1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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20 #include <basegfx/tools/tools.hxx>
21 #include <basegfx/range/b2drange.hxx>
32 inline double distance( const double& nX
,
34 const ::basegfx::B2DVector
& rNormal
,
37 return nX
*rNormal
.getX() + nY
*rNormal
.getY() - nC
;
40 void moveLineOutsideRect( ::basegfx::B2DPoint
& io_rStart
,
41 ::basegfx::B2DPoint
& io_rEnd
,
42 const ::basegfx::B2DVector
& rMoveDirection
,
43 const ::basegfx::B2DRange
& rFitTarget
)
45 // calc c for normal line form equation n x - c = 0
46 const double nC( rMoveDirection
.scalar( io_rStart
) );
48 // calc maximum orthogonal distance for all four bound
49 // rect corners to the line
50 const double nMaxDistance( ::std::max(
53 distance(rFitTarget
.getMinX(),
58 distance(rFitTarget
.getMinX(),
63 distance(rFitTarget
.getMaxX(),
67 distance(rFitTarget
.getMaxX(),
72 // now move line points, such that the bound rect
73 // points are all either 'on' or on the negative side
75 io_rStart
+= nMaxDistance
*rMoveDirection
;
76 io_rEnd
+= nMaxDistance
*rMoveDirection
;
80 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
)
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.
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 ::basegfx::B2DVector
aDirectionVertical( io_rLeftTop
- io_rLeftBottom
);
102 aDirectionVertical
.normalize();
104 const ::basegfx::B2DVector
aNormalTop( aDirectionVertical
);
105 const ::basegfx::B2DVector
aNormalBottom( -aDirectionVertical
);
107 // now extend parallelogram, such that the bound rect
108 // point are included
109 moveLineOutsideRect( io_rLeftTop
, io_rRightTop
, aNormalTop
, rFitTarget
);
110 moveLineOutsideRect( io_rLeftBottom
, io_rRightBottom
, aNormalBottom
, rFitTarget
);
115 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */