Support sharing a reduced quality preview

app/android/app/src/main/kotlin/com/nkming/nc_photos/ShareChannelHandler.kt

@@ -1,6 +1,7 @@
 package com.nkming.nc_photos
 
 import android.app.Activity
+import android.content.ClipData
 import android.content.Intent
 import android.net.Uri
 import io.flutter.plugin.common.MethodCall
@@ -54,14 +55,26 @@ class ShareChannelHandler(activity: Activity) :
 		val shareIntent = if (uris.size == 1) Intent().apply {
 			action = Intent.ACTION_SEND
 			putExtra(Intent.EXTRA_STREAM, uris[0])
+			// setting clipdata is needed for FLAG_GRANT_READ_URI_PERMISSION to
+			// work, see: https://developer.android.com/reference/android/content/Intent#ACTION_SEND
+			clipData =
+				ClipData.newUri(_context.contentResolver, "Share", uris[0])
 			type = mimeTypes[0] ?: "*/*"
 			addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
 			addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
 		} else Intent().apply {
 			action = Intent.ACTION_SEND_MULTIPLE
 			putParcelableArrayListExtra(Intent.EXTRA_STREAM, ArrayList(uris))
-			type =
+			clipData =
-				if (mimeTypes.all { it?.startsWith("image/") == true }) "image/*" else "*/*"
+				ClipData.newUri(_context.contentResolver, "Share", uris[0])
+					.apply {
+						for (uri in uris.subList(1, uris.size)) {
+							addItem(ClipData.Item(uri))
+						}
+					}
+			type = if (mimeTypes.all {
+					it?.startsWith("image/") == true
+				}) "image/*" else "*/*"
 			addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
 			addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
 		}

app/android/app/src/main/res/xml/file_paths.xml

@@ -1,4 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <paths>
     <external-path name="downloads" path="Download"/>
+    <cache-path name="previews" path="largeImageCache"/>
 </paths>

app/lib/cache_manager_util.dart

@@ -51,6 +51,7 @@ class ThumbnailCacheManager {
 /// very large in size. Since large images are only viewed one by one (unlike
 /// thumbnails), they are less critical to the overall app responsiveness
 class LargeImageCacheManager {
+  // used in file_paths.xml, must not change
   static const key = "largeImageCache";
   static CacheManager inst = CacheManager(
     Config(

app/lib/l10n/app_en.arb

@@ -906,11 +906,16 @@
 	"@shareMethodDialogTitle": {
 		"description": "Let the user pick how they want to share"
 	},
-	"shareMethodFileTitle": "File",
+	"shareMethodPreviewTitle": "Preview",
-	"@shareMethodFileTitle": {
+	"@shareMethodPreviewTitle": {
-		"description": "Share the actual file"
+		"description": "Share the preview of a file"
 	},
-	"shareMethodFileDescription": "Download the file and share it to other apps",
+	"shareMethodPreviewDescription": "Share a reduced quality preview to other apps (only support images)",
+	"shareMethodOriginalFileTitle": "Original file",
+	"@shareMethodOriginalFileTitle": {
+		"description": "Share the original file"
+	},
+	"shareMethodOriginalFileDescription": "Download the original file and share it to other apps",
 	"shareMethodPublicLinkTitle": "Public link",
 	"@shareMethodPublicLinkTitle": {
 		"description": "Create a share link on server and share it"

