glfw/src/internal.h

//========================================================================
// GLFW 3.1 - www.glfw.org
//------------------------------------------------------------------------
// Copyright (c) 2002-2006 Marcus Geelnard
// Copyright (c) 2006-2010 Camilla Berglund <elmindreda@elmindreda.org>
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
//    claim that you wrote the original software. If you use this software
//    in a product, an acknowledgment in the product documentation would
//    be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not
//    be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
//    distribution.
//
//========================================================================

#ifndef _internal_h_
#define _internal_h_


#if defined(_GLFW_USE_CONFIG_H)
 #include "glfw_config.h"
#endif

#define _GLFW_VERSION_NUMBER "3.1.0"

#if defined(_GLFW_USE_OPENGL)
 // This is the default for glfw3.h
#elif defined(_GLFW_USE_GLESV1)
 #define GLFW_INCLUDE_ES1
#elif defined(_GLFW_USE_GLESV2)
 #define GLFW_INCLUDE_ES2
#else
 #error "No supported client library selected"
#endif

// Disable the inclusion of the platform glext.h by gl.h to allow proper
// inclusion of our own, newer glext.h below
#define GL_GLEXT_LEGACY

#include "../include/GLFW/glfw3.h"

#if defined(_GLFW_USE_OPENGL)
 // This path may need to be changed if you build GLFW using your own setup
 // GLFW comes with its own copy of glext.h since it uses fairly new extensions
 // and not all development environments come with an up-to-date version
 #include "../deps/GL/glext.h"
#endif

typedef struct _GLFWwndconfig   _GLFWwndconfig;
typedef struct _GLFWctxconfig   _GLFWctxconfig;
typedef struct _GLFWfbconfig    _GLFWfbconfig;
typedef struct _GLFWwindow      _GLFWwindow;
typedef struct _GLFWlibrary     _GLFWlibrary;
typedef struct _GLFWmonitor     _GLFWmonitor;
typedef struct _GLFWcursor      _GLFWcursor;

#if defined(_GLFW_COCOA)
 #include "cocoa_platform.h"
#elif defined(_GLFW_WIN32)
 #include "win32_platform.h"
#elif defined(_GLFW_X11)
 #include "x11_platform.h"
#elif defined(_GLFW_WAYLAND)
 #include "wl_platform.h"
#elif defined(_GLFW_MIR)
 #include "mir_platform.h"
#else
 #error "No supported window creation API selected"
#endif


//========================================================================
// Doxygen group definitions
//========================================================================

/*! @defgroup platform Platform interface
 *  @brief The interface implemented by the platform-specific code.
 *
 *  The platform API is the interface exposed by the platform-specific code for
 *  each platform and is called by the shared code of the public API It mirrors
 *  the public API except it uses objects instead of handles.
 */
/*! @defgroup event Event interface
 *  @brief The interface used by the platform-specific code to report events.
 *
 *  The event API is used by the platform-specific code to notify the shared
 *  code of events that can be translated into state changes and/or callback
 *  calls.
 */
/*! @defgroup utility Utility functions
 *  @brief Various utility functions for internal use.
 *
 *  These functions are shared code and may be used by any part of GLFW
 *  Each platform may add its own utility functions, but those may only be
 *  called by the platform-specific code
 */


//========================================================================
// Helper macros
//========================================================================

// Checks for whether the library has been intitalized
#define _GLFW_REQUIRE_INIT()                         \
    if (!_glfwInitialized)                           \
    {                                                \
        _glfwInputError(GLFW_NOT_INITIALIZED, NULL); \
        return;                                      \
    }
#define _GLFW_REQUIRE_INIT_OR_RETURN(x)              \
    if (!_glfwInitialized)                           \
    {                                                \
        _glfwInputError(GLFW_NOT_INITIALIZED, NULL); \
        return x;                                    \
    }

// Swaps the provided pointers
#define _GLFW_SWAP_POINTERS(x, y) \
    {                             \
        void* t;                  \
        t = x;                    \
        x = y;                    \
        y = t;                    \
    }


