创建鼠标聚光灯

Question

我正在尝试创建一个简单的应用程序，将聚光灯放在鼠标光标位置周围（使其他所有东西变暗）并用鼠标移动聚光灯。你知道吗

像这样：

我对Qt没有太多的经验。我从this example开始，但走不了多远。你知道吗

我创建了一个保持在顶部的窗口并设置其不透明度。但我不知道如何使它的一部分完全透明。你知道吗

Answer 1

要设置透明背景色，必须设置属性Qt::WA_TranslucentBackground，然后绘制一个矩形减去一个圆，如下所示：

from PyQt5 import QtCore, QtGui, QtWidgets

class SpotlightWidget(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(SpotlightWidget, self).__init__(parent, QtCore.Qt.WindowStaysOnTopHint)
        self.setAttribute(QtCore.Qt.WA_TranslucentBackground)
        self.setAttribute(QtCore.Qt.WA_TransparentForMouseEvents)
        self.showFullScreen()
        self.setMouseTracking(True)
        self.center = QtCore.QPoint()

        self.setContextMenuPolicy(QtCore.Qt.ActionsContextMenu)
        self.quitAction = QtWidgets.QAction("Salir", self,shortcut="Ctrl+Q", triggered=self.close)
        self.addAction(self.quitAction)

    def mouseMoveEvent(self, event):
        self.center = event.pos()
        self.update()
        super(SpotlightWidget, self).mouseMoveEvent(event)

    def paintEvent(self, event):
        painter = QtGui.QPainter(self)
        painter.setPen(QtCore.Qt.NoPen)
        painter.setRenderHint(QtGui.QPainter.Antialiasing)
        painter.setBrush(QtGui.QColor(108, 119, 125, 220))
        radius = 100
        path = QtGui.QPainterPath()
        if not self.center.isNull():
            path.moveTo(self.center + radius/2*QtCore.QPoint(1, 0))
            path.arcTo(QtCore.QRectF(self.center - radius/2*QtCore.QPointF(1, 1), radius*QtCore.QSizeF(1, 1)), 0, 360)
        path.addRect(QtCore.QRectF(self.rect()))
        painter.drawPath(path)


if __name__ == '__main__':
    import sys

    app = QtWidgets.QApplication(sys.argv)
    w = SpotlightWidget()
    w.show()
    sys.exit(app.exec_())