In 1c73379ed8483dcf71c5ccfc459c2c22516a9aef I changed

FontConfig::_available_fonts to use the font ID as a key, but that's
totally wrong because the same Font object with the same ID can have
its font filename/data changed, and in that case we don't want to
use the cached font.

Here we use the actual TTF/OTF font data as the key.  We could have
just hashed the data (whether it comes from a disk file or is held
in memory) but this is slower in the case where we have the filename,
as then the file must be loaded from disk for each comparison.

This fixes #2518.

1 files changed, 5 insertions, 2 deletions

diff --git a/src/lib/font_config.cc b/src/lib/font_config.cc
index d4a442fc1..8804bd6d9 100644
--- a/src/lib/font_config.cc
+++ b/src/lib/font_config.cc
@@ -56,7 +56,7 @@ FontConfig::~FontConfig()
 string
 FontConfig::make_font_available(shared_ptr<dcpomatic::Font> font)
 {
-	auto existing = _available_fonts.find(font->id());
+	auto existing = _available_fonts.find(font->content());
 	if (existing != _available_fonts.end()) {
 		return existing->second;
 	}
@@ -107,7 +107,10 @@ FontConfig::make_font_available(shared_ptr<dcpomatic::Font> font)
 
 	DCPOMATIC_ASSERT(font_name);
 
-	_available_fonts[font->id()] = *font_name;
+	/* We need to use the font object as the key, as we may be passed the same shared_ptr to a modified
+	 * Font object in the future and in that case we need to load the new font.
+	 */
+	_available_fonts[font->content()] = *font_name;
 
 	FcConfigBuildFonts(_config);
 	return *font_name;