app/lib/l10n/untranslated-messages.txt

@@ -41,6 +41,10 @@
     "sortOptionFilenameDescendingLabel",
     "sortOptionManualLabel",
     "helpButtonLabel",
+    "shareMethodPreviewTitle",
+    "shareMethodPreviewDescription",
+    "shareMethodOriginalFileTitle",
+    "shareMethodOriginalFileDescription",
     "collectionSharingLabel",
     "fileLastSharedDescription",
     "fileLastSharedByOthersDescription",
@@ -210,8 +214,10 @@
     "slideshowSetupDialogRepeatTitle",
     "linkCopiedNotification",
     "shareMethodDialogTitle",
-    "shareMethodFileTitle",
+    "shareMethodPreviewTitle",
-    "shareMethodFileDescription",
+    "shareMethodPreviewDescription",
+    "shareMethodOriginalFileTitle",
+    "shareMethodOriginalFileDescription",
     "shareMethodPublicLinkTitle",
     "shareMethodPublicLinkDescription",
     "shareMethodPasswordLinkTitle",
@@ -346,6 +352,10 @@
     "settingsMemoriesRangeTitle",
     "settingsMemoriesRangeValueText",
     "settingsDoubleTapExitTitle",
+    "shareMethodPreviewTitle",
+    "shareMethodPreviewDescription",
+    "shareMethodOriginalFileTitle",
+    "shareMethodOriginalFileDescription",
     "enhanceStyleTransferStyleDialogTitle",
     "doubleTapExitNotification",
     "imageEditDiscardDialogTitle",
@@ -397,6 +407,10 @@
     "settingsMemoriesRangeTitle",
     "settingsMemoriesRangeValueText",
     "rootPickerSkipConfirmationDialogContent2",
+    "shareMethodPreviewTitle",
+    "shareMethodPreviewDescription",
+    "shareMethodOriginalFileTitle",
+    "shareMethodOriginalFileDescription",
     "imageEditToolbarColorLabel",
     "imageEditToolbarTransformLabel",
     "imageEditTransformOrientation",
@@ -415,6 +429,10 @@
     "settingsPhotosPageTitle",
     "settingsMemoriesRangeTitle",
     "settingsMemoriesRangeValueText",
+    "shareMethodPreviewTitle",
+    "shareMethodPreviewDescription",
+    "shareMethodOriginalFileTitle",
+    "shareMethodOriginalFileDescription",
     "imageEditToolbarColorLabel",
     "imageEditToolbarTransformLabel",
     "imageEditTransformOrientation",
@@ -451,6 +469,10 @@
     "helpTooltip",
     "helpButtonLabel",
     "removeFromAlbumTooltip",
+    "shareMethodPreviewTitle",
+    "shareMethodPreviewDescription",
+    "shareMethodOriginalFileTitle",
+    "shareMethodOriginalFileDescription",
     "enhanceTooltip",
     "enhanceButtonLabel",
     "enhanceIntroDialogTitle",
@@ -527,6 +549,10 @@
     "settingsPhotosTabSortByNameTitle",
     "sortOptionFilenameAscendingLabel",
     "sortOptionFilenameDescendingLabel",
+    "shareMethodPreviewTitle",
+    "shareMethodPreviewDescription",
+    "shareMethodOriginalFileTitle",
+    "shareMethodOriginalFileDescription",
     "createCollectionTooltip",
     "createCollectionDialogAlbumLabel",
     "createCollectionDialogAlbumDescription",
@@ -624,6 +650,10 @@
     "settingsPhotosTabSortByNameTitle",
     "sortOptionFilenameAscendingLabel",
     "sortOptionFilenameDescendingLabel",
+    "shareMethodPreviewTitle",
+    "shareMethodPreviewDescription",
+    "shareMethodOriginalFileTitle",
+    "shareMethodOriginalFileDescription",
     "enhanceTooltip",
     "enhanceButtonLabel",
     "enhanceIntroDialogTitle",
@@ -700,6 +730,10 @@
     "settingsPhotosTabSortByNameTitle",
     "sortOptionFilenameAscendingLabel",
     "sortOptionFilenameDescendingLabel",
+    "shareMethodPreviewTitle",
+    "shareMethodPreviewDescription",
+    "shareMethodOriginalFileTitle",
+    "shareMethodOriginalFileDescription",
     "enhanceTooltip",
     "enhanceButtonLabel",
     "enhanceIntroDialogTitle",
@@ -776,6 +810,10 @@
     "settingsPhotosTabSortByNameTitle",
     "sortOptionFilenameAscendingLabel",
     "sortOptionFilenameDescendingLabel",
+    "shareMethodPreviewTitle",
+    "shareMethodPreviewDescription",
+    "shareMethodOriginalFileTitle",
+    "shareMethodOriginalFileDescription",
     "enhanceTooltip",
     "enhanceButtonLabel",
     "enhanceIntroDialogTitle",
@@ -852,6 +890,10 @@
     "settingsPhotosTabSortByNameTitle",
     "sortOptionFilenameAscendingLabel",
     "sortOptionFilenameDescendingLabel",
+    "shareMethodPreviewTitle",
+    "shareMethodPreviewDescription",
+    "shareMethodOriginalFileTitle",
+    "shareMethodOriginalFileDescription",
     "enhanceTooltip",
     "enhanceButtonLabel",
     "enhanceIntroDialogTitle",

