114 lines
5.8 KiB
C++
114 lines
5.8 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* This file incorporates work covered by the following license notice:
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed
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* with this work for additional information regarding copyright
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* ownership. The ASF licenses this file to you under the Apache
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* License, Version 2.0 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at http://www.apache.org/licenses/LICENSE-2.0 .
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*/
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#include <basegfx/tools/tools.hxx>
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#include <basegfx/range/b2drange.hxx>
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#include <algorithm>
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namespace basegfx
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{
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namespace tools
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{
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namespace
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{
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inline double distance( const double& nX,
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const double& nY,
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const ::basegfx::B2DVector& rNormal,
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const double& nC )
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{
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return nX*rNormal.getX() + nY*rNormal.getY() - nC;
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}
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void moveLineOutsideRect( ::basegfx::B2DPoint& io_rStart,
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::basegfx::B2DPoint& io_rEnd,
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const ::basegfx::B2DVector& rMoveDirection,
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const ::basegfx::B2DRange& rFitTarget )
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{
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// calc c for normal line form equation n x - c = 0
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const double nC( rMoveDirection.scalar( io_rStart ) );
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// calc maximum orthogonal distance for all four bound
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// rect corners to the line
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const double nMaxDistance( ::std::max(
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0.0,
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::std::max(
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distance(rFitTarget.getMinX(),
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rFitTarget.getMinY(),
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rMoveDirection,
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nC),
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::std::max(
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distance(rFitTarget.getMinX(),
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rFitTarget.getMaxY(),
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rMoveDirection,
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nC),
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::std::max(
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distance(rFitTarget.getMaxX(),
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rFitTarget.getMinY(),
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rMoveDirection,
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nC),
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distance(rFitTarget.getMaxX(),
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rFitTarget.getMaxY(),
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rMoveDirection,
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nC) ) ) ) ) );
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// now move line points, such that the bound rect
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// points are all either 'on' or on the negative side
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// of the half-plane
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io_rStart += nMaxDistance*rMoveDirection;
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io_rEnd += nMaxDistance*rMoveDirection;
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}
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}
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void infiniteLineFromParallelogram( ::basegfx::B2DPoint& io_rLeftTop,
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::basegfx::B2DPoint& io_rLeftBottom,
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::basegfx::B2DPoint& io_rRightTop,
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::basegfx::B2DPoint& io_rRightBottom,
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const ::basegfx::B2DRange& rFitTarget )
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{
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// For the top and bottom border line of the
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// parallelogram, we determine the distance to all four
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// corner points of the bound rect (tl, tr, bl, br). When
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// using the unit normal form for lines (n x - c = 0), and
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// choosing n to point 'outwards' the parallelogram, then
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// all bound rect corner points having positive distance
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// to the line lie outside the extended gradient rect, and
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// thus, the corresponding border line must be moved the
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// maximum distance outwards.
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// don't use the top and bottom border line direction, and
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// calculate the normal from them. Instead, use the
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// vertical lines (lt - lb or rt - rb), as they more
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// faithfully represent the direction of the
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// to-be-generated infinite line
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::basegfx::B2DVector aDirectionVertical( io_rLeftTop - io_rLeftBottom );
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aDirectionVertical.normalize();
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const ::basegfx::B2DVector aNormalTop( aDirectionVertical );
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const ::basegfx::B2DVector aNormalBottom( -aDirectionVertical );
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// now extend parallelogram, such that the bound rect
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// point are included
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moveLineOutsideRect( io_rLeftTop, io_rRightTop, aNormalTop, rFitTarget );
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moveLineOutsideRect( io_rLeftBottom, io_rRightBottom, aNormalBottom, rFitTarget );
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}
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}
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}
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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