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Dynamsoft Barcode Reader SDK一款多功能的条码读取控件，只需要几行代码就可以将条码读取功能嵌入到Web或桌面应用程序。这可以节省数月的开发时间和成本。能支持多种图像文件格式以及从摄像机或扫描仪获取的DIB格式。使用Dynamsoft Barcode Reader SDK，你可以创建强大且实用的条形码扫描仪软件，以满足你的业务需求。

点击下载Dynamsoft Barcode Reader最新版

Qt Designer是用于使用Qt小部件构建跨平台图形用户界面（GUI）的Qt工具。在本文中，我将使用Qt设计器通过适用于Windows，Linux，macOS和Raspberry Pi OS的Dynamsoft Python条形码SDK创建高级桌面条形码读取器应用程序。该应用程序包含Dynamsoft条码阅读器的所有强大功能。

使用Qt Designer构造UI

所需的Qt小部件包括：
菜单栏

• 打开文件
• 打开文件夹
• 保存模板
• 输入许可证密钥
• 关于

• 显示状态信息

• 列出已加载的文件名

• 显示图像或摄像头框架

• 摄像机，模板和条形码类型设置的组

• 启动相机
• 停止摄像头
• 加载条形码模板文件
• 导出条形码模板文件

• 相机解析度

• 条形码识别完成后自动停止摄像头视图
• 同步或异步显示条形码结果

• 输入参数模板
• 显示条形码解码结果

pyside2-uic design.ui -o design.py

让我们逐步构建条形码阅读器应用程序。

要求

安装相关的Python软件包。对于Raspberry Pi OS，我们可以通过以下apt-get命令安装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

因为UI代码已经准备好，所以我们可以按以下方式加载它：

'''
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()

下一步是创建一些全局变量并将小部件信号绑定到插槽：

# 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载图像文件，从文件夹加载一批图像文件，加载和保存模板文件。

• 加载文件：

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

      filename = filename[0]

• 从文件夹加载文件：

 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]

如果您更喜欢OpenCV API，则可以像下面这样解码条形码：

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))

我们触发一个计时器来显示网络摄像头流：

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)

解码条形码是一项占用大量CPU的任务。为了避免实时阻塞UI，我们创建了一个Python进程来运行代码：

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