src/SDL_hints.c
author Sam Lantinga <slouken@libsdl.org>
Sat, 02 Jan 2016 10:10:34 -0800
changeset 9998 f67cf37e9cd4
parent 9619 b94b6d0bff0f
child 10499 363c1c7e7a41
permissions -rw-r--r--
Updated copyright to 2016
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2016 Sam Lantinga <slouken@libsdl.org>
     4 
     5   This software is provided 'as-is', without any express or implied
     6   warranty.  In no event will the authors be held liable for any damages
     7   arising from the use of this software.
     8 
     9   Permission is granted to anyone to use this software for any purpose,
    10   including commercial applications, and to alter it and redistribute it
    11   freely, subject to the following restrictions:
    12 
    13   1. The origin of this software must not be misrepresented; you must not
    14      claim that you wrote the original software. If you use this software
    15      in a product, an acknowledgment in the product documentation would be
    16      appreciated but is not required.
    17   2. Altered source versions must be plainly marked as such, and must not be
    18      misrepresented as being the original software.
    19   3. This notice may not be removed or altered from any source distribution.
    20 */
    21 #include "./SDL_internal.h"
    22 
    23 #include "SDL_hints.h"
    24 #include "SDL_error.h"
    25 
    26 
    27 /* Assuming there aren't many hints set and they aren't being queried in
    28    critical performance paths, we'll just use linked lists here.
    29  */
    30 typedef struct SDL_HintWatch {
    31     SDL_HintCallback callback;
    32     void *userdata;
    33     struct SDL_HintWatch *next;
    34 } SDL_HintWatch;
    35 
    36 typedef struct SDL_Hint {
    37     char *name;
    38     char *value;
    39     SDL_HintPriority priority;
    40     SDL_HintWatch *callbacks;
    41     struct SDL_Hint *next;
    42 } SDL_Hint;
    43 
    44 static SDL_Hint *SDL_hints;
    45 
    46 SDL_bool
    47 SDL_SetHintWithPriority(const char *name, const char *value,
    48                         SDL_HintPriority priority)
    49 {
    50     const char *env;
    51     SDL_Hint *hint;
    52     SDL_HintWatch *entry;
    53 
    54     if (!name || !value) {
    55         return SDL_FALSE;
    56     }
    57 
    58     env = SDL_getenv(name);
    59     if (env && priority < SDL_HINT_OVERRIDE) {
    60         return SDL_FALSE;
    61     }
    62 
    63     for (hint = SDL_hints; hint; hint = hint->next) {
    64         if (SDL_strcmp(name, hint->name) == 0) {
    65             if (priority < hint->priority) {
    66                 return SDL_FALSE;
    67             }
    68             if (!hint->value || !value || SDL_strcmp(hint->value, value) != 0) {
    69                 for (entry = hint->callbacks; entry; ) {
    70                     /* Save the next entry in case this one is deleted */
    71                     SDL_HintWatch *next = entry->next;
    72                     entry->callback(entry->userdata, name, hint->value, value);
    73                     entry = next;
    74                 }
    75                 SDL_free(hint->value);
    76                 hint->value = value ? SDL_strdup(value) : NULL;
    77             }
    78             hint->priority = priority;
    79             return SDL_TRUE;
    80         }
    81     }
    82 
    83     /* Couldn't find the hint, add a new one */
    84     hint = (SDL_Hint *)SDL_malloc(sizeof(*hint));
    85     if (!hint) {
    86         return SDL_FALSE;
    87     }
    88     hint->name = SDL_strdup(name);
    89     hint->value = value ? SDL_strdup(value) : NULL;
    90     hint->priority = priority;
    91     hint->callbacks = NULL;
    92     hint->next = SDL_hints;
    93     SDL_hints = hint;
    94     return SDL_TRUE;
    95 }
    96 
    97 SDL_bool
    98 SDL_SetHint(const char *name, const char *value)
    99 {
