basegfx/source/tools/tools.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
  13  *   with this work for additional information regarding copyright
  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #include <basegfx/utils/tools.hxx>
  21 #include <basegfx/range/b2drange.hxx>
  22
  23 #include <algorithm>
  24
  25 namespace basegfx
  26 {
  27     namespace utils
  28     {
  29         namespace
  30         {
  31             inline double distance( const double&                   nX,
  32                                     const double&                   nY,
  33                                     const ::basegfx::B2DVector&     rNormal,
  34                                     const double&                   nC )
  35             {
  36                 return nX*rNormal.getX() + nY*rNormal.getY() - nC;
  37             }
  38
  39             void moveLineOutsideRect( ::basegfx::B2DPoint&          io_rStart,
  40                                       ::basegfx::B2DPoint&          io_rEnd,
  41                                       const ::basegfx::B2DVector&   rMoveDirection,
  42                                       const ::basegfx::B2DRange&    rFitTarget      )
  43             {
  44                 // calc c for normal line form equation n x - c = 0
  45                 const double nC( rMoveDirection.scalar( io_rStart ) );
  46
  47                 // calc maximum orthogonal distance for all four bound
  48                 // rect corners to the line
  49                 const double nMaxDistance( std::max(
  50                                                0.0,
  51                                                std::max(
  52                                                    distance(rFitTarget.getMinX(),
  53                                                             rFitTarget.getMinY(),
  54                                                             rMoveDirection,
  55                                                             nC),
  56                                                    std::max(
  57                                                        distance(rFitTarget.getMinX(),
  58                                                                 rFitTarget.getMaxY(),
  59                                                                 rMoveDirection,
  60                                                                 nC),
  61                                                        std::max(
  62                                                            distance(rFitTarget.getMaxX(),
  63                                                                     rFitTarget.getMinY(),
  64                                                                     rMoveDirection,
  65                                                                     nC),
  66                                                            distance(rFitTarget.getMaxX(),
  67                                                                     rFitTarget.getMaxY(),
  68                                                                     rMoveDirection,
  69                                                                     nC) ) ) ) ) );
  70
  71                 // now move line points, such that the bound rect
  72                 // points are all either 'on' or on the negative side
  73                 // of the half-plane
  74                 io_rStart += nMaxDistance*rMoveDirection;
  75                 io_rEnd   += nMaxDistance*rMoveDirection;
  76             }
  77         }
  78
  79         void infiniteLineFromParallelogram( ::basegfx::B2DPoint&        io_rLeftTop,
  80                                             ::basegfx::B2DPoint&        io_rLeftBottom,
  81                                             ::basegfx::B2DPoint&        io_rRightTop,
  82                                             ::basegfx::B2DPoint&        io_rRightBottom,
  83                                             const ::basegfx::B2DRange&  rFitTarget  )
  84         {
  85             // For the top and bottom border line of the
  86             // parallelogram, we determine the distance to all four
  87             // corner points of the bound rect (tl, tr, bl, br). When
  88             // using the unit normal form for lines (n x - c = 0), and
  89             // choosing n to point 'outwards' the parallelogram, then
  90             // all bound rect corner points having positive distance
  91             // to the line lie outside the extended gradient rect, and
  92             // thus, the corresponding border line must be moved the
  93             // maximum distance outwards.
  94
  95             // don't use the top and bottom border line direction, and
  96             // calculate the normal from them. Instead, use the
  97             // vertical lines (lt - lb or rt - rb), as they more
  98             // faithfully represent the direction of the
  99             // to-be-generated infinite line
 100             ::basegfx::B2DVector aDirectionVertical( io_rLeftTop - io_rLeftBottom );
 101             aDirectionVertical.normalize();
 102
 103             const ::basegfx::B2DVector aNormalTop( aDirectionVertical );
 104             const ::basegfx::B2DVector aNormalBottom( -aDirectionVertical );
 105
 106             // now extend parallelogram, such that the bound rect
 107             // point are included
 108             moveLineOutsideRect( io_rLeftTop, io_rRightTop, aNormalTop, rFitTarget );
 109             moveLineOutsideRect( io_rLeftBottom, io_rRightBottom, aNormalBottom, rFitTarget );
 110         }
 111     }
 112 }
 113
 114 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */