lru_scale_cache - cache the same bitmap at multiple scales.

Helps accelerate different views at different scales, as well as
document / image thumbnailing on save, as well as stray views that
can get rendered behind the scenes at odd scales on mobile.

Each scale + bitmap combination is another key in the LRU table.

Change-Id: Id82ce2e4180608082c9ca16fad35bba9e8c2e81a
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/89497
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Michael Meeks <michael.meeks@collabora.com>
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/89503
Tested-by: Jenkins

4 files changed, 49 insertions, 8 deletions

diff --git a/vcl/inc/svdata.hxx b/vcl/inc/svdata.hxx
index e41ec23488b3..654b9ec968f1 100644
--- a/vcl/inc/svdata.hxx
+++ b/vcl/inc/svdata.hxx
@@ -165,6 +165,44 @@ struct ImplSVAppData
     DECL_LINK(VclEventTestingHdl, Timer*, void);
 };
 
+/// Cache multiple scalings for the same bitmap
+struct ScaleCacheKey {
+    SalBitmap *mpBitmap;
+    Size       maDestSize;
+    ScaleCacheKey(SalBitmap *pBitmap, const Size &aDestSize)
+    {
+        mpBitmap = pBitmap;
+        maDestSize = aDestSize;
+    }
+    ScaleCacheKey(const ScaleCacheKey &key)
+    {
+        mpBitmap = key.mpBitmap;
+        maDestSize = key.maDestSize;
+    }
+    bool operator==(ScaleCacheKey const& rOther) const
+    {
+        return mpBitmap == rOther.mpBitmap && maDestSize == rOther.maDestSize;
+    }
+};
+
+namespace std
+{
+template <> struct hash<ScaleCacheKey>
+{
+    std::size_t operator()(ScaleCacheKey const& k) const noexcept
+    {
+        std::size_t seed = 0;
+        boost::hash_combine(seed, k.mpBitmap);
+        boost::hash_combine(seed, k.maDestSize.getWidth());
+        boost::hash_combine(seed, k.maDestSize.getHeight());
+        return seed;
+    }
+};
+
+} // end std namespace
+
+typedef o3tl::lru_map<ScaleCacheKey, BitmapEx> lru_scale_cache;
+
 struct ImplSVGDIData
 {
     ~ImplSVGDIData();
@@ -181,7 +219,7 @@ struct ImplSVGDIData
     std::unique_ptr<ImplPrnQueueList> mpPrinterQueueList;   // List of all printer queue
     std::shared_ptr<PhysicalFontCollection> mxScreenFontList; // Screen-Font-List
     std::shared_ptr<ImplFontCache> mxScreenFontCache;       // Screen-Font-Cache
-    o3tl::lru_map<SalBitmap*, BitmapEx> maScaleCache = o3tl::lru_map<SalBitmap*, BitmapEx>(10); // Cache for scaled images
+    lru_scale_cache         maScaleCache = lru_scale_cache(10); // Cache for scaled images
     ImplDirectFontSubstitution* mpDirectFontSubst = nullptr; // Font-Substitutions defined in Tools->Options->Fonts
     GraphicConverter*       mpGrfConverter = nullptr;       // Converter for graphics
     long                    mnAppFontX = 0;                 // AppFont X-Numenator for 40/tel Width
diff --git a/vcl/source/app/salvtables.cxx b/vcl/source/app/salvtables.cxx
index 9bfeb9997041..d9d25ee5494f 100644
--- a/vcl/source/app/salvtables.cxx
+++ b/vcl/source/app/salvtables.cxx
@@ -157,8 +157,8 @@ void SalBitmap::DropScaledCache()
     if (ImplSVData* pSVData = ImplGetSVData())
     {
         auto& rCache = pSVData->maGDIData.maScaleCache;
-        rCache.remove_if([this] (const o3tl::lru_map<SalBitmap*, BitmapEx>::key_value_pair_t& rKeyValuePair)
-                         { return rKeyValuePair.first == this; });
+        rCache.remove_if([this] (const lru_scale_cache::key_value_pair_t& rKeyValuePair)
+                         { return rKeyValuePair.first.mpBitmap == this; });
     }
 }
 
diff --git a/vcl/source/app/svmain.cxx b/vcl/source/app/svmain.cxx
index e032edcc710f..b0e3ce33b973 100644
--- a/vcl/source/app/svmain.cxx
+++ b/vcl/source/app/svmain.cxx
@@ -564,7 +564,7 @@ void DeInitVCL()
 
     pSVData->maGDIData.mxScreenFontList.reset();
     pSVData->maGDIData.mxScreenFontCache.reset();
-    pSVData->maGDIData.maScaleCache.remove_if([](const o3tl::lru_map<SalBitmap*, BitmapEx>::key_value_pair_t&)
+    pSVData->maGDIData.maScaleCache.remove_if([](const lru_scale_cache::key_value_pair_t&)
                                                 { return true; });
 
     pSVData->maGDIData.maThemeDrawCommandsCache.clear();
diff --git a/vcl/source/bitmap/BitmapScaleSuperFilter.cxx b/vcl/source/bitmap/BitmapScaleSuperFilter.cxx
index 9ee6e80c7b40..bd6b7bd00b56 100644
--- a/vcl/source/bitmap/BitmapScaleSuperFilter.cxx
+++ b/vcl/source/bitmap/BitmapScaleSuperFilter.cxx
@@ -1016,8 +1016,6 @@ BitmapScaleSuperFilter::~BitmapScaleSuperFilter()
 BitmapEx BitmapScaleSuperFilter::execute(BitmapEx const& rBitmap) const
 {
     Bitmap aBitmap(rBitmap.GetBitmap());
-    SalBitmap* pKey = aBitmap.ImplGetSalBitmap().get();
-
     bool bRet = false;
 
     const Size aSizePix(rBitmap.GetSizePixel());
@@ -1037,13 +1035,18 @@ BitmapEx BitmapScaleSuperFilter::execute(BitmapEx const& rBitmap) const
         return BitmapEx();
 
     // check cache for a previously scaled version of this
+    ScaleCacheKey aKey(aBitmap.ImplGetSalBitmap().get(),
+                       Size(nDstW, nDstH));
+
     ImplSVData* pSVData = ImplGetSVData();
     auto& rCache = pSVData->maGDIData.maScaleCache;
-    auto aFind = rCache.find(pKey);
+    auto aFind = rCache.find(aKey);
     if (aFind != rCache.end())
     {
         if (aFind->second.GetSizePixel().Width() == nDstW && aFind->second.GetSizePixel().Height() == nDstH)
             return aFind->second;
+        else
+            SAL_WARN("vcl.gdi", "Error: size mismatch in scale cache");
     }
 
     {
@@ -1187,7 +1190,7 @@ BitmapEx BitmapScaleSuperFilter::execute(BitmapEx const& rBitmap) const
         tools::Rectangle aRect(Point(0, 0), Point(nDstW, nDstH));
         aBitmap.Crop(aRect);
         BitmapEx aRet(aBitmap);
-        rCache.insert(std::make_pair(pKey, aRet));
+        rCache.insert(std::make_pair(aKey, aRet));
         return aRet;
     }