org.firstinspires.ftc.teamcode.Testop.CaptureImages Class Reference

This OpMode illustrates how to open a webcam and retrieve images from it. More...

Inheritance diagram for org.firstinspires.ftc.teamcode.Testop.CaptureImages:

Public Member Functions
void	runOpMode ()

Private Member Functions
void	onNewFrame (Bitmap frame)
	Do something with the frame.
void	initializeFrameQueue (int capacity)
void	openCamera ()
void	startCamera ()
void	stopCamera ()
void	closeCamera ()
void	error (String msg)
void	error (String format, Object... args)
boolean	contains (int[] array, int value)
void	saveBitmap (Bitmap bitmap)

Private Attributes
CameraManager	cameraManager
	State regarding our interaction with the camera.
WebcamName	cameraName
Camera	camera
CameraCaptureSession	cameraCaptureSession
EvictingBlockingQueue< Bitmap >	frameQueue
	The queue into which all frames from the camera are placed as they become available.
int	captureCounter = 0
	State regarding where and how to save frames when the 'A' button is pressed.
final File	captureDirectory = AppUtil.ROBOT_DATA_DIR
Handler	callbackHandler
	A utility object that indicates where the asynchronous callbacks from the camera infrastructure are to run.

Static Private Attributes
static final String	TAG = "Webcam 1"
static final int	secondsPermissionTimeout = Integer.MAX_VALUE
	How long we are to wait to be granted permission to use the camera before giving up.

Detailed Description

This OpMode illustrates how to open a webcam and retrieve images from it.

It requires a configuration containing a webcam with the default name ("Webcam 1"). When the opmode runs, pressing the 'A' button will cause a frame from the camera to be written to a file on the device, which can then be retrieved by various means (e.g.: Device File Explorer in Android Studio; plugging the device into a PC and using Media Transfer; ADB; etc.)

Member Function Documentation

initializeFrameQueue()

void org.firstinspires.ftc.teamcode.Testop.CaptureImages.initializeFrameQueue ( int capacity )

private

The frame queue will automatically throw away bitmap frames if they are not processed quickly by the OpMode. This avoids a buildup of frames in memory

startCamera()

void org.firstinspires.ftc.teamcode.Testop.CaptureImages.startCamera ( )

private

YUY2 is supported by all Webcams, per the USB Webcam standard: See "USB Device Class Definition for Video Devices: Uncompressed Payload, Table 2-1". Further, often this is the only image format supported by a camera

Verify that the image is supported, and fetch size and desired frame rate if so

Some logic below runs asynchronously on other threads. Use of the synchronizer here allows us to wait in this method until all that asynchrony completes before returning.

Create a session in which requests to capture frames can be made

The session is ready to go. Start requesting frames

A new frame is available. The frame data has not been copied for us, and we can only access it for the duration of the callback. So we copy here manually.

Wait for all the asynchrony to complete

Retrieve the created session. This will be null on error.

Member Data Documentation

callbackHandler

Handler org.firstinspires.ftc.teamcode.Testop.CaptureImages.callbackHandler

private

A utility object that indicates where the asynchronous callbacks from the camera infrastructure are to run.

In this OpMode, that's all hidden from you (but see startCamera if you're curious): no knowledge of multi-threading is needed here.

frameQueue

EvictingBlockingQueue<Bitmap> org.firstinspires.ftc.teamcode.Testop.CaptureImages.frameQueue

private

The queue into which all frames from the camera are placed as they become available.

Frames which are not processed by the OpMode are automatically discarded.

secondsPermissionTimeout

final int org.firstinspires.ftc.teamcode.Testop.CaptureImages.secondsPermissionTimeout = Integer.MAX_VALUE

staticprivate

How long we are to wait to be granted permission to use the camera before giving up.

Here, we wait indefinitely

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The documentation for this class was generated from the following file:

• CenterStage/TeamCode/src/main/java/org/firstinspires/ftc/teamcode/Testop/CaptureImages.java