python - pyqt drawing on an exsiting widget of GUI

Question

I am new to pyqt. I am doing a program that allows you clicks on the picture and remember the coordinates of points you clicks and draw a stickfigure on a widget of the GUI. My code right now can prompt out a new window to show a polygon with 4 points. However, I hope it can be displayed on the ui file I alreay made by pyqt. The object name for the widget is called widget.I hope someone can help me to modify the code to display the polygon on the gui widget not prompting out a new window.

Thank you so much!!!

import sys
from PyQt4.QtCore import *
from PyQt4 import QtGui, QtCore
from PyQt4.QtGui import *
from Main_window import *

global imgloc
imgloc = "1.jpg"
array = []
clicks = 0

class MyForm(QtGui.QMainWindow):

    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)
        self.ui = Ui_MainWindow()
        self.ui.setupUi(self)
        self.local_image = QImage(imgloc)
        self.imageLocation = imgloc
        self.local_scene = QGraphicsScene()
        self.pixMapItem = QGraphicsPixmapItem(QPixmap(self.local_image), None, self.local_scene)
        self.ui.graphicsView_5.setScene( self.local_scene )
        self.pixMapItem.mousePressEvent = self.pixelSelect

    def pixelSelect(self,event):
        global imgloc
        a = event.pos().x()
        b = event.pos().y()
        global clicks
        global array
        if clicks != 4:
            clicks += 1
            point = QPoint(a,b)
            array.append(point)
        else:
            clicks = 0
            dialog = DialogBody()
            dialog.show()
            dialog.exec_()
            array = []

class DialogBody(QDialog):
    def __init__(self,parent=None):
        super(QDialog,self).__init__(parent)
        self.setGeometry(100, 100, QImage(imgloc).height(), QImage(imgloc).width())

    def paintEvent(self,e):
        qp = QtGui.QPainter()
        qp.begin(self)
        self.drawBody(qp)
        qp.end()

    def drawBody(self, qp):
        qp.setPen(QtCore.Qt.red)
        qp.drawPolygon(array[0],array[1],array[2],array[3])
        qp.drawEllipse(array[0],2,2)
        qp.drawEllipse(array[1],2,2)
        qp.drawEllipse(array[2],2,2)
        qp.drawEllipse(array[3],2,2)

if __name__ == "__main__":
   app = QtGui.QApplication(sys.argv)
   myapp= MyForm()
   myapp.show()
   sys.exit(app.exec_())

Answer 1

Looks like you want to draw items on QGraphicsScene? In this case you could add items to the scene:

#!/usr/bin/env python
import sys

from PyQt4 import QtCore, QtGui


class MainWidget(QtGui.QWidget):
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)
        self.scene = QtGui.QGraphicsScene()
        self.view = QtGui.QGraphicsView(self.scene)
        layout = QtGui.QVBoxLayout()
        layout.addWidget(self.view)
        self.setLayout(layout)
        self.pixmap_item = QtGui.QGraphicsPixmapItem(QtGui.QPixmap('image.png'), None, self.scene)
        self.pixmap_item.mousePressEvent = self.pixelSelect
        self.click_positions = []

    def pixelSelect(self, event):
        self.click_positions.append(event.pos())
        if len(self.click_positions) < 4:
            return
        pen = QtGui.QPen(QtCore.Qt.red)
        self.scene.addPolygon(QtGui.QPolygonF(self.click_positions), pen)
        for point in self.click_positions:
            self.scene.addEllipse(point.x(), point.y(), 2, 2, pen)
        self.click_positions = []


if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    widget = MainWidget()
    widget.resize(640, 480)
    widget.show()
    sys.exit(app.exec_())

QGraphicsScene has many features.

Read Graphics View Framework overview in Qt docs.