//========================================================================
// Platform-independent structures
//========================================================================

/*! @brief Window configuration.
 *
 *  Parameters relating to the creation of the window but not directly related
 *  to the framebuffer.  This is used to pass window creation parameters from
 *  shared code to the platform API.
 */
struct _GLFWwndconfig
{
    int           width;
    int           height;
    const char*   title;
    GLboolean     resizable;
    GLboolean     visible;
    GLboolean     decorated;
    GLboolean     focused;
    GLboolean     autoIconify;
    GLboolean     floating;
    _GLFWmonitor* monitor;
};


/*! @brief Context configuration.
 *
 *  Parameters relating to the creation of the context but not directly related
 *  to the framebuffer.  This is used to pass context creation parameters from
 *  shared code to the platform API.
 */
struct _GLFWctxconfig
{
    int           api;
    int           major;
    int           minor;
    GLboolean     forward;
    GLboolean     debug;
    int           profile;
    int           robustness;
    int           release;
    _GLFWwindow*  share;
};


/*! @brief Framebuffer configuration.
 *
 *  This describes buffers and their sizes.  It also contains
 *  a platform-specific ID used to map back to the backend API's object.
 *
 *  It is used to pass framebuffer parameters from shared code to the platform
 *  API and also to enumerate and select available framebuffer configs.
 */
struct _GLFWfbconfig
{
    int         redBits;
    int         greenBits;
    int         blueBits;
    int         alphaBits;
    int         depthBits;
    int         stencilBits;
    int         accumRedBits;
    int         accumGreenBits;
    int         accumBlueBits;
    int         accumAlphaBits;
    int         auxBuffers;
    int         stereo;
    int         samples;
    int         sRGB;
    int         doublebuffer;

    // This is defined in the context API's context.h
    _GLFW_PLATFORM_FBCONFIG;
};


/*! @brief Window and context structure.
 */
struct _GLFWwindow
{
    struct _GLFWwindow* next;

    // Window settings and state
    GLboolean           iconified;
    GLboolean           resizable;
    GLboolean           decorated;
    GLboolean           autoIconify;
    GLboolean           floating;
    GLboolean           visible;
    GLboolean           closed;
    void*               userPointer;
    GLFWvidmode         videoMode;
    _GLFWmonitor*       monitor;
    _GLFWcursor*        cursor;

    // Window input state
    GLboolean           stickyKeys;
    GLboolean           stickyMouseButtons;
    double              cursorPosX, cursorPosY;
    int                 cursorMode;
    char                mouseButtons[GLFW_MOUSE_BUTTON_LAST + 1];
    char                keys[GLFW_KEY_LAST + 1];

    // OpenGL extensions and context attributes
    struct {
        int             api;
        int             major, minor, revision;
        GLboolean       forward, debug;
        int             profile;
        int             robustness;
        int             release;
    } context;

#if defined(_GLFW_USE_OPENGL)
    PFNGLGETSTRINGIPROC GetStringi;
#endif

    struct {
        GLFWwindowposfun        pos;
        GLFWwindowsizefun       size;
        GLFWwindowclosefun      close;
        GLFWwindowrefreshfun    refresh;
        GLFWwindowfocusfun      focus;
        GLFWwindowiconifyfun    iconify;
        GLFWframebuffersizefun  fbsize;
        GLFWmousebuttonfun      mouseButton;
        GLFWcursorposfun        cursorPos;
        GLFWcursorenterfun      cursorEnter;
        GLFWscrollfun           scroll;
        GLFWkeyfun              key;
        GLFWcharfun             character;
        GLFWcharmodsfun         charmods;
        GLFWdropfun             drop;
    } callbacks;

    // This is defined in the window API's platform.h
    _GLFW_PLATFORM_WINDOW_STATE;
    // This is defined in the context API's context.h
    _GLFW_PLATFORM_CONTEXT_STATE;
};


/*! @brief Monitor structure.
 */
struct _GLFWmonitor
{
    char*           name;

    // Physical dimensions in millimeters.
    int             widthMM, heightMM;

