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+/*************************************************************************
+ *
+ * OpenOffice.org - a multi-platform office productivity suite
+ *
+ * $RCSfile: rectcliptools.hxx,v $
+ *
+ * $Revision: 1.2 $
+ *
+ * last change: $Author: hr $ $Date: 2006-08-11 17:40:45 $
+ *
+ * The Contents of this file are made available subject to
+ * the terms of GNU Lesser General Public License Version 2.1.
+ *
+ *
+ * GNU Lesser General Public License Version 2.1
+ * =============================================
+ * Copyright 2005 by Sun Microsystems, Inc.
+ * 901 San Antonio Road, Palo Alto, CA 94303, USA
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software Foundation.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ *
+ ************************************************************************/
+
+#ifndef _BGFX_TOOLS_RECTCLIPTOOLS_HXX
+#define _BGFX_TOOLS_RECTCLIPTOOLS_HXX
+
+#ifndef _SAL_TYPES_H_
+#include <sal/types.h>
+#endif
+
+//////////////////////////////////////////////////////////////////////////////
+
+namespace basegfx
+{
+ namespace tools
+ {
+ namespace RectClipFlags
+ {
+ static const sal_uInt32 LEFT = (sal_Int32)0x01;
+ static const sal_uInt32 RIGHT = (sal_Int32)0x02;
+ static const sal_uInt32 TOP = (sal_Int32)0x04;
+ static const sal_uInt32 BOTTOM = (sal_Int32)0x08;
+ }
+
+ /** Calc clip mask for Cohen-Sutherland rectangle clip
+
+ This function returns a clip mask used for the
+ Cohen-Sutherland rectangle clip method, where one or more
+ of the lower four bits are set, if the given point is
+ outside one or more of the four half planes defining the
+ rectangle (see RectClipFlags for possible values)
+ */
+ template< class Point, class Rect > inline
+ sal_uInt32 getCohenSutherlandClipFlags( const Point& rP,
+ const Rect& rR )
+ {
+ // maxY | minY | maxX | minX
+ sal_uInt32 clip = (rP.getX() < rR.getMinX()) << 0;
+ clip |= (rP.getX() > rR.getMaxX()) << 1;
+ clip |= (rP.getY() < rR.getMinY()) << 2;
+ clip |= (rP.getY() > rR.getMaxY()) << 3;
+ return clip;
+ }
+
+ /** Determine number of clip planes hit by given clip mask
+
+ This method returns the number of one bits in the four
+ least significant bits of the argument, which amounts to
+ the number of clip planes hit within the
+ getCohenSutherlandClipFlags() method.
+ */
+ sal_uInt32 getNumberOfClipPlanes( sal_uInt32 nFlags )
+ {
+ // classic bit count algo, see e.g. Reingold, Nievergelt,
+ // Deo: Combinatorial Algorithms, Theory and Practice,
+ // Prentice-Hall 1977
+ nFlags = (nFlags & 0x05) + ((nFlags >> 1) & 0x05);
+ nFlags = (nFlags & 0x03) + (nFlags >> 2); // no need for &
+ // 0x03, can't
+ // overflow
+ return nFlags;
+ }
+ }
+}
+
+#endif // _BGFX_TOOLS_RECTCLIPTOOLS_HXX