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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/tools/tools.hxx"
21 : #include "basegfx/range/b2drange.hxx"
22 :
23 : #include <algorithm>
24 :
25 :
26 : namespace basegfx
27 : {
28 : namespace tools
29 : {
30 : namespace
31 : {
32 0 : inline double distance( const double& nX,
33 : const double& nY,
34 : const ::basegfx::B2DVector& rNormal,
35 : const double& nC )
36 : {
37 0 : return nX*rNormal.getX() + nY*rNormal.getY() - nC;
38 : }
39 :
40 0 : void moveLineOutsideRect( ::basegfx::B2DPoint& io_rStart,
41 : ::basegfx::B2DPoint& io_rEnd,
42 : const ::basegfx::B2DVector& rMoveDirection,
43 : const ::basegfx::B2DRange& rFitTarget )
44 : {
45 : // calc c for normal line form equation n x - c = 0
46 0 : const double nC( rMoveDirection.scalar( io_rStart ) );
47 :
48 : // calc maximum orthogonal distance for all four bound
49 : // rect corners to the line
50 : const double nMaxDistance( ::std::max(
51 : 0.0,
52 : ::std::max(
53 0 : distance(rFitTarget.getMinX(),
54 0 : rFitTarget.getMinY(),
55 : rMoveDirection,
56 0 : nC),
57 : ::std::max(
58 0 : distance(rFitTarget.getMinX(),
59 0 : rFitTarget.getMaxY(),
60 : rMoveDirection,
61 0 : nC),
62 : ::std::max(
63 0 : distance(rFitTarget.getMaxX(),
64 0 : rFitTarget.getMinY(),
65 : rMoveDirection,
66 0 : nC),
67 0 : distance(rFitTarget.getMaxX(),
68 0 : rFitTarget.getMaxY(),
69 : rMoveDirection,
70 0 : nC) ) ) ) ) );
71 :
72 : // now move line points, such that the bound rect
73 : // points are all either 'on' or on the negative side
74 : // of the half-plane
75 0 : io_rStart += nMaxDistance*rMoveDirection;
76 0 : io_rEnd += nMaxDistance*rMoveDirection;
77 0 : }
78 : }
79 :
80 0 : void infiniteLineFromParallelogram( ::basegfx::B2DPoint& io_rLeftTop,
81 : ::basegfx::B2DPoint& io_rLeftBottom,
82 : ::basegfx::B2DPoint& io_rRightTop,
83 : ::basegfx::B2DPoint& io_rRightBottom,
84 : const ::basegfx::B2DRange& rFitTarget )
85 : {
86 : // For the top and bottom border line of the
87 : // parallelogram, we determine the distance to all four
88 : // corner points of the bound rect (tl, tr, bl, br). When
89 : // using the unit normal form for lines (n x - c = 0), and
90 : // choosing n to point 'outwards' the parallelogram, then
91 : // all bound rect corner points having positive distance
92 : // to the line lie outside the extended gradient rect, and
93 : // thus, the corresponding border line must be moved the
94 : // maximum distance outwards.
95 :
96 : // don't use the top and bottom border line direction, and
97 : // calculate the normal from them. Instead, use the
98 : // vertical lines (lt - lb or rt - rb), as they more
99 : // faithfully represent the direction of the
100 : // to-be-generated infinite line
101 0 : ::basegfx::B2DVector aDirectionVertical( io_rLeftTop - io_rLeftBottom );
102 0 : aDirectionVertical.normalize();
103 :
104 0 : const ::basegfx::B2DVector aNormalTop( aDirectionVertical );
105 0 : const ::basegfx::B2DVector aNormalBottom( -aDirectionVertical );
106 :
107 : // now extend parallelogram, such that the bound rect
108 : // point are included
109 0 : moveLineOutsideRect( io_rLeftTop, io_rRightTop, aNormalTop, rFitTarget );
110 0 : moveLineOutsideRect( io_rLeftBottom, io_rRightBottom, aNormalBottom, rFitTarget );
111 0 : }
112 : }
113 : }
114 :
115 : /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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