1 /************************************************************** 2 * 3 * Licensed to the Apache Software Foundation (ASF) under one 4 * or more contributor license agreements. See the NOTICE file 5 * distributed with this work for additional information 6 * regarding copyright ownership. The ASF licenses this file 7 * to you under the Apache License, Version 2.0 (the 8 * "License"); you may not use this file except in compliance 9 * with the License. You may obtain a copy of the License at 10 * 11 * http://www.apache.org/licenses/LICENSE-2.0 12 * 13 * Unless required by applicable law or agreed to in writing, 14 * software distributed under the License is distributed on an 15 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 16 * KIND, either express or implied. See the License for the 17 * specific language governing permissions and limitations 18 * under the License. 19 * 20 *************************************************************/ 21 22 23 24 #ifndef _BGFX_TOOLS_RECTCLIPTOOLS_HXX 25 #define _BGFX_TOOLS_RECTCLIPTOOLS_HXX 26 27 #include <sal/types.h> 28 29 ////////////////////////////////////////////////////////////////////////////// 30 31 namespace basegfx 32 { 33 namespace tools 34 { 35 namespace RectClipFlags 36 { 37 static const sal_uInt32 LEFT = (sal_Int32)0x01; 38 static const sal_uInt32 RIGHT = (sal_Int32)0x02; 39 static const sal_uInt32 TOP = (sal_Int32)0x04; 40 static const sal_uInt32 BOTTOM = (sal_Int32)0x08; 41 } 42 43 /** Calc clip mask for Cohen-Sutherland rectangle clip 44 45 This function returns a clip mask used for the 46 Cohen-Sutherland rectangle clip method, where one or more 47 of the lower four bits are set, if the given point is 48 outside one or more of the four half planes defining the 49 rectangle (see RectClipFlags for possible values) 50 */ 51 template< class Point, class Rect > inline getCohenSutherlandClipFlags(const Point & rP,const Rect & rR)52 sal_uInt32 getCohenSutherlandClipFlags( const Point& rP, 53 const Rect& rR ) 54 { 55 // maxY | minY | maxX | minX 56 sal_uInt32 clip = (rP.getX() < rR.getMinX()) << 0; 57 clip |= (rP.getX() > rR.getMaxX()) << 1; 58 clip |= (rP.getY() < rR.getMinY()) << 2; 59 clip |= (rP.getY() > rR.getMaxY()) << 3; 60 return clip; 61 } 62 63 /** Determine number of clip planes hit by given clip mask 64 65 This method returns the number of one bits in the four 66 least significant bits of the argument, which amounts to 67 the number of clip planes hit within the 68 getCohenSutherlandClipFlags() method. 69 */ getNumberOfClipPlanes(sal_uInt32 nFlags)70 inline sal_uInt32 getNumberOfClipPlanes( sal_uInt32 nFlags ) 71 { 72 // classic bit count algo, see e.g. Reingold, Nievergelt, 73 // Deo: Combinatorial Algorithms, Theory and Practice, 74 // Prentice-Hall 1977 75 nFlags = (nFlags & 0x05) + ((nFlags >> 1) & 0x05); 76 nFlags = (nFlags & 0x03) + (nFlags >> 2); // no need for & 77 // 0x03, can't 78 // overflow 79 return nFlags; 80 } 81 } 82 } 83 84 #endif // _BGFX_TOOLS_RECTCLIPTOOLS_HXX 85