src/zoom_func.h

   1 /* $Id$ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * 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.
   6  * 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.
   7  * 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/>.
   8  */
   9
  10 /** @file zoom_func.h Functions related to zooming. */
  11
  12 #ifndef ZOOM_FUNC_H
  13 #define ZOOM_FUNC_H
  14
  15 #include "zoom_type.h"
  16
  17 /**
  18  * Scale by zoom level, usually shift left (when zoom > ZOOM_LVL_NORMAL)
  19  * When shifting right, value is rounded up
  20  * @param value value to shift
  21  * @param zoom  zoom level to shift to
  22  * @return shifted value
  23  */
  24 static inline int ScaleByZoom(int value, ZoomLevel zoom)
  25 {
  26         assert(zoom >= 0);
  27         return value << zoom;
  28 }
  29
  30 /**
  31  * Scale by zoom level, usually shift right (when zoom > ZOOM_LVL_NORMAL)
  32  * When shifting right, value is rounded up
  33  * @param value value to shift
  34  * @param zoom  zoom level to shift to
  35  * @return shifted value
  36  */
  37 static inline int UnScaleByZoom(int value, ZoomLevel zoom)
  38 {
  39         assert(zoom >= 0);
  40         return (value + (1 << zoom) - 1) >> zoom;
  41 }
  42
  43 /**
  44  * Scale by zoom level, usually shift left (when zoom > ZOOM_LVL_NORMAL)
  45  * @param value value to shift
  46  * @param zoom  zoom level to shift to
  47  * @return shifted value
  48  */
  49 static inline int ScaleByZoomLower(int value, ZoomLevel zoom)
  50 {
  51         assert(zoom >= 0);
  52         return value << zoom;
  53 }
  54
  55 /**
  56  * Scale by zoom level, usually shift right (when zoom > ZOOM_LVL_NORMAL)
  57  * @param value value to shift
  58  * @param zoom  zoom level to shift to
  59  * @return shifted value
  60  */
  61 static inline int UnScaleByZoomLower(int value, ZoomLevel zoom)
  62 {
  63         assert(zoom >= 0);
  64         return value >> zoom;
  65 }
  66
  67 #endif /* ZOOM_FUNC_H */