Grab_Callback.py

Get Image(s) via Callback

It shows how to get images via callback. The major steps include creating a handle, turning on the camera, registering a callback, starting grabbing images, getting image information via callback, stopping grabbing images, turning off the camera, and destroying the handle.

# -- coding: utf-8 --

import sys
import copy
import platform
import os
from ctypes import *


# Compatible with different operating systems to load DDL
currentsystem = platform.system()
if currentsystem == 'Windows':
    sys.path.append(os.path.join(os.getenv('MVCAM_COMMON_RUNENV'), "Samples", "Python", "MvImport"))
else:
    sys.path.append(os.path.join("..", "..", "MvImport"))

from MvCameraControl_class import *


# Compatible with input processing of Python 2.X and 3.X
if sys.version_info[0] < 3:
    # Python 2.x
    input_func = raw_input
else: 
    # Python 3.x
    input_func = input

# Decoding Characters
def decoding_char(ctypes_char_array):
    """
    Safely decode a string from a ctypes character array.
    Compatible with Python 2.x and 3.x, as well as 32-bit and 64-bit environments.
    """
    byte_str = memoryview(ctypes_char_array).tobytes()
    
    # Truncate at the first null character
    null_index = byte_str.find(b'\x00')
    if null_index != -1:
        byte_str = byte_str[:null_index]
    
    # Attempt to decode using multiple encodings
    for encoding in ['gbk', 'utf-8', 'latin-1']:
        try:
            return byte_str.decode(encoding)
        except UnicodeDecodeError:
            continue
    
    # If all encodings fail, use a replacement strategy
    return byte_str.decode('latin-1', errors='replace')
    
    
fun_ctype = get_platform_functype()
FrameInfoCallBack2 = fun_ctype(None, POINTER(MV_FRAME_OUT), c_void_p, c_bool)
def image_callback2(pstFrame, pUser, bAutoFree):
        stFrame = cast(pstFrame, POINTER(MV_FRAME_OUT)).contents
        if stFrame:
            print ("get one frame: Width[%d], Height[%d], nFrameNum[%d]" % (stFrame.stFrameInfo.nWidth, stFrame.stFrameInfo.nHeight, stFrame.stFrameInfo.nFrameNum))
        
        #Non automatic release mode. Releasing resources manually is required.
        if bAutoFree == False :
            if pUser != None: 
                User = ctypes.cast(pUser, ctypes.py_object).value
                User.MV_CC_FreeImageBuffer(stFrame)
            else :
                print ("user is null, invalid")

CALL_BACK_FUN2 = FrameInfoCallBack2(image_callback2)



if __name__ == "__main__":
    try:
        # Initialize SDK resources
        MvCamera.MV_CC_Initialize()

        SDKVersion = MvCamera.MV_CC_GetSDKVersion()
        print ("SDKVersion[0x%x]" % SDKVersion)
        
        deviceList = MV_CC_DEVICE_INFO_LIST()
        tlayerType = (MV_GIGE_DEVICE | MV_USB_DEVICE | MV_GENTL_CAMERALINK_DEVICE
                      | MV_GENTL_CXP_DEVICE | MV_GENTL_XOF_DEVICE)
        
        # Enumerate devices
        ret = MvCamera.MV_CC_EnumDevices(tlayerType, deviceList)
        if ret != 0:
            print ("enum devices fail! ret[0x%x]" % ret)
            sys.exit()
        
        if deviceList.nDeviceNum == 0:
            print ("find no device!")
            sys.exit()

        print ("find %d devices!" % deviceList.nDeviceNum)

        for i in range(0, deviceList.nDeviceNum):
            mvcc_dev_info = cast(deviceList.pDeviceInfo[i], POINTER(MV_CC_DEVICE_INFO)).contents
            if mvcc_dev_info.nTLayerType == MV_GIGE_DEVICE or mvcc_dev_info.nTLayerType == MV_GENTL_GIGE_DEVICE:
                print ("\ngige device: [%d]" % i)
                strModeName = decoding_char(mvcc_dev_info.SpecialInfo.stGigEInfo.chModelName)
                print ("device model name: %s" % strModeName)
                strSerialNumber = decoding_char(mvcc_dev_info.SpecialInfo.stGigEInfo.chSerialNumber)
                print("device serial number: %s" % strSerialNumber)
                nip1 = ((mvcc_dev_info.SpecialInfo.stGigEInfo.nCurrentIp & 0xff000000) >> 24)
                nip2 = ((mvcc_dev_info.SpecialInfo.stGigEInfo.nCurrentIp & 0x00ff0000) >> 16)
                nip3 = ((mvcc_dev_info.SpecialInfo.stGigEInfo.nCurrentIp & 0x0000ff00) >> 8)
                nip4 = (mvcc_dev_info.SpecialInfo.stGigEInfo.nCurrentIp & 0x000000ff)
                print ("current ip: %d.%d.%d.%d\n" % (nip1, nip2, nip3, nip4))
            elif mvcc_dev_info.nTLayerType == MV_USB_DEVICE:
                print ("\nu3v device: [%d]" % i)
                strModeName = decoding_char(mvcc_dev_info.SpecialInfo.stUsb3VInfo.chModelName)
                print ("device model name: %s" % strModeName)

