Dynamsoft Barcode Reader SDK一款多功能的條碼讀取控件，只需要幾行代碼就可以將條碼讀取功能嵌入到Web或桌面應(yīng)用程序。這可以節(jié)省數(shù)月的開發(fā)時(shí)間和成本。能支持多種圖像文件格式以及從攝像機(jī)或掃描儀獲取的DIB格式。使用Dynamsoft Barcode Reader SDK，你可以創(chuàng)建強(qiáng)大且實(shí)用的條形碼掃描儀軟件，以滿足你的業(yè)務(wù)需求。

點(diǎn)擊下載Dynamsoft Barcode Reader最新版

Qt Designer是用于使用Qt小部件構(gòu)建跨平臺圖形用戶界面（GUI）的Qt工具。在本文中，我將使用Qt設(shè)計(jì)器通過適用于Windows，Linux，macOS和Raspberry Pi OS的Dynamsoft Python條形碼SDK創(chuàng)建高級桌面條形碼讀取器應(yīng)用程序。該應(yīng)用程序包含Dynamsoft條碼閱讀器的所有強(qiáng)大功能。

使用Qt Designer構(gòu)造UI

所需的Qt小部件包括：
菜單欄

• 打開文件
• 打開文件夾
• 保存模板
• 輸入許可證密鑰
• 關(guān)于

• 顯示狀態(tài)信息

• 列出已加載的文件名

• 顯示圖像或攝像頭框架

• 攝像機(jī)，模板和條形碼類型設(shè)置的組

• 啟動相機(jī)
• 停止攝像頭
• 加載條形碼模板文件
• 導(dǎo)出條形碼模板文件

• 相機(jī)解析度

• 條形碼識別完成后自動停止攝像頭視圖
• 同步或異步顯示條形碼結(jié)果

• 輸入?yún)?shù)模板
• 顯示條形碼解碼結(jié)果

pyside2-uic design.ui -o design.py

讓我們逐步構(gòu)建條形碼閱讀器應(yīng)用程序。

要求

安裝相關(guān)的Python軟件包。對于Raspberry Pi OS，我們可以通過以下apt-get命令安裝PySide2 ：

python3 -m pip install opencv-python
python3 -m pip install dbr

# Windows, Linux and macOS
python3 -m pip install PySide2

# Raspberry Pi OS
sudo apt-get install python3-pyside2.qt3dcore python3-pyside2.qt3dinput python3-pyside2.qt3dlogic python3-pyside2.qt3drender python3-pyside2.qtcharts python3-pyside2.qtconcurrent python3-pyside2.qtcore python3-pyside2.qtgui python3-pyside2.qthelp python3-pyside2.qtlocation python3-pyside2.qtmultimedia python3-pyside2.qtmultimediawidgets python3-pyside2.qtnetwork python3-pyside2.qtopengl python3-pyside2.qtpositioning python3-pyside2.qtprintsupport python3-pyside2.qtqml python3-pyside2.qtquick python3-pyside2.qtquickwidgets python3-pyside2.qtscript python3-pyside2.qtscripttools python3-pyside2.qtsensors python3-pyside2.qtsql python3-pyside2.qtsvg python3-pyside2.qttest python3-pyside2.qttexttospeech python3-pyside2.qtuitools python3-pyside2.qtwebchannel python3-pyside2.qtwebsockets python3-pyside2.qtwidgets python3-pyside2.qtx11extras python3-pyside2.qtxml python3-pyside2.qtxmlpatterns python3-pyside2uic

因?yàn)閁I代碼已經(jīng)準(zhǔn)備好，所以我們可以按以下方式加載它：

'''
Usage:
   app.py <license.txt>
'''

import sys
from PySide2.QtGui import QPixmap, QImage
from PySide2.QtWidgets import QApplication, QMainWindow, QInputDialog
from PySide2.QtCore import QFile, QTimer
from PySide2.QtWidgets import *
from design import Ui_MainWindow

from barcode_manager import *
import os
import cv2
from dbr import EnumBarcodeFormat, EnumBarcodeFormat_2

class MainWindow(QMainWindow):
    def __init__(self, license):
        super(MainWindow, self).__init__()
        self.ui = Ui_MainWindow()
        self.ui.setupUi(self)
        
def main():
    try:
        with open(sys.argv[1]) as f:
            license = f.read()
    except:
        license = ""

    app = QApplication(sys.argv)

    window = MainWindow(license)
    window.show()

    sys.exit(app.exec_())


if __name__ == '__main__':
    print(__doc__)
    main()

下一步是創(chuàng)建一些全局變量并將小部件信號綁定到插槽：

# Initialization
self._all_data = {}
self._results = None

# Dynamsoft Barcode Reader
self._barcodeManager = BarcodeManager(license)

# Create a timer.
self.timer = None

# Open camera
self._cap = None
# self.openCamera()

# Resolution list
self.ui.comboBox.currentTextChanged.connect(self.onComboBoxChanged)

# The current path.
self._path = os.path.dirname(os.path.realpath(__file__))

# Camera button
self.ui.pushButton_open.clicked.connect(self.openCamera)
self.ui.pushButton_stop.clicked.connect(self.stopCamera)

