Modules | Macros | Typedefs | Functions
Initialization, version and error reference

Description

This is the reference documentation for initialization and termination of the library, version management and error handling. For more task-oriented information, see the Introduction to the API.

Modules

 Error codes
 Error codes.
 

Macros

#define GLFW_TRUE   1
 One. More...
 
#define GLFW_FALSE   0
 Zero. More...
 
#define GLFW_JOYSTICK_HAT_BUTTONS   0x00050001
 Joystick hat buttons init hint. More...
 
#define GLFW_ANGLE_PLATFORM_TYPE   0x00050002
 ANGLE rendering backend init hint. More...
 
#define GLFW_PLATFORM   0x00050003
 Platform selection init hint. More...
 
#define GLFW_COCOA_CHDIR_RESOURCES   0x00051001
 macOS specific init hint. More...
 
#define GLFW_COCOA_MENUBAR   0x00051002
 macOS specific init hint. More...
 
#define GLFW_X11_XCB_VULKAN_SURFACE   0x00052001
 X11 specific init hint. More...
 
#define GLFW_ANY_PLATFORM   0x00060000
 Hint value that enables automatic platform selection. More...
 
#define GLFW_PLATFORM_WIN32   0x00060001
 
#define GLFW_PLATFORM_COCOA   0x00060002
 
#define GLFW_PLATFORM_WAYLAND   0x00060003
 
#define GLFW_PLATFORM_X11   0x00060004
 
#define GLFW_PLATFORM_NULL   0x00060005
 

Typedefs

typedef void *(* GLFWallocatefun) (size_t size, void *user)
 The function pointer type for memory allocation callbacks. More...
 
typedef void *(* GLFWreallocatefun) (void *block, size_t size, void *user)
 The function pointer type for memory reallocation callbacks. More...
 
typedef void(* GLFWdeallocatefun) (void *block, void *user)
 The function pointer type for memory deallocation callbacks. More...
 
typedef void(* GLFWerrorfun) (int error_code, const char *description)
 The function pointer type for error callbacks. More...
 
typedef struct GLFWallocator GLFWallocator
 

Functions

int glfwInit (void)
 Initializes the GLFW library. More...
 
void glfwTerminate (void)
 Terminates the GLFW library. More...
 
void glfwInitHint (int hint, int value)
 Sets the specified init hint to the desired value. More...
 
void glfwInitAllocator (const GLFWallocator *allocator)
 Sets the init allocator to the desired value. More...
 
void glfwInitVulkanLoader (PFN_vkGetInstanceProcAddr loader)
 Sets the desired Vulkan vkGetInstanceProcAddr function. More...
 
void glfwGetVersion (int *major, int *minor, int *rev)
 Retrieves the version of the GLFW library. More...
 
const char * glfwGetVersionString (void)
 Returns a string describing the compile-time configuration. More...
 
int glfwGetError (const char **description)
 Returns and clears the last error for the calling thread. More...
 
GLFWerrorfun glfwSetErrorCallback (GLFWerrorfun callback)
 Sets the error callback. More...
 
int glfwGetPlatform (void)
 Returns the currently selected platform. More...
 
int glfwPlatformSupported (int platform)
 Returns whether the library includes support for the specified platform. More...
 

Macro Definition Documentation

◆ GLFW_VERSION_MAJOR

#define GLFW_VERSION_MAJOR   3

The major version number of the GLFW header. This is incremented when the API is changed in non-compatible ways.

◆ GLFW_VERSION_MINOR

#define GLFW_VERSION_MINOR   4

The minor version number of the GLFW header. This is incremented when features are added to the API but it remains backward-compatible.

◆ GLFW_VERSION_REVISION

#define GLFW_VERSION_REVISION   0

The revision number of the GLFW header. This is incremented when a bug fix release is made that does not contain any API changes.

◆ GLFW_TRUE

#define GLFW_TRUE   1

This is only semantic sugar for the number 1. You can instead use 1 or true or _True or GL_TRUE or VK_TRUE or anything else that is equal to one.

