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/* -*- 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 .
*/
#ifndef INCLUDED_BASEGFX_TOOLS_RECTCLIPTOOLS_HXX
#define INCLUDED_BASEGFX_TOOLS_RECTCLIPTOOLS_HXX
#include <sal/types.h>
#include <basegfx/range/b2ibox.hxx>
//////////////////////////////////////////////////////////////////////////////
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;
}
/// Cohen-Sutherland mask calculation - overload for boxes.
template< class Point > inline
sal_uInt32 getCohenSutherlandClipFlags( const Point& rP,
const B2IBox& rB )
{
// maxY | minY | maxX | minX
sal_uInt32 clip = (rP.getX() < rB.getMinX()) << 0;
clip |= (rP.getX() >= rB.getMaxX()) << 1;
clip |= (rP.getY() < rB.getMinY()) << 2;
clip |= (rP.getY() >= rB.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.
*/
inline 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 // INCLUDED_BASEGFX_TOOLS_RECTCLIPTOOLS_HXX
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