不使用paintEvent进行绘制

Question

我有一个带有canvas小部件的GUI。所以我需要用点来感受这幅画布。问题是我需要创建一个单独的进程来运行图形用户界面，因为这些点的(x,y)是从其他类生成的。所以我不知道如何从paintEvent外部绘制这些点，或者如何(如果有必要)再次触发paintEvent。

编辑：

我需要运行遗传算法，获得每一代的适应度结果，并在画布区域将其表示为折线图！但我需要动态地绘制/绘制结果。

因此，每次GA完成一个适应度周期时，我都需要将结果发送到画布区域。

我从http://zetcode.com/tutorials/pyqt4/drawing/获得了这个示例代码，并做了一些修改！

#!/usr/bin/python
# -*- coding: utf-8 -*-

"""
ZetCode PyQt4 tutorial 

In the example, we draw randomly 1000 red points 
on the window.

author: Jan Bodnar
website: zetcode.com 
last edited: September 2011
"""

import sys, random , time
from multiprocessing import Process
from PyQt4 import QtGui, QtCore

class Example(QtGui.QWidget):

    def status( self , text ):

        print '[GUI] ', text

    def __init__(self):

        super(Example, self).__init__()

        self.initUI()

    def initUI(self):      

        self.status('init ui')

        self.setGeometry(300, 300, 280, 170)
        self.setWindowTitle('Points')

        self.status('showing widgets')

        self.show()

    def paintEvent(self, e):

        self.status( 'playing with types : '+str(e) )

        self.status('paint event was called')

        qp = QtGui.QPainter()
        qp.begin(self)

        #self.drawPoints(qp)

        #self.drawRectangles(qp)

        self.draw_all_axis(qp, 300)

        self.draw_dot( 20, 20 )

        qp.end()

    def draw_all_axis( self , qp , length ):

        self.draw_x_axis( qp , length )
        self.draw_y_axis( qp , length )

    def draw_x_axis( self , qp , length ):

        color = QtGui.QColor(0, 0, 0)
        color.setNamedColor('#d49EBD8')
        qp.setPen(color)

        qp.setBrush(QtGui.QColor(73, 235, 216))
        qp.drawLine( 10 , length , length , length )

    def draw_y_axis( self , qp , length):

        color = QtGui.QColor(0, 0, 0)
        color.setNamedColor('#d49EBD8')
        qp.setPen(color)

        qp.setBrush(QtGui.QColor(73, 235, 216))
        qp.drawLine( 10, 10, 10, length )

    def draw_dot( self , x , y ):

        qp = QtGui.QPainter()
        qp.begin(self)

        color = QtGui.QColor(0, 0, 0)
        color.setNamedColor('#d4d4d4')
        qp.setPen(color)

        qp.setBrush(QtGui.QColor(200, 0, 0))
        qp.drawRect( x , y , x + 0.25, y + 0.25 )

    def drawPoints(self, qp):

        qp.setPen(QtCore.Qt.red)
        size = self.size()

        for i in range(1000):

            x = random.randint(1, size.width()-1)

            y = random.randint(1, size.height()-1)

            qp.drawPoint(x, y)     

    def drawRectangles(self, qp):

        color = QtGui.QColor(0, 0, 0)
        color.setNamedColor('#d4d4d4')
        qp.setPen(color)

        qp.setBrush(QtGui.QColor(200, 0, 0))
        qp.drawRect(10, 15, 90, 60)

        qp.setBrush(QtGui.QColor(255, 80, 0, 160))
        qp.drawRect(130, 15, 90, 60)

        qp.setBrush(QtGui.QColor(25, 0, 90, 200))
        qp.drawRect(250, 15, 90, 60)      

def external_dot_drawer( main_window ):


    for i in range(20, 100):

        main_window.draw_dot( i , i )


def main( ):

    print 'launching main window obj as app'
    sys.exit(app.exec_())
    print 'done!'

if __name__ == '__main__':

    print 'loading application abstraction'
    app = QtGui.QApplication(sys.argv)

    print 'building main window obj'
    gui = Example()

    print 'preparing to launch window as a separated process'
    p_main = Process( name='window' , target=main , args=( )  )

    print 'running new process'
    p_main.start()

    time.sleep(3)

    print 'trying to triggering paintEvent'
    p_external_dot_drawer = Process( name='extern_dot_drawer' , target=external_dot_drawer , args=( gui ) )

Answer 1

调度对paintEvent的调用的正确方法是使用QWidget.update()。

我还建议使用任何现有的python绘图库，而不是自己编写。PyQtGraph有一些很好的多进程特性：

import pyqtgraph as pg
app = pg.QtGui.QApplication([])
import pyqtgraph.multiprocess as mp

## start child process
proc = mp.QtProcess()

## import pyqtgraph in the child process, create a plot window there
remotepg = proc._import('pyqtgraph')
win = remotepg.plot()

## create a scatter plot
plot = win.plot([1,4,2,3], [4,6,3,4], pen=None, symbol='o')

## ..after some processing, update the plot data
plot.setData(x=[1,2,3,4], y=[5,7,2,3])