vcl: improve accounting of SVG images in graphics cache

The problem is that the graphics cache only counts the size of the SVG
text, which is stored in SvgData::maSvgDataArray.  However the
SvgData::maSequence may use a lot more memory, as it may contain
de-compressed bitmaps that are stored as base64-encoded PNGs in the SVG
text.

For example icon-themes/galaxy/brand/flat_logo.svg is 812 Ko but contains
60 Mo of bitmaps.

This may cause excessive memory usage and failure to export documents
due to OOM; according to valgrind massif, the bitmap buffers use 90% of
the heap.

Add a new interface com::sun::star::util::XAccounting, and implement
it in drawinglayer BasePrimitive2D.  VCL SvgData can't access
drawinglayer via C++ directly so this looks like the best approach.

Change-Id: I5a7c3147733e23473c1decabed24c1f79d951c7d
Reviewed-on: https://gerrit.libreoffice.org/30669
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/offapi/com/sun/star/util/XAccounting.idl b/offapi/com/sun/star/util/XAccounting.idl
new file mode 100644
index 000000000000..545a16ad5a00
--- /dev/null
+++ b/offapi/com/sun/star/util/XAccounting.idl
@@ -0,0 +1,34 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#ifndef __com_sun_star_util_XAccounting_idl__
+#define __com_sun_star_util_XAccounting_idl__
+
+#include <com/sun/star/uno/XInterface.idl>
+
+module com { module sun { module star { module util {
+
+/** allows estimating the memory usage of a service.
+
+    @since LibreOffice 5.3
+ */
+interface XAccounting : com::sun::star::uno::XInterface
+{
+
+    /** @returns an estimate of the current memory usage, in octets.
+     */
+    hyper estimateUsage();
+
+};
+
+}; }; }; };
+
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */