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| -rw-r--r-- | basegfx/source/tools/tools.cxx | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/basegfx/source/tools/tools.cxx b/basegfx/source/tools/tools.cxx new file mode 100644 index 000000000..4a7f2c962 --- /dev/null +++ b/basegfx/source/tools/tools.cxx @@ -0,0 +1,111 @@ +/* -*- 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: */ |