我怎样才能结合这两个代码？ （python图像查看器+鼠标拖动图像ROI裁剪）

Question

我是 Python 和 PyQt 的初学者。我尝试基于 acbetter 的代码创建图像查看器，并希望添加图像裁剪功能。使用这两个代码，最终我想创建一个代码，我可以在其中打开某个图像并裁剪图像的特定部分并将其显示在另一个窗口中。您想帮忙如何组合这两个代码吗？

1. acbetter 的图像查看器代码 https://gist.github.com/acbetter/32c575803ec361c3e82064e60db4e3e0

from PyQt5.QtCore import Qt
from PyQt5.QtGui import QImage, QPixmap, QPalette, QPainter
from PyQt5.QtPrintSupport import QPrintDialog, QPrinter
from PyQt5.QtWidgets import QLabel, QSizePolicy, QScrollArea, QMessageBox, QMainWindow, QMenu, QAction, \
    qApp, QFileDialog


class QImageViewer(QMainWindow):
    def __init__(self):
        super().__init__()

        self.printer = QPrinter()
        self.scaleFactor = 0.0

        self.imageLabel = QLabel()
        self.imageLabel.setBackgroundRole(QPalette.Base)
        self.imageLabel.setSizePolicy(QSizePolicy.Ignored, QSizePolicy.Ignored)
        self.imageLabel.setScaledContents(True)

        self.scrollArea = QScrollArea()
        self.scrollArea.setBackgroundRole(QPalette.Dark)
        self.scrollArea.setWidget(self.imageLabel)
        self.scrollArea.setVisible(False)

        self.setCentralWidget(self.scrollArea)

        self.createActions()
        self.createMenus()

        self.setWindowTitle("Image Viewer")
        self.resize(800, 600)

    def open(self):
        options = QFileDialog.Options()
        # fileName = QFileDialog.getOpenFileName(self, "Open File", QDir.currentPath())
        fileName, _ = QFileDialog.getOpenFileName(self, 'QFileDialog.getOpenFileName()', '',
                                                  'Images (*.png *.jpeg *.jpg *.bmp *.gif)', options=options)
        if fileName:
            image = QImage(fileName)
            if image.isNull():
                QMessageBox.information(self, "Image Viewer", "Cannot load %s." % fileName)
                return

            self.imageLabel.setPixmap(QPixmap.fromImage(image))
            self.scaleFactor = 1.0

            self.scrollArea.setVisible(True)
            self.printAct.setEnabled(True)
            self.fitToWindowAct.setEnabled(True)
            self.updateActions()

            if not self.fitToWindowAct.isChecked():
                self.imageLabel.adjustSize()

    def print_(self):
        dialog = QPrintDialog(self.printer, self)
        if dialog.exec_():
            painter = QPainter(self.printer)
            rect = painter.viewport()
            size = self.imageLabel.pixmap().size()
            size.scale(rect.size(), Qt.KeepAspectRatio)
            painter.setViewport(rect.x(), rect.y(), size.width(), size.height())
            painter.setWindow(self.imageLabel.pixmap().rect())
            painter.drawPixmap(0, 0, self.imageLabel.pixmap())

    def zoomIn(self):
        self.scaleImage(1.25)

    def zoomOut(self):
        self.scaleImage(0.8)

    def normalSize(self):
        self.imageLabel.adjustSize()
        self.scaleFactor = 1.0

    def fitToWindow(self):
        fitToWindow = self.fitToWindowAct.isChecked()
        self.scrollArea.setWidgetResizable(fitToWindow)
        if not fitToWindow:
            self.normalSize()

        self.updateActions()

    def about(self):
        QMessageBox.about(self, "About Image Viewer",
                          "<p>The <b>Image Viewer</b> example shows how to combine "
                          "QLabel and QScrollArea to display an image. QLabel is "
                          "typically used for displaying text, but it can also display "
                          "an image. QScrollArea provides a scrolling view around "
                          "another widget. If the child widget exceeds the size of the "
                          "frame, QScrollArea automatically provides scroll bars.</p>"
                          "<p>The example demonstrates how QLabel's ability to scale "
                          "its contents (QLabel.scaledContents), and QScrollArea's "
                          "ability to automatically resize its contents "
                          "(QScrollArea.widgetResizable), can be used to implement "
                          "zooming and scaling features.</p>"
                          "<p>In addition the example shows how to use QPainter to "
                          "print an image.</p>")

    def createActions(self):
        self.openAct = QAction("&Open...", self, shortcut="Ctrl+O", triggered=self.open)
        self.printAct = QAction("&Print...", self, shortcut="Ctrl+P", enabled=False, triggered=self.print_)
        self.exitAct = QAction("E&xit", self, shortcut="Ctrl+Q", triggered=self.close)
        self.zoomInAct = QAction("Zoom &In (25%)", self, shortcut="Ctrl++", enabled=False, triggered=self.zoomIn)
        self.zoomOutAct = QAction("Zoom &Out (25%)", self, shortcut="Ctrl+-", enabled=False, triggered=self.zoomOut)
        self.normalSizeAct = QAction("&Normal Size", self, shortcut="Ctrl+S", enabled=False, triggered=self.normalSize)
        self.fitToWindowAct = QAction("&Fit to Window", self, enabled=False, checkable=True, shortcut="Ctrl+F",
                                      triggered=self.fitToWindow)
        self.aboutAct = QAction("&About", self, triggered=self.about)
        self.aboutQtAct = QAction("About &Qt", self, triggered=qApp.aboutQt)

    def createMenus(self):
        self.fileMenu = QMenu("&File", self)
        self.fileMenu.addAction(self.openAct)
        self.fileMenu.addAction(self.printAct)
        self.fileMenu.addSeparator()
        self.fileMenu.addAction(self.exitAct)

