Also detect fonts used in drawings in font collector

src/font_file_lister.cpp

@@ -139,14 +139,20 @@ void FontCollector::ProcessDialogueLine(const AssDialogue *line, int index) {
 			break;
 		}
 		case AssBlockType::DRAWING:
+			used_styles[style].drawing = true;
+			break;
 		case AssBlockType::COMMENT:
 			break;
 		}
 	}
 }
 
 void FontCollector::ProcessChunk(std::pair<StyleInfo, UsageData> const& style) {
-	if (style.second.chars.empty()) return;
+	if (style.second.chars.empty() && !style.second.drawing) return;
+
+	if (style.second.chars.empty() && style.second.drawing) {
+		status_callback(fmt_tl("Font '%s' is used in a drawing, but not in any text.\n", style.first.facename), 3);
+	}
 
 	auto res = lister.GetFontPaths(style.first.facename, style.first.bold, style.first.italic, style.second.chars);
 

src/font_file_lister.h

@@ -126,6 +126,7 @@ class FontCollector {
 	/// Data about where each style is used
 	struct UsageData {
 		std::vector<int> chars;          ///< Characters used in this style which glyphs will be needed for
+		bool drawing = false;            ///< Whether this style is used for a drawing
 		std::vector<int> lines;          ///< Lines on which this style is used via overrides
 		std::vector<std::string> styles; ///< ASS styles which use this style
 	};