speed up monospace fonts

src/coders/vector_fonts.cpp

@@ -30,6 +30,7 @@ namespace {
     public:
         FTFontFile(FT_Face face, util::Buffer<ubyte> buffer)
             : face(std::move(face)), buffer(std::move(buffer)) {
+            monospace = this->face->face_flags & FT_FACE_FLAG_FIXED_WIDTH;
         }
 
         ~FTFontFile() {

src/coders/vector_fonts.hpp

@@ -19,6 +19,12 @@ namespace vector_fonts {
         virtual std::unique_ptr<Texture> renderPage(
             int pageid, std::vector<Glyph>& glyphs, int size
         ) = 0;
+
+        bool isMonospace() const {
+            return monospace;
+        }
+    protected:
+        bool monospace = true;
     };
 
     void initialize();