◆ GLFW_FALSE

#define GLFW_FALSE   0

This is only semantic sugar for the number 0. You can instead use 0 or false or _False or GL_FALSE or VK_FALSE or anything else that is equal to zero.

◆ GLFW_JOYSTICK_HAT_BUTTONS

#define GLFW_JOYSTICK_HAT_BUTTONS   0x00050001

Joystick hat buttons init hint.

◆ GLFW_ANGLE_PLATFORM_TYPE

#define GLFW_ANGLE_PLATFORM_TYPE   0x00050002

ANGLE rendering backend init hint.

◆ GLFW_PLATFORM

#define GLFW_PLATFORM   0x00050003

Platform selection init hint.

◆ GLFW_COCOA_CHDIR_RESOURCES

#define GLFW_COCOA_CHDIR_RESOURCES   0x00051001

macOS specific init hint.

◆ GLFW_COCOA_MENUBAR

#define GLFW_COCOA_MENUBAR   0x00051002

macOS specific init hint.

◆ GLFW_X11_XCB_VULKAN_SURFACE

#define GLFW_X11_XCB_VULKAN_SURFACE   0x00052001

X11 specific init hint.

◆ GLFW_ANY_PLATFORM

#define GLFW_ANY_PLATFORM   0x00060000

Hint value for GLFW_PLATFORM that enables automatic platform selection.

◆ GLFW_PLATFORM_WIN32

#define GLFW_PLATFORM_WIN32   0x00060001

◆ GLFW_PLATFORM_COCOA

#define GLFW_PLATFORM_COCOA   0x00060002

◆ GLFW_PLATFORM_WAYLAND

#define GLFW_PLATFORM_WAYLAND   0x00060003

◆ GLFW_PLATFORM_X11

#define GLFW_PLATFORM_X11   0x00060004

◆ GLFW_PLATFORM_NULL

#define GLFW_PLATFORM_NULL   0x00060005

Typedef Documentation

◆ GLFWallocatefun

typedef void *(* GLFWallocatefun) (size_t size, void *user)

This is the function pointer type for memory allocation callbacks. A memory allocation callback function has the following signature:

void* function_name(size_t size, void* user)

This function must return either a memory block at least size bytes long, or NULL if allocation failed. Note that not all parts of GLFW handle allocation failures gracefully yet.

This function may be called during glfwInit but before the library is flagged as initialized, as well as during glfwTerminate after the library is no longer flagged as initialized.

Any memory allocated by this function will be deallocated during library termination or earlier.

The size will always be greater than zero. Allocations of size zero are filtered out before reaching the custom allocator.

Parameters
[in]sizeThe minimum size, in bytes, of the memory block.
[in]userThe user-defined pointer from the allocator.
Returns
The address of the newly allocated memory block, or NULL if an error occurred.
Pointer lifetime
The returned memory block must be valid at least until it is deallocated.
Reentrancy
This function should not call any GLFW function.
Thread safety
This function may be called from any thread that calls GLFW functions.
See also
Custom heap memory allocator
GLFWallocator
Since
Added in version 3.4.

◆ GLFWreallocatefun

typedef void *(* GLFWreallocatefun) (void *block, size_t size, void *user)

This is the function pointer type for memory reallocation callbacks. A memory reallocation callback function has the following signature:

void* function_name(void* block, size_t size, void* user)

This function must return a memory block at least size bytes long, or NULL if allocation failed. Note that not all parts of GLFW handle allocation failures gracefully yet.

This function may be called during glfwInit but before the library is flagged as initialized, as well as during glfwTerminate after the library is no longer flagged as initialized.

Any memory allocated by this function will be deallocated during library termination or earlier.

The block address will never be NULL and the size will always be greater than zero. Reallocations of a block to size zero are converted into deallocations. Reallocations of NULL to a non-zero size are converted into regular allocations.

