drop PNGReader and use only PngImageReader

PNGReader is a home-made PNG reader that does not use libpng,
so it's more code, presumably less optimized and it apparently also
doesn't always map colors properly.
The only two features it has that PngImageReader doesn't are explicit
chunk reading (used only for reading Microsoft's GIF in PNG, I
implemented that for PngImageReader in a previous commit), and it
loads paletted images as BitmapEx with a palette instead of
converting to direct-color 24/32bpp or 8bpp-gray. The latter is even
questional if nowadays that's feature or a misfeature, as it saves
memory at the expense of speed. I can implement that if somebody
misses it.
I had to adjust some tests:
- CVE-2016-0952-1.png - invalid CRC of the PNG header, neither Gimp
nor Gwenview can display that, it should fail
- afl-sample-Z_NEED_DICT.png - failure while decompressing data,
but the loader considers that only a partially broken image since
the header is correct, so it "passes" (like in Gimp or Gwenview)
- SdImportTest::testTdf134210() and
testPictureWithSchemeColor::Load_Verify_Reload_Verify()
need the colors tested changed, because apparently gamma correction
or something is now applied correctly, and it wasn't before (again
checked the loaded images with Gimp)

Change-Id: Id46f8d8a01256daf48ca64264b47c4e609183837
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/112042
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>

2 files changed, 6 insertions, 6 deletions

diff --git a/sfx2/source/control/recentdocsview.cxx b/sfx2/source/control/recentdocsview.cxx
index d137d366837c..ca822d0c3487 100644
--- a/sfx2/source/control/recentdocsview.cxx
+++ b/sfx2/source/control/recentdocsview.cxx
@@ -24,7 +24,7 @@
 #include <tools/diagnose_ex.h>
 #include <unotools/historyoptions.hxx>
 #include <vcl/event.hxx>
-#include <vcl/pngread.hxx>
+#include <vcl/filter/PngImageReader.hxx>
 #include <vcl/ptrstyle.hxx>
 #include <vcl/svapp.hxx>
 #include <tools/stream.hxx>
@@ -264,8 +264,8 @@ void RecentDocsView::Reload()
                     comphelper::Base64::decode(aDecoded, aBase64);
 
                     SvMemoryStream aStream(aDecoded.getArray(), aDecoded.getLength(), StreamMode::READ);
-                    vcl::PNGReader aReader(aStream);
-                    aThumbnail = aReader.Read();
+                    vcl::PngImageReader aReader(aStream);
+                    aThumbnail = aReader.read();
                 } else
                 {
                     INetURLObject aUrl(aURL);
diff --git a/sfx2/source/control/thumbnailview.cxx b/sfx2/source/control/thumbnailview.cxx
index 071e73f54c9c..f9624027755e 100644
--- a/sfx2/source/control/thumbnailview.cxx
+++ b/sfx2/source/control/thumbnailview.cxx
@@ -30,7 +30,7 @@
 #include <vcl/svapp.hxx>
 #include <vcl/settings.hxx>
 #include <vcl/event.hxx>
-#include <vcl/pngread.hxx>
+#include <vcl/filter/PngImageReader.hxx>
 
 #include <com/sun/star/accessibility/AccessibleEventId.hpp>
 #include <com/sun/star/embed/ElementModes.hpp>
@@ -138,8 +138,8 @@ BitmapEx ThumbnailView::readThumbnail(const OUString &msURL)
     {
         std::unique_ptr<SvStream> pStream (
             ::utl::UcbStreamHelper::CreateStream (xIStream));
-        vcl::PNGReader aReader (*pStream);
-        aThumbnail = aReader.Read ();
+        vcl::PngImageReader aReader (*pStream);
+        aThumbnail = aReader.read ();
     }
 
     // Note that the preview is returned without scaling it to the desired