同时跟踪多个小部件中的鼠标移动

Question

当鼠标习惯于calculation (of values for progress bars)时，我想跟踪draw in one of the two QGraphicsView的鼠标移动。使用下面的代码，您可以在QGraphicsView 或中绘制，以获取鼠标在QGraphicsView上的移动坐标，但不能一次绘制两个坐标。如何做到这一点？

---

main.py

gridLayout

---

mainwindow.ui

import sys
from PyQt5.QtCore import Qt
from PyQt5.QtGui import QCursor, QPainterPath, QPen
from PyQt5.QtWidgets import QApplication, QMainWindow, QGraphicsView, QGraphicsScene, QGraphicsPathItem
from PyQt5.uic import loadUi

app = None


class MainWindow(QMainWindow):
    def __init__(self, parent=None):
        super().__init__(parent)
        loadUi("mainwindow.ui", self)
        self.showMaximized()
        self.setMouseTracking(True)
        self.centralWidget().setAttribute(Qt.WA_MouseTracking)

        self._old_x = QCursor.pos().x()
        self._old_y = QCursor.pos().y()

        self.verticalLayout_top.addWidget(GraphicsView())
        self.verticalLayout_bottom.addWidget(GraphicsView())

    @staticmethod
    def _update_bar(progress_bar, delta):
        current_value = progress_bar.value()
        new_value = current_value + delta
        progress_bar.setValue(new_value)

    def mouseMoveEvent(self, event):
        new_x = event.x()
        new_y = event.y()

        if new_x > self._old_x:
            self._update_bar(self.progressBar_x_plus, new_x - self._old_x)
        if new_x < self._old_x:
            self._update_bar(self.progressBar_x_minus, self._old_x - new_x)

        if new_y > self._old_y:
            self._update_bar(self.progressBar_y_plus, new_y - self._old_y)
        if new_y < self._old_y:
            self._update_bar(self.progressBar_y_minus, self._old_y - new_y)

        self._old_x = new_x
        self._old_y = new_y


class GraphicsView(QGraphicsView):
    def __init__(self):
        super().__init__()
        self.start = None
        self.end = None

        self.setScene(QGraphicsScene())
        self.path = QPainterPath()
        self.item = GraphicsPathItem()
        self.scene().addItem(self.item)

        self.contents_rect = self.contentsRect()
        self.setSceneRect(0, 0, self.contents_rect.width(), self.contents_rect.height())
        self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)

    def mousePressEvent(self, event):
        self.start = self.mapToScene(event.pos())
        self.path.moveTo(self.start)

    def mouseMoveEvent(self, event):
        self.end = self.mapToScene(event.pos())
        self.path.lineTo(self.end)
        self.start = self.end
        self.item.setPath(self.path)


class GraphicsPathItem(QGraphicsPathItem):
    def __init__(self):
        super().__init__()
        pen = QPen()
        pen.setColor(Qt.black)
        pen.setWidth(5)
        self.setPen(pen)


def main():
    global app
    app = QApplication(sys.argv)
    main_window = MainWindow()
    main_window.show()
    sys.exit(app.exec_())


if __name__ == "__main__":
    main()

Answer 1

问题是，除了您的重写mouseMoveEvent的策略外，mousePressEvent不一定从父窗口小部件传播到子窗口小部件（行为取决于每种类型的窗口小部件，例如QLabel如果它传播鼠标事件）。如果您想听其他小部件的事件，则方法是有限的。

考虑到上述情况，一种可能的解决方案是使用eventFilter侦听任何小部件的事件，另一个改进是使用全局位置而不是局部位置，以便当鼠标从QGraphicsView更改时不受以下影响。本地坐标系。

