python3+PyQt5实现自定义窗口部件Counters

本文通过Python3+PyQt5实现自定义部件–Counters自定 窗口部件。这个窗口是3*3的网格。本文有两个例子如下：

/home/yrd/eric_workspace/chap11/counters.py。
/home/yrd/eric_workspace/chap11/counters_dnd.py

第二个例子在第一个例子的基础上实现能通过鼠标拖拽球到不同的网格中。

/home/yrd/eric_workspace/chap11/counters.py

#!/usr/bin/env python3from PyQt5.QtCore import (QRectF, QSize, Qt)from PyQt5.QtWidgets import (QApplication, QSizePolicy,QWidget)from PyQt5.QtGui import QPainter,QPenBLANK, RED, YELLOW = range(3)class CountersWidget(QWidget):  def __init__(self, parent=None):    super(CountersWidget, self).__init__(parent)    self.setSizePolicy(QSizePolicy(QSizePolicy.Expanding,                    QSizePolicy.Expanding))    self.grid = [[BLANK] * 3 for i in range(3)]    self.selected = [0, 0]    self.setMinimumSize(self.minimumSizeHint())  def sizeHint(self):    return QSize(200, 200)  def minimumSizeHint(self):    return QSize(100, 100)  def mousePressEvent(self, event):    xOffset = self.width() / 3    yOffset = self.height() / 3    if event.x() < xOffset:      x = 0    elif event.x() < 2 * xOffset:      x = 1    else:      x = 2    if event.y() < yOffset:      y = 0    elif event.y() < 2 * yOffset:      y = 1    else:      y = 2    cell = self.grid[x][y]    if cell == BLANK:      cell = RED    elif cell == RED:      cell = YELLOW    else:      cell = BLANK    self.grid[x][y] = cell    self.selected = [x, y]    self.update()  def keyPressEvent(self, event):    if event.key() == Qt.Key_Left:      self.selected[0] = (2 if self.selected[0] == 0                else self.selected[0] - 1)    elif event.key() == Qt.Key_Right:      self.selected[0] = (0 if self.selected[0] == 2                else self.selected[0] + 1)    elif event.key() == Qt.Key_Up:      self.selected[1] = (2 if self.selected[1] == 0                else self.selected[1] - 1)    elif event.key() == Qt.Key_Down:      self.selected[1] = (0 if self.selected[1] == 2                else self.selected[1] + 1)    elif event.key() == Qt.Key_Space:      x, y = self.selected      cell = self.grid[x][y]      if cell == BLANK:        cell = RED      elif cell == RED:        cell = YELLOW      else:        cell = BLANK      self.grid[x][y] = cell    self.update()  def paintEvent(self, event=None):    painter = QPainter(self)    painter.setRenderHint(QPainter.Antialiasing, True)    xOffset = self.width() / 3    yOffset = self.height() / 3    for x in range(3):      for y in range(3):        cell = self.grid[x][y]        rect = (QRectF(x * xOffset, y * yOffset,            xOffset, yOffset).adjusted(0.5, 0.5, -0.5, -0.5))        color = None        if cell == RED:          color = Qt.red        elif cell == YELLOW:          color = Qt.yellow        if color is not None:          painter.save()          painter.setPen(Qt.black)          painter.setBrush(color)          painter.drawEllipse(rect.adjusted(2, 2, -2, -2))          painter.restore()        if [x, y] == self.selected:          painter.setPen(QPen(Qt.blue, 3))        else:          painter.setPen(Qt.black)        painter.drawRect(rect)if __name__ == "__main__":  import sys  app = QApplication(sys.argv)  form = CountersWidget()  form.setWindowTitle("Counters")  form.show()  app.exec_()