| /************************************************************** |
| * |
| * 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 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| * |
| *************************************************************/ |
| |
| |
| |
| // MARKER(update_precomp.py): autogen include statement, do not remove |
| #include "precompiled_basegfx.hxx" |
| |
| #include "basegfx/tools/tools.hxx" |
| #include "basegfx/numeric/ftools.hxx" |
| #include "basegfx/range/b2drange.hxx" |
| |
| |
| namespace basegfx |
| { |
| namespace tools |
| { |
| namespace |
| { |
| // see Foley/vanDam, pp. 122 for the Liang-Barsky line |
| // clipping algorithm |
| inline bool liangBarskyClipT( double nDenom, |
| double nNumerator, |
| double& io_rTE, |
| double& io_rTL ) |
| { |
| double t; |
| if( nDenom > 0 ) |
| { |
| t = nNumerator / nDenom; |
| if( t > io_rTL ) |
| return false; |
| else if( t > io_rTE ) |
| io_rTE = t; |
| } |
| else if( nDenom < 0 ) |
| { |
| t = nNumerator / nDenom; |
| if( t < io_rTE ) |
| return false; |
| else |
| io_rTL = t; |
| } |
| else if( nNumerator > 0 ) |
| { |
| return false; |
| } |
| |
| return true; |
| } |
| } |
| |
| // see Foley/vanDam, pp. 122 for the Liang-Barsky line |
| // clipping algorithm |
| bool liangBarskyClip2D( ::basegfx::B2DPoint& io_rStart, |
| ::basegfx::B2DPoint& io_rEnd, |
| const ::basegfx::B2DRange& rClipRect ) |
| { |
| const double nDX( io_rEnd.getX() - io_rStart.getX() ); |
| const double nDY( io_rEnd.getY() - io_rStart.getY() ); |
| |
| if( ::basegfx::fTools::equalZero( nDX ) && |
| ::basegfx::fTools::equalZero( nDY ) ) |
| { |
| return rClipRect.isInside( io_rStart ); |
| } |
| else |
| { |
| double nTE( 0.0 ); |
| double nTL( 1.0 ); |
| if( liangBarskyClipT(nDX, rClipRect.getMinX() - io_rStart.getX(), |
| nTE, nTL ) ) // inside wrt. left edge |
| { |
| if( liangBarskyClipT(-nDX, io_rStart.getX() - rClipRect.getMaxX(), |
| nTE, nTL ) ) // inside wrt. right edge |
| { |
| if( liangBarskyClipT(nDY, rClipRect.getMinY() - io_rStart.getY(), |
| nTE, nTL ) ) // inside wrt. bottom edge |
| { |
| if( liangBarskyClipT(-nDY, io_rStart.getY() - rClipRect.getMaxY(), |
| nTE, nTL ) ) // inside wrt. top edge |
| { |
| // compute actual intersection points, |
| // if nTL has changed |
| if( nTL < 1.0 ) |
| { |
| io_rEnd.setX( io_rStart.getX() + nTL*nDX ); |
| io_rEnd.setY( io_rStart.getY() + nTL*nDY ); |
| } |
| |
| // compute actual intersection points, |
| // if nTE has changed |
| if( nTE > 0.0 ) |
| { |
| io_rStart.setX( io_rStart.getX() + nTE*nDX ); |
| io_rStart.setY( io_rStart.getY() + nTE*nDY ); |
| } |
| |
| // line is (at least partially) visible |
| return true; |
| } |
| } |
| } |
| } |
| } |
| |
| return false; |
| } |
| } |
| } |
