SDL 3.0
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#include <SDL3/SDL_stdinc.h>
#include <SDL3/SDL_error.h>
#include <SDL3/SDL_pixels.h>
#include <SDL3/SDL_properties.h>
#include <SDL3/SDL_surface.h>
#include <SDL3/SDL_begin_code.h>
#include <SDL3/SDL_close_code.h>
Go to the source code of this file.
Data Structures | |
struct | SDL_CameraSpec |
Typedefs | |
typedef Uint32 | SDL_CameraID |
typedef struct SDL_Camera | SDL_Camera |
Enumerations | |
enum | SDL_CameraPosition { SDL_CAMERA_POSITION_UNKNOWN , SDL_CAMERA_POSITION_FRONT_FACING , SDL_CAMERA_POSITION_BACK_FACING } |
Functions | |
int | SDL_GetNumCameraDrivers (void) |
const char * | SDL_GetCameraDriver (int index) |
const char * | SDL_GetCurrentCameraDriver (void) |
SDL_CameraID * | SDL_GetCameras (int *count) |
SDL_CameraSpec ** | SDL_GetCameraSupportedFormats (SDL_CameraID devid, int *count) |
const char * | SDL_GetCameraName (SDL_CameraID instance_id) |
SDL_CameraPosition | SDL_GetCameraPosition (SDL_CameraID instance_id) |
SDL_Camera * | SDL_OpenCamera (SDL_CameraID instance_id, const SDL_CameraSpec *spec) |
int | SDL_GetCameraPermissionState (SDL_Camera *camera) |
SDL_CameraID | SDL_GetCameraID (SDL_Camera *camera) |
SDL_PropertiesID | SDL_GetCameraProperties (SDL_Camera *camera) |
bool | SDL_GetCameraFormat (SDL_Camera *camera, SDL_CameraSpec *spec) |
SDL_Surface * | SDL_AcquireCameraFrame (SDL_Camera *camera, Uint64 *timestampNS) |
void | SDL_ReleaseCameraFrame (SDL_Camera *camera, SDL_Surface *frame) |
void | SDL_CloseCamera (SDL_Camera *camera) |
typedef struct SDL_Camera SDL_Camera |
The opaque structure used to identify an opened SDL camera.
Definition at line 67 of file SDL_camera.h.
typedef Uint32 SDL_CameraID |
Video capture for the SDL library.
This API lets apps read input from video sources, like webcams. Camera devices can be enumerated, queried, and opened. Once opened, it will provide SDL_Surface objects as new frames of video come in. These surfaces can be uploaded to an SDL_Texture or processed as pixels in memory. This is a unique ID for a camera device for the time it is connected to the system, and is never reused for the lifetime of the application.
If the device is disconnected and reconnected, it will get a new ID.
The value 0 is an invalid ID.
Definition at line 60 of file SDL_camera.h.
enum SDL_CameraPosition |
The position of camera in relation to system device.
Enumerator | |
---|---|
SDL_CAMERA_POSITION_UNKNOWN | |
SDL_CAMERA_POSITION_FRONT_FACING | |
SDL_CAMERA_POSITION_BACK_FACING |
Definition at line 97 of file SDL_camera.h.
SDL_Surface * SDL_AcquireCameraFrame | ( | SDL_Camera * | camera, |
Uint64 * | timestampNS | ||
) |
Acquire a frame.
The frame is a memory pointer to the image data, whose size and format are given by the spec requested when opening the device.
This is a non blocking API. If there is a frame available, a non-NULL surface is returned, and timestampNS will be filled with a non-zero value.
Note that an error case can also return NULL, but a NULL by itself is normal and just signifies that a new frame is not yet available. Note that even if a camera device fails outright (a USB camera is unplugged while in use, etc), SDL will send an event separately to notify the app, but continue to provide blank frames at ongoing intervals until SDL_CloseCamera() is called, so real failure here is almost always an out of memory condition.
After use, the frame should be released with SDL_ReleaseCameraFrame(). If you don't do this, the system may stop providing more video!
Do not call SDL_FreeSurface() on the returned surface! It must be given back to the camera subsystem with SDL_ReleaseCameraFrame!