    GLFWvidmode*    modes;
    int             modeCount;
    GLFWvidmode     currentMode;

    GLFWgammaramp   originalRamp;
    GLFWgammaramp   currentRamp;

    // This is defined in the window API's platform.h
    _GLFW_PLATFORM_MONITOR_STATE;
};


/*! @brief Cursor structure
 */
struct _GLFWcursor
{
    _GLFWcursor*    next;

    // This is defined in the window API's platform.h
    _GLFW_PLATFORM_CURSOR_STATE;
};

/*! @brief Library global data.
 */
struct _GLFWlibrary
{
    struct {
        int         redBits;
        int         greenBits;
        int         blueBits;
        int         alphaBits;
        int         depthBits;
        int         stencilBits;
        int         accumRedBits;
        int         accumGreenBits;
        int         accumBlueBits;
        int         accumAlphaBits;
        int         auxBuffers;
        int         stereo;
        int         resizable;
        int         visible;
        int         decorated;
        int         focused;
        int         autoIconify;
        int         floating;
        int         samples;
        int         sRGB;
        int         refreshRate;
        int         doublebuffer;
        int         api;
        int         major;
        int         minor;
        int         forward;
        int         debug;
        int         profile;
        int         robustness;
        int         release;
    } hints;

    double          cursorPosX, cursorPosY;

    _GLFWcursor*    cursorListHead;

    _GLFWwindow*    windowListHead;
    _GLFWwindow*    focusedWindow;

    _GLFWmonitor**  monitors;
    int             monitorCount;

    struct {
        GLFWmonitorfun  monitor;
    } callbacks;

    // This is defined in the window API's platform.h
    _GLFW_PLATFORM_LIBRARY_WINDOW_STATE;
    // This is defined in the context API's context.h
    _GLFW_PLATFORM_LIBRARY_CONTEXT_STATE;
    // This is defined in the platform's time.h
    _GLFW_PLATFORM_LIBRARY_TIME_STATE;
    // This is defined in the platform's joystick.h
    _GLFW_PLATFORM_LIBRARY_JOYSTICK_STATE;
    // This is defined in the platform's tls.h
    _GLFW_PLATFORM_LIBRARY_TLS_STATE;
};


//========================================================================
// Global state shared between compilation units of GLFW
//========================================================================

/*! @brief Flag indicating whether GLFW has been successfully initialized.
 */
extern GLboolean _glfwInitialized;

/*! @brief All global data protected by @ref _glfwInitialized.
 *  This should only be touched after a call to @ref glfwInit that has not been
 *  followed by a call to @ref glfwTerminate.
 */
extern _GLFWlibrary _glfw;


//========================================================================
// Platform API functions
//========================================================================

/*! @brief Initializes the platform-specific part of the library.
 *  @return `GL_TRUE` if successful, or `GL_FALSE` if an error occurred.
 *  @ingroup platform
 */
int _glfwPlatformInit(void);

/*! @brief Terminates the platform-specific part of the library.
 *  @ingroup platform
 */
void _glfwPlatformTerminate(void);

/*! @copydoc glfwGetVersionString
 *  @ingroup platform
 *
 *  @note The returned string must be available for the duration of the program.
 *
 *  @note The returned string must not change for the duration of the program.
 */
const char* _glfwPlatformGetVersionString(void);

/*! @copydoc glfwSetCursorPos
 *  @ingroup platform
 */
void _glfwPlatformSetCursorPos(_GLFWwindow* window, double xpos, double ypos);

/*! @brief Applies the cursor mode of the specified window to the system.
 *  @param[in] window The window whose cursor mode to apply.
 *  @ingroup platform
 */
void _glfwPlatformApplyCursorMode(_GLFWwindow* window);

/*! @copydoc glfwGetMonitors
 *  @ingroup platform
 */
_GLFWmonitor** _glfwPlatformGetMonitors(int* count);

