tdf#123165 cache recently scaled bitmaps for reuse

dropping the cached scaled bitmap when the bitmap
is accesed via BitmapAccessMode::Write for writing

Change-Id: Ib6539522944838238bd699ec3531039d21dc0f8b
Reviewed-on: https://gerrit.libreoffice.org/67459
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

vcl/inc/salbmp.hxx

@@ -73,6 +73,8 @@ public:
 
     virtual bool            ScalingSupported() const = 0;
     virtual bool            Scale( const double& rScaleX, const double& rScaleY, BmpScaleFlag nScaleFlag ) = 0;
+    void                    DropScaledCache();
+
     virtual bool            Replace( const Color& rSearchColor, const Color& rReplaceColor, sal_uInt8 nTol ) = 0;
 
     virtual bool            ConvertToGreyscale()

vcl/inc/svdata.hxx

@@ -22,6 +22,7 @@
 
 #include <config_version.h>
 
+#include <o3tl/lru_map.hxx>
 #include <tools/fldunit.hxx>
 #include <unotools/options.hxx>
 #include <vcl/bitmapex.hxx>
@@ -194,6 +195,7 @@ 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
     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

vcl/source/app/salvtables.cxx

@@ -144,8 +144,19 @@ SalTimer::~SalTimer() COVERITY_NOEXCEPT_FALSE
 {
 }
 
+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; });
+    }
+}
+
 SalBitmap::~SalBitmap()
 {
+    DropScaledCache();
 }
 
 SalI18NImeStatus::~SalI18NImeStatus()

vcl/source/app/svmain.cxx

@@ -574,6 +574,8 @@ 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&)
+                                                { return true; });
 
     // Deinit Sal
     if (pSVData->mpDefInst)

vcl/source/bitmap/BitmapScaleSuperFilter.cxx

@@ -27,6 +27,7 @@
 
 #include <algorithm>
 #include <memory>
+#include <svdata.hxx>
 #include <sal/log.hxx>
 
 namespace {
@@ -934,6 +935,7 @@ BitmapScaleSuperFilter::~BitmapScaleSuperFilter()
 BitmapEx BitmapScaleSuperFilter::execute(BitmapEx const& rBitmap) const
 {
     Bitmap aBitmap(rBitmap.GetBitmap());
+    SalBitmap* pKey = aBitmap.ImplGetSalBitmap().get();
 
     bool bRet = false;
 
@@ -953,6 +955,16 @@ BitmapEx BitmapScaleSuperFilter::execute(BitmapEx const& rBitmap) const
     if (nDstW <= 1 || nDstH <= 1)
         return BitmapEx();
 
+    // check cache for a previously scaled version of this
+    ImplSVData* pSVData = ImplGetSVData();
+    auto& rCache = pSVData->maGDIData.maScaleCache;
+    auto aFind = rCache.find(pKey);
+    if (aFind != rCache.end())
+    {
+        if (aFind->second.GetSizePixel().Width() == nDstW && aFind->second.GetSizePixel().Height() == nDstH)
+            return aFind->second;
+    }
+
     {
         Bitmap::ScopedReadAccess pReadAccess(aBitmap);
 
@@ -1076,7 +1088,9 @@ BitmapEx BitmapScaleSuperFilter::execute(BitmapEx const& rBitmap) const
     {
         tools::Rectangle aRect(Point(0, 0), Point(nDstW, nDstH));
         aBitmap.Crop(aRect);
-        return BitmapEx(aBitmap);
+        BitmapEx aRet(aBitmap);
+        rCache.insert(std::make_pair(pKey, aRet));
+        return aRet;
     }
 
     return BitmapEx();

vcl/source/gdi/bmpacc.cxx

@@ -41,11 +41,16 @@ BitmapInfoAccess::BitmapInfoAccess( Bitmap& rBitmap, BitmapAccessMode nMode ) :
     if( !xImpBmp )
         return;
 
-    if( mnAccessMode == BitmapAccessMode::Write && xImpBmp.use_count() > 2 )
+    if (mnAccessMode == BitmapAccessMode::Write)
     {
-        xImpBmp.reset();
-        rBitmap.ImplMakeUnique();
-        xImpBmp = rBitmap.ImplGetSalBitmap();
+        xImpBmp->DropScaledCache();
+
+        if (xImpBmp.use_count() > 2)
+        {
+            xImpBmp.reset();
+            rBitmap.ImplMakeUnique();
+            xImpBmp = rBitmap.ImplGetSalBitmap();
+        }
     }
 
     mpBuffer = xImpBmp->AcquireBuffer( mnAccessMode );