Can cancel file sending

lib/ui/screens/conversation_screen.dart

@@ -24,6 +24,7 @@ import 'package:comunic/utils/list_utils.dart';
 import 'package:comunic/utils/log_utils.dart';
 import 'package:comunic/utils/ui_utils.dart';
 import 'package:comunic/utils/video_utils.dart';
+import 'package:dio/dio.dart';
 import 'package:emoji_picker/emoji_picker.dart';
 import 'package:flutter/material.dart';
 import 'package:mime/mime.dart';
@@ -65,6 +66,9 @@ class _ConversationScreenState extends SafeState<ConversationScreen> {
   ScrollWatcher _scrollController;
   _OlderMessagesLevel _loadingOlderMessages = _OlderMessagesLevel.NONE;
 
+  CancelToken _sendCancel;
+  double _sendProgress;
+
   String get textMessage => _textController.text;
 
   bool get _isMessageValid =>
@@ -292,17 +296,28 @@ class _ConversationScreenState extends SafeState<ConversationScreen> {
           maxWidth: srvConfig.conversationsPolicy.maxThumbnailWidth,
         );
 
-      await _submitMessage(
+      _sendCancel = CancelToken();
+      final progressCb =
+          (count, total) => setState(() => _sendProgress = count / total);
+      final res = await ConversationsHelper().sendMessage(
         NewConversationMessage(
             conversationID: widget.conversationID,
             message: null,
             file: file,
             thumbnail: thumbnail),
+        sendProgress: progressCb,
+        cancelToken: _sendCancel,
       );
+      assert(res == SendMessageResult.SUCCESS);
     } catch (e, s) {
       logError(e, s);
       showSimpleSnack(context, tr("Failed to send a file!"));
     }
+
+    setState(() {
+      _sendCancel = null;
+      _sendProgress = null;
+    });
   }
 
   /// Send a new text message
@@ -590,6 +605,28 @@ class _ConversationScreenState extends SafeState<ConversationScreen> {
         numRecommended: 50,
       );
 
+  Widget _buildSendingWidget() => Container(
+        height: 68,
+        color: _senderColor,
+        child: Row(
+          children: <Widget>[
+            Spacer(flex: 1),
+            Flexible(
+              child: LinearProgressIndicator(value: _sendProgress),
+              flex: 5,
+            ),
+            Spacer(flex: 1),
+            Text("${(_sendProgress * 100).toInt()}%"),
+            Spacer(flex: 1),
+            OutlineButton(
+              onPressed: () => _sendCancel.cancel(),
+              child: Text(tr("Cancel").toUpperCase()),
+            ),
+            Spacer(flex: 1),
+          ],
+        ),
+      );
+
   @override
   Widget build(BuildContext context) {
     if (_error == ErrorLevel.MAJOR) return _buildError();
@@ -607,7 +644,7 @@ class _ConversationScreenState extends SafeState<ConversationScreen> {
               : null,
         ),
         _messages.length == 0 ? _buildNoMessagesNotice() : _buildMessagesList(),
-        _buildSendMessageForm(),
+        _sendCancel != null ? _buildSendingWidget() : _buildSendMessageForm(),
         _showEmojiPicker ? _buildEmojiContainer() : Container(),
       ],
     );