                strSerialNumber = decoding_char(mvcc_dev_info.SpecialInfo.stUsb3VInfo.chSerialNumber)                
                print ("device serial number: %s" % strSerialNumber)
            elif mvcc_dev_info.nTLayerType == MV_GENTL_CAMERALINK_DEVICE:
                print ("\nCML device: [%d]" % i)
                strModeName = decoding_char(mvcc_dev_info.SpecialInfo.stCMLInfo.chModelName)
                print ("device model name: %s" % strModeName)

                strSerialNumber = decoding_char(mvcc_dev_info.SpecialInfo.stCMLInfo.chSerialNumber)
                print ("device serial number: %s" % strSerialNumber)
            elif mvcc_dev_info.nTLayerType == MV_GENTL_CXP_DEVICE:
                print ("\nCXP device: [%d]" % i)
                strModeName = decoding_char(mvcc_dev_info.SpecialInfo.stCXPInfo.chModelName)
                print ("device model name: %s" % strModeName)
                
                strSerialNumber = decoding_char(mvcc_dev_info.SpecialInfo.stCXPInfo.chSerialNumber)
                print ("device serial number: %s" % strSerialNumber)
            elif mvcc_dev_info.nTLayerType == MV_GENTL_XOF_DEVICE:
                print ("\nXoF device: [%d]" % i)
                strModeName = decoding_char(mvcc_dev_info.SpecialInfo.stXoFInfo.chModelName)
                print ("device model name: %s" % strModeName)

                strSerialNumber = decoding_char(mvcc_dev_info.SpecialInfo.stXoFInfo.chSerialNumber)
                print ("device serial number: %s" % strSerialNumber)

        nConnectionNum = input_func("please input the number of the device to connect:")

        if int(nConnectionNum) >= deviceList.nDeviceNum:
            print ("intput error!")
            sys.exit()
        
        # Create the camera instance
        cam = MvCamera()

        # Select a device, and create a handle
        stDeviceList = cast(deviceList.pDeviceInfo[int(nConnectionNum)], POINTER(MV_CC_DEVICE_INFO)).contents

        ret = cam.MV_CC_CreateHandle(stDeviceList)
        if ret != 0:
            raise Exception ("create handle fail! ret[0x%x]" % ret)

        # Turn on the device
        ret = cam.MV_CC_OpenDevice(MV_ACCESS_Exclusive, 0)
        if ret != 0:
            raise Exception ("open device fail! ret[0x%x]" % ret)
        
        # Get optimal packet size (only supported by GigE devices)
        if stDeviceList.nTLayerType == MV_GIGE_DEVICE or stDeviceList.nTLayerType == MV_GENTL_GIGE_DEVICE:
            nPacketSize = cam.MV_CC_GetOptimalPacketSize()
            if int(nPacketSize) > 0:
                ret = cam.MV_CC_SetIntValue("GevSCPSPacketSize",nPacketSize)
                if ret != 0:
                    print ("Warning: Set Packet Size fail! ret[0x%x]" % ret)
            else:
                print ("Warning: Get Packet Size fail! ret[0x%x]" % nPacketSize)

        # Set trigger mode to off
        ret = cam.MV_CC_SetEnumValue("TriggerMode", MV_TRIGGER_MODE_OFF)
        if ret != 0:
            raise Exception ("set trigger mode fail! ret[0x%x]" % ret)

        #Register an image grabbing callback
        ret = cam.MV_CC_RegisterImageCallBackEx2(CALL_BACK_FUN2, ctypes.py_object(cam), True)
        if ret != 0:
            raise Exception ("register image callback fail! ret[0x%x]" % ret)

        # Start grabbing images
        ret = cam.MV_CC_StartGrabbing()
        if ret != 0:
            raise Exception ("start grabbing fail! ret[0x%x]" % ret)
            
        print ("press Enter key to stop grabbing.")
        input_func()

        # Stop grabbing images
        ret = cam.MV_CC_StopGrabbing()
        if ret != 0:
            raise Exception ("stop grabbing fail! ret[0x%x]" % ret)

        # Turn off the device
        ret = cam.MV_CC_CloseDevice()
        if ret != 0:
            raise Exception ("close deivce fail! ret[0x%x]" % ret)

        # Destroy the handle
        cam.MV_CC_DestroyHandle()

    except Exception as e:
        print(e)
        cam.MV_CC_CloseDevice()
        cam.MV_CC_DestroyHandle()
    finally:
        # Release SDK resources
        MvCamera.MV_CC_Finalize()