Drawer now draws tofu

Closes #2

drawer.go

@@ -25,13 +25,19 @@ func (drawer Drawer) Draw (
 		char     rune,
 		position fixed.Point26_6,
 	) bool {
+		// leave empty space for space characters
+		if unicode.IsSpace(char){
+			return true
+		}
+		
+		dot := fixed.P (
+			offset.X + position.X.Round(),
+			offset.Y + position.Y.Round())
 		destinationRectangle,
-		mask, maskPoint, _, ok := drawer.face.Glyph (
-			fixed.P (
-				offset.X + position.X.Round(),
-				offset.Y + position.Y.Round()),
-			char)
-		if !ok || unicode.IsSpace(char) || char == 0 {
+		mask, maskPoint, _, ok := drawer.face.Glyph(dot, char)
+		// tofu
+		if !ok {
+			drawer.drawTofu(char, destination, color, dot)
 			return true
 		}
 
@@ -50,3 +56,29 @@ func (drawer Drawer) Draw (
 	})
 	return
 }
+
+func (drawer Drawer) drawTofu (
+	char rune,
+	destination draw.Image,
+	col         color.Color,
+	position    fixed.Point26_6,
+) {
+	bounds, _ := tofuBounds(drawer.face)
+	rectBounds := image.Rect (
+		bounds.Min.X.Round(),
+		bounds.Min.Y.Round(),
+		bounds.Max.X.Round(),
+		bounds.Max.Y.Round()).Add(image.Pt(
+			position.X.Round(),
+			position.Y.Round()))
+	for x := rectBounds.Min.X; x < rectBounds.Max.X; x ++ {
+		destination.Set(x, rectBounds.Min.Y, col)
+	}
+	for y := rectBounds.Min.Y; y < rectBounds.Max.Y; y ++ {
+		destination.Set(rectBounds.Min.X, y, col)
+		destination.Set(rectBounds.Max.X - 1, y, col)
+	}
+	for x := rectBounds.Min.X; x < rectBounds.Max.X; x ++ {
+		destination.Set(x, rectBounds.Max.Y - 1, col)
+	}
+}

layout.go

@@ -220,3 +220,11 @@ func tofuAdvance (face font.Face) fixed.Int26_6 {
 		return 16
 	}
 }
+
+func tofuBounds (face font.Face) (fixed.Rectangle26_6, fixed.Int26_6) {
+	if bounds, advance, ok := face.GlyphBounds('M'); ok {
+		return bounds, advance
+	} else {
+		return fixed.R(0, -16, 14, 0), 16
+	}
+}