app/lib/share_handler.dart

@@ -10,6 +10,7 @@ import 'package:nc_photos/app_localizations.dart';
 import 'package:nc_photos/debug_util.dart';
 import 'package:nc_photos/di_container.dart';
 import 'package:nc_photos/entity/file.dart';
+import 'package:nc_photos/entity/file_util.dart' as file_util;
 import 'package:nc_photos/entity/local_file.dart';
 import 'package:nc_photos/entity/share.dart';
 import 'package:nc_photos/entity/share/data_source.dart';
@@ -24,6 +25,7 @@ import 'package:nc_photos/use_case/copy.dart';
 import 'package:nc_photos/use_case/create_dir.dart';
 import 'package:nc_photos/use_case/create_share.dart';
 import 'package:nc_photos/use_case/download_file.dart';
+import 'package:nc_photos/use_case/download_preview.dart';
 import 'package:nc_photos/use_case/share_local.dart';
 import 'package:nc_photos/widget/processing_dialog.dart';
 import 'package:nc_photos/widget/share_link_multiple_files_dialog.dart';
@@ -67,7 +69,7 @@ class ShareHandler {
 
   Future<void> shareFiles(Account account, List<File> files) async {
     try {
-      final method = await _askShareMethod();
+      final method = await _askShareMethod(files);
       if (method == null) {
         // user canceled
         return;
@@ -75,6 +77,8 @@ class ShareHandler {
         return await _shareAsLink(account, files, false);
       } else if (method == ShareMethod.passwordLink) {
         return await _shareAsLink(account, files, true);
+      } else if (method == ShareMethod.preview) {
+        return await _shareAsPreview(account, files);
       } else {
         return await _shareAsFile(account, files);
       }
@@ -91,9 +95,59 @@ class ShareHandler {
     }
   }
 
-  Future<ShareMethod?> _askShareMethod() {
+  Future<ShareMethod?> _askShareMethod(List<File> files) {
     return showDialog<ShareMethod>(
-        context: context, builder: (context) => const ShareMethodDialog());
+      context: context,
+      builder: (context) => ShareMethodDialog(
+        isSupportPerview: files.any((f) => file_util.isSupportedImageFormat(f)),
+      ),
+    );
+  }
+
+  Future<void> _shareAsPreview(Account account, List<File> files) async {
+    assert(platform_k.isAndroid);
+    final controller = StreamController<String>();
+    unawaited(
+      showDialog(
+        context: context,
+        builder: (context) => StreamBuilder(
+          stream: controller.stream,
+          builder: (context, snapshot) => ProcessingDialog(
+            text: L10n.global().shareDownloadingDialogContent +
+                (snapshot.hasData ? " ${snapshot.data}" : ""),
+          ),
+        ),
+      ),
+    );
+    final results = <Tuple2<File, dynamic>>[];
+    for (final pair in files.withIndex()) {
+      final i = pair.item1, f = pair.item2;
+      controller.add("($i/${files.length})");
+      try {
+        final dynamic uri;
+        if (file_util.isSupportedImageFormat(f) &&
+            f.contentType != "image/gif") {
+          uri = await DownloadPreview()(account, f);
+        } else {
+          uri = await DownloadFile()(account, f);
+        }
+        results.add(Tuple2(f, uri));
+      } catch (e, stacktrace) {
+        _log.shout(
+            "[_shareAsPreview] Failed while DownloadPreview", e, stacktrace);
+        SnackBarManager().showSnackBar(SnackBar(
+          content: Text(exception_util.toUserString(e)),
+          duration: k.snackBarDurationNormal,
+        ));
+      }
+    }
+    // dismiss the dialog
+    Navigator.of(context).pop();
+
+    final share = AndroidFileShare(
+        results.map((e) => e.item2 as String).toList(),
+        results.map((e) => e.item1.contentType).toList());
+    return share.share();
   }
 
