• Introduction
  • Programmer's Guide
  • Technical Articles
  • API Documentation
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    • IC Imaging Control 4 .NET Class Library
      • What's New
        • Version History
        • Transitioning from IC Imaging Control 3.x .NET Component
      • Library Organization
      • Programmer's Guide
        • Getting Started
        • Device Enumeration
        • Configuring the Video Capture Device
        • Grabbing an Image
      • Example Programs
      • Technical Articles
        • Grabber States
        • Accessing Device Properties
        • Error Handling
        • Logging
        • Distributing Your Applications

    Grabber States

    During its lifetime, the Grabber object transitions through multiple states.

    The current grabber state can be observed through a collection state query functions:

    • IsDeviceOpen
    • IsDeviceValid
    • IsStreaming
    • IsAcquisitionActive

    Initial State

    Initially, the grabber has not opened a video capture device.

    Property Value
    IsDeviceOpen false
    IsDeviceValid false
    IsStreaming false
    IsAcquisitionActive false

    Calling DeviceClose always brings the grabber back to the Initial state.

    Opening a device using DeviceOpen or one of its sibling functions puts the grabber into the Device Opened state.

    Device Opened

    In this state, a device was opened, but streaming has not been started yet. Once opened, the device should be configured to prepare the required settings for streaming.

    Property Value
    IsDeviceOpen true
    IsDeviceValid true
    IsStreaming false
    IsAcquisitionActive false

    Calling DeviceClose brings the grabber back to the Initial state.

    Calling StreamSetup or one of its sibling functions elevates the grabber state to Streaming. If the setupOption parameter of the call is set to AcquisitionStart, acquisition is started immediately and the grabber state moves to Acquisition Active.

    If the connection to the device is lost (e.g. it is unplugged), the grabber moves into the Device Invalid state. Additionally, the DeviceLost event is raised.

    Streaming

    In this state, a streaming connection between the device and the host has been established. Everything is prepared for the device to send and the host to receive image data.

    Property Value
    IsDeviceOpen true
    IsDeviceValid true
    IsStreaming true
    IsAcquisitionActive false

    To start acquisition, call AcquisitionStart or execute the AcquisitionStart command in the device's property map. After that, the grabber is in the Acquisition Active state.

    Calling StreamStop stops the data stream and moves the grabber back to the Device Opened state.

    Calling DeviceClose stops the data stream, closes the device and puts the grabber back to the Initial state.

    If the connection to the device is lost (e.g. it is unplugged), the grabber moves into the Device Invalid state. Additionally, the DeviceLost event is raised.

    Acquisition Active

    In this state, the device is sending images to the host.

    Property Value
    IsDeviceOpen true
    IsDeviceValid true
    IsStreaming true
    IsAcquisitionActive true

    Please note that the device may pause transmission because of certain device settings, e.g. TriggerMode.

    To stop acquisition, call AcquisitionStop or execute the AcquisitionStop command in the device's property map. After that, the grabber is in the Streaming state.

    Calling StreamStop stops acquisition in the device, stops the data stream and moves the grabber back to the Device Opened state.

    Calling DeviceClose stops the data stream, closes the device and puts the grabber back to the Initial state.

    If the connection to the device is lost (e.g. it is unplugged), the grabber moves into the Device Invalid state. Additionally, the DeviceLost event is raised.

    Device Invalid

    In this state, the connection to the device was lost. IsDeviceValid returns false.

    Property Value
    IsDeviceOpen true
    IsDeviceValid false

    Calling DeviceClose puts the grabber back to the Initial state.

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