注意几个关键点:
- 初始化
python
class CustomGraphicsView(QGraphicsView):
def __init__(self, parent=None):
super(CustomGraphicsView, self).__init__(parent)
self.scene = QGraphicsScene()
self.setScene(self.scene)
self.setGeometry(0, 0, 1024, 600)
# 以下初始化代码较为重要
self.setMouseTracking(True)
self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff) # 按需开启
# self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff) # 按需开启
self.setTransformationAnchor(QGraphicsView.AnchorUnderMouse)
self.setResizeAnchor(QGraphicsView.AnchorUnderMouse)
- 关键实现函数:重定义滚轮缩放事件(可能会达不到预期效果,请看步骤3或确认初始化)
python
def wheelEvent(self, event: QWheelEvent) -> None:
if event.modifiers() == Qt.ControlModifier:
mouse_pos = event.pos()
scene_pos = self.mapToScene(mouse_pos) #缩放前鼠标在scene的位置
s = 1.2 #按需调整
if(event.angleDelta().y() > 0):
self.scale(s,s)
else:
self.scale(1/s,1/s)
view_point = self.mapFromScene(scene_pos) #缩放后原scene进行映射新鼠标位置
self.verticalScrollBar().setValue(int(view_point.y()-mouse_pos.y())) #通过滚动条进行移动视图
self.horizontalScrollBar().setValue(int(view_point.x()-mouse_pos.x()))
return
else:
return super().wheelEvent(event) # 保证滚动条能滚动
- 如果未到达预期效果,可能还需重写所有鼠标事件:
python
def mousePressEvent(self, event: QMouseEvent) -> None:
if event.button() == Qt.LeftButton:
self.dragStartPos = event.pos() #用于鼠标拖拽视图
return
python
def mouseReleaseEvent(self, event: QMouseEvent) -> None:
pass
return
python
def mouseMoveEvent(self, event):
if event.buttons() and Qt.LeftButton: # 实现鼠标拖拽视图
newpos = event.pos()
delta = newpos - self.dragStartPos
self.dragStartPos = newpos
self.verticalScrollBar().setValue(self.verticalScrollBar().value() - delta.y())
self.horizontalScrollBar().setValue(self.horizontalScrollBar().value() - delta.x())
return
仅此记录,未重定义鼠标所有事件导致了近半个月的苦恼,虽然修复了但是仍不知道什么原因