src/video/SDL_rect.c
branchSDL-1.3
changeset 1735 8dd28c4ef746
child 2223 175754591a13
equal deleted inserted replaced
1734:f7c667ded87d 1735:8dd28c4ef746
       
     1 /*
       
     2     SDL - Simple DirectMedia Layer
       
     3     Copyright (C) 1997-2006 Sam Lantinga
       
     4 
       
     5     This library is free software; you can redistribute it and/or
       
     6     modify it under the terms of the GNU Lesser General Public
       
     7     License as published by the Free Software Foundation; either
       
     8     version 2.1 of the License, or (at your option) any later version.
       
     9 
       
    10     This library is distributed in the hope that it will be useful,
       
    11     but WITHOUT ANY WARRANTY; without even the implied warranty of
       
    12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
       
    13     Lesser General Public License for more details.
       
    14 
       
    15     You should have received a copy of the GNU Lesser General Public
       
    16     License along with this library; if not, write to the Free Software
       
    17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
       
    18 
       
    19     Sam Lantinga
       
    20     slouken@libsdl.org
       
    21 */
       
    22 #include "SDL_config.h"
       
    23 
       
    24 #include "SDL_video.h"
       
    25 #include "SDL_rect_c.h"
       
    26 
       
    27 SDL_bool
       
    28 SDL_HasIntersection(const SDL_Rect * A, const SDL_Rect * B)
       
    29 {
       
    30     int Amin, Amax, Bmin, Bmax;
       
    31 
       
    32     /* Horizontal intersection */
       
    33     Amin = A->x;
       
    34     Amax = Amin + A->w;
       
    35     Bmin = B->x;
       
    36     Bmax = Bmin + B->w;
       
    37     if (Bmin > Amin)
       
    38         Amin = Bmin;
       
    39     if (Bmax < Amax)
       
    40         Amax = Bmax;
       
    41     if (Amax <= Amin)
       
    42         return SDL_FALSE;
       
    43 
       
    44     /* Vertical intersection */
       
    45     Amin = A->y;
       
    46     Amax = Amin + A->h;
       
    47     Bmin = B->y;
       
    48     Bmax = Bmin + B->h;
       
    49     if (Bmin > Amin)
       
    50         Amin = Bmin;
       
    51     if (Bmax < Amax)
       
    52         Amax = Bmax;
       
    53     if (Amax <= Amin)
       
    54         return SDL_FALSE;
       
    55 
       
    56     return SDL_TRUE;
       
    57 }
       
    58 
       
    59 SDL_bool
       
    60 SDL_IntersectRect(const SDL_Rect * A, const SDL_Rect * B, SDL_Rect * result)
       
    61 {
       
    62     int Amin, Amax, Bmin, Bmax;
       
    63 
       
    64     /* Horizontal intersection */
       
    65     Amin = A->x;
       
    66     Amax = Amin + A->w;
       
    67     Bmin = B->x;
       
    68     Bmax = Bmin + B->w;
       
    69     if (Bmin > Amin)
       
    70         Amin = Bmin;
       
    71     result->x = Amin;
       
    72     if (Bmax < Amax)
       
    73         Amax = Bmax;
       
    74     result->w = Amax - Amin;
       
    75 
       
    76     /* Vertical intersection */
       
    77     Amin = A->y;
       
    78     Amax = Amin + A->h;
       
    79     Bmin = B->y;
       
    80     Bmax = Bmin + B->h;
       
    81     if (Bmin > Amin)
       
    82         Amin = Bmin;
       
    83     result->y = Amin;
       
    84     if (Bmax < Amax)
       
    85         Amax = Bmax;
       
    86     result->h = Amax - Amin;
       
    87 
       
    88     return !SDL_RectEmpty(result);
       
    89 }
       
    90 
       
    91 void
       
    92 SDL_UnionRect(const SDL_Rect * A, const SDL_Rect * B, SDL_Rect * result)
       
    93 {
       
    94     int Amin, Amax, Bmin, Bmax;
       
    95 
       
    96     /* Horizontal union */
       
    97     Amin = A->x;
       
    98     Amax = Amin + A->w;
       
    99     Bmin = B->x;
       
   100     Bmax = Bmin + B->w;
       
   101     if (Bmin < Amin)
       
   102         Amin = Bmin;
       
   103     result->x = Amin;
       
   104     if (Bmax > Amax)
       
   105         Amax = Bmax;
       
   106     result->w = Amax - Amin;
       
   107 
       
   108     /* Vertical intersection */
       
   109     Amin = A->y;
       
   110     Amax = Amin + A->h;
       
   111     Bmin = B->y;
       
   112     Bmax = Bmin + B->h;
       
   113     if (Bmin < Amin)
       
   114         Amin = Bmin;
       
   115     result->y = Amin;
       
   116     if (Bmax > Amax)
       
   117         Amax = Bmax;
       
   118     result->h = Amax - Amin;
       
   119 }
       
   120 
       
   121 void
       
   122 SDL_AddDirtyRect(SDL_DirtyRectList * list, const SDL_Rect * rect)
       
   123 {
       
   124     SDL_DirtyRect *dirty;
       
   125     SDL_DirtyRect *check, *prev, *next;
       
   126 
       
   127     if (list->free) {
       
   128         dirty = list->free;
       
   129         list->free = dirty->next;
       
   130     } else {
       
   131         dirty = (SDL_DirtyRect *) SDL_malloc(sizeof(*dirty));
       
   132         if (!dirty) {
       
   133             return;
       
   134         }
       
   135     }
       
   136     dirty->rect = *rect;
       
   137 
       
   138     /* FIXME: At what point is this optimization too expensive? */
       
   139     for (prev = NULL, check = list->list; check; check = next) {
       
   140         next = check->next;
       
   141 
       
   142         if (SDL_HasIntersection(&dirty->rect, &check->rect)) {
       
   143             SDL_UnionRect(&dirty->rect, &check->rect, &dirty->rect);
       
   144             if (prev) {
       
   145                 prev->next = next;
       
   146             } else {
       
   147                 list->list = next;
       
   148             }
       
   149             check->next = list->free;
       
   150             list->free = check;
       
   151             --list->count;
       
   152         } else {
       
   153             prev = check;
       
   154         }
       
   155     }
       
   156 
       
   157     dirty->next = list->list;
       
   158     list->list = dirty;
       
   159     ++list->count;
       
   160 }
       
   161 
       
   162 void
       
   163 SDL_ClearDirtyRects(SDL_DirtyRectList * list)
       
   164 {
       
   165     while (list->list) {
       
   166         SDL_DirtyRect *elem = list->list;
       
   167         list->list = elem->next;
       
   168         elem->next = list->free;
       
   169         list->free = elem;
       
   170     }
       
   171     list->count = 0;
       
   172 }
       
   173 
       
   174 void
       
   175 SDL_FreeDirtyRects(SDL_DirtyRectList * list)
       
   176 {
       
   177     while (list->list) {
       
   178         SDL_DirtyRect *elem = list->list;
       
   179         list->list = elem->next;
       
   180         SDL_free(elem);
       
   181     }
       
   182     while (list->free) {
       
   183         SDL_DirtyRect *elem = list->free;
       
   184         list->free = elem->next;
       
   185         SDL_free(elem);
       
   186     }
       
   187 }
       
   188 
       
   189 /* vi: set ts=4 sw=4 expandtab: */