[英]PyQt4 scroll glitch
我編寫了一個小應用程序,該應用程序基於QGraphicsView。 您可以縮放和平移視圖。 問題是,當您放大(因此視圖將大於窗口)並平移視圖時,將顯示以下故障( 圖片 )
我的代碼:
import sys
import math
from PyQt4 import QtGui, QtCore
class GraphWidget(QtGui.QGraphicsView):
def __init__(self):
super(GraphWidget, self).__init__()
scene = QtGui.QGraphicsScene(self)
scene.setItemIndexMethod(QtGui.QGraphicsScene.NoIndex)
scene.setSceneRect(0, 0, 400, 400)
self.setScene(scene)
self.setCacheMode(QtGui.QGraphicsView.CacheBackground)
self.setViewportUpdateMode(QtGui.QGraphicsView.BoundingRectViewportUpdate)
self.setRenderHint(QtGui.QPainter.Antialiasing)
self.setResizeAnchor(QtGui.QGraphicsView.AnchorViewCenter)
self.sFactor=1
self.scale(1, 1)
self.setMinimumSize(400, 400)
self.setWindowTitle("test")
self.setDragMode(QtGui.QGraphicsView.ScrollHandDrag)
self.setViewportUpdateMode(QtGui.QGraphicsView.FullViewportUpdate)
#print self.viewportUpdateMode()
def keyPressEvent(self, event):
key = event.key()
if key == QtCore.Qt.Key_Plus:
self.scaleView(1.2)
elif key == QtCore.Qt.Key_Minus:
self.scaleView(1 / 1.2)
else:
super(GraphWidget, self).keyPressEvent(event)
def wheelEvent(self, event):
self.setTransformationAnchor(QtGui.QGraphicsView.AnchorUnderMouse)
self.scaleView(math.pow(2.0, -event.delta() / 240.0))
def drawBackground(self, painter, rect):
painter.setRenderHint(QtGui.QPainter.Antialiasing, True)
pen = QtGui.QPen(QtCore.Qt.black, 2/self.sFactor, QtCore.Qt.SolidLine)
painter.setPen(pen)
line=painter.drawLine(0, 0, 300, 200)
def mouseReleaseEvent(self, event):
#self.update()
#self.viewport().repaint()
self.viewport().update()
#self.scaleView(1.2)
super(GraphWidget, self).mouseReleaseEvent(event)
def scaleView(self, scaleFactor):
self.sFactor = self.matrix().scale(scaleFactor, scaleFactor).mapRect(QtCore.QRectF(0, 0, 1, 1)).width()
if self.sFactor < 0.07 or self.sFactor > 100:
return
self.scale(scaleFactor, scaleFactor)
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
widget = GraphWidget()
widget.show()
sys.exit(app.exec_())
如果在mousereleaseEvent中調用self.scaleView(1.2),則滑動消失,但僅在事件發生時才消失。 我認為這是因為我沒有調用正確的重繪/更新,但是我沒有找到正確的重繪/更新。
請勿更改后台的默認緩存模式-如果刪除以下行,則可以解決問題: self.setCacheMode(QtGui.QGraphicsView.CacheBackground)
。
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