vcl: introduce a BitmapEx::DumpAsPng()

This is mostly useful for ad-hoc debugging, so you don't need to
manually create an SvFileStream, a vcl::PngImageWriter & connect them,
but you can step through code in the debugger and call DumpAsPng() at
random code locations.

The filename type is intentionally a 'const char*', so you can call
DumpAsPng(0) from gdb; that would not be possible for a 'const
OUString&' parameter type.

Change-Id: I7e6c9bfe8410892969a1cbd1f827e2d62f409400
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/145361
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

1 files changed, 16 insertions, 0 deletions

diff --git a/vcl/qa/cppunit/png/PngFilterTest.cxx b/vcl/qa/cppunit/png/PngFilterTest.cxx
index fd5747d8e9c8..dae007eb7898 100644
--- a/vcl/qa/cppunit/png/PngFilterTest.cxx
+++ b/vcl/qa/cppunit/png/PngFilterTest.cxx
@@ -176,6 +176,7 @@ public:
     void testPngRoundtrip24_8();
     void testPngRoundtrip32();
     void testPngWrite8BitRGBPalette();
+    void testDump();
 
     CPPUNIT_TEST_SUITE(PngFilterTest);
     CPPUNIT_TEST(testPng);
@@ -186,6 +187,7 @@ public:
     CPPUNIT_TEST(testPngRoundtrip24_8);
     CPPUNIT_TEST(testPngRoundtrip32);
     CPPUNIT_TEST(testPngWrite8BitRGBPalette);
+    CPPUNIT_TEST(testDump);
     CPPUNIT_TEST_SUITE_END();
 };
 
@@ -1956,6 +1958,20 @@ void PngFilterTest::testPngWrite8BitRGBPalette()
     }
 }
 
+void PngFilterTest::testDump()
+{
+    utl::TempFileNamed aTempFile;
+    Bitmap aBitmap(Size(1, 1), vcl::PixelFormat::N24_BPP);
+    {
+        BitmapScopedWriteAccess pWriteAccessBitmap(aBitmap);
+        pWriteAccessBitmap->SetPixel(0, 0, BitmapColor());
+    }
+    BitmapEx aBitmapEx(aBitmap);
+    aBitmapEx.DumpAsPng(aTempFile.GetURL().toUtf8().getStr());
+    SvStream* pStream = aTempFile.GetStream(StreamMode::READ);
+    CPPUNIT_ASSERT_GREATER(static_cast<sal_uInt64>(0), pStream->remainingSize());
+}
+
 CPPUNIT_TEST_SUITE_REGISTRATION(PngFilterTest);
 
 CPPUNIT_PLUGIN_IMPLEMENT();