18 - Python PyQt (Interfaz gráfica) - QGraphicsView Polygon (Dibujar polígonos)

En este capítulo del tutorial de Python 3 más PyQt5 nos basaremos en el sencillo programa de los dos capítulos anteriores el cual nos permite crear gráficos con diferentes herramientas. Concretamente veremos como dibujar polígonos o también conocidos como polilíneas.

Capítulos anteriores:

16 - Python PyQt (Interfaz gráfica) - QGraphicsView (Herramientas de dibujo)
17 - Python PyQt (Interfaz gráfica) - Dibujar objetos (addLine, addRect & addEllipse)

El procedimiento será el siguiente: al hacer click y soltar el mouse en un lugar del plano de dibujo almacenaremos ese punto QPointF(x, y) en una lista, el usuario podrá agregar tantos puntos como necesite, cada punto señalado en el plano marcará el punto de unión de cada línea del polígono.

Para crear el polígono utilizaremos el siguiente método: addPolygon(QPolygonF(), QPen(), QBrush())

graficos.pyw

import sys
from PyQt5.QtWidgets import QApplication, QDialog, QGraphicsView, QGraphicsScene, QGridLayout, QPushButton, QComboBox
from PyQt5.QtCore import QPointF, QRectF, Qt
from PyQt5.QtGui import QPen, QBrush, QPolygonF
from PyQt5 import uic

class Paint(QGraphicsView):
 def __init__(self):
  QGraphicsView.__init__(self)
  self.setSceneRect(QRectF(self.viewport().rect()))
  self.scene = QGraphicsScene()
  self.isPaint = False
  self.isDelete = False
  self.isClear = False
  self.isObject = None
  self.startX = None
  self.startY = None
  self.pointPolygon = None
  self.arrayPolygon = []
  
  
 def tools(self, e):
  if self.isPaint == True:
   pen = QPen(Qt.black)
   brush = QBrush(Qt.SolidPattern)
   self.scene.addItem(self.scene.addEllipse(e.x(), e.y(), 3, 3, pen, brush))
   self.setScene(self.scene)
  if self.isDelete == True:
   items = self.items(e.x(), e.y())
   for item in items:
    self.scene.removeItem(item)
    
 def paintObject(self, e):
  if self.isObject != None:
   object = self.isObject
   if object == 1: #Line
    pen = QPen(Qt.black)
    self.scene.addItem(self.scene.addLine(self.startX, self.startY, e.x(), e.y(), pen))
    self.setScene(self.scene)
   elif object == 2: #Rect
    pen = QPen(Qt.black)
    brush = QBrush(Qt.SolidPattern)
    self.scene.addItem(self.scene.addRect(self.startX, self.startY, e.x()-self.startX, e.y()-self.startY, pen, brush))
    self.setScene(self.scene)
   elif object == 3: #Ellipse
    pen = QPen(Qt.black)
    brush = QBrush(Qt.SolidPattern)
    self.scene.addItem(self.scene.addEllipse(self.startX, self.startY, e.x()-self.startX, e.y()-self.startY, pen, brush))
    self.setScene(self.scene)
    
 def paintPolygon(self, e):
  if self.isObject != None:
   object = self.isObject
   if object == 4: #Polygon
    self.pointPolygon = QPointF(e.x(), e.y())
    self.arrayPolygon.append(self.pointPolygon)
    pen = QPen(Qt.green)
    brush = QBrush()
    self.scene.addItem(self.scene.addPolygon(QPolygonF(self.arrayPolygon), pen, brush))
    self.setScene(self.scene)
    
    
 def mousePressEvent(self, event):
  e = QPointF(self.mapToScene(event.pos()))
  self.tools(e)
  self.startX = e.x()
  self.startY = e.y()
  
 def mouseReleaseEvent(self, event):
  e = QPointF(self.mapToScene(event.pos()))
  self.paintObject(e)
  self.paintPolygon(e)
  
 def mouseMoveEvent(self, event):
  e = QPointF(self.mapToScene(event.pos()))
  self.tools(e)

