add offline attachment rendering

lib/src/message_input.dart

@@ -573,6 +573,10 @@ class _MessageInputState extends State<MessageInput> {
       file = await FilePicker.getFile(type: type);
     }
 
+    if (file == null) {
+      return;
+    }
+
     final channel = StreamChannel.of(context).channel;
 
     final bytes = await file.readAsBytes();
@@ -717,6 +721,7 @@ class _MessageInputState extends State<MessageInput> {
         imageUrl: attachment.type == FileType.IMAGE ? attachment.url : null,
         assetUrl: attachment.url,
         type: type,
+        localUri: attachment.file.uri,
       );
     });
   }

lib/src/message_widget.dart

@@ -1,3 +1,4 @@
+import 'dart:io';
 import 'dart:math';
 
 import 'package:cached_network_image/cached_network_image.dart';
@@ -450,22 +451,8 @@ class _MessageWidgetState extends State<MessageWidget>
     );
   }
 
-  Padding _buildMessageText(
+  Widget _buildSendingError(Widget child) {
-    int nOfAttachmentWidgets,
+    return Column(
-    String text,
-    BuildContext context,
-  ) {
-    return Padding(
-      padding: EdgeInsets.only(
-        right: _isMyMessage ? 0.0 : 8.0,
-        left: _isMyMessage ? 8.0 : 0.0,
-      ),
-      child: Container(
-        decoration:
-            _buildBoxDecoration(_isLastUser || nOfAttachmentWidgets > 0),
-        padding: EdgeInsets.all(10),
-        constraints: BoxConstraints.loose(Size.fromWidth(300)),
-        child: Column(
       mainAxisSize: MainAxisSize.min,
       crossAxisAlignment: CrossAxisAlignment.start,
       children: <Widget>[
@@ -485,12 +472,32 @@ class _MessageWidgetState extends State<MessageWidget>
               fontSize: 11,
             ),
           ),
+        child,
+      ],
+    );
+  }
+
+  Padding _buildMessageText(
+    int nOfAttachmentWidgets,
+    String text,
+    BuildContext context,
+  ) {
+    return Padding(
+      padding: EdgeInsets.only(
+        right: _isMyMessage ? 0.0 : 8.0,
+        left: _isMyMessage ? 8.0 : 0.0,
+      ),
+      child: Container(
+        decoration:
+            _buildBoxDecoration(_isLastUser || nOfAttachmentWidgets > 0),
+        padding: EdgeInsets.all(10),
+        constraints: BoxConstraints.loose(Size.fromWidth(300)),
+        child: _buildSendingError(
           MarkdownBody(
             data: text,
             onTapLink: (link) {
               if (link.startsWith('@')) {
-                  final mentionedUser =
+                final mentionedUser = widget.message.mentionedUsers.firstWhere(
-                      widget.message.mentionedUsers.firstWhere(
                   (u) => '@${u.name.replaceAll(' ', '')}' == link,
                   orElse: () => null,
                 );
@@ -520,7 +527,6 @@ class _MessageWidgetState extends State<MessageWidget>
               p: _messageTheme.messageText,
             ),
           ),
-          ],
         ),
       ),
     );
@@ -896,7 +902,12 @@ class _MessageWidgetState extends State<MessageWidget>
   Widget _buildImage(
     Attachment attachment,
   ) {
+    return Hero(
+      tag: attachment.imageUrl ?? attachment.assetUrl ?? attachment.thumbUrl,
+      child: CachedNetworkImage(
+        imageBuilder: (context, provider) {
           return GestureDetector(
+            child: Image(image: provider),
             onTap: () {
               print(attachment.toJson());
               Navigator.push(context, MaterialPageRoute(builder: (_) {
@@ -907,9 +918,8 @@ class _MessageWidgetState extends State<MessageWidget>
                 );
               }));
             },
-      child: Hero(
+          );
-        tag: attachment.imageUrl ?? attachment.assetUrl ?? attachment.thumbUrl,
+        },
-        child: CachedNetworkImage(
         placeholder: (_, __) {
           return Container(
             width: 200,
@@ -918,8 +928,20 @@ class _MessageWidgetState extends State<MessageWidget>
         },
         imageUrl:
             attachment.thumbUrl ?? attachment.imageUrl ?? attachment.assetUrl,
-          errorWidget: (context, url, error) {
+        errorWidget: (context, url, error) => _buildErrorImage(attachment),
-            return Container(
+        fit: BoxFit.cover,
+      ),
+    );
+  }
+
+  Widget _buildErrorImage(Attachment attachment) {
+    if (attachment.localUri != null) {
+      return Image.file(
+        File(attachment.localUri.path),
+      );
+    }
+    return Center(
+      child: Container(
         width: 200,
         height: 140,
         color: Color(0xffd0021B).withAlpha(26),
@@ -929,10 +951,6 @@ class _MessageWidgetState extends State<MessageWidget>
             color: Colors.white,
           ),
         ),
-            );
-          },
-          fit: BoxFit.cover,
-        ),
       ),
     );
   }
@@ -956,6 +974,9 @@ class _MessageWidgetState extends State<MessageWidget>
           videoPlayerController: videoController,
           autoInitialize: true,
           errorBuilder: (_, e) {
+            if (attachment.thumbUrl == null) {
+              return _buildErrorImage(attachment);
+            }
             return Stack(
               children: <Widget>[
                 Container(