implement lazy font loading

1 files changed, 17 insertions, 10 deletions

diff --git a/source/core/StarFont.cpp b/source/core/StarFont.cpp
index d854d52..dc0a2a7 100644
--- a/source/core/StarFont.cpp
+++ b/source/core/StarFont.cpp
@@ -39,13 +39,6 @@ FontPtr Font::loadFont(String const& fileName, unsigned pixelSize) {
 FontPtr Font::loadFont(ByteArrayConstPtr const& bytes, unsigned pixelSize) {
   FontPtr font = make_shared<Font>();
   font->m_fontBuffer = bytes;
-
-  shared_ptr<FontImpl> fontImpl = make_shared<FontImpl>();
-  if (FT_New_Memory_Face(
-          ftContext.library, (FT_Byte const*)font->m_fontBuffer->ptr(), font->m_fontBuffer->size(), 0, &fontImpl->face))
-    throw FontException("Could not load font from buffer");
-
-  font->m_fontImpl = fontImpl;
   font->setPixelSize(pixelSize);
 
   return font;
@@ -65,8 +58,6 @@ void Font::setPixelSize(unsigned pixelSize) {
   if (m_pixelSize == pixelSize)
     return;
 
-  if (FT_Set_Pixel_Sizes(m_fontImpl->face, pixelSize, 0))
-    throw FontException(strf("Cannot set font pixel size to: {}", pixelSize));
   m_pixelSize = pixelSize;
 }
 
@@ -82,6 +73,7 @@ unsigned Font::width(String::Char c) {
   if (auto width = m_widthCache.maybe({c, m_pixelSize})) {
     return *width;
   } else {
+	loadFontImpl();
     FT_Load_Char(m_fontImpl->face, c, FontLoadFlags);
     unsigned newWidth = (m_fontImpl->face->glyph->linearHoriAdvance + 32768) / 65536;
     m_widthCache.insert({c, m_pixelSize}, newWidth);
@@ -89,11 +81,25 @@ unsigned Font::width(String::Char c) {
   }
 }
 
+void Font::loadFontImpl() {
+  if (!m_fontImpl) {
+	shared_ptr<FontImpl> fontImpl = make_shared<FontImpl>();
+	if (FT_New_Memory_Face(ftContext.library, (FT_Byte const*)m_fontBuffer->ptr(), m_fontBuffer->size(), 0, &fontImpl->face))
+	  throw FontException("Could not load font from buffer");
+
+	if (FT_Set_Pixel_Sizes(fontImpl->face, m_pixelSize, 0))
+	  throw FontException(strf("Cannot set font pixel size to: {}", m_pixelSize));
+
+	m_fontImpl = fontImpl;
+  }
+}
 
 tuple<Image, Vec2I, bool> Font::render(String::Char c) {
-  if (!m_fontImpl)
+  if (!m_fontImpl && !m_fontBuffer)
     throw FontException("Font::render called on uninitialized font.");
 
+  loadFontImpl();
+
   FT_Face face = m_fontImpl->face;
   if (FT_Load_Glyph(face, FT_Get_Char_Index(face, c), FontLoadFlags) != 0)
     return {};
@@ -152,6 +158,7 @@ tuple<Image, Vec2I, bool> Font::render(String::Char c) {
 }
 
 bool Font::exists(String::Char c) {
+  loadFontImpl();
   return FT_Get_Char_Index(m_fontImpl->face, c);
 }