If the system is waiting for the user to approve access to the camera, as some platforms require, this will return NULL (no frames available); you should either wait for an SDL_EVENT_CAMERA_DEVICE_APPROVED (or SDL_EVENT_CAMERA_DEVICE_DENIED) event, or poll SDL_GetCameraPermissionState() occasionally until it returns non-zero.
camera | opened camera device. |
timestampNS | a pointer filled in with the frame's timestamp, or 0 on error. Can be NULL. |
\threadsafety It is safe to call this function from any thread.
void SDL_CloseCamera | ( | SDL_Camera * | camera | ) |
Use this function to shut down camera processing and close the camera device.
camera | opened camera device. |
\threadsafety It is safe to call this function from any thread, but no thread may reference device
once this function is called.
const char * SDL_GetCameraDriver | ( | int | index | ) |
Use this function to get the name of a built in camera driver.
The list of camera drivers is given in the order that they are normally initialized by default; the drivers that seem more reasonable to choose first (as far as the SDL developers believe) are earlier in the list.
The names of drivers are all simple, low-ASCII identifiers, like "v4l2", "coremedia" or "android". These never have Unicode characters, and are not meant to be proper names.
index | the index of the camera driver; the value ranges from 0 to SDL_GetNumCameraDrivers() - 1. |
\threadsafety It is safe to call this function from any thread.
bool SDL_GetCameraFormat | ( | SDL_Camera * | camera, |
SDL_CameraSpec * | spec | ||
) |
Get the spec that a camera is using when generating images.
Note that this might not be the native format of the hardware, as SDL might be converting to this format behind the scenes.
If the system is waiting for the user to approve access to the camera, as some platforms require, this will return false, but this isn't necessarily a fatal error; you should either wait for an SDL_EVENT_CAMERA_DEVICE_APPROVED (or SDL_EVENT_CAMERA_DEVICE_DENIED) event, or poll SDL_GetCameraPermissionState() occasionally until it returns non-zero.
camera | opened camera device. |
spec | the SDL_CameraSpec to be initialized by this function. |
\threadsafety It is safe to call this function from any thread.
SDL_CameraID SDL_GetCameraID | ( | SDL_Camera * | camera | ) |
Get the instance ID of an opened camera.
camera | an SDL_Camera to query. |
\threadsafety It is safe to call this function from any thread.
const char * SDL_GetCameraName | ( | SDL_CameraID | instance_id | ) |
Get the human-readable device name for a camera.
instance_id | the camera device instance ID. |
\threadsafety It is safe to call this function from any thread.
int SDL_GetCameraPermissionState | ( | SDL_Camera * | camera | ) |
Query if camera access has been approved by the user.
Cameras will not function between when the device is opened by the app and when the user permits access to the hardware. On some platforms, this presents as a popup dialog where the user has to explicitly approve access; on others the approval might be implicit and not alert the user at all.
This function can be used to check the status of that approval. It will return 0 if still waiting for user response, 1 if the camera is approved for use, and -1 if the user denied access.
Instead of polling with this function, you can wait for a SDL_EVENT_CAMERA_DEVICE_APPROVED (or SDL_EVENT_CAMERA_DEVICE_DENIED) event in the standard SDL event loop, which is guaranteed to be sent once when permission to use the camera is decided.
If a camera is declined, there's nothing to be done but call SDL_CloseCamera() to dispose of it.
camera | the opened camera device to query. |
\threadsafety It is safe to call this function from any thread.
SDL_CameraPosition SDL_GetCameraPosition | ( | SDL_CameraID | instance_id | ) |
Get the position of the camera in relation to the system.
Most platforms will report UNKNOWN, but mobile devices, like phones, can often make a distinction between cameras on the front of the device (that points towards the user, for taking "selfies") and cameras on the back (for filming in the direction the user is facing).
instance_id | the camera device instance ID. |
\threadsafety It is safe to call this function from any thread.
SDL_PropertiesID SDL_GetCameraProperties | ( | SDL_Camera * | camera | ) |
Get the properties associated with an opened camera.
camera | the SDL_Camera obtained from SDL_OpenCamera(). |
\threadsafety It is safe to call this function from any thread.
SDL_CameraID * SDL_GetCameras | ( | int * | count | ) |
Get a list of currently connected camera devices.
count | a pointer filled in with the number of cameras returned, may be NULL. |
\threadsafety It is safe to call this function from any thread.