   Future<void> _shareAsFile(Account account, List<File> files) async {

app/lib/use_case/download_preview.dart

@@ -0,0 +1,26 @@
+import 'package:nc_photos/account.dart';
+import 'package:nc_photos/api/api.dart';
+import 'package:nc_photos/api/api_util.dart' as api_util;
+import 'package:nc_photos/cache_manager_util.dart';
+import 'package:nc_photos/entity/file.dart';
+import 'package:nc_photos/k.dart' as k;
+import 'package:nc_photos/platform/k.dart' as platform_k;
+import 'package:nc_photos_plugin/nc_photos_plugin.dart';
+
+class DownloadPreview {
+  Future<dynamic> call(Account account, File file) async {
+    assert(platform_k.isAndroid);
+    final previewUrl = api_util.getFilePreviewUrl(
+      account,
+      file,
+      width: k.photoLargeSize,
+      height: k.photoLargeSize,
+      a: true,
+    );
+    final fileInfo =
+        await LargeImageCacheManager.inst.getSingleFile(previewUrl, headers: {
+      "authorization": Api.getAuthorizationHeaderValue(account),
+    });
+    return ContentUri.getUriForFile(fileInfo.absolute.path);
+  }
+}

app/lib/widget/share_method_dialog.dart

@@ -4,30 +4,43 @@ import 'package:nc_photos/platform/k.dart' as platform_k;
 
 enum ShareMethod {
   file,
+  preview,
   publicLink,
   passwordLink,
 }
 
 class ShareMethodDialog extends StatelessWidget {
   const ShareMethodDialog({
-    Key? key,
+    super.key,
-  }) : super(key: key);
+    required this.isSupportPerview,
+  });
 
   @override
   build(BuildContext context) {
     return SimpleDialog(
       title: Text(L10n.global().shareMethodDialogTitle),
       children: [
-        if (platform_k.isAndroid)
+        if (platform_k.isAndroid) ...[
+          if (isSupportPerview)
+            SimpleDialogOption(
+              child: ListTile(
+                title: Text(L10n.global().shareMethodPreviewTitle),
+                subtitle: Text(L10n.global().shareMethodPreviewDescription),
+              ),
+              onPressed: () {
+                Navigator.of(context).pop(ShareMethod.preview);
+              },
+            ),
           SimpleDialogOption(
             child: ListTile(
-              title: Text(L10n.global().shareMethodFileTitle),
+              title: Text(L10n.global().shareMethodOriginalFileTitle),
-              subtitle: Text(L10n.global().shareMethodFileDescription),
+              subtitle: Text(L10n.global().shareMethodOriginalFileDescription),
             ),
             onPressed: () {
               Navigator.of(context).pop(ShareMethod.file);
             },
           ),
+        ],
         SimpleDialogOption(
           child: ListTile(
             title: Text(L10n.global().shareMethodPublicLinkTitle),
@@ -49,4 +62,6 @@ class ShareMethodDialog extends StatelessWidget {
       ],
     );
   }
+
+  final bool isSupportPerview;
 }

plugin/android/src/main/kotlin/com/nkming/nc_photos/plugin/ContentUriChannelHandler.kt

@@ -2,8 +2,10 @@ package com.nkming.nc_photos.plugin
 
 import android.content.Context
 import android.net.Uri
+import androidx.core.content.FileProvider
 import io.flutter.plugin.common.MethodCall
 import io.flutter.plugin.common.MethodChannel
+import java.io.File
 import java.io.FileNotFoundException
 
 class ContentUriChannelHandler(context: Context) :
@@ -24,6 +26,14 @@ class ContentUriChannelHandler(context: Context) :
 				}
 			}
 
+			"getUriForFile" -> {
+				try {
+					getUriForFile(call.argument("filePath")!!, result)
+				} catch (e: Throwable) {
+					result.error("systemException", e.toString(), null)
+				}
+			}
+
 			else -> result.notImplemented()
 		}
 	}
@@ -46,5 +56,18 @@ class ContentUriChannelHandler(context: Context) :
 		}
 	}
 
+	private fun getUriForFile(filePath: String, result: MethodChannel.Result) {
+		try {
+			val file = File(filePath)
+			val contentUri = FileProvider.getUriForFile(
+				context, "${context.packageName}.fileprovider", file
+			)
+			result.success(contentUri.toString())
+		} catch (e: IllegalArgumentException) {
+			logE(TAG, "[getUriForFile] Unsupported file path: $filePath")
+			throw e
+		}
+	}
+
 	private val context = context
 }

plugin/lib/src/content_uri.dart

@@ -20,6 +20,12 @@ class ContentUri {
     }
   }
 
+  static Future<String> getUriForFile(String filePath) async {
+    return await _methodChannel.invokeMethod("getUriForFile", <String, dynamic>{
+      "filePath": filePath,
+    });
+  }
+
   static const _methodChannel = MethodChannel("${k.libId}/content_uri_method");
 
   static const _exceptionFileNotFound = "fileNotFoundException";