+
+/**
+ * A link a share button has raised [ShareLinkSheet] for.
+ *
+ * [message] is what leaves the app — the named line a recipient reads — while [link] is the bare
+ * address that goes into the code and onto the clipboard. Sharing the message and copying the
+ * address is deliberate: a pasted link is usually about to be opened, and a pasted sentence is not.
+ */
+data class ShareLinkTarget(
+    val title: String,
+    val link: String,
+    val message: String,
+    @StringRes val chooserTitle: Int,
+)

androidApp/src/main/kotlin/com/github/jvsena42/loopky/ui/decks/DeckDetailScreen.kt

@@ -36,8 +36,10 @@ import androidx.compose.material3.TextButton
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberUpdatedState
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.alpha
@@ -63,6 +65,8 @@ import com.github.jvsena42.loopky.ui.components.CardPreviewRow
 import com.github.jvsena42.loopky.ui.components.ExpandableLinkedText
 import com.github.jvsena42.loopky.ui.components.LoopkyLoadingScreen
 import com.github.jvsena42.loopky.ui.components.LoopkyPrimaryButton
+import com.github.jvsena42.loopky.ui.components.ShareLinkSheetHost
+import com.github.jvsena42.loopky.ui.components.ShareLinkTarget
 import com.github.jvsena42.loopky.ui.components.SharePromptDialog
 import com.github.jvsena42.loopky.ui.components.SignInPromptDialog
 import com.github.jvsena42.loopky.ui.components.errorMessage
@@ -72,7 +76,6 @@ import com.github.jvsena42.loopky.ui.layout.contentPane
 import com.github.jvsena42.loopky.ui.layout.windowWidthClass
 import com.github.jvsena42.loopky.ui.theme.LoopkyTheme
 import com.github.jvsena42.loopky.ui.util.label
-import com.github.jvsena42.loopky.ui.util.shareText
 import com.github.jvsena42.loopky.ui.util.toast
 import kotlinx.coroutines.flow.collectLatest
 import org.koin.compose.viewmodel.koinViewModel
@@ -108,16 +111,20 @@ fun DeckDetailRoute(
     val currentOpenProfile by rememberUpdatedState(onOpenProfile)
     val currentOpenClone by rememberUpdatedState(onOpenClone)
 
+    var shareTarget by remember { mutableStateOf<ShareLinkTarget?>(null) }
+
     LaunchedEffect(viewModel) {
         viewModel.effects.collectLatest { effect ->
             when (effect) {
                 DeckDetailEffect.NavigateBack -> currentBack()
                 is DeckDetailEffect.NavigateEditDeck -> currentEditDeck(effect.deckId)
                 DeckDetailEffect.NavigateStudy -> currentStudy(deckId)
                 DeckDetailEffect.NavigateStudyPreview -> currentPreview(deckId)
-                is DeckDetailEffect.Share -> context.shareText(
-                    text = context.getString(R.string.share_deck_body, effect.title, effect.uri),
-                    chooserTitle = context.getString(R.string.share_deck_chooser_title),
+                is DeckDetailEffect.Share -> shareTarget = ShareLinkTarget(
+                    title = effect.title,
+                    link = effect.uri,
+                    message = context.getString(R.string.share_deck_body, effect.title, effect.uri),
+                    chooserTitle = R.string.share_deck_chooser_title,
                 )
                 DeckDetailEffect.Deleted -> currentBack()
                 is DeckDetailEffect.Cloned -> currentOpenClone(effect.deckId)
@@ -170,6 +177,8 @@ fun DeckDetailRoute(
             onNeverAsk = viewModel::onShareNeverAsk,
         )
     }
+
+    ShareLinkSheetHost(target = shareTarget, onDismiss = { shareTarget = null })
 }
 
 @Composable