Detailed explanation of python3+PyQt5 custom view

This article mainly introduces the relevant information of python3 PyQt5 custom views in detail. It has certain reference value. Interested friends can refer to the several view classes provided by

pyqt. Can work better, including QLisView, QTableView and QTreeView. But for some data that are difficult to present in existing ways, we can create our own view subclass and use it for visualization of model data to solve this problem. This article implements 16 chapters of python Qt GUI rapid programming examples through Python3 pyqt5.

#!/usr/bin/env python3

import gzip
import os
import platform
import sys
from PyQt5.QtCore import (QAbstractTableModel, QDateTime, QModelIndex,
    QSize, QTimer, QVariant, Qt,pyqtSignal)
from PyQt5.QtGui import ( QColor, QCursor, QFont,
    QFontDatabase, QFontMetrics, QPainter, QPalette, QPixmap)
from PyQt5.QtWidgets import QApplication,QDialog,QHBoxLayout, QLabel, QMessageBox,QScrollArea, QSplitter, QTableView,QWidget


(TIMESTAMP, TEMPERATURE, INLETFLOW, TURBIDITY, CONDUCTIVITY,
 COAGULATION, RAWPH, FLOCCULATEDPH) = range(8)

TIMESTAMPFORMAT = "yyyy-MM-dd hh:mm"


class WaterQualityModel(QAbstractTableModel):

  def __init__(self, filename):
    super(WaterQualityModel, self).__init__()
    self.filename = filename
    self.results = []


  def load(self):
    self.beginResetModel()
    exception = None
    fh = None
    try:
      if not self.filename:
        raise IOError("no filename specified for loading")
      self.results = []
      line_data = gzip.open(self.filename).read()
      for line in line_data.decode("utf8").splitlines():
        parts = line.rstrip().split(",")
        date = QDateTime.fromString(parts[0] + ":00",
                      Qt.ISODate)

        result = [date]
        for part in parts[1:]:
          result.append(float(part))
        self.results.append(result)

    except (IOError, ValueError) as e:
      exception = e
    finally:
      if fh is not None:
        fh.close()
      self.endResetModel()
      if exception is not None:
        raise exception


  def data(self, index, role=Qt.DisplayRole):
    if (not index.isValid() or
      not (0 <= index.row() < len(self.results))):
      return QVariant()
    column = index.column()
    result = self.results[index.row()]
    if role == Qt.DisplayRole:
      item = result[column]
      if column == TIMESTAMP:
        #item = item.toString(TIMESTAMPFORMAT)
        item=item
      else:
        #item = QString("%1").arg(item, 0, "f", 2)
        item = "{0:.2f}".format(item)
      return item
    elif role == Qt.TextAlignmentRole:
      if column != TIMESTAMP:
        return QVariant(int(Qt.AlignRight|Qt.AlignVCenter))
      return QVariant(int(Qt.AlignLeft|Qt.AlignVCenter))
    elif role == Qt.TextColorRole and column == INLETFLOW:
      if result[column] < 0:
        return QVariant(QColor(Qt.red))
    elif (role == Qt.TextColorRole and
       column in (RAWPH, FLOCCULATEDPH)):
      ph = result[column]
      if ph < 7:
        return QVariant(QColor(Qt.red))
      elif ph >= 8:
        return QVariant(QColor(Qt.blue))
      else:
        return QVariant(QColor(Qt.darkGreen))
    return QVariant()


  def headerData(self, section, orientation, role=Qt.DisplayRole):
    if role == Qt.TextAlignmentRole:
      if orientation == Qt.Horizontal:
        return QVariant(int(Qt.AlignCenter))
      return QVariant(int(Qt.AlignRight|Qt.AlignVCenter))
    if role != Qt.DisplayRole:
      return QVariant()
    if orientation == Qt.Horizontal:
      if section == TIMESTAMP:
        return "Timestamp"
      elif section == TEMPERATURE:
        return "\u00B0" +"C"
      elif section == INLETFLOW:
        return "Inflow"
      elif section == TURBIDITY:
        return "NTU"
      elif section == CONDUCTIVITY:
        return "\u03BCS/cm"
      elif section == COAGULATION:
        return "mg/L"
      elif section == RAWPH:
        return "Raw Ph"
      elif section == FLOCCULATEDPH:
        return "Floc Ph"
    return int(section + 1)


  def rowCount(self, index=QModelIndex()):
    return len(self.results)


