我正在尝试在场景中选择的项目周围绘制一个矩形(通过RubberBandDrag或ctrl +单击每个项目)。
为了做到这一点,我已经对QGraphicsScene进行了子类化并重新实现了selectionChanged
方法,在所选区域周围添加了一个QGraphicsRectItem,但由于某种原因,当选择或取消选择项时,不会调用此方法在场景中。我确保这些物品实际上是可选择的。
以下是我尝试做的最小例子:
from PyQt4.QtGui import *
from PyQt4.QtCore import *
import sys
class DiagramScene(QGraphicsScene):
def __init__(self, parent=None):
super().__init__(parent)
self.selRect = None
def selectionChanged(self):
area = self.selectionArea().boundingRect()
pen = QPen()
pen.setColor(Qt.black)
pen.setStyle(Qt.DashLine)
self.selRect = self.addRect(area, pen)
if __name__ == "__main__":
app = QApplication(sys.argv)
view = QGraphicsView()
view.setDragMode(QGraphicsView.RubberBandDrag)
scene = DiagramScene()
scene.setSceneRect(0, 0, 500, 500)
rect1 = scene.addRect(20, 20, 100, 50)
rect2 = scene.addRect(80, 80, 100, 50)
rect3 = scene.addRect(140, 140, 100, 50)
rect1.setFlag(QGraphicsItem.ItemIsSelectable, True)
rect2.setFlag(QGraphicsItem.ItemIsSelectable, True)
rect3.setFlag(QGraphicsItem.ItemIsSelectable, True)
view.setScene(scene)
view.show()
sys.exit(app.exec_())
答案 0 :(得分:1)
selectionChanged
是一个信号,而不是您必须实施的方法。您需要做的是将此信号连接到插槽以及插槽中的实现,因此无论何时发出信号,您的代码都会被执行:
from PyQt4.QtGui import *
from PyQt4.QtCore import *
import sys
class DiagramScene(QGraphicsScene):
def __init__(self, parent=None):
super().__init__(parent)
self.selRect = None
self.selectionChanged.connect(self.onSelectionChanged)
@pyqtSlot()
def onSelectionChanged(self):
area = self.selectionArea().boundingRect()
pen = QPen()
pen.setColor(Qt.black)
pen.setStyle(Qt.DashLine)
self.selRect = self.addRect(area, pen)
if __name__ == "__main__":
app = QApplication(sys.argv)
view = QGraphicsView()
view.setDragMode(QGraphicsView.RubberBandDrag)
scene = DiagramScene()
scene.setSceneRect(0, 0, 500, 500)
rect1 = scene.addRect(20, 20, 100, 50)
rect2 = scene.addRect(80, 80, 100, 50)
rect3 = scene.addRect(140, 140, 100, 50)
rect1.setFlag(QGraphicsItem.ItemIsSelectable, True)
rect2.setFlag(QGraphicsItem.ItemIsSelectable, True)
rect3.setFlag(QGraphicsItem.ItemIsSelectable, True)
view.setScene(scene)
view.show()
sys.exit(app.exec_())