Added a hint system to allow configuration hints to be specified by the application.

src/SDL_hints.c

@@ -0,0 +1,115 @@
+/*
+    SDL - Simple DirectMedia Layer
+    Copyright (C) 1997-2010 Sam Lantinga
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 2.1 of the License, or (at your option) any later version.
+
+    This library 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.  See the GNU
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+    Sam Lantinga
+    slouken@libsdl.org
+*/
+#include "SDL_config.h"
+
+#include "SDL_hints.h"
+
+
+/* Assuming there aren't many hints set and they aren't being queried in
+   critical performance paths, we'll just use a linked list here.
+ */
+typedef struct SDL_Hint {
+    char *name;
+    char *value;
+    SDL_HintPriority priority;
+    struct SDL_Hint *next;
+} SDL_Hint;
+
+static SDL_Hint *SDL_hints;
+
+
+SDL_bool
+SDL_SetHint(const char *name, const char *value, SDL_HintPriority priority)
+{
+    const char *env;
+    SDL_Hint *prev, *hint;
+
+    if (!name || !value) {
+        return SDL_FALSE;
+    }
+
+    env = SDL_getenv(name);
+    if (env && priority < SDL_HINT_OVERRIDE) {
+        return SDL_FALSE;
+    }
+
+    prev = NULL;
+    for (hint = SDL_hints; hint; prev = hint, hint = hint->next) {
+        if (SDL_strcmp(name, hint->name) == 0) {
+            if (priority < hint->priority) {
+                return SDL_FALSE;
+            }
+            if (SDL_strcmp(hint->value, value) != 0) {
+                SDL_free(hint->value);
+                hint->value = SDL_strdup(value);
+            }
+            hint->priority = priority;
+            return SDL_TRUE;
+        }
+    }
+
+    /* Couldn't find the hint, add a new one */
+    hint = (SDL_Hint *)SDL_malloc(sizeof(*hint));
+    if (!hint) {
+        return SDL_FALSE;
+    }
+    hint->name = SDL_strdup(name);
+    hint->value = SDL_strdup(value);
+    hint->priority = priority;
+    hint->next = SDL_hints;
+    SDL_hints = hint;
+    return SDL_TRUE;
+}
+
+const char *
+SDL_GetHint(const char *name)
+{
+    const char *env;
+    SDL_Hint *hint;
+
+    env = SDL_getenv(name);
+    for (hint = SDL_hints; hint; hint = hint->next) {
+        if (SDL_strcmp(name, hint->name) == 0) {
+            if (!env || hint->priority == SDL_HINT_OVERRIDE) {
+                return hint->value;
+            }
+            break;
+        }
+    }
+    return env;
+}
+
+void SDL_ClearHints()
+{
+    SDL_Hint *hint;
+
+    while (SDL_hints) {
+        hint = SDL_hints;
+        SDL_hints = hint->next;
+
+        SDL_free(hint->name);
+        SDL_free(hint->value);
+        SDL_free(hint);
+    }
+}
+
+/* vi: set ts=4 sw=4 expandtab: */