Parameters
[in]blockThe address of the memory block to reallocate.
[in]sizeThe new minimum size, in bytes, of the memory block.
[in]userThe user-defined pointer from the allocator.
Returns
The address of the newly allocated or resized memory block, or NULL if an error occurred.
Pointer lifetime
The returned memory block must be valid at least until it is deallocated.
Reentrancy
This function should not call any GLFW function.
Thread safety
This function may be called from any thread that calls GLFW functions.
See also
Custom heap memory allocator
GLFWallocator
Since
Added in version 3.4.

◆ GLFWdeallocatefun

typedef void(* GLFWdeallocatefun) (void *block, void *user)

This is the function pointer type for memory deallocation callbacks. A memory deallocation callback function has the following signature:

void function_name(void* block, void* user)

This function may deallocate the specified memory block. This memory block will have been allocated with the same allocator.

This function may be called during glfwInit but before the library is flagged as initialized, as well as during glfwTerminate after the library is no longer flagged as initialized.

The block address will never be NULL. Deallocations of NULL are filtered out before reaching the custom allocator.

Parameters
[in]blockThe address of the memory block to deallocate.
[in]userThe user-defined pointer from the allocator.
Pointer lifetime
The specified memory block will not be accessed by GLFW after this function is called.
Reentrancy
This function should not call any GLFW function.
Thread safety
This function may be called from any thread that calls GLFW functions.
See also
Custom heap memory allocator
GLFWallocator
Since
Added in version 3.4.

◆ GLFWerrorfun

typedef void(* GLFWerrorfun) (int error_code, const char *description)

This is the function pointer type for error callbacks. An error callback function has the following signature:

void callback_name(int error_code, const char* description)
Parameters
[in]error_codeAn error code. Future releases may add more error codes.
[in]descriptionA UTF-8 encoded string describing the error.
Pointer lifetime
The error description string is valid until the callback function returns.
See also
Error handling
glfwSetErrorCallback
Since
Added in version 3.0.

◆ GLFWallocator

typedef struct GLFWallocator GLFWallocator
See also
Custom heap memory allocator
glfwInitAllocator
Since
Added in version 3.4.

Function Documentation

◆ glfwInit()

int glfwInit ( void  )

This function initializes the GLFW library. Before most GLFW functions can be used, GLFW must be initialized, and before an application terminates GLFW should be terminated in order to free any resources allocated during or after initialization.

If this function fails, it calls glfwTerminate before returning. If it succeeds, you should call glfwTerminate before the application exits.

Additional calls to this function after successful initialization but before termination will return GLFW_TRUE immediately.

The GLFW_PLATFORM init hint controls which platforms are considered during initialization. This also depends on which platforms the library was compiled to support.

Returns
GLFW_TRUE if successful, or GLFW_FALSE if an error occurred.
Errors
Possible errors include GLFW_PLATFORM_UNAVAILABLE and GLFW_PLATFORM_ERROR.
Remarks
macOS: This function will change the current directory of the application to the Contents/Resources subdirectory of the application's bundle, if present. This can be disabled with the GLFW_COCOA_CHDIR_RESOURCES init hint.
macOS: This function will create the main menu and dock icon for the application. If GLFW finds a MainMenu.nib it is loaded and assumed to contain a menu bar. Otherwise a minimal menu bar is created manually with common commands like Hide, Quit and About. The About entry opens a minimal about dialog with information from the application's bundle. The menu bar and dock icon can be disabled entirely with the GLFW_COCOA_MENUBAR init hint.
X11: This function will set the LC_CTYPE category of the application locale according to the current environment if that category is still "C". This is because the "C" locale breaks Unicode text input.
Thread safety
This function must only be called from the main thread.
See also
Initialization and termination
glfwInitHint
glfwInitAllocator
glfwTerminate
Since
Added in version 1.0.

◆ glfwTerminate()

void glfwTerminate ( void  )

This function destroys all remaining windows and cursors, restores any modified gamma ramps and frees any other allocated resources. Once this function is called, you must again call glfwInit successfully before you will be able to use most GLFW functions.

