better cache size limit for SalLayoutGlyphsCache

With just limit on the number of cached SalLayoutGlyphs instances
the actual memory used could vary wildly depending on how long
the text is.

Change-Id: Ibcf6918e562e81276d21876c532838996e275bd6
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/133673
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/include/vcl/glyphitemcache.hxx b/include/vcl/glyphitemcache.hxx
index a7a49ca7a8f2..998dcf97f915 100644
--- a/include/vcl/glyphitemcache.hxx
+++ b/include/vcl/glyphitemcache.hxx
@@ -85,7 +85,13 @@ private:
     {
         size_t operator()(const CachedGlyphsKey& key) const { return key.hashValue; }
     };
-    typedef o3tl::lru_map<CachedGlyphsKey, SalLayoutGlyphs, CachedGlyphsHash> GlyphsCache;
+    struct GlyphsCost
+    {
+        size_t operator()(const SalLayoutGlyphs&) const;
+    };
+    typedef o3tl::lru_map<CachedGlyphsKey, SalLayoutGlyphs, CachedGlyphsHash,
+                          std::equal_to<CachedGlyphsKey>, GlyphsCost>
+        GlyphsCache;
     GlyphsCache mCachedGlyphs;
     // Last temporary glyphs returned (pointer is returned, so the object needs to be kept somewhere).
     std::optional<CachedGlyphsKey> mLastTemporaryKey;