我在这个主题中遇到了同样的问题：当我调整窗口大小时 QRubberBand 移动，经过几次尝试，我意识到本主题的解决方案不适用于 QGraphics 视图。当我调整窗口大小时，为什么我的选择会围绕 QgraphicsView 移动。
import sys
from PyQt5 import QtCore, QtGui, QtWidgets
# from PyQt4 import QtCore, QtWidgets
class ResizableRubberBand(QtWidgets.QGraphicsView):
def __init__(self, parent=None):
super(ResizableRubberBand, self).__init__(parent)
self.draggable = False
self.mousePressPos = None
self.mouseMovePos = None
self._band = QtWidgets.QRubberBand(QtWidgets.QRubberBand.Rectangle, self)
self._band.setGeometry(550, 550, 550, 550)
self._band.show()
self.show()
def mousePressEvent(self, event):
if event.button() == QtCore.Qt.RightButton:
self.mousePressPos = event.globalPos() # global
self.mouseMovePos = event.globalPos() - self.pos() # local
self.draggable = True
elif event.button() == QtCore.Qt.LeftButton:
self.position = QtCore.QPoint(event.pos())
self.upper_left = self.position
self.lower_right = self.position
self.mode = "drag_lower_right"
self._band.show()
def mouseMoveEvent(self, event):
if self.draggable and event.buttons() & QtCore.Qt.RightButton:
globalPos = event.globalPos()
print(globalPos)
diff = globalPos - self.mouseMovePos
self.move(diff)
self.mouseMovePos = globalPos - self.pos()
elif self._band.isVisible():
# visible selection
if self.mode is "drag_lower_right":
self.lower_right = QtCore.QPoint(event.pos())
# print(str(self.lower_right))
elif self.mode is "drag_upper_left":
self.upper_left = QtCore.QPoint(event.pos())
# print(str(self.upper_left))
# update geometry
self._band.setGeometry(QtCore.QRect(self.upper_left, self.lower_right).normalized())
def mouseReleaseEvent(self, event):
self.draggable = False
我的主要课程：
class Window(QtWidgets.QWidget):
def __init__(self):
super(Window, self).__init__()
self.band = ResizableRubberBand()
scene = QtWidgets.QGraphicsScene(self)
photo = QtGui.QPixmap('image.jpg')
scene.addPixmap(photo)
self.band.setScene(scene)
layout = QtWidgets.QVBoxLayout(self)
layout.addWidget(self.band)
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
window = Window()
window.setGeometry(800, 100, 600, 500)
window.show()
sys.exit(app.exec_())
调整大小之前：
调整大小后：
该问题的产生是因为图像的坐标系与QRubberBand的坐标系不一样。所以解决方案是你们共享相同的坐标系，为此我们将 QRubberBand 添加到场景中。
from PyQt5 import QtCore, QtGui, QtWidgets
class GraphicsView(QtWidgets.QGraphicsView):
def __init__(self, parent=None):
super(GraphicsView, self).__init__(parent)
self.setScene(QtWidgets.QGraphicsScene(self))
self.m_rubberBand = QtWidgets.QRubberBand(
QtWidgets.QRubberBand.Rectangle
)
self.m_rubberBand.setGeometry(QtCore.QRect(-1, -1, 2, 2))
self.m_rubberBand.hide()
item = self.scene().addWidget(self.m_rubberBand)
item.setZValue(1)
self.m_draggable = False
self.m_origin = QtCore.QPoint()
def mousePressEvent(self, event):
self.m_origin = self.mapToScene(event.pos()).toPoint()
self.m_rubberBand.setGeometry(
QtCore.QRect(self.m_origin, QtCore.QSize())
)
self.m_rubberBand.show()
self.m_draggable = True
super(GraphicsView, self).mousePressEvent(event)
def mouseMoveEvent(self, event):
if self.m_draggable:
end_pos = self.mapToScene(event.pos()).toPoint()
self.m_rubberBand.setGeometry(
QtCore.QRect(self.m_origin, end_pos).normalized()
)
self.m_rubberBand.show()
def mouseReleaseEvent(self, event):
end_pos = self.mapToScene(event.pos()).toPoint()
self.m_rubberBand.setGeometry(
QtCore.QRect(self.m_origin, end_pos).normalized()
)
self.m_draggable = False
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
w = GraphicsView()
photo = QtGui.QPixmap("image.jpg")
w.scene().addPixmap(photo)
w.resize(640, 480)
w.show()
sys.exit(app.exec_())
