PyQt Reizable 和可拖动的矩形选择

如何解决PyQt Reizable 和可拖动的矩形选择

重新实现类SelectImageTool中的paintEvent()方法有没有简单的修改QRect的方法来实现：

• 可拖动以选择图像的不同部分
• 用鼠标调整大小

或者我必须使用使用其他类或方法的不同方式？ 我在谷歌和这个网站上搜索过，找到了 RubberBand 类，但我应该重新实现这个类，所以我更喜欢其他方法（如果存在的话）。

这是代码：

from PyQt5.QtWidgets import (
                            QWidget,QApplication,QLabel,QVBoxLayout,QHBoxLayout,QMainWindow,QScrollArea,QPushButton
                            )
from PyQt5.QtCore import QRect,Qt
from PyQt5.QtGui import QImage,QPixmap,QPainter,QPen
import cv2,sys


from PIL import Image


I_MAX_CROP_IMAGE_WIDTH = 500

class SelectImageTool(QLabel):
    def __init__(self,mStrImageName,mFlScaleFactor):
        super().__init__()
        self.aStrImageName=mStrImageName
        self.iPosX0 = 0
        self.iPosY0 = 0
        self.iPosX1 = 0
        self.iPosY1 = 0
        self.aFlScaleFactor=mFlScaleFactor
        self.blnMousePress = False
    
    def mousePressEvent(self,event):
        self.blnMousePress = True
        self.iPosX0 = event.x()
        self.iPosY0 = event.y()

    def mouseReleaseEvent(self,event):
        self.blnMousePress = False
    
    def mouseMoveEvent(self,event):
        if self.blnMousePress:
            self.iPosX1 = event.x()
            self.iPosY1 = event.y()
            self.update()

    def paintEvent(self,event):
        super().paintEvent(event)
        rctCropArea =QRect(self.iPosX0,self.iPosY0,abs(self.iPosX1-self.iPosX0),abs(self.iPosY1-self.iPosY0))
        pntSelectionRectangle = QPainter(self)
        pntSelectionRectangle.setPen(QPen(Qt.red,4,Qt.DashLine))
        pntSelectionRectangle.drawRect(rctCropArea)
        

    def setSelectionEdge(self):
       
        iScalePosX0 = self.scaleCoordinates(self.iPosX0)
        iScalePosX1 = self.scaleCoordinates(self.iPosX1)
        iScalePosY0 = self.scaleCoordinates(self.iPosY0)
        iScalePosY1 = self.scaleCoordinates(self.iPosY1)
        
        iLeft = iScalePosX0
        iTop = iScalePosY0
        iWidth = abs(iScalePosX1-iScalePosX0)
        iHeight = abs(iScalePosY1-iScalePosY0)
        iRight = iLeft+iWidth
        iBottom = iTop+iHeight
        print (str(iLeft) + " " + str(iTop) + " "+  str(iRight) + " " +  str(iBottom))
        
        return iLeft,iTop,iRight,iBottom
        

    def scaleCoordinates(self,mIntCoordinate):
        
        return round(self.aFlScaleFactor*mIntCoordinate)
                
    
        
    def cropImageSelection(self):
        
        iLeft,iBottom = self.setSelectionEdge()
        
        try:
            imgSourcePicture = Image.open(self.aStrImageName)

            tupSize = imgSourcePicture.size
            
            iLeft = self.checkCoordinateLimit(iLeft,0)
            iTop = self.checkCoordinateLimit(iTop,0)          
            iRight = self.checkCoordinateLimit(iRight,tupSize[0])
            iBottom = self.checkCoordinateLimit(iBottom,tupSize[1])
            
            imgCropped = imgSourcePicture.crop((iLeft,iBottom))
            
            imgCropped.save("cropped.jpg")

        except IOError:
            pass
        

    def checkCoordinateLimit(self,mIntCoord,mIntLimit):
        
        if mIntLimit==0:
            iCoord = mIntCoord if mIntCoord >=mIntLimit else mIntLimit
        else:
            iCoord = mIntCoord if mIntCoord <=mIntLimit else mIntLimit
    
        return iCoord


        
class ImageCropperBox(QMainWindow):
    def __init__(self):
        super().__init__()
        
        self.resize(600,700)
        self.setWindowTitle('Seleziona la parte dell\'immagine da salvare')
        
        strImgName = "1.jpg"
        imgSourceImage = cv2.imread(strImgName)
        pxmSourceImage,iWidth,iHeight = self.createPixMap(imgSourceImage)
        
        if iWidth>I_MAX_CROP_IMAGE_WIDTH:
            pxmSourceImage = pxmSourceImage.scaledToWidth(I_MAX_CROP_IMAGE_WIDTH)
            flScaleFactor = round(iWidth/I_MAX_CROP_IMAGE_WIDTH,2)
        else:
            flScaleFactor=1
        
        self.sitImageLabel = SelectImageTool(strImgName,flScaleFactor)
        self.sitImageLabel.setStyleSheet("background:navy")
        self.sitImageLabel.setFixedSize(pxmSourceImage.width(),pxmSourceImage.height())
        self.sitImageLabel.setPixmap(pxmSourceImage)
        self.sitImageLabel.setCursor(Qt.CrossCursor)
        
        widImagePanel = QWidget()
        layvImagePanel = QVBoxLayout()
        saImagePanel = QScrollArea()
        
        widImgBox = QWidget()
        layvImgBox = QVBoxLayout()

        widButtonBox = QWidget()
        layhButtonBox = QHBoxLayout()
        
        widImgBox.setLayout(layvImgBox)
        
        widButtonBox.setLayout(layhButtonBox)
        
        butSave = QPushButton("Salva l'immagine")
        butDelete = QPushButton("Elimina l'immagine")
        
        butSave.clicked.connect(lambda state: self.saveImageSelection(self.sitImageLabel))
        
        layhButtonBox.addWidget(butSave)
        layhButtonBox.addWidget(butDelete)        
        
        widImagePanel.setLayout(layvImagePanel)
        saImagePanel.setWidget(widImagePanel)
        self.setScrollAreaProperties(saImagePanel)
        
        layvImagePanel.addWidget(widImgBox)
        layvImagePanel.addWidget(widButtonBox)

        layvImgBox.addWidget(self.sitImageLabel)
        self.setCentralWidget(saImagePanel)
        
        
    def setScrollAreaProperties(self,saImgBox):
        saImgBox.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOn)
        saImgBox.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOn)
        saImgBox.setWidgetResizable(True)
        
        
    def createPixMap(self,imgSourceImage):

        iHeight,bytesPerComponent = imgSourceImage.shape
        bytesPerLine = 3 * iWidth
        cv2.cvtColor(imgSourceImage,cv2.COLOR_BGR2RGB,imgSourceImage)
        QImg = QImage(imgSourceImage.data,iHeight,bytesPerLine,QImage.Format_RGB888)
        pxmSourceImage = QPixmap.fromImage(QImg)
        
        return pxmSourceImage,iHeight


    def saveImageSelection(self,msitImageLabel):
        msitImageLabel.cropImageSelection()
       
        
if __name__ == '__main__':
    app = QApplication(sys.argv)
    icbMain = ImageCropperBox()
    icbMain.show()
    sys.exit(app.exec_())