[PyQt5] QGraphicsView로 Canvas 구현하기

Pyqt5로 캔버스 구현하기.

 

근데 QLabel 대신 QGraphicsView 사용.

import sys

from PyQt5.QtWidgets import QApplication, QMainWindow, QWidget, QPushButton, QFileDialog, QLabel, QGraphicsView, QGraphicsScene
from PyQt5.QtWidgets import QHBoxLayout, QVBoxLayout
from PyQt5.QtGui import QPixmap, QImage, QPainter, QPen, QColor, QBrush
from PyQt5.QtCore import QPointF, QRectF, Qt


class GraphicView(QGraphicsView):
    def __init__(self, parent):
        super().__init__(parent)       

        self.scene = QGraphicsScene()        
        self.setScene(self.scene)
        
        self.items = {}
        self.items['rect'] = []

        self.start = QPointF()
        self.end = QPointF()

        self.pen = QPen(QColor(0,0,0), 3)
 
        self.setRenderHint(QPainter.HighQualityAntialiasing)

    def moveEvent(self, e):
        rect = QRectF(self.rect())
        rect.adjust(0,0,-2,-2)
        self.scene.setSceneRect(rect)

    def mousePressEvent(self, e):
        if e.button() == Qt.LeftButton:
            self.start = e.pos()
            self.end = e.pos()
            
            rect = QRectF(self.start, self.end)
            self.items['rect'].append(self.scene.addRect(rect, self.pen))

        if e.button() == Qt.RightButton:
            if self.scene.items():
                self.scene.removeItem(self.items['rect'][-1])
                del(self.items['rect'][-1])

    def mouseMoveEvent(self, e):  
        if e.buttons() & Qt.LeftButton:           
            self.end = e.pos()

            if self.scene.items():
                self.scene.removeItem(self.items['rect'][-1])
                del(self.items['rect'][-1])

            rect = QRectF(self.start, self.end)
            self.items['rect'].append(self.scene.addRect(rect, self.pen))
    
    def mouseReleaseEvent(self, e):
        if e.button() == Qt.LeftButton:
            if self.scene.items():
                self.scene.removeItem(self.items['rect'][-1])
                del(self.items['rect'][-1])

            rect = QRectF(self.start, self.end)
            self.items['rect'].append(self.scene.addRect(rect, self.pen))

class Demo(QMainWindow):
    def __init__(self):
        super().__init__()
        self.initUI()
    
    def initUI(self):
        self.view = GraphicView(self)
        self.view.setFixedSize(640, 480)

        main_layout = QHBoxLayout()
        main_layout.addWidget(self.view)

        widget = QWidget(parent=self)
        widget.setLayout(main_layout)
        self.setCentralWidget(widget)
        
        self.show()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = Demo()
    sys.exit(app.exec_())

 

드래그하면 사각형이 그려진다.

우클릭하면 마지막에 그린 사각형을 삭제한다.