  def columnCount(self, index=QModelIndex()):
    return 8


class WaterQualityView(QWidget):
  clicked = pyqtSignal(QModelIndex)
  FLOWCHARS = (chr(0x21DC), chr(0x21DD), chr(0x21C9))

  def __init__(self, parent=None):
    super(WaterQualityView, self).__init__(parent)
    self.scrollarea = None
    self.model = None
    self.setFocusPolicy(Qt.StrongFocus)
    self.selectedRow = -1
    self.flowfont = self.font()
    size = self.font().pointSize()
    if platform.system() == "Windows":
      fontDb = QFontDatabase()
      for face in [face.toLower() for face in fontDb.families()]:
        if face.contains("unicode"):
          self.flowfont = QFont(face, size)
          break
      else:
        self.flowfont = QFont("symbol", size)
        WaterQualityView.FLOWCHARS = (chr(0xAC), chr(0xAE),
                       chr(0xDE))


  def setModel(self, model):
    self.model = model
    #self.connect(self.model,
    #    SIGNAL("dataChanged(QModelIndex,QModelIndex)"),
    #    self.setNewSize)
    self.model.dataChanged.connect(self.setNewSize)
    #self.connect(self.model, SIGNAL("modelReset()"), self.setNewSize)
    self.model.modelReset.connect(self.setNewSize)
    self.setNewSize()


  def setNewSize(self):
    self.resize(self.sizeHint())
    self.update()
    self.updateGeometry()


  def minimumSizeHint(self):
    size = self.sizeHint()
    fm = QFontMetrics(self.font())
    size.setHeight(fm.height() * 3)
    return size


  def sizeHint(self):
    fm = QFontMetrics(self.font())
    size = fm.height()
    return QSize(fm.width("9999-99-99 99:99 ") + (size * 4),
           (size / 4) + (size * self.model.rowCount()))


  def paintEvent(self, event):
    if self.model is None:
      return
    fm = QFontMetrics(self.font())
    timestampWidth = fm.width("9999-99-99 99:99 ")
    size = fm.height()
    indicatorSize = int(size * 0.8)
    offset = int(1.5 * (size - indicatorSize))
    minY = event.rect().y()
    maxY = minY + event.rect().height() + size
    minY -= size
    painter = QPainter(self)
    painter.setRenderHint(QPainter.Antialiasing)
    painter.setRenderHint(QPainter.TextAntialiasing)
    y = 0
    for row in range(self.model.rowCount()):
      x = 0
      if minY <= y <= maxY:
        painter.save()
        painter.setPen(self.palette().color(QPalette.Text))
        if row == self.selectedRow:
          painter.fillRect(x, y + (offset * 0.8),
              self.width(), size, self.palette().highlight())
          painter.setPen(self.palette().color(
              QPalette.HighlightedText))
        #timestamp = self.model.data(
            #self.model.index(row, TIMESTAMP)).toDateTime()
        timestamp = self.model.data(self.model.index(row, TIMESTAMP))    
        painter.drawText(x, y + size,
            timestamp.toString(TIMESTAMPFORMAT))
        #print(timestamp.toString(TIMESTAMPFORMAT))
        x += timestampWidth
        temperature = self.model.data(
            self.model.index(row, TEMPERATURE))
        #temperature = temperature.toDouble()[0]
        temperature = float(temperature)
        if temperature < 20:
          color = QColor(0, 0,
              int(255 * (20 - temperature) / 20))
        elif temperature > 25:
          color = QColor(int(255 * temperature / 100), 0, 0)
        else:
          color = QColor(0, int(255 * temperature / 100), 0)
        painter.setPen(Qt.NoPen)
        painter.setBrush(color)
        painter.drawEllipse(x, y + offset, indicatorSize,
                  indicatorSize)
        x += size
        rawPh = self.model.data(self.model.index(row, RAWPH))
        #rawPh = rawPh.toDouble()[0]
        rawPh = float(rawPh)
        if rawPh < 7:
          color = QColor(int(255 * rawPh / 10), 0, 0)
        elif rawPh >= 8:
          color = QColor(0, 0, int(255 * rawPh / 10))
        else:
          color = QColor(0, int(255 * rawPh / 10), 0)
        painter.setBrush(color)
        painter.drawEllipse(x, y + offset, indicatorSize,
                  indicatorSize)
        x += size
        flocPh = self.model.data(
            self.model.index(row, FLOCCULATEDPH))
        #flocPh = flocPh.toDouble()[0]
        flocPh = float(flocPh)
        if flocPh < 7:
          color = QColor(int(255 * flocPh / 10), 0, 0)
        elif flocPh >= 8:
          color = QColor(0, 0, int(255 * flocPh / 10))
        else:
          color = QColor(0, int(255 * flocPh / 10), 0)
        painter.setBrush(color)
        painter.drawEllipse(x, y + offset, indicatorSize,
                  indicatorSize)
        painter.restore()
        painter.save()
        x += size
        flow = self.model.data(
            self.model.index(row, INLETFLOW))
        #flow = flow.toDouble()[0]
        flow = float(flow)
        char = None
        if flow <= 0:
          char = WaterQualityView.FLOWCHARS[0]
        elif flow < 3.6:
          char = WaterQualityView.FLOWCHARS[1]
        elif flow > 4.7:
          char = WaterQualityView.FLOWCHARS[2]
        if char is not None:
          painter.setFont(self.flowfont)
          painter.drawText(x, y + size, char)
        painter.restore()
      y += size
      if y > maxY:
        break