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>1003</width>
    <height>703</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>Mouse Pointer</string>
  </property>
  <property name="locale">
   <locale language="English" country="UnitedKingdom"/>
  </property>
  <widget class="QWidget" name="centralwidget">
   <layout class="QGridLayout" name="gridLayout_2">
    <item row="0" column="0">
     <layout class="QVBoxLayout" name="verticalLayout_top"/>
    </item>
    <item row="1" column="0">
     <layout class="QGridLayout" name="gridLayout">
      <item row="0" column="0">
       <widget class="QLabel" name="label_x_plus">
        <property name="text">
         <string>X+</string>
        </property>
        <property name="alignment">
         <set>Qt::AlignLeading|Qt::AlignLeft|Qt::AlignVCenter</set>
        </property>
       </widget>
      </item>
      <item row="0" column="1">
       <widget class="QProgressBar" name="progressBar_x_plus">
        <property name="maximum">
         <number>1000</number>
        </property>
        <property name="value">
         <number>0</number>
        </property>
       </widget>
      </item>
      <item row="1" column="0">
       <widget class="QLabel" name="label_x_minus">
        <property name="text">
         <string>X-</string>
        </property>
        <property name="alignment">
         <set>Qt::AlignLeading|Qt::AlignLeft|Qt::AlignVCenter</set>
        </property>
       </widget>
      </item>
      <item row="1" column="1">
       <widget class="QProgressBar" name="progressBar_x_minus">
        <property name="maximum">
         <number>1000</number>
        </property>
        <property name="value">
         <number>0</number>
        </property>
       </widget>
      </item>
      <item row="2" column="0">
       <widget class="QLabel" name="label_y_plus">
        <property name="text">
         <string>Y+</string>
        </property>
        <property name="alignment">
         <set>Qt::AlignLeading|Qt::AlignLeft|Qt::AlignVCenter</set>
        </property>
       </widget>
      </item>
      <item row="2" column="1">
       <widget class="QProgressBar" name="progressBar_y_plus">
        <property name="maximum">
         <number>1000</number>
        </property>
        <property name="value">
         <number>0</number>
        </property>
       </widget>
      </item>
      <item row="3" column="0">
       <widget class="QLabel" name="label_y_minus">
        <property name="text">
         <string>Y-</string>
        </property>
        <property name="alignment">
         <set>Qt::AlignLeading|Qt::AlignLeft|Qt::AlignVCenter</set>
        </property>
       </widget>
      </item>
      <item row="3" column="1">
       <widget class="QProgressBar" name="progressBar_y_minus">
        <property name="maximum">
         <number>1000</number>
        </property>
        <property name="value">
         <number>0</number>
        </property>
       </widget>
      </item>
     </layout>
    </item>
    <item row="2" column="0">
     <layout class="QVBoxLayout" name="verticalLayout_bottom"/>
    </item>
   </layout>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>1003</width>
     <height>24</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

更新：

class MouseListener(QObject):
    posChanged = pyqtSignal(QPoint)

    def __init__(self, widget):
        super().__init__(widget)
        self._widget = widget
        self._widget.setMouseTracking(True)
        self._widget.installEventFilter(self)

    def eventFilter(self, obj, event):
        if obj is self._widget and event.type() == QEvent.MouseMove:
            self.posChanged.emit(event.globalPos())
        return super().eventFilter(obj, event)


class MainWindow(QMainWindow):
    def __init__(self, parent=None):
        super().__init__(parent)
        loadUi("mainwindow.ui", self)
        self.showMaximized()
        self.global_pos = QCursor.pos()
        for lay in (self.verticalLayout_top, self.verticalLayout_bottom):
            view = GraphicsView()
            listener = MouseListener(view.viewport())
            listener.posChanged.connect(self.on_pos_changed)
            lay.addWidget(view)

    @staticmethod
    def _update_bar(progress_bar, delta):
        current_value = progress_bar.value()
        new_value = current_value + delta
        progress_bar.setValue(new_value)

    def on_pos_changed(self, pos):
        new_x = pos.x()
        new_y = pos.y()
        old_x = self.global_pos.x()
        old_y = self.global_pos.y()
        if new_x > old_x:
            self._update_bar(self.progressBar_x_plus, new_x - old_x)
        if new_x < old_x:
            self._update_bar(self.progressBar_x_minus, old_x - new_x)
        if new_y > old_y:
            self._update_bar(self.progressBar_y_plus, new_y - old_y)
        if new_y < old_y:
            self._update_bar(self.progressBar_y_minus, old_y - new_y)
        self.global_pos = pos