tdf#124987 sw: Fixed off-by-one error in draw obj anchor clipping rect

Since tdf#91260, Writer clips drawing objects to pages by checking
whether their anchors are contained by a bounding rectangle. The code
that calculated this rectangle had an off-by-one error causing the
clipping rectangle to always be exactly 1 twip shorter and narrower than
the actual page frame rectangle. As a result, anything with an anchor
position on the right or bottom edge of the screen would fail to render
- including any objects anchored to an RTL page.

Regression from commit 689cead9e0
  Author: Michael Stahl <mstahl@redhat.com>
  Date:   Tue Dec 6 22:59:40 2016 +0100
  tdf#91260 svx, sw: don't paint off-page part of drawing object

Change-Id: Ife6c817f0689ca2b31d22df31f740c30ab548c8c
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/205114
Reviewed-by: Jonathan Clark <jonathan@libreoffice.org>
Tested-by: Jenkins

include/vcl/canvastools.hxx

@@ -161,6 +161,7 @@ namespace vcl::unotools
         tools::Rectangle                   VCL_DLLPUBLIC rectangleFromB2IRectangle( const basegfx::B2IRange& );
         basegfx::B2IPoint           VCL_DLLPUBLIC b2IPointFromPoint(const Point&);
         basegfx::B2IRectangle       VCL_DLLPUBLIC b2IRectangleFromRectangle(const tools::Rectangle&);
+        basegfx::B2IRectangle       VCL_DLLPUBLIC b2IRectangleFromClosedRectangle(const tools::Rectangle&);
 
 }
 

sw/source/core/view/vdraw.cxx

@@ -136,7 +136,11 @@ void SwViewShellImp::PaintLayer( const SdrLayerID _nLayerID,
     }
 
     pOutDev->Push( vcl::PushFlags::LINECOLOR );
-    basegfx::B2IRectangle const pageFrame = vcl::unotools::b2IRectangleFromRectangle(rPageFrame.getFrameArea().SVRect());
+
+    // tdf#124987: Writer considers frame rectangles closed ranges, and may position anchors
+    // at the edges of the rectangle. Convert this to B2IRectangle as a closed range, not open.
+    basegfx::B2IRectangle const pageFrame
+        = vcl::unotools::b2IRectangleFromClosedRectangle(rPageFrame.getFrameArea().SVRect());
     GetPageView()->DrawLayer(_nLayerID, pOutDev, pRedirector, aPaintRect.SVRect(), &pageFrame);
     pOutDev->Pop();
 

vcl/CppunitTest_vcl_text.mk

@@ -16,6 +16,7 @@ $(eval $(call gb_CppunitTest_set_include,vcl_text,\
 
 $(eval $(call gb_CppunitTest_add_exception_objects,vcl_text, \
 	vcl/qa/cppunit/canvasbitmaptest \
+	vcl/qa/cppunit/canvastoolstest \
 	vcl/qa/cppunit/complextext \
 	vcl/qa/cppunit/justificationdata \
 	vcl/qa/cppunit/text \

vcl/qa/cppunit/canvastoolstest.cxx

@@ -0,0 +1,60 @@
+/* -*- 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/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#include <test/bootstrapfixture.hxx>
+#include <vcl/canvastools.hxx>
+
+using namespace ::com::sun::star;
+using namespace vcl::unotools;
+
+namespace
+{
+class CanvasToolsTest : public CppUnit::TestFixture
+{
+public:
+    void testB2IRectangleFromClosedRectangle();
+
+    CPPUNIT_TEST_SUITE(CanvasToolsTest);
+    CPPUNIT_TEST(testB2IRectangleFromClosedRectangle);
+    CPPUNIT_TEST_SUITE_END();
+};
+
+void CanvasToolsTest::testB2IRectangleFromClosedRectangle()
+{
+    // tdf#124987: Characterization test for a use that was causing an off-by-one
+    // error when clipping draw objects to the page containing the anchor
+
+    tools::Rectangle aRect{ /*nLeft*/ 100, /*nTop*/ 100, /*nRight*/ 200, /*nBottom*/ 300 };
+
+    // With the original code, the simulated RTL anchor would be considered off-screen
+    auto aBadPageFrame = b2IRectangleFromRectangle(aRect);
+    CPPUNIT_ASSERT_EQUAL(sal_Int32(200), aBadPageFrame.getMaxX());
+    CPPUNIT_ASSERT_EQUAL(sal_Int32(300), aBadPageFrame.getMaxY());
+
+    // With the new code, the simulated RTL anchor would be considered on-screen
+    auto aPageFrame = b2IRectangleFromClosedRectangle(aRect);
+    CPPUNIT_ASSERT_EQUAL(sal_Int32(201), aPageFrame.getMaxX());
+    CPPUNIT_ASSERT_EQUAL(sal_Int32(301), aPageFrame.getMaxY());
+}
+
+} // namespace
+
+CPPUNIT_TEST_SUITE_REGISTRATION(CanvasToolsTest);
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */

vcl/source/helper/canvastools.cxx

@@ -338,6 +338,19 @@ namespace vcl::unotools
                                   rRect.IsHeightEmpty() ? rRect.Top() : rRect.Bottom() );
         }
 
+        basegfx::B2IRectangle b2IRectangleFromClosedRectangle(tools::Rectangle const& rRect)
+        {
+            // although B2IRange internally has separate height/width emptiness, it doesn't
+            // expose any API to let us set them separately, so just do the best we can.
+            if (rRect.IsWidthEmpty() && rRect.IsHeightEmpty())
+            {
+                return basegfx::B2IRange(basegfx::B2ITuple(rRect.Left(), rRect.Top()));
+            }
+
+            return basegfx::B2IRange(rRect.Left(), rRect.Top(), rRect.Left() + rRect.GetWidth(),
+                                     rRect.Top() + rRect.GetHeight());
+        }
+
         basegfx::B2DSize b2DSizeFromSize(const Size& rSize)
         {
             return basegfx::B2DSize(rSize.Width(), rSize.Height());