class Dialogo(QDialog):
 def __init__(self):
  QDialog.__init__(self)
  self.resize(500, 500)
  self.layout = QGridLayout()
  self.setLayout(self.layout)
  self.paint = Paint()
  self.btn_paint = QPushButton("Dibujar")
  self.combo_object = QComboBox()
  self.combo_object.addItem("Seleccionar")
  self.combo_object.addItem("Line")
  self.combo_object.addItem("Rect")
  self.combo_object.addItem("Ellipse")
  self.combo_object.addItem("Polygon")
  self.btn_delete = QPushButton("Borrar")
  self.btn_clear = QPushButton("Clear")
  self.layout.addWidget(self.btn_paint)
  self.layout.addWidget(self.combo_object)
  self.layout.addWidget(self.btn_delete)
  self.layout.addWidget(self.btn_clear)
  self.layout.addWidget(self.paint)
  self.btnDefault = "background-color: grey; border: 0; padding: 10px"
  self.btnActive = "background-color: orange; border: 0; padding: 10px"
  
  self.btn_paint.setStyleSheet(self.btnDefault)
  self.combo_object.setStyleSheet(self.btnDefault)
  self.btn_delete.setStyleSheet(self.btnDefault)
  self.btn_clear.setStyleSheet(self.btnDefault)
  
  self.btn_paint.clicked.connect(self.isPaint)
  self.combo_object.currentIndexChanged.connect(self.isObject)
  self.combo_object.activated.connect(self.isObject)
  self.btn_delete.clicked.connect(self.isDelete)
  self.btn_clear.clicked.connect(self.isClear)
  
 def resizeEvent(self, event):
  self.paint.setSceneRect(QRectF(self.paint.viewport().rect()))
   
 def isPaint(self):
  if self.paint.isPaint == False:
   self.paint.isPaint = True
   self.btn_paint.setStyleSheet(self.btnActive)
  else:
   self.paint.isPaint = False
   self.btn_paint.setStyleSheet(self.btnDefault)
  
  self.paint.isObject = None  
  self.paint.isDelete = False
  self.paint.isClear = False
  self.btn_delete.setStyleSheet(self.btnDefault)
  self.btn_clear.setStyleSheet(self.btnDefault)
  del self.paint.arrayPolygon[:]
  
 def isObject(self):
  object = self.combo_object.currentIndex()
  self.paint.isObject = object
  self.paint.isPaint = False
  self.paint.isDelete = False
  self.paint.isClear = False
  self.btn_paint.setStyleSheet(self.btnDefault)
  self.btn_delete.setStyleSheet(self.btnDefault)
  self.btn_clear.setStyleSheet(self.btnDefault)
  del self.paint.arrayPolygon[:]
  
   
 def isDelete(self):
  if self.paint.isDelete == False:
   self.paint.isDelete = True
   self.btn_delete.setStyleSheet(self.btnActive)
  else:
   self.paint.isDelete = False
   self.btn_delete.setStyleSheet(self.btnDefault)
   
  self.paint.isObject = None 
  self.paint.isPaint = False
  self.paint.isClear = False
  self.btn_paint.setStyleSheet(self.btnDefault)
  self.btn_clear.setStyleSheet(self.btnDefault)
  del self.paint.arrayPolygon[:]
  
 def isClear(self):
  if self.paint.isClear == False:
   self.paint.isClear = True
   self.btn_clear.setStyleSheet(self.btnActive)
  else:
   self.paint.isClear = False
   self.btn_clear.setStyleSheet(self.btnDefault)
   
  self.paint.isObject = None 
  self.paint.isPaint = False
  self.paint.isDelete = False
  self.btn_paint.setStyleSheet(self.btnDefault)
  self.btn_delete.setStyleSheet(self.btnDefault)
  self.paint.scene.clear()
  del self.paint.arrayPolygon[:]
  
app = QApplication(sys.argv)
dialogo = Dialogo()
dialogo.show()
app.exec_()