   100     return SDL_SetHintWithPriority(name, value, SDL_HINT_NORMAL);
   101 }
   102 
   103 const char *
   104 SDL_GetHint(const char *name)
   105 {
   106     const char *env;
   107     SDL_Hint *hint;
   108 
   109     env = SDL_getenv(name);
   110     for (hint = SDL_hints; hint; hint = hint->next) {
   111         if (SDL_strcmp(name, hint->name) == 0) {
   112             if (!env || hint->priority == SDL_HINT_OVERRIDE) {
   113                 return hint->value;
   114             }
   115             break;
   116         }
   117     }
   118     return env;
   119 }
   120 
   121 void
   122 SDL_AddHintCallback(const char *name, SDL_HintCallback callback, void *userdata)
   123 {
   124     SDL_Hint *hint;
   125     SDL_HintWatch *entry;
   126     const char *value;
   127 
   128     if (!name || !*name) {
   129         SDL_InvalidParamError("name");
   130         return;
   131     }
   132     if (!callback) {
   133         SDL_InvalidParamError("callback");
   134         return;
   135     }
   136 
   137     SDL_DelHintCallback(name, callback, userdata);
   138 
   139     entry = (SDL_HintWatch *)SDL_malloc(sizeof(*entry));
   140     if (!entry) {
   141         SDL_OutOfMemory();
   142         return;
   143     }
   144     entry->callback = callback;
   145     entry->userdata = userdata;
   146 
   147     for (hint = SDL_hints; hint; hint = hint->next) {
   148         if (SDL_strcmp(name, hint->name) == 0) {
   149             break;
   150         }
   151     }
   152     if (!hint) {
   153         /* Need to add a hint entry for this watcher */
   154         hint = (SDL_Hint *)SDL_malloc(sizeof(*hint));
   155         if (!hint) {
   156             SDL_OutOfMemory();
   157             SDL_free(entry);
   158             return;
   159         }
   160         hint->name = SDL_strdup(name);
   161         hint->value = NULL;
   162         hint->priority = SDL_HINT_DEFAULT;
   163         hint->callbacks = NULL;
   164         hint->next = SDL_hints;
   165         SDL_hints = hint;
   166     }
   167 
   168     /* Add it to the callbacks for this hint */
   169     entry->next = hint->callbacks;
   170     hint->callbacks = entry;
   171 
   172     /* Now call it with the current value */
   173     value = SDL_GetHint(name);
   174     callback(userdata, name, value, value);
   175 }
   176 
   177 void
   178 SDL_DelHintCallback(const char *name, SDL_HintCallback callback, void *userdata)
   179 {
   180     SDL_Hint *hint;
   181     SDL_HintWatch *entry, *prev;
   182 
   183     for (hint = SDL_hints; hint; hint = hint->next) {
   184         if (SDL_strcmp(name, hint->name) == 0) {
   185             prev = NULL;
   186             for (entry = hint->callbacks; entry; entry = entry->next) {
   187                 if (callback == entry->callback && userdata == entry->userdata) {
   188                     if (prev) {
   189                         prev->next = entry->next;
   190                     } else {
   191                         hint->callbacks = entry->next;
   192                     }
   193                     SDL_free(entry);
   194                     break;
   195                 }
   196                 prev = entry;
   197             }
   198             return;
   199         }
   200     }
   201 }
   202 
   203 void SDL_ClearHints(void)
   204 {
   205     SDL_Hint *hint;
   206     SDL_HintWatch *entry;
   207 
   208     while (SDL_hints) {
   209         hint = SDL_hints;
   210         SDL_hints = hint->next;
   211 
   212         SDL_free(hint->name);
   213         SDL_free(hint->value);
   214         for (entry = hint->callbacks; entry; ) {
   215             SDL_HintWatch *freeable = entry;
   216             entry = entry->next;
   217             SDL_free(freeable);
   218         }
   219         SDL_free(hint);
   220     }
   221 }
   222 
   223 /* vi: set ts=4 sw=4 expandtab: */