If GLFW has been successfully initialized, this function should be called before the application exits. If initialization fails, there is no need to call this function, as it is called by glfwInit before it returns failure.

This function has no effect if GLFW is not initialized.

Errors
Possible errors include GLFW_PLATFORM_ERROR.
Remarks
This function may be called before glfwInit.
Warning
The contexts of any remaining windows must not be current on any other thread when this function is called.
Reentrancy
This function must not be called from a callback.
Thread safety
This function must only be called from the main thread.
See also
Initialization and termination
glfwInit
Since
Added in version 1.0.

◆ glfwInitHint()

void glfwInitHint ( int  hint,
int  value 
)

This function sets hints for the next initialization of GLFW.

The values you set hints to are never reset by GLFW, but they only take effect during initialization. Once GLFW has been initialized, any values you set will be ignored until the library is terminated and initialized again.

Some hints are platform specific. These may be set on any platform but they will only affect their specific platform. Other platforms will ignore them. Setting these hints requires no platform specific headers or functions.

Parameters
[in]hintThe init hint to set.
[in]valueThe new value of the init hint.
Errors
Possible errors include GLFW_INVALID_ENUM and GLFW_INVALID_VALUE.
Remarks
This function may be called before glfwInit.
Thread safety
This function must only be called from the main thread.
See also
init_hints
glfwInit
Since
Added in version 3.3.

◆ glfwInitAllocator()

void glfwInitAllocator ( const GLFWallocator allocator)

To use the default allocator, call this function with a NULL argument.

If you specify an allocator struct, every member must be a valid function pointer. If any member is NULL, this function emits GLFW_INVALID_VALUE and the init allocator is unchanged.

Parameters
[in]allocatorThe allocator to use at the next initialization, or NULL to use the default one.
Errors
Possible errors include GLFW_INVALID_VALUE.
Pointer lifetime
The specified allocator is copied before this function returns.
Thread safety
This function must only be called from the main thread.
See also
Custom heap memory allocator
glfwInit
Since
Added in version 3.4.

◆ glfwInitVulkanLoader()

void glfwInitVulkanLoader ( PFN_vkGetInstanceProcAddr  loader)

This function sets the vkGetInstanceProcAddr function that GLFW will use for all Vulkan related entry point queries.

This feature is mostly useful on macOS, if your copy of the Vulkan loader is in a location where GLFW cannot find it through dynamic loading, or if you are still using the static library version of the loader.

If set to NULL, GLFW will try to load the Vulkan loader dynamically by its standard name and get this function from there. This is the default behavior.

The standard name of the loader is vulkan-1.dll on Windows, libvulkan.so.1 on Linux and other Unix-like systems and libvulkan.1.dylib on macOS. If your code is also loading it via these names then you probably don't need to use this function.

The function address you set is never reset by GLFW, but it only takes effect during initialization. Once GLFW has been initialized, any updates will be ignored until the library is terminated and initialized again.

Parameters
[in]loaderThe address of the function to use, or NULL.
Loader function signature
PFN_vkVoidFunction vkGetInstanceProcAddr(VkInstance instance, const char* name)
For more information about this function, see the Vulkan Registry.
Errors
None.
Remarks
This function may be called before glfwInit.
Thread safety
This function must only be called from the main thread.
See also
Finding the Vulkan loader
glfwInit
Since
Added in version 3.4.

◆ glfwGetVersion()

void glfwGetVersion ( int *  major,
int *  minor,
int *  rev 
)

This function retrieves the major, minor and revision numbers of the GLFW library. It is intended for when you are using GLFW as a shared library and want to ensure that you are using the minimum required version.

Any or all of the version arguments may be NULL.

Parameters
[out]majorWhere to store the major version number, or NULL.
[out]minorWhere to store the minor version number, or NULL.
[out]revWhere to store the revision number, or NULL.
Errors
None.
Remarks
This function may be called before glfwInit.
Thread safety
This function may be called from any thread.
See also
Version management
glfwGetVersionString
Since
Added in version 1.0.