/*! @brief Checks whether two monitor objects represent the same monitor.
 *
 *  @param[in] first The first monitor.
 *  @param[in] second The second monitor.
 *  @return @c GL_TRUE if the monitor objects represent the same monitor, or @c
 *  GL_FALSE otherwise.
 *  @ingroup platform
 */
GLboolean _glfwPlatformIsSameMonitor(_GLFWmonitor* first, _GLFWmonitor* second);

/*! @copydoc glfwGetMonitorPos
 *  @ingroup platform
 */
void _glfwPlatformGetMonitorPos(_GLFWmonitor* monitor, int* xpos, int* ypos);

/*! @copydoc glfwGetVideoModes
 *  @ingroup platform
 */
GLFWvidmode* _glfwPlatformGetVideoModes(_GLFWmonitor* monitor, int* count);

/*! @ingroup platform
 */
void _glfwPlatformGetVideoMode(_GLFWmonitor* monitor, GLFWvidmode* mode);

/*! @copydoc glfwGetGammaRamp
 *  @ingroup platform
 */
void _glfwPlatformGetGammaRamp(_GLFWmonitor* monitor, GLFWgammaramp* ramp);

/*! @copydoc glfwSetGammaRamp
 *  @ingroup platform
 */
void _glfwPlatformSetGammaRamp(_GLFWmonitor* monitor, const GLFWgammaramp* ramp);

/*! @copydoc glfwSetClipboardString
 *  @ingroup platform
 */
void _glfwPlatformSetClipboardString(_GLFWwindow* window, const char* string);

/*! @copydoc glfwGetClipboardString
 *  @ingroup platform
 *
 *  @note The returned string must be valid until the next call to @ref
 *  _glfwPlatformGetClipboardString or @ref _glfwPlatformSetClipboardString.
 */
const char* _glfwPlatformGetClipboardString(_GLFWwindow* window);

/*! @copydoc glfwJoystickPresent
 *  @ingroup platform
 */
int _glfwPlatformJoystickPresent(int joy);

/*! @copydoc glfwGetJoystickAxes
 *  @ingroup platform
 */
const float* _glfwPlatformGetJoystickAxes(int joy, int* count);

/*! @copydoc glfwGetJoystickButtons
 *  @ingroup platform
 */
const unsigned char* _glfwPlatformGetJoystickButtons(int joy, int* count);

/*! @copydoc glfwGetJoystickName
 *  @ingroup platform
 */
const char* _glfwPlatformGetJoystickName(int joy);

/*! @copydoc glfwGetTime
 *  @ingroup platform
 */
double _glfwPlatformGetTime(void);

/*! @copydoc glfwSetTime
 *  @ingroup platform
 */
void _glfwPlatformSetTime(double time);

/*! @ingroup platform
 */
int _glfwPlatformCreateWindow(_GLFWwindow* window,
                              const _GLFWwndconfig* wndconfig,
                              const _GLFWctxconfig* ctxconfig,
                              const _GLFWfbconfig* fbconfig);

/*! @ingroup platform
 */
void _glfwPlatformDestroyWindow(_GLFWwindow* window);

/*! @copydoc glfwSetWindowTitle
 *  @ingroup platform
 */
void _glfwPlatformSetWindowTitle(_GLFWwindow* window, const char* title);

/*! @copydoc glfwGetWindowPos
 *  @ingroup platform
 */
void _glfwPlatformGetWindowPos(_GLFWwindow* window, int* xpos, int* ypos);

/*! @copydoc glfwSetWindowPos
 *  @ingroup platform
 */
void _glfwPlatformSetWindowPos(_GLFWwindow* window, int xpos, int ypos);

/*! @copydoc glfwGetWindowSize
 *  @ingroup platform
 */
void _glfwPlatformGetWindowSize(_GLFWwindow* window, int* width, int* height);

/*! @copydoc glfwSetWindowSize
 *  @ingroup platform
 */
void _glfwPlatformSetWindowSize(_GLFWwindow* window, int width, int height);

/*! @copydoc glfwGetFramebufferSize
 *  @ingroup platform
 */
void _glfwPlatformGetFramebufferSize(_GLFWwindow* window, int* width, int* height);

