How to get dockwiget splitter-handler? - python-3.x

Question

I want to get handle in QDockWidget(red line show in picture),So that when handle was click, move, or mouse event and so on.I want to catch it and then do something else,But I can't find how to get it,Can someone know how to get it?
Code Sample
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
class View(QMainWindow):
def __init__(self):
super().__init__()
self.addDockWidget(Qt.LeftDockWidgetArea, QDockWidget("abc", self))
self.setCentralWidget(QPushButton("ABC"))
app = QApplication([])
v = View()
v.show()
app.exec()
Below Is New Update
The view in the QDockWidget,When mouse drag handle,I want to the view always show global mini map of the scene,but use re-szie event will be very slow.So I want to get mouse-release event,then use fitInView redraw mini map.
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
import random
import math
r = lambda : random.randint(0, 255)
r255 = lambda : (r(), r(), r())
class Scene(QGraphicsScene):
def __init__(self):
super().__init__()
for i in range(1000*300):
item = QGraphicsEllipseItem()
item.setRect(0, 0, r(), r())
item.setBrush(QColor(*r255()))
item.setPos(r()*100, r()*100)
self.addItem(item)
class MainView(QGraphicsView):
def wheelEvent(self, event: QWheelEvent) -> None:
factor = math.pow(2.7, event.angleDelta().y()/360)
self.scale(factor, factor)
super().wheelEvent(event)
class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
self.scene = Scene()
self.main = MainView()
self.main.setDragMode(QGraphicsView.ScrollHandDrag)
self.side = QGraphicsView()
self.side.setBackgroundBrush(Qt.black)
self.main.setScene(self.scene)
self.side.setScene(self.scene)
self.setCentralWidget(self.main)
dock = QDockWidget()
dock.setWidget(self.side)
self.addDockWidget(Qt.LeftDockWidgetArea, dock)
#
dock.installEventFilter(self)
def eventFilter(self, w: 'QObject', e: 'QEvent') -> bool:
if isinstance(e, QResizeEvent):
self.side.fitInView(self.scene.itemsBoundingRect(), Qt.KeepAspectRatio)
return super().eventFilter(w, e)
app = QApplication([])
v = MainWindow()
v.show()
app.exec()