zoom_func.h

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00001 /* $Id: zoom_func.h 18351 2009-11-30 11:29:52Z rubidium $ */
00002 
00003 /*
00004  * This file is part of OpenTTD.
00005  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
00006  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
00007  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
00008  */
00009 
00012 #ifndef ZOOM_FUNC_H
00013 #define ZOOM_FUNC_H
00014 
00015 #include "zoom_type.h"
00016 
00024 static inline int ScaleByZoom(int value, ZoomLevel zoom)
00025 {
00026   if (zoom == ZOOM_LVL_NORMAL) return value;
00027   int izoom = zoom - ZOOM_LVL_NORMAL;
00028   return (zoom > ZOOM_LVL_NORMAL) ? value << izoom : (value + (1 << -izoom) - 1) >> -izoom;
00029 }
00030 
00038 static inline int UnScaleByZoom(int value, ZoomLevel zoom)
00039 {
00040   if (zoom == ZOOM_LVL_NORMAL) return value;
00041   int izoom = zoom - ZOOM_LVL_NORMAL;
00042   return (zoom > ZOOM_LVL_NORMAL) ? (value + (1 << izoom) - 1) >> izoom : value << -izoom;
00043 }
00044 
00051 static inline int ScaleByZoomLower(int value, ZoomLevel zoom)
00052 {
00053   if (zoom == ZOOM_LVL_NORMAL) return value;
00054   int izoom = zoom - ZOOM_LVL_NORMAL;
00055   return (zoom > ZOOM_LVL_NORMAL) ? value << izoom : value >> -izoom;
00056 }
00057 
00064 static inline int UnScaleByZoomLower(int value, ZoomLevel zoom)
00065 {
00066   if (zoom == ZOOM_LVL_NORMAL) return value;
00067   int izoom = zoom - ZOOM_LVL_NORMAL;
00068   return (zoom > ZOOM_LVL_NORMAL) ? value >> izoom : value << -izoom;
00069 }
00070 
00071 #endif /* ZOOM_FUNC_H */

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