tdf#123420 Fix RGB/BGR issue with PNG reader

Change-Id: I4c6ffc89a21f46dea8775d4ec9aacc4f7ca71d94
Reviewed-on: https://gerrit.libreoffice.org/67764
Tested-by: Jenkins
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>

vcl/source/filter/png/PngImageReader.cxx

@@ -88,8 +88,6 @@ bool reader(SvStream& rStream, BitmapEx& rBitmapEx)
     Bitmap aBitmap(Size(width, height), 24);
     AlphaMask aBitmapAlpha(Size(width, height), nullptr);
 
-    png_set_bgr(pPng);
-
     if (colorType == PNG_COLOR_TYPE_PALETTE)
         png_set_palette_to_rgb(pPng);
 
@@ -138,6 +136,9 @@ bool reader(SvStream& rStream, BitmapEx& rBitmapEx)
             size_t aRowSizeBytes = png_get_rowbytes(pPng, pInfo);
 
             BitmapScopedWriteAccess pWriteAccess(aBitmap);
+            ScanlineFormat eFromat = pWriteAccess->GetScanlineFormat();
+            if (eFromat == ScanlineFormat::N24BitTcBgr)
+                png_set_bgr(pPng);
 
             std::vector<png_byte> aRow(aRowSizeBytes, 0);
 
@@ -165,6 +166,10 @@ bool reader(SvStream& rStream, BitmapEx& rBitmapEx)
             BitmapScopedWriteAccess pWriteAccess(aBitmap);
             AlphaScopedWriteAccess pWriteAccessAlpha(aBitmapAlpha);
 
+            ScanlineFormat eFromat = pWriteAccess->GetScanlineFormat();
+            if (eFromat == ScanlineFormat::N24BitTcBgr)
+                png_set_bgr(pPng);
+
             std::vector<png_byte> aRow(aRowSizeBytes, 0);
 
             for (int pass = 0; pass < nNumberOfPasses; pass++)