我正在使用下面的类来添加橡皮筋。但是，每次我创建橡皮筋（左键单击）时，都会闪烁/闪烁。我不知道为什么会这样。另外，我将橡皮筋放在 ScrolledWindow 中。
import wx
class wxPyRubberBander:
""" A class to manage mouse events/ rubberbanding of a wx.Python
canvas object """
def __init__(self, canvas):
# canvas object
self._canvas = canvas
# mouse selection start point
self.m_stpoint=wx.Point(0,0)
# mouse selection end point
self.m_endpoint=wx.Point(0,0)
# mouse selection cache point
self.m_savepoint=wx.Point(0,0)
# flags for left click/ selection
self._leftclicked=False
self._selected=False
# Register event handlers for mouse
self.RegisterEventHandlers()
def RegisterEventHandlers(self):
""" Register event handlers for this object """
wx.EVT_LEFT_DOWN(self._canvas, self.OnMouseEvent)
wx.EVT_LEFT_UP(self._canvas, self.OnMouseEvent)
wx.EVT_MOTION(self._canvas, self.OnMouseEvent)
def OnMouseEvent(self, event):
""" This function manages mouse events """
if event:
# set mouse cursor
# get device context of canvas
dc= wx.ClientDC(self._canvas)
# Set logical function to XOR for rubberbanding
dc.SetLogicalFunction(wx.XOR)
# Set dc brush and pen
# Here I set brush and pen to white and grey respectively
# You can set it to your own choices
# The brush setting is not really needed since we
# dont do any filling of the dc. It is set just for
# the sake of completion.
wbrush = wx.Brush(wx.Colour(255,255,255), wx.TRANSPARENT)
wpen = wx.Pen(wx.Colour(200, 200, 200), 1, wx.SOLID)
dc.SetBrush(wbrush)
dc.SetPen(wpen)
if event.LeftDown():
# Left mouse button down, change cursor to
# something else to denote event capture
self.m_stpoint = event.GetPosition()
# invalidate current canvas
self._canvas.Refresh()
# cache current position
self.m_savepoint = self.m_stpoint
self._selected = False
self._leftclicked = True
elif event.Dragging():
# User is dragging the mouse, check if
# left button is down
if self._leftclicked:
# reset dc bounding box
dc.ResetBoundingBox()
dc.BeginDrawing()
w = (self.m_savepoint.x - self.m_stpoint.x)
h = (self.m_savepoint.y - self.m_stpoint.y)
# To erase previous rectangle
dc.DrawRectangle(self.m_stpoint.x, self.m_stpoint.y, w, h)
# Draw new rectangle
self.m_endpoint = event.GetPosition()
w = (self.m_endpoint.x - self.m_stpoint.x)
h = (self.m_endpoint.y - self.m_stpoint.y)
# Set clipping region to rectangle corners
dc.SetClippingRegion(self.m_stpoint.x, self.m_stpoint.y, w,h)
dc.DrawRectangle(self.m_stpoint.x, self.m_stpoint.y, w, h)
dc.EndDrawing()
self.m_savepoint = self.m_endpoint # cache current endpoint
elif event.LeftUp():
# User released left button, change cursor back
self._selected = True #selection is done
self._leftclicked = False # end of clicking
def GetCurrentSelection(self):
""" Return the current selected rectangle """
# if there is no selection, selection defaults to
# current viewport
left = wx.Point(0,0)
right = wx.Point(0,0)
# user dragged mouse to right
if self.m_endpoint.y > self.m_stpoint.y:
right = self.m_endpoint
left = self.m_stpoint
# user dragged mouse to left
elif self.m_endpoint.y < self.m_stpoint.y:
right = self.m_stpoint
left = self.m_endpoint
return (left.x, left.y, right.x, right.y)
def ClearCurrentSelection(self):
""" Clear the current selected rectangle """
box = self.GetCurrentSelection()
dc=wx.ClientDC(self._canvas)
w = box[2] - box[0]
h = box[3] - box[1]
dc.SetClippingRegion(box[0], box[1], w, h)
dc.SetLogicalFunction(wx.XOR)
# The brush is not really needed since we
# dont do any filling of the dc. It is set for
# sake of completion.
wbrush = wx.Brush(wx.Colour(255,255,255), wx.TRANSPARENT)
wpen = wx.Pen(wx.Colour(200, 200, 200), 1, wx.SOLID)
dc.SetBrush(wbrush)
dc.SetPen(wpen)
dc.DrawRectangle(box[0], box[1], w,h)
self._selected = False
# reset selection to canvas size
self.ResetSelection()
def ResetSelection(self):
""" Resets the mouse selection to entire canvas """
self.m_stpoint = wx.Point(0,0)
sz=self._canvas.GetSize()
w,h=sz.GetWidth(), sz.GetHeight()
self.m_endpoint = wx.Point(w,h)