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>

3 files changed, 39 insertions, 2 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;
diff --git a/officecfg/registry/schema/org/openoffice/Office/Common.xcs b/officecfg/registry/schema/org/openoffice/Office/Common.xcs
index f839f5778316..67fa3478b8fe 100644
--- a/officecfg/registry/schema/org/openoffice/Office/Common.xcs
+++ b/officecfg/registry/schema/org/openoffice/Office/Common.xcs
@@ -1591,6 +1591,20 @@
           <value>64000000</value>
         </prop>
       </group>
+      <group oor:name="Font">
+        <info>
+          <desc>Specifies the cache related options for fonts.</desc>
+        </info>
+        <prop oor:name="GlyphsCacheSize" oor:type="xs:long" oor:nillable="false">
+          <info>
+            <desc>Specifies the maximum cache size in bytes for all glyphs used
+            when laying out text. Larger size may improve text drawing performance
+            in large documents.</desc>
+            <label>Glyphs Cache Size</label>
+          </info>
+          <value>20000000</value>
+        </prop>
+      </group>
     </group>
     <group oor:name="Path">
       <!-- UIHints: Tools - Options - General - Paths -->
diff --git a/vcl/source/gdi/impglyphitem.cxx b/vcl/source/gdi/impglyphitem.cxx
index 0ae4e979e141..769c1afb9743 100644
--- a/vcl/source/gdi/impglyphitem.cxx
+++ b/vcl/source/gdi/impglyphitem.cxx
@@ -24,6 +24,7 @@
 #include <tools/stream.hxx>
 #include <TextLayoutCache.hxx>
 #include <config_fuzzers.h>
+#include <officecfg/Office/Common.hxx>
 
 // These need being explicit because of SalLayoutGlyphsImpl being private in vcl.
 SalLayoutGlyphs::SalLayoutGlyphs() {}
@@ -208,7 +209,8 @@ bool SalLayoutGlyphsImpl::IsValid() const
 
 SalLayoutGlyphsCache* SalLayoutGlyphsCache::self()
 {
-    static vcl::DeleteOnDeinit<SalLayoutGlyphsCache> cache(1000);
+    static vcl::DeleteOnDeinit<SalLayoutGlyphsCache> cache(
+        officecfg::Office::Common::Cache::Font::GlyphsCacheSize::get());
     return cache.get();
 }
 
@@ -419,4 +421,19 @@ inline bool SalLayoutGlyphsCache::CachedGlyphsKey::operator==(const CachedGlyphs
     // Slower things last in the comparison.
 }
 
+size_t SalLayoutGlyphsCache::GlyphsCost::operator()(const SalLayoutGlyphs& glyphs) const
+{
+    size_t cost = 0;
+    for (int level = 0;; ++level)
+    {
+        const SalLayoutGlyphsImpl* impl = glyphs.Impl(level);
+        if (impl == nullptr)
+            break;
+        // Count size in bytes, both the SalLayoutGlyphsImpl instance and contained GlyphItem's.
+        cost += sizeof(*impl);
+        cost += impl->size() * sizeof(impl->front());
+    }
+    return cost;
+}
+
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */