Add UnifontEx fallback for glyphs that are missing from the current font

6 files changed, 21 insertions, 5 deletions

diff --git a/assets/opensb/font/unifont.woff2 b/assets/opensb/font/unifont.woff2
new file mode 100644
index 0000000..5da6c98
--- /dev/null
+++ b/assets/opensb/font/unifont.woff2
diff --git a/source/core/StarFont.cpp b/source/core/StarFont.cpp
index 63356ad..b21b85a 100644
--- a/source/core/StarFont.cpp
+++ b/source/core/StarFont.cpp
@@ -133,4 +133,8 @@ std::pair<Image, Vec2I> Font::render(String::Char c) {
   return { std::move(image), {slot->bitmap_left - 1, (slot->bitmap_top - height) + (m_pixelSize / 4) - 1} };
 }
 
+bool Font::exists(String::Char c) {
+  return FT_Get_Char_Index(m_fontImpl->face, c);
+}
+
 }
diff --git a/source/core/StarFont.hpp b/source/core/StarFont.hpp
index ec10533..dee50f7 100644
--- a/source/core/StarFont.hpp
+++ b/source/core/StarFont.hpp
@@ -35,6 +35,7 @@ public:
   // render a box, but if there is an internal freetype error this may return
   // an empty image).
   std::pair<Image, Vec2I> render(String::Char c);
+  bool exists(String::Char c);
 
 private:
   FontImplPtr m_fontImpl;
diff --git a/source/rendering/StarFontTextureGroup.cpp b/source/rendering/StarFontTextureGroup.cpp
index fb3a107..d5e6ef9 100644
--- a/source/rendering/StarFontTextureGroup.cpp
+++ b/source/rendering/StarFontTextureGroup.cpp
@@ -39,13 +39,19 @@ void FontTextureGroup::clearFonts() {
   m_font = m_defaultFont;
 }
 
+void FontTextureGroup::setFallbackFont(String const& fontName) {
+  if (auto font = m_fonts.ptr(fontName))
+    m_fallbackFont = *font;
+}
+
 const FontTextureGroup::GlyphTexture& FontTextureGroup::glyphTexture(String::Char c, unsigned size, Directives const* processingDirectives)
 {
-  auto res = m_glyphs.insert(GlyphDescriptor{c, size, processingDirectives ? processingDirectives->hash() : 0, m_font.get()}, GlyphTexture());
+  Font* font = (m_font->exists(c) || !m_fallbackFont) ? m_font.get() : m_fallbackFont.get();
+  auto res = m_glyphs.insert(GlyphDescriptor{c, size, processingDirectives ? processingDirectives->hash() : 0, font}, GlyphTexture());
 
   if (res.second) {
-    m_font->setPixelSize(size);
-    auto pair = m_font->render(c);
+    font->setPixelSize(size);
+    auto pair = font->render(c);
     Image& image = pair.first;
     if (processingDirectives) {
       try {
@@ -83,8 +89,9 @@ TexturePtr FontTextureGroup::glyphTexturePtr(String::Char c, unsigned size, Dire
 }
 
 unsigned FontTextureGroup::glyphWidth(String::Char c, unsigned fontSize) {
-  m_font->setPixelSize(fontSize);
-  return m_font->width(c);
+  Font* font = (m_font->exists(c) || !m_fallbackFont) ? m_font.get() : m_fallbackFont.get();
+  font->setPixelSize(fontSize);
+  return font->width(c);
 }
 
 }
diff --git a/source/rendering/StarFontTextureGroup.hpp b/source/rendering/StarFontTextureGroup.hpp
index 9a32daf..864b44f 100644
--- a/source/rendering/StarFontTextureGroup.hpp
+++ b/source/rendering/StarFontTextureGroup.hpp
@@ -37,11 +37,14 @@ public:
   String const& activeFont();
   void addFont(FontPtr const& font, String const& name, bool isDefault = false);
   void clearFonts();
+  void setFallbackFont(String const& fontName);
+
 private:
   CaseInsensitiveStringMap<FontPtr> m_fonts;
   String m_fontName;
   FontPtr m_font;
   FontPtr m_defaultFont;
+  FontPtr m_fallbackFont;
 
   TextureGroupPtr m_textureGroup;
   HashMap<GlyphDescriptor, GlyphTexture> m_glyphs;
diff --git a/source/rendering/StarTextPainter.cpp b/source/rendering/StarTextPainter.cpp
index 8198969..19e48f1 100644
--- a/source/rendering/StarTextPainter.cpp
+++ b/source/rendering/StarTextPainter.cpp
@@ -331,6 +331,7 @@ void TextPainter::reloadFonts() {
   loadFontsByExtension("ttf");
   loadFontsByExtension("woff2");
   m_fontTextureGroup.addFont(defaultFont, defaultName, true);
+  m_fontTextureGroup.setFallbackFont("unifont");
 }
 
 void TextPainter::cleanup(int64_t timeout) {