python - 同时跟踪多个小部件中的鼠标移动(Track mouse movements in several widgets at the same time)

Question

I would like to track the mouse movement for calculation (of values for progress bars) while the mouse is used to draw in one of the two QGraphicsView .

(我想跟踪鼠标的移动以进行计算（进度条的值），同时使用鼠标绘制两个QGraphicsView 。)

With the code below you can draw either in a QGraphicsView or get the coordinates of mouse movements over the gridLayout , but not both at once.

(下面你的代码可以在绘制QGraphicsView 或克服鼠标移动的坐标gridLayout不能同时一次，但。)

How can this be done?

(如何才能做到这一点？)

---

main.py (main.py)

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()

---

mainwindow.ui (mainwindow.ui)

<?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>

  ask by Atalanttore translate from so

Answer 1

The problem is that the mousePressEvent does not necessarily propagate from the parent widget to the child widget (that behavior depends on each type of widget, for example QLabel if it propagates the mouse events), in addition to your strategy of overriding the mouseMoveEvent method is limited if you want Listen to the events of other widgets.

(问题在于，除了覆盖mouseMoveEvent方法的策略外，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，则限制。)

Considering the above, a possible solution is to use an eventFilter to listen to the events of any widget, and another improvement is to use the global position instead of the local one so that when the mouse changes from QGraphicsView it is not affected by the local coordinate system.

(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本地位置，以便当鼠标从QGraphicsView更改时，它不受本地影响。坐标系。)

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