Fix font glyph generation to work correctly with other fonts

1 files changed, 17 insertions, 17 deletions

diff --git a/source/core/StarFont.cpp b/source/core/StarFont.cpp
index 6308784..9c8636a 100644
--- a/source/core/StarFont.cpp
+++ b/source/core/StarFont.cpp
@@ -7,6 +7,8 @@
 
 namespace Star {
 
+constexpr int FontLoadFlags = FT_LOAD_FORCE_AUTOHINT;
+
 struct FTContext {
   FT_Library library;
 
@@ -49,9 +51,7 @@ FontPtr Font::loadTrueTypeFont(ByteArrayConstPtr const& bytes, unsigned pixelSiz
   return font;
 }
 
-Font::Font() {
-  m_pixelSize = 0;
-}
+Font::Font() : m_pixelSize(0) {}
 
 FontPtr Font::clone() const {
   return Font::loadTrueTypeFont(m_fontBuffer, m_pixelSize);
@@ -78,38 +78,38 @@ unsigned Font::width(String::Char c) {
   if (auto width = m_widthCache.maybe({c, m_pixelSize})) {
     return *width;
   } else {
-    FT_Load_Char(m_fontImpl->face, c, FT_LOAD_FORCE_AUTOHINT);
+    FT_Load_Char(m_fontImpl->face, c, FontLoadFlags);
     unsigned newWidth = (m_fontImpl->face->glyph->advance.x + 32) / 64;
     m_widthCache.insert({c, m_pixelSize}, newWidth);
     return newWidth;
   }
 }
 
-Image Font::render(String::Char c) {
+
+std::pair<Image, int> Font::render(String::Char c) {
   if (!m_fontImpl)
     throw FontException("Font::render called on uninitialized font.");
 
-  FT_UInt glyph_index = FT_Get_Char_Index(m_fontImpl->face, c);
-  if (FT_Load_Glyph(m_fontImpl->face, glyph_index, FT_LOAD_FORCE_AUTOHINT) != 0)
+  FT_Face face = m_fontImpl->face;
+  FT_UInt glyph_index = FT_Get_Char_Index(face, c);
+  if (FT_Load_Glyph(face, glyph_index, FontLoadFlags) != 0)
     return {};
 
   /* convert to an anti-aliased bitmap */
-  if (FT_Render_Glyph(m_fontImpl->face->glyph, FT_RENDER_MODE_NORMAL) != 0)
+  if (FT_Render_Glyph(face->glyph, FT_RENDER_MODE_NORMAL) != 0)
     return {};
 
-  FT_GlyphSlot slot = m_fontImpl->face->glyph;
+  FT_GlyphSlot slot = face->glyph;
 
-  int width = (slot->advance.x + 32) / 64;
-  int height = m_pixelSize;
+  unsigned int width = slot->bitmap.width;
+  unsigned int height = slot->bitmap.rows;
 
   Image image(width, height, PixelFormat::RGBA32);
   for (int y = 0; y < height; ++y) {
+    unsigned char* p = slot->bitmap.buffer + y * slot->bitmap.pitch;
     for (int x = 0; x < width; ++x) {
-      int bx = x;
-      int by = y + slot->bitmap_top - m_fontImpl->face->size->metrics.ascender / 64;
-      if (bx >= 0 && by >= 0 && bx < (int)slot->bitmap.width && by < (int)slot->bitmap.rows) {
-        unsigned char* p = slot->bitmap.buffer + by * slot->bitmap.pitch;
-        unsigned char val = *(p + bx);
+      if (x >= 0 && y >= 0 && x < width && y < height) {
+        unsigned char val = *(p + x);
         image.set(x, height - y - 1, Vec4B(255, 255, 255, val));
       } else {
         image.set(x, height - y - 1, Vec4B(255, 255, 255, 0));
@@ -117,7 +117,7 @@ Image Font::render(String::Char c) {
     }
   }
 
-  return image;
+  return { move(image), (slot->bitmap_top - (int)height) + m_pixelSize / 4 };
 }
 
 }