◆ glfwGetVersionString()

const char * glfwGetVersionString ( void  )

This function returns the compile-time generated version string of the GLFW library binary. It describes the version, platforms, compiler and any platform or operating system specific compile-time options. It should not be confused with the OpenGL or OpenGL ES version string, queried with glGetString.

Do not use the version string to parse the GLFW library version. The glfwGetVersion function provides the version of the running library binary in numerical format.

Do not use the version string to parse what platforms are supported. The glfwPlatformSupported function lets you query platform support.

Returns
The ASCII encoded GLFW version string.
Errors
None.
Remarks
This function may be called before glfwInit.
Pointer lifetime
The returned string is static and compile-time generated.
Thread safety
This function may be called from any thread.
See also
Version management
glfwGetVersion
Since
Added in version 3.0.

◆ glfwGetError()

int glfwGetError ( const char **  description)

This function returns and clears the error code of the last error that occurred on the calling thread, and optionally a UTF-8 encoded human-readable description of it. If no error has occurred since the last call, it returns GLFW_NO_ERROR (zero) and the description pointer is set to NULL.

Parameters
[in]descriptionWhere to store the error description pointer, or NULL.
Returns
The last error code for the calling thread, or GLFW_NO_ERROR (zero).
Errors
None.
Pointer lifetime
The returned string is allocated and freed by GLFW. You should not free it yourself. It is guaranteed to be valid only until the next error occurs or the library is terminated.
Remarks
This function may be called before glfwInit.
Thread safety
This function may be called from any thread.
See also
Error handling
glfwSetErrorCallback
Since
Added in version 3.3.

◆ glfwSetErrorCallback()

GLFWerrorfun glfwSetErrorCallback ( GLFWerrorfun  callback)

This function sets the error callback, which is called with an error code and a human-readable description each time a GLFW error occurs.

The error code is set before the callback is called. Calling glfwGetError from the error callback will return the same value as the error code argument.

The error callback is called on the thread where the error occurred. If you are using GLFW from multiple threads, your error callback needs to be written accordingly.

Because the description string may have been generated specifically for that error, it is not guaranteed to be valid after the callback has returned. If you wish to use it after the callback returns, you need to make a copy.

Once set, the error callback remains set even after the library has been terminated.

Parameters
[in]callbackThe new callback, or NULL to remove the currently set callback.
Returns
The previously set callback, or NULL if no callback was set.
Callback signature
void callback_name(int error_code, const char* description)
For more information about the callback parameters, see the callback pointer type.
Errors
None.
Remarks
This function may be called before glfwInit.
Thread safety
This function must only be called from the main thread.
See also
Error handling
glfwGetError
Since
Added in version 3.0.

◆ glfwGetPlatform()

int glfwGetPlatform ( void  )

This function returns the platform that was selected during initialization. The returned value will be one of GLFW_PLATFORM_WIN32, GLFW_PLATFORM_COCOA, GLFW_PLATFORM_WAYLAND, GLFW_PLATFORM_X11 or GLFW_PLATFORM_NULL.

Returns
The currently selected platform, or zero if an error occurred.
Errors
Possible errors include GLFW_NOT_INITIALIZED.
Thread safety
This function may be called from any thread.
See also
Runtime platform selection
glfwPlatformSupported
Since
Added in version 3.4.

◆ glfwPlatformSupported()

int glfwPlatformSupported ( int  platform)

This function returns whether the library was compiled with support for the specified platform. The platform must be one of GLFW_PLATFORM_WIN32, GLFW_PLATFORM_COCOA, GLFW_PLATFORM_WAYLAND, GLFW_PLATFORM_X11 or GLFW_PLATFORM_NULL.

Parameters
[in]platformThe platform to query.
Returns
GLFW_TRUE if the platform is supported, or GLFW_FALSE otherwise.
Errors
Possible errors include GLFW_INVALID_ENUM.
Remarks
This function may be called before glfwInit.
Thread safety
This function may be called from any thread.
See also
Runtime platform selection
glfwGetPlatform
Since
Added in version 3.4.