/*! @copydoc glfwGetWindowFrameSize
 *  @ingroup platform
 */
void _glfwPlatformGetWindowFrameSize(_GLFWwindow* window, int* left, int* top, int* right, int* bottom);

/*! @copydoc glfwIconifyWindow
 *  @ingroup platform
 */
void _glfwPlatformIconifyWindow(_GLFWwindow* window);

/*! @copydoc glfwRestoreWindow
 *  @ingroup platform
 */
void _glfwPlatformRestoreWindow(_GLFWwindow* window);

/*! @copydoc glfwShowWindow
 *  @ingroup platform
 */
void _glfwPlatformShowWindow(_GLFWwindow* window);

/*! @ingroup platform
 */
void _glfwPlatformUnhideWindow(_GLFWwindow* window);

/*! @copydoc glfwHideWindow
 *  @ingroup platform
 */
void _glfwPlatformHideWindow(_GLFWwindow* window);

/*! @copydoc glfwPollEvents
 *  @ingroup platform
 */
void _glfwPlatformPollEvents(void);

/*! @copydoc glfwWaitEvents
 *  @ingroup platform
 */
void _glfwPlatformWaitEvents(void);

/*! @copydoc glfwPostEmptyEvent
 *  @ingroup platform
 */
void _glfwPlatformPostEmptyEvent(void);

/*! @copydoc glfwMakeContextCurrent
 *  @ingroup platform
 */
void _glfwPlatformMakeContextCurrent(_GLFWwindow* window);

/*! @copydoc glfwGetCurrentContext
 *  @ingroup platform
 */
_GLFWwindow* _glfwPlatformGetCurrentContext(void);

/*! @copydoc glfwSwapBuffers
 *  @ingroup platform
 */
void _glfwPlatformSwapBuffers(_GLFWwindow* window);

/*! @copydoc glfwSwapInterval
 *  @ingroup platform
 */
void _glfwPlatformSwapInterval(int interval);

/*! @copydoc glfwExtensionSupported
 *  @ingroup platform
 */
int _glfwPlatformExtensionSupported(const char* extension);

/*! @copydoc glfwGetProcAddress
 *  @ingroup platform
 */
GLFWglproc _glfwPlatformGetProcAddress(const char* procname);

/*! @copydoc glfwCreateCursor
 *  @ingroup platform
 */
int _glfwPlatformCreateCursor(_GLFWcursor* cursor, const GLFWimage* image, int xhot, int yhot);

/*! @copydoc glfwDestroyCursor
 *  @ingroup platform
 */
void _glfwPlatformDestroyCursor(_GLFWcursor* cursor);

/*! @copydoc glfwSetCursor
 *  @ingroup platform
 */
void _glfwPlatformSetCursor(_GLFWwindow* window, _GLFWcursor* cursor);


//========================================================================
// Event API functions
//========================================================================

/*! @brief Notifies shared code of a window focus event.
 *  @param[in] window The window that received the event.
 *  @param[in] focused `GL_TRUE` if the window received focus, or `GL_FALSE`
 *  if it lost focus.
 *  @ingroup event
 */
void _glfwInputWindowFocus(_GLFWwindow* window, GLboolean focused);

/*! @brief Notifies shared code of a window movement event.
 *  @param[in] window The window that received the event.
 *  @param[in] xpos The new x-coordinate of the client area of the window.
 *  @param[in] ypos The new y-coordinate of the client area of the window.
 *  @ingroup event
 */
void _glfwInputWindowPos(_GLFWwindow* window, int xpos, int ypos);

/*! @brief Notifies shared code of a window resize event.
 *  @param[in] window The window that received the event.
 *  @param[in] width The new width of the client area of the window.
 *  @param[in] height The new height of the client area of the window.
 *  @ingroup event
 */
void _glfwInputWindowSize(_GLFWwindow* window, int width, int height);

