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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 .
*/
#include <basegfx/utils/tools.hxx>
#include <basegfx/range/b2drange.hxx>
#include <algorithm>
namespace basegfx::utils
{
namespace
{
double distance( const double& nX,
const double& nY,
const ::basegfx::B2DVector& rNormal,
const double& nC )
{
return nX*rNormal.getX() + nY*rNormal.getY() - nC;
}
void moveLineOutsideRect( ::basegfx::B2DPoint& io_rStart,
::basegfx::B2DPoint& io_rEnd,
const ::basegfx::B2DVector& rMoveDirection,
const ::basegfx::B2DRange& rFitTarget )
{
// calc c for normal line form equation n x - c = 0
const double nC( rMoveDirection.scalar( io_rStart ) );
// calc maximum orthogonal distance for all four bound
// rect corners to the line
const double nMaxDistance( std::max(
0.0,
std::max(
distance(rFitTarget.getMinX(),
rFitTarget.getMinY(),
rMoveDirection,
nC),
std::max(
distance(rFitTarget.getMinX(),
rFitTarget.getMaxY(),
rMoveDirection,
nC),
std::max(
distance(rFitTarget.getMaxX(),
rFitTarget.getMinY(),
rMoveDirection,
nC),
distance(rFitTarget.getMaxX(),
rFitTarget.getMaxY(),
rMoveDirection,
nC) ) ) ) ) );
// now move line points, such that the bound rect
// points are all either 'on' or on the negative side
// of the half-plane
io_rStart += nMaxDistance*rMoveDirection;
io_rEnd += nMaxDistance*rMoveDirection;
}
}
void infiniteLineFromParallelogram( ::basegfx::B2DPoint& io_rLeftTop,
::basegfx::B2DPoint& io_rLeftBottom,
::basegfx::B2DPoint& io_rRightTop,
::basegfx::B2DPoint& io_rRightBottom,
const ::basegfx::B2DRange& rFitTarget )
{
// For the top and bottom border line of the
// parallelogram, we determine the distance to all four
// corner points of the bound rect (tl, tr, bl, br). When
// using the unit normal form for lines (n x - c = 0), and
// choosing n to point 'outwards' the parallelogram, then
// all bound rect corner points having positive distance
// to the line lie outside the extended gradient rect, and
// thus, the corresponding border line must be moved the
// maximum distance outwards.
// don't use the top and bottom border line direction, and
// calculate the normal from them. Instead, use the
// vertical lines (lt - lb or rt - rb), as they more
// faithfully represent the direction of the
// to-be-generated infinite line
::basegfx::B2DVector aDirectionVertical( io_rLeftTop - io_rLeftBottom );
aDirectionVertical.normalize();
const ::basegfx::B2DVector aNormalTop( aDirectionVertical );
const ::basegfx::B2DVector aNormalBottom( -aDirectionVertical );
// now extend parallelogram, such that the bound rect
// point are included
moveLineOutsideRect( io_rLeftTop, io_rRightTop, aNormalTop, rFitTarget );
moveLineOutsideRect( io_rLeftBottom, io_rRightBottom, aNormalBottom, rFitTarget );
}
}
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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