MacVideoPlayer: Show decoding errors

Author: nico

Meta/Lagom/Contrib/MacVideoPlayer/Document.mm

@@ -88,11 +88,11 @@ - (BOOL)readFromData:(NSData*)data ofType:(NSString*)typeName error:(NSError**)o
     auto manager_or = Media::PlaybackManager::from_data(ReadonlyBytes { [data bytes], [data length] });
     if (manager_or.is_error()) {
         auto description = manager_or.error().description();
-        NSLog(@"failed to load: %.*s", (int)description.length(), description.characters_without_null_termination());
+        NSString* error_message = [NSString stringWithFormat:@"%.*s", (int)description.length(), description.characters_without_null_termination()];
         if (outError) {
             *outError = [NSError errorWithDomain:NSOSStatusErrorDomain
                                             code:unimpErr
-                                        userInfo:nil];
+                                        userInfo:@{ NSLocalizedRecoverySuggestionErrorKey : error_message }];
         }
         return NO;
     }

Meta/Lagom/Contrib/MacVideoPlayer/View.mm

@@ -12,6 +12,7 @@ @interface View ()
 {
     Media::PlaybackManager* _manager;
     NSBitmapImageRep* _currentFrame;
+    NSString* _errorMessage;
 }
 @end
 
@@ -52,6 +53,27 @@ - (void)setPlaybackManager:(Media::PlaybackManager*)manager
         if (strong_self) {
             auto* ns_frame = ns_from_gfx(move(frame));
             strong_self->_currentFrame = ns_frame;
+            strong_self->_errorMessage = nil;
+            [strong_self setNeedsDisplay:YES];
+        }
+    };
+
+    _manager->on_decoder_error = [weak_self](auto error) {
+        View* strong_self = weak_self;
+        if (strong_self) {
+            auto error_string = error.description();
+            strong_self->_currentFrame = nil;
+            strong_self->_errorMessage = [NSString stringWithFormat:@"Decoder error: %.*s", (int)error_string.length(), error_string.characters_without_null_termination()];
+            [strong_self setNeedsDisplay:YES];
+        }
+    };
+
+    _manager->on_fatal_playback_error = [weak_self](auto const& error) {
+        View* strong_self = weak_self;
+        if (strong_self) {
+            auto error_string = error.string_literal();
+            strong_self->_currentFrame = nil;
+            strong_self->_errorMessage = [NSString stringWithFormat:@"Fatal playback error: %.*s", (int)error_string.length(), error_string.characters_without_null_termination()];
             [strong_self setNeedsDisplay:YES];
         }
     };
@@ -64,6 +86,23 @@ - (void)drawRect:(NSRect)rect
     [[NSColor blackColor] setFill];
     NSRectFill(rect);
 
+    if (_errorMessage) {
+        NSFont* font = [NSFont preferredFontForTextStyle:NSFontTextStyleTitle1 options:@{}];
+
+        NSMutableParagraphStyle* paragraph_style = [[NSMutableParagraphStyle defaultParagraphStyle] mutableCopy];
+        paragraph_style.alignment = NSTextAlignmentCenter;
+
+        NSRect bounding_rect = self.bounds;
+        bounding_rect.size.height *= 0.66;
+
+        [_errorMessage drawInRect:bounding_rect
+                   withAttributes:@{
+                       NSFontAttributeName : font,
+                       NSForegroundColorAttributeName : [NSColor whiteColor],
+                       NSParagraphStyleAttributeName : paragraph_style,
+                   }];
+    }
+
     if (!_currentFrame)
         return;