src/SDL_hints.c
author Sam Lantinga <slouken@libsdl.org>
Tue, 16 Oct 2018 08:29:27 -0700
changeset 12332 c80f702e4b8b
parent 11811 5d94cb6b24d3
child 12503 806492103856
permissions -rw-r--r--
Support vibration magnitude on Android 8.0 (thanks Rachel!)
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2018 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 SDL_bool
   122 SDL_GetHintBoolean(const char *name, SDL_bool default_value)
   123 {
   124     const char *hint = SDL_GetHint(name);
   125     if (!hint || !*hint) {
   126         return default_value;
   127     }
   128     if (*hint == '0' || SDL_strcasecmp(hint, "false") == 0) {
   129         return SDL_FALSE;
   130     }
   131     return SDL_TRUE;
   132 }
   133 
   134 void
   135 SDL_AddHintCallback(const char *name, SDL_HintCallback callback, void *userdata)
   136 {
   137     SDL_Hint *hint;
   138     SDL_HintWatch *entry;
   139     const char *value;
   140 
   141     if (!name || !*name) {
   142         SDL_InvalidParamError("name");
   143         return;
   144     }
   145     if (!callback) {
   146         SDL_InvalidParamError("callback");
   147         return;
   148     }
   149 
   150     SDL_DelHintCallback(name, callback, userdata);
   151 
   152     entry = (SDL_HintWatch *)SDL_malloc(sizeof(*entry));
   153     if (!entry) {
   154         SDL_OutOfMemory();
   155         return;
   156     }
   157     entry->callback = callback;
   158     entry->userdata = userdata;
   159 
   160     for (hint = SDL_hints; hint; hint = hint->next) {
   161         if (SDL_strcmp(name, hint->name) == 0) {
   162             break;
   163         }
   164     }
   165     if (!hint) {
   166         /* Need to add a hint entry for this watcher */
   167         hint = (SDL_Hint *)SDL_malloc(sizeof(*hint));
   168         if (!hint) {
   169             SDL_OutOfMemory();
   170             SDL_free(entry);
   171             return;
   172         }
   173         hint->name = SDL_strdup(name);
   174         hint->value = NULL;
   175         hint->priority = SDL_HINT_DEFAULT;
   176         hint->callbacks = NULL;
   177         hint->next = SDL_hints;
   178         SDL_hints = hint;
   179     }
   180 
   181     /* Add it to the callbacks for this hint */
   182     entry->next = hint->callbacks;
   183     hint->callbacks = entry;
   184 
   185     /* Now call it with the current value */
   186     value = SDL_GetHint(name);
   187     callback(userdata, name, value, value);
   188 }
   189 
   190 void
   191 SDL_DelHintCallback(const char *name, SDL_HintCallback callback, void *userdata)
   192 {
   193     SDL_Hint *hint;
   194     SDL_HintWatch *entry, *prev;
   195 
   196     for (hint = SDL_hints; hint; hint = hint->next) {
   197         if (SDL_strcmp(name, hint->name) == 0) {
   198             prev = NULL;
   199             for (entry = hint->callbacks; entry; entry = entry->next) {
   200                 if (callback == entry->callback && userdata == entry->userdata) {
   201                     if (prev) {
   202                         prev->next = entry->next;
   203                     } else {
   204                         hint->callbacks = entry->next;
   205                     }
   206                     SDL_free(entry);
   207                     break;
   208                 }
   209                 prev = entry;
   210             }
   211             return;
   212         }
   213     }
   214 }
   215 
   216 void SDL_ClearHints(void)
   217 {
   218     SDL_Hint *hint;
   219     SDL_HintWatch *entry;
   220 
   221     while (SDL_hints) {
   222         hint = SDL_hints;
   223         SDL_hints = hint->next;
   224 
   225         SDL_free(hint->name);
   226         SDL_free(hint->value);
   227         for (entry = hint->callbacks; entry; ) {
   228             SDL_HintWatch *freeable = entry;
   229             entry = entry->next;
   230             SDL_free(freeable);
   231         }
   232         SDL_free(hint);
   233     }
   234 }
   235 
   236 /* vi: set ts=4 sw=4 expandtab: */