/*! @brief Notifies shared code of a framebuffer resize event.
 *  @param[in] window The window that received the event.
 *  @param[in] width The new width, in pixels, of the framebuffer.
 *  @param[in] height The new height, in pixels, of the framebuffer.
 *  @ingroup event
 */
void _glfwInputFramebufferSize(_GLFWwindow* window, int width, int height);

/*! @brief Notifies shared code of a window iconification event.
 *  @param[in] window The window that received the event.
 *  @param[in] iconified `GL_TRUE` if the window was iconified, or `GL_FALSE`
 *  if it was restored.
 *  @ingroup event
 */
void _glfwInputWindowIconify(_GLFWwindow* window, int iconified);

/*! @brief Notifies shared code of a window show/hide event.
 *  @param[in] window The window that received the event.
 *  @param[in] visible `GL_TRUE` if the window was shown, or `GL_FALSE` if it
 *  was hidden.
 *  @ingroup event
 */
void _glfwInputWindowVisibility(_GLFWwindow* window, int visible);

/*! @brief Notifies shared code of a window damage event.
 *  @param[in] window The window that received the event.
 */
void _glfwInputWindowDamage(_GLFWwindow* window);

/*! @brief Notifies shared code of a window close request event
 *  @param[in] window The window that received the event.
 *  @ingroup event
 */
void _glfwInputWindowCloseRequest(_GLFWwindow* window);

/*! @brief Notifies shared code of a physical key event.
 *  @param[in] window The window that received the event.
 *  @param[in] key The key that was pressed or released.
 *  @param[in] scancode The system-specific scan code of the key.
 *  @param[in] action @ref GLFW_PRESS or @ref GLFW_RELEASE.
 *  @param[in] mods The modifiers pressed when the event was generated.
 *  @ingroup event
 */
void _glfwInputKey(_GLFWwindow* window, int key, int scancode, int action, int mods);

/*! @brief Notifies shared code of a Unicode character input event.
 *  @param[in] window The window that received the event.
 *  @param[in] codepoint The Unicode code point of the input character.
 *  @param[in] mods Bit field describing which modifier keys were held down.
 *  @param[in] plain `GL_TRUE` if the character is regular text input, or
 *  `GL_FALSE` otherwise.
 *  @ingroup event
 */
void _glfwInputChar(_GLFWwindow* window, unsigned int codepoint, int mods, int plain);

/*! @brief Notifies shared code of a scroll event.
 *  @param[in] window The window that received the event.
 *  @param[in] x The scroll offset along the x-axis.
 *  @param[in] y The scroll offset along the y-axis.
 *  @ingroup event
 */
void _glfwInputScroll(_GLFWwindow* window, double x, double y);

/*! @brief Notifies shared code of a mouse button click event.
 *  @param[in] window The window that received the event.
 *  @param[in] button The button that was pressed or released.
 *  @param[in] action @ref GLFW_PRESS or @ref GLFW_RELEASE.
 *  @ingroup event
 */
void _glfwInputMouseClick(_GLFWwindow* window, int button, int action, int mods);

/*! @brief Notifies shared code of a cursor motion event.
 *  @param[in] window The window that received the event.
 *  @param[in] x The new x-coordinate of the cursor, relative to the left edge
 *  of the client area of the window.
 *  @param[in] y The new y-coordinate of the cursor, relative to the top edge
 *  of the client area of the window.
 *  @ingroup event
 */
void _glfwInputCursorMotion(_GLFWwindow* window, double x, double y);

/*! @brief Notifies shared code of a cursor enter/leave event.
 *  @param[in] window The window that received the event.
 *  @param[in] entered `GL_TRUE` if the cursor entered the client area of the
 *  window, or `GL_FALSE` if it left it.
 *  @ingroup event
 */
void _glfwInputCursorEnter(_GLFWwindow* window, int entered);

/*! @ingroup event
 */
void _glfwInputMonitorChange(void);

/*! @brief Notifies shared code of an error.
 *  @param[in] error The error code most suitable for the error.
 *  @param[in] format The `printf` style format string of the error
 *  description.
 *  @ingroup event
 */
void _glfwInputError(int error, const char* format, ...);