# Load file
self.ui.actionOpen_File.triggered.connect(self.openFile)

# Load directory
self.ui.actionOpen_Folder.triggered.connect(self.openFolder)

# Export template
self.ui.actionExport_template.triggered.connect(self.exportTemplate)

# About
self.ui.actionAbout.triggered.connect(self.about)

# Set license
self.ui.actionEnter_License_Key.triggered.connect(self.setLicense)

## List widget
self.ui.listWidget.currentItemChanged.connect(self.currentItemChanged)

## Template load button
self.ui.pushButton_template.clicked.connect(self.loadTemplate)

## Template export button
self.ui.pushButton_export_template.clicked.connect(self.exportTemplate)

基本的文件操作包括加載圖像文件，從文件夾加載一批圖像文件，加載和保存模板文件。

• 加載文件：

  def openFile(self):
      filename = QFileDialog.getOpenFileName(self, 'Open File',
                                              self._path, "Barcode images (*)")
      if filename is None or filename[0] == '':
          return

      filename = filename[0]

• 從文件夾加載文件：

 def openFolder(self):
      dir = QFileDialog.getExistingDirectory(self, 'Open Folder',
                                              self._path, QFileDialog.ShowDirsOnly)
      if dir is '':
          return

      files = [os.path.join(dir, f) for f in os.listdir(dir) if os.path.isfile(os.path.join(dir, f))]
      if len(files) == 0:
          return

      for filename in files:
          self.appendFile(filename)

• 保存文件：

  def exportTemplate(self):
      filename = QFileDialog.getSaveFileName(self, 'Save File',
                                              self._path, "Barcode Template (*.json)")
      if filename is None or filename[0] == '':
          return

      filename = filename[0]

如果您更喜歡OpenCV API，則可以像下面這樣解碼條形碼：

frame = cv2.imread(filename)
results = self._reader.decode_buffer(frame)

results = self._reader.decode_file(filename)

intermediate_results = self._reader.get_all_intermediate_results()

imageData =  intermediate_results[0].results[0]
buffer = imageData.bytes
width = imageData.width
height = imageData.height
stride = imageData.stride
format = imageData.image_pixel_format
channel = 3
if format == EnumImagePixelFormat.IPF_RGB_888:
    channel = 3
elif format == EnumImagePixelFormat.IPF_BINARY or format == EnumImagePixelFormat.IPF_GRAYSCALED or format == EnumImagePixelFormat.IPF_BINARYINVERTED:
    channel = 1

if format == EnumImagePixelFormat.IPF_BINARY or format == EnumImagePixelFormat.IPF_BINARYINVERTED:
    whiteValue = 1
    if format == EnumImagePixelFormat.IPF_BINARYINVERTED:
        whiteValue = 0
    
    binData = bytearray(len(buffer) << 3)
    count = 0
    for pos in range(len(buffer)):
        for bit in range(7, -1, -1):
            if (buffer[pos] >> bit) & 0x01 == whiteValue:
                binData[count] = 255
            else:
                binData[count] = 0
            
            count += 1

    frame = np.ndarray((height, width, channel), np.uint8, binData, 0, (stride << 3, channel, 1))
else:

    frame = np.ndarray((height, width, channel), np.uint8, buffer, 0, (stride, channel, 1))

我們觸發(fā)一個(gè)計(jì)時(shí)器來顯示網(wǎng)絡(luò)攝像頭流：

def openCamera(self):

    width = 640; height = 480
    self._cap = cv2.VideoCapture(0)
    self._cap.set(cv2.CAP_PROP_FRAME_WIDTH, width)
    self._cap.set(cv2.CAP_PROP_FRAME_HEIGHT, height)

    if not self._cap.isOpened(): 
        self.showMessageBox('Error', "Failed to open camera.")
        return

    self.timer = QTimer()
    self.timer.timeout.connect(self.nextFrameUpdate)
    self.timer.start(1000./24)

def nextFrameUpdate(self):
    ret, frame = self._cap.read()
    frame, self._results = self._barcodeManager.decode_frame(frame)

    self.showResults(frame, self._results)

解碼條形碼是一項(xiàng)占用大量CPU的任務(wù)。為了避免實(shí)時(shí)阻塞UI，我們創(chuàng)建了一個(gè)Python進(jìn)程來運(yùn)行代碼：

def create_barcode_process(self):
    size = 1
    self.frameQueue = Queue(size)
    self.resultQueue = Queue(size)
    self.barcodeScanning = Process(target=process_barcode_frame, args=(self._license, self.frameQueue, self.resultQueue, self._template, self._types, self._types2))
    self.barcodeScanning.start()

python3 app_advanced.py license.txt