Support sharing images to reverse search

app/src/main/AndroidManifest.xml

@@ -2,6 +2,12 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+    <!-- android:configChanges="uiMode" is added to prevent the activity from recreating itself
+         during night mode change, avoiding unnecessary state resets wherever possible.
+
+         android:documentLaunchMode="intoExisting" is added to prevent the activity from stacking
+         on top of the current app while sharing images (if no existing instance of Breadboard was
+         found) on older Android versions. -->
     <application
         android:allowBackup="true"
         android:dataExtractionRules="@xml/data_extraction_rules"
@@ -12,29 +18,32 @@
         android:supportsRtl="true"
         android:theme="@style/Theme.Breadboard"
         android:windowSoftInputMode="adjustResize"
-        android:enableOnBackInvokedCallback="true">
+        android:enableOnBackInvokedCallback="true"
+        android:configChanges="uiMode"
+        android:documentLaunchMode="intoExisting">
         <activity
             android:name=".MainActivity"
             android:launchMode="singleTop"
             android:taskAffinity="moe.apex.breadboard.MainActivity"
             android:exported="true"
-            android:theme="@style/Theme.Breadboard"
-            android:configChanges="uiMode"> <!-- Add "uiMode" to "configChanges" to prevent the
-                                                 activity from recreating itself during night mode
-                                                 change, avoiding unnecessary state resets wherever
-                                                 possible. -->
+            android:theme="@style/Theme.Breadboard">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
+            <intent-filter android:label="SauceNAO">
+                <action android:name="android.intent.action.SEND" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <data android:mimeType="image/*" />
+                <data android:mimeType="text/plain" />
+            </intent-filter>
         </activity>
         <activity
             android:name=".DeepLinkActivity"
             android:taskAffinity="moe.apex.breadboard.DeepLinkActivity"
             android:launchMode="singleTop"
             android:exported="true"
-            android:theme="@style/Theme.Breadboard"
-            android:configChanges="uiMode">
+            android:theme="@style/Theme.Breadboard">
 
             <intent-filter>
                 <action android:name="android.intent.action.VIEW" />

app/src/main/java/moe/apex/breadboard/MainActivity.kt

@@ -35,6 +35,7 @@ import moe.apex.breadboard.navigation.Favourites
 import moe.apex.breadboard.navigation.Home
 import moe.apex.breadboard.navigation.Navigation
 import moe.apex.breadboard.navigation.Results
+import moe.apex.breadboard.navigation.ReverseSearch
 import moe.apex.breadboard.navigation.Search
 import moe.apex.breadboard.preferences.DarkTheme
 import moe.apex.breadboard.preferences.ImageSource
@@ -90,6 +91,19 @@ class MainActivity : SingletonImageLoader.Factory, ComponentActivity(), VolumeBu
 
 
     private fun determineDestination(intent: Intent): Any? {
+        // Handle Intent.ACTION_SEND intent for reverse search
+        if (intent.action == Intent.ACTION_SEND) {
+            /* Sometimes a shared link may contain an image clipData of the favicon, so we must
+               prioritise the text over the clipData. Providing them both would be bad. */
+            intent.extras?.getString(Intent.EXTRA_TEXT)?.let { initialImageUrl ->
+                return ReverseSearch(initialImageUrl = initialImageUrl)
+            }
+
+            intent.clipData?.getItemAt(0)?.uri?.let { initialFileUri ->
+                return ReverseSearch(initialFileUri = initialFileUri.toString())
+            }
+        }
+
         return when (intent.getStringExtra("destination")) {
             "artist" -> maybePrepareArtistDestination(intent)
             "search" -> maybePrepareResultsDestination(intent)

app/src/main/java/moe/apex/breadboard/navigation/Destinations.kt

@@ -88,7 +88,7 @@ object FollowedArtists
 object Search
 
 @Serializable
-object ReverseSearch
+data class ReverseSearch(val initialImageUrl: String? = null, val initialFileUri: String? = null)
 
 @Serializable
 data class Results(

app/src/main/java/moe/apex/breadboard/navigation/Navigation.kt

@@ -202,8 +202,8 @@ fun Navigation(navController: NavHostController, startDestination: Any = Search)
                             },
                             onClick = {
                                 if (!currentRoute.routeIs(ReverseSearch::class)) {
-                                    navController.navigate(ReverseSearch) {
-                                        popUpTo(ReverseSearch) { inclusive = true }
+                                    navController.navigate(ReverseSearch()) {
+                                        popUpTo(ReverseSearch()) { inclusive = true }
                                     }
                                 }
                             }
@@ -288,7 +288,10 @@ fun Navigation(navController: NavHostController, startDestination: Any = Search)
                 }
                 composable<Home> { HomeScreen(navController) { isNavigationBarVisible = it } }
                 composable<Search> { SearchScreen(navController, focusRequester) }
-                composable<ReverseSearch> { ReverseSearchScreen(navController) }
+                composable<ReverseSearch> {
+                    val args = it.toRoute<ReverseSearch>()
+                    ReverseSearchScreen(navController, args.initialImageUrl, args.initialFileUri)
+                }
                 composable<Results> {
                     val args = it.toRoute<Results>()
                     SearchResults(navController, args.source, args.tags)

app/src/main/java/moe/apex/breadboard/saucenao/ReverseSearchScreen.kt

@@ -80,14 +80,18 @@ import moe.apex.breadboard.util.showToast
 
 @OptIn(ExperimentalMaterial3ExpressiveApi::class, ExperimentalMaterial3Api::class)
 @Composable
-fun ReverseSearchScreen(navController: NavController) {
+fun ReverseSearchScreen(
+    navController: NavController,
+    initialImageUrl: String? = null,
+    initialFileUri: String? = null
+) {
     val context = LocalContext.current
     val clipboard = LocalClipboard.current
     val prefs = LocalPreferences.current
     val scope = rememberCoroutineScope()
 
-    var imageUrl by rememberSaveable { mutableStateOf("") }
-    var selectedFileUri by rememberSaveable { mutableStateOf<Uri?>(null) }
+    var imageUrl by rememberSaveable { mutableStateOf(initialImageUrl ?: "") }
+    var selectedFileUri by rememberSaveable { mutableStateOf(initialFileUri?.toUri()) }
 
     val imagePickerLauncher = rememberLauncherForActivityResult(
         contract = ActivityResultContracts.GetContent()
@@ -197,13 +201,26 @@ fun ReverseSearchScreen(navController: NavController) {
                             IconButton(
                                 onClick = {
                                     scope.launch {
-                                        val clipboardText =
+                                        val clipboardItem =
                                             clipboard.nativeClipboard.primaryClip?.getItemAt(
                                                 0
-                                            )?.text?.toString()
-                                        if (clipboardText != null) {
-                                            imageUrl = clipboardText
-                                            selectedFileUri = null
+                                            )
+
+                                        if (clipboardItem != null) {
+                                            val uri = clipboardItem.uri
+                                            val mimeType = uri?.let {
+                                                context.contentResolver.getType(it)
+                                            }
+
+                                            if (mimeType?.startsWith("image/") == true) {
+                                                selectedFileUri = uri
+                                            } else {
+                                                /* onValueChange does not trigger when you mutate
+                                                   imageUrl via code, so we still have to reset
+                                                   selectedFileUri here. */
+                                                selectedFileUri = null
+                                                imageUrl = clipboardItem.text.toString()
+                                            }
                                         } else {
                                             showToast(context, "Nothing on the clipboard")
                                         }