SDL  2.0
SDL_hints.c
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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 {
32  void *userdata;
35 
36 typedef struct SDL_Hint {
37  char *name;
38  char *value;
41  struct SDL_Hint *next;
42 } SDL_Hint;
43 
45 
47 SDL_SetHintWithPriority(const char *name, const char *value,
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 
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
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
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: */
void * userdata
Definition: SDL_hints.c:32
const char * SDL_GetHint(const char *name)
Get a hint.
Definition: SDL_hints.c:104
void SDL_DelHintCallback(const char *name, SDL_HintCallback callback, void *userdata)
Remove a function watching a particular hint.
Definition: SDL_hints.c:191
struct SDL_Hint * next
Definition: SDL_hints.c:41
void SDL_AddHintCallback(const char *name, SDL_HintCallback callback, void *userdata)
Add a function to watch a particular hint.
Definition: SDL_hints.c:135
SDL_bool SDL_SetHintWithPriority(const char *name, const char *value, SDL_HintPriority priority)
Set a hint with a specific priority.
Definition: SDL_hints.c:47
SDL_HintPriority
An enumeration of hint priorities.
Definition: SDL_hints.h:936
#define SDL_InvalidParamError(param)
Definition: SDL_error.h:54
#define SDL_strcasecmp
GLuint const GLchar * name
#define SDL_free
GLsizei const GLfloat * value
SDL_bool SDL_SetHint(const char *name, const char *value)
Set a hint with normal priority.
Definition: SDL_hints.c:98
SDL_HintWatch * callbacks
Definition: SDL_hints.c:40
SDL_bool SDL_GetHintBoolean(const char *name, SDL_bool default_value)
Get a hint.
Definition: SDL_hints.c:122
#define SDL_getenv
#define NULL
Definition: begin_code.h:164
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
SDL_bool
Definition: SDL_stdinc.h:139
SDL_HintPriority priority
Definition: SDL_hints.c:39
void(* SDL_HintCallback)(void *userdata, const char *name, const char *oldValue, const char *newValue)
type definition of the hint callback function.
Definition: SDL_hints.h:982
#define SDL_strdup
void SDL_ClearHints(void)
Clear all hints.
Definition: SDL_hints.c:216
#define SDL_malloc
#define SDL_strcmp
char * value
Definition: SDL_hints.c:38
SDL_HintCallback callback
Definition: SDL_hints.c:31
struct SDL_HintWatch * next
Definition: SDL_hints.c:33
char * name
Definition: SDL_hints.c:37
static SDL_Hint * SDL_hints
Definition: SDL_hints.c:44