Loading of multiple fonts for bold and italic

backends/x/draw.go

@@ -86,9 +86,51 @@ func (backend *Backend) drawRune (
 	// application background color as the background. that way, we won't
 	// need to redraw the characters *or* composite them.
 
+	face := backend.font.normal
+
+	highlight := runeStyle & stone.StyleHighlight > 0
+	bold      := runeStyle & stone.StyleBold      > 0
+	italic    := runeStyle & stone.StyleItalic    > 0
+
+	boldTransform   := false
+	italicTransform := false
+
+	switch {
+	case bold && italic:
+		if backend.font.boldItalic == nil {
+			switch {
+			case
+				backend.font.bold == nil && backend.font.italic != nil,
+				backend.font.bold != nil && backend.font.italic != nil:
+				
+				boldTransform = true
+				face = backend.font.italic
+			case backend.font.italic == nil && backend.font.bold != nil:
+				italicTransform = true
+				face = backend.font.bold
+			default:
+				boldTransform   = true
+				italicTransform = true
+			}
+		} else {
+			face = backend.font.boldItalic
+		}
+	case bold:
+		if backend.font.bold == nil {
+			boldTransform = true
+		} else {
+			face = backend.font.bold
+		}
+	case italic:
+		if backend.font.italic == nil {
+			italicTransform = true
+		} else {
+			face = backend.font.italic
+		}
+	}
+	
 	var background xgraphics.BGRA
 	var foreground xgraphics.BGRA
-	highlight := runeStyle & stone.StyleHighlight > 0
 
 	if highlight {
 		background = backend.colors[runeColor]