SDL_CameraSpec ** SDL_GetCameraSupportedFormats | ( | SDL_CameraID | devid, |
int * | count | ||
) |
Get the list of native formats/sizes a camera supports.
This returns a list of all formats and frame sizes that a specific camera can offer. This is useful if your app can accept a variety of image formats and sizes and so want to find the optimal spec that doesn't require conversion.
This function isn't strictly required; if you call SDL_OpenCamera with a NULL spec, SDL will choose a native format for you, and if you instead specify a desired format, it will transparently convert to the requested format on your behalf.
If count
is not NULL, it will be filled with the number of elements in the returned array.
Note that it's legal for a camera to supply an empty list. This is what will happen on Emscripten builds, since that platform won't tell anything about available cameras until you've opened one, and won't even tell if there is a camera until the user has given you permission to check through a scary warning popup.
devid | the camera device instance ID to query. |
count | a pointer filled in with the number of elements in the list, may be NULL. |
\threadsafety It is safe to call this function from any thread.
const char * SDL_GetCurrentCameraDriver | ( | void | ) |
Get the name of the current camera driver.
The names of drivers are all simple, low-ASCII identifiers, like "v4l2", "coremedia" or "android". These never have Unicode characters, and are not meant to be proper names.
\threadsafety It is safe to call this function from any thread.
int SDL_GetNumCameraDrivers | ( | void | ) |
Use this function to get the number of built-in camera drivers.
This function returns a hardcoded number. This never returns a negative value; if there are no drivers compiled into this build of SDL, this function returns zero. The presence of a driver in this list does not mean it will function, it just means SDL is capable of interacting with that interface. For example, a build of SDL might have v4l2 support, but if there's no kernel support available, SDL's v4l2 driver would fail if used.
By default, SDL tries all drivers, in its preferred order, until one is found to be usable.
\threadsafety It is safe to call this function from any thread.
SDL_Camera * SDL_OpenCamera | ( | SDL_CameraID | instance_id, |
const SDL_CameraSpec * | spec | ||
) |
Open a video recording device (a "camera").
You can open the device with any reasonable spec, and if the hardware can't directly support it, it will convert data seamlessly to the requested format. This might incur overhead, including scaling of image data.
If you would rather accept whatever format the device offers, you can pass a NULL spec here and it will choose one for you (and you can use SDL_Surface's conversion/scaling functions directly if necessary).
You can call SDL_GetCameraFormat() to get the actual data format if passing a NULL spec here. You can see the exact specs a device can support without conversion with SDL_GetCameraSupportedFormats().
SDL will not attempt to emulate framerate; it will try to set the hardware to the rate closest to the requested speed, but it won't attempt to limit or duplicate frames artificially; call SDL_GetCameraFormat() to see the actual framerate of the opened the device, and check your timestamps if this is crucial to your app!
Note that the camera is not usable until the user approves its use! On some platforms, the operating system will prompt the user to permit access to the camera, and they can choose Yes or No at that point. Until they do, the camera will not be usable. The app should either wait for an SDL_EVENT_CAMERA_DEVICE_APPROVED (or SDL_EVENT_CAMERA_DEVICE_DENIED) event, or poll SDL_GetCameraPermissionState() occasionally until it returns non-zero. On platforms that don't require explicit user approval (and perhaps in places where the user previously permitted access), the approval event might come immediately, but it might come seconds, minutes, or hours later!
instance_id | the camera device instance ID. |
spec | the desired format for data the device will provide. Can be NULL. |
\threadsafety It is safe to call this function from any thread.
void SDL_ReleaseCameraFrame | ( | SDL_Camera * | camera, |
SDL_Surface * | frame | ||
) |
Release a frame of video acquired from a camera.
Let the back-end re-use the internal buffer for camera.
This function must be called only on surface objects returned by SDL_AcquireCameraFrame(). This function should be called as quickly as possible after acquisition, as SDL keeps a small FIFO queue of surfaces for video frames; if surfaces aren't released in a timely manner, SDL may drop upcoming video frames from the camera.
If the app needs to keep the surface for a significant time, they should make a copy of it and release the original.
The app should not use the surface again after calling this function; assume the surface is freed and the pointer is invalid.
camera | opened camera device. |
frame | the video frame surface to release. |
\threadsafety It is safe to call this function from any thread.