/*! @brief Notifies dropped object over window.
 *  @param[in] window The window that received the event.
 *  @param[in] count The number of dropped objects.
 *  @param[in] names The names of the dropped objects.
 *  @ingroup event
 */
void _glfwInputDrop(_GLFWwindow* window, int count, const char** names);


//========================================================================
// Utility functions
//========================================================================

/*! @ingroup utility
 */
const GLFWvidmode* _glfwChooseVideoMode(_GLFWmonitor* monitor,
                                        const GLFWvidmode* desired);

/*! @brief Performs lexical comparison between two @ref GLFWvidmode structures.
 *  @ingroup utility
 */
int _glfwCompareVideoModes(const GLFWvidmode* first, const GLFWvidmode* second);

/*! @brief Splits a color depth into red, green and blue bit depths.
 *  @ingroup utility
 */
void _glfwSplitBPP(int bpp, int* red, int* green, int* blue);

/*! @brief Searches an extension string for the specified extension.
 *  @param[in] string The extension string to search.
 *  @param[in] extensions The extension to search for.
 *  @return `GL_TRUE` if the extension was found, or `GL_FALSE` otherwise.
 *  @ingroup utility
 */
int _glfwStringInExtensionString(const char* string, const GLubyte* extensions);

/*! @brief Chooses the framebuffer config that best matches the desired one.
 *  @param[in] desired The desired framebuffer config.
 *  @param[in] alternatives The framebuffer configs supported by the system.
 *  @param[in] count The number of entries in the alternatives array.
 *  @return The framebuffer config most closely matching the desired one, or @c
 *  NULL if none fulfilled the hard constraints of the desired values.
 *  @ingroup utility
 */
const _GLFWfbconfig* _glfwChooseFBConfig(const _GLFWfbconfig* desired,
                                         const _GLFWfbconfig* alternatives,
                                         unsigned int count);

/*! @brief Retrieves the attributes of the current context.
 *  @param[in] ctxconfig The desired context attributes.
 *  @return `GL_TRUE` if successful, or `GL_FALSE` if the context is unusable.
 *  @ingroup utility
 */
GLboolean _glfwRefreshContextAttribs(const _GLFWctxconfig* ctxconfig);

/*! @brief Checks whether the desired context attributes are valid.
 *  @param[in] ctxconfig The context attributes to check.
 *  @return `GL_TRUE` if the context attributes are valid, or `GL_FALSE`
 *  otherwise.
 *  @ingroup utility
 *
 *  This function checks things like whether the specified client API version
 *  exists and whether all relevant options have supported and non-conflicting
 *  values.
 */
GLboolean _glfwIsValidContextConfig(const _GLFWctxconfig* ctxconfig);

/*! @brief Checks whether the current context fulfils the specified hard
 *  constraints.
 *  @param[in] ctxconfig The desired context attributes.
 *  @return `GL_TRUE` if the context fulfils the hard constraints, or `GL_FALSE`
 *  otherwise.
 *  @ingroup utility
 */
GLboolean _glfwIsValidContext(const _GLFWctxconfig* ctxconfig);

/*! @ingroup utility
 */
void _glfwAllocGammaArrays(GLFWgammaramp* ramp, unsigned int size);

/*! @ingroup utility
 */
void _glfwFreeGammaArrays(GLFWgammaramp* ramp);

/*! @brief Allocates and returns a monitor object with the specified name
 *  and dimensions.
 *  @param[in] name The name of the monitor.
 *  @param[in] widthMM The width, in mm, of the monitor's display area.
 *  @param[in] heightMM The height, in mm, of the monitor's display area.
 *  @return The newly created object.
 *  @ingroup utility
 */
_GLFWmonitor* _glfwAllocMonitor(const char* name, int widthMM, int heightMM);

/*! @brief Frees a monitor object and any data associated with it.
 *  @ingroup utility
  */
void _glfwFreeMonitor(_GLFWmonitor* monitor);

/*! @ingroup utility
  */
void _glfwFreeMonitors(_GLFWmonitor** monitors, int count);

#endif // _internal_h_