  def mousePressEvent(self, event):
    fm = QFontMetrics(self.font())
    self.selectedRow = event.y() // fm.height()
    self.update()
    #self.emit(SIGNAL("clicked(QModelIndex)"),
    #     self.model.index(self.selectedRow, 0))
    self.clicked.emit(self.model.index(self.selectedRow, 0))



  def keyPressEvent(self, event):
    if self.model is None:
      return
    row = -1
    if event.key() == Qt.Key_Up:
      row = max(0, self.selectedRow - 1)
    elif event.key() == Qt.Key_Down:
      row = min(self.selectedRow + 1, self.model.rowCount() - 1)
    if row != -1 and row != self.selectedRow:
      self.selectedRow = row
      if self.scrollarea is not None:
        fm = QFontMetrics(self.font())
        y = fm.height() * self.selectedRow
        print(y)
        self.scrollarea.ensureVisible(0, y)
      self.update()
      #self.emit(SIGNAL("clicked(QModelIndex)"),
      #     self.model.index(self.selectedRow, 0))
      self.clicked.emit(self.model.index(self.selectedRow, 0))
    else:
      QWidget.keyPressEvent(self, event)


class MainForm(QDialog):

  def __init__(self, parent=None):
    super(MainForm, self).__init__(parent)

    self.model = WaterQualityModel(os.path.join(
        os.path.dirname(__file__), "waterdata.csv.gz"))
    self.tableView = QTableView()
    self.tableView.setAlternatingRowColors(True)
    self.tableView.setModel(self.model)
    self.waterView = WaterQualityView()
    self.waterView.setModel(self.model)
    scrollArea = QScrollArea()
    scrollArea.setBackgroundRole(QPalette.Light)
    scrollArea.setWidget(self.waterView)
    self.waterView.scrollarea = scrollArea

    splitter = QSplitter(Qt.Horizontal)
    splitter.addWidget(self.tableView)
    splitter.addWidget(scrollArea)
    splitter.setSizes([600, 250])
    layout = QHBoxLayout()
    layout.addWidget(splitter)
    self.setLayout(layout)

    self.setWindowTitle("Water Quality Data")
    QTimer.singleShot(0, self.initialLoad)


  def initialLoad(self):
    QApplication.setOverrideCursor(QCursor(Qt.WaitCursor))
    splash = QLabel(self)
    pixmap = QPixmap(os.path.join(os.path.dirname(__file__),
        "iss013-e-14802.jpg"))
    #print(os.path.join(os.path.dirname(__file__),
    #    "iss013-e-14802.jpg"))
    splash.setPixmap(pixmap)
    splash.setWindowFlags(Qt.SplashScreen)
    splash.move(self.x() + ((self.width() - pixmap.width()) / 2),
          self.y() + ((self.height() - pixmap.height()) / 2))
    splash.show()
    QApplication.processEvents()
    try:
      self.model.load()
    except IOError as e:
      QMessageBox.warning(self, "Water Quality - Error", e)
    else:
      self.tableView.resizeColumnsToContents()
    splash.close()
    QApplication.processEvents()
    QApplication.restoreOverrideCursor()


app = QApplication(sys.argv)
form = MainForm()
form.resize(850, 620)
form.show()
app.exec_()

Run results:

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