        self.viewMenu = QMenu("&View", self)
        self.viewMenu.addAction(self.zoomInAct)
        self.viewMenu.addAction(self.zoomOutAct)
        self.viewMenu.addAction(self.normalSizeAct)
        self.viewMenu.addSeparator()
        self.viewMenu.addAction(self.fitToWindowAct)

        self.helpMenu = QMenu("&Help", self)
        self.helpMenu.addAction(self.aboutAct)
        self.helpMenu.addAction(self.aboutQtAct)

        self.menuBar().addMenu(self.fileMenu)
        self.menuBar().addMenu(self.viewMenu)
        self.menuBar().addMenu(self.helpMenu)

    def updateActions(self):
        self.zoomInAct.setEnabled(not self.fitToWindowAct.isChecked())
        self.zoomOutAct.setEnabled(not self.fitToWindowAct.isChecked())
        self.normalSizeAct.setEnabled(not self.fitToWindowAct.isChecked())

    def scaleImage(self, factor):
        self.scaleFactor *= factor
        self.imageLabel.resize(self.scaleFactor * self.imageLabel.pixmap().size())

        self.adjustScrollBar(self.scrollArea.horizontalScrollBar(), factor)
        self.adjustScrollBar(self.scrollArea.verticalScrollBar(), factor)

        self.zoomInAct.setEnabled(self.scaleFactor < 3.0)
        self.zoomOutAct.setEnabled(self.scaleFactor > 0.333)

    def adjustScrollBar(self, scrollBar, factor):
        scrollBar.setValue(int(factor * scrollBar.value()
                               + ((factor - 1) * scrollBar.pageStep() / 2)))


if __name__ == '__main__':
    import sys
    from PyQt5.QtWidgets import QApplication

    app = QApplication(sys.argv)
    imageViewer = QImageViewer()
    imageViewer.show()
    sys.exit(app.exec_())

1. 使用 opencv 的图像裁剪代码

import cv2 
mouse_is_pressing = False
start_x, start_y = -1, -1

def mouse_callback(event, x, y, flags, param):
    global start_x, start_y, mouse_is_pressing 

    img_result = src.copy()

    if event == cv2.EVENT_LBUTTONDOWN:

        mouse_is_pressing = True
        start_x, start_y = x,y

        cv2.circle(img_result, (x,y), 10, (0,255,0),-1)
        cv2.imshow("img_color", img_result)

    elif event == cv2.EVENT_MOUSEMOVE:
        if mouse_is_pressing: 
            cv2.rectangle(img_result, (start_x, start_y), (x,y), (0,255,0), 3)
            cv2.imshow("img_color", img_result)

    elif event == cv2.EVENT_LBUTTONUP:
        mouse_is_pressing = False 

        img_part = img_result[start_y:y, start_x:x]
        cv2.imshow("img_color", img_result)
        cv2.imshow("img_part", img_part)

src = cv2.imread("D:/python data/image/image.jpg")
cv2.imshow("img_color", src)
cv2.setMouseCallback("img_color", mouse_callback)
cv2.waitKey(0)
cv2.destroyAllWindows()

Answer 1

使用 QLabel 在基于 QScrollArea 的查看器中实现裁剪是不必要的复杂，因为跟踪转换很复杂，而是使用 QGraphicsView、QGraphicsScene 和 QGraphicsPixmapItem 实现相同的逻辑。如此多的逻辑已经实现，如下所示：

from PyQt5 import QtCore, QtGui, QtWidgets, QtPrintSupport


class Viewer(QtWidgets.QGraphicsView):
    def __init__(self, parent=None):
        super().__init__(QtWidgets.QGraphicsScene(), parent)
        self.pixmap_item = self.scene().addPixmap(QtGui.QPixmap())
        self.setAlignment(QtCore.Qt.AlignTop | QtCore.Qt.AlignLeft)
        self.setBackgroundRole(QtGui.QPalette.Dark)
        self.setDragMode(QtWidgets.QGraphicsView.RubberBandDrag)
        self.rubberBandChanged.connect(self.onRubberBandChanged)
        self.last_rect = QtCore.QPointF()

    def setPixmap(self, pixmap):
        self.pixmap_item.setPixmap(pixmap)

    def zoomIn(self):
        self.scale(1.25, 1.25)

    def zoomOut(self):
        self.scale(0.8, 0.8)

    def resetZoom(self):
        self.resetTransform()

    def fitToWindow(self):
        self.fitInView(self.pixmap_item)

    @QtCore.pyqtSlot(QtCore.QRect, QtCore.QPointF, QtCore.QPointF)
    def onRubberBandChanged(self, rubberBandRect, fromScenePoint, toScenePoint):
        if rubberBandRect.isNull():
            pixmap = self.pixmap_item.pixmap()
            rect = self.pixmap_item.mapFromScene(self.last_rect).boundingRect().toRect()
            if not rect.intersected(pixmap.rect()).isNull():
                crop_pixmap = pixmap.copy(rect)
                label = QtWidgets.QLabel(pixmap=crop_pixmap)
                dialog = QtWidgets.QDialog(self)
                lay = QtWidgets.QVBoxLayout(dialog)
                lay.addWidget(label)
                dialog.exec_()
            self.last_rect = QtCore.QRectF()
        else:
            self.last_rect = QtCore.QRectF(fromScenePoint, toScenePoint)


class QImageViewer(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super().__init__()

        self.view = Viewer()
        self.setCentralWidget(self.view)

        self.printer = QtPrintSupport.QPrinter()

        self.createActions()
        self.createMenus()

        self.setWindowTitle("Image Viewer")
        self.resize(800, 600)

    def open(self):
        fileName, _ = QtWidgets.QFileDialog.getOpenFileName(
            self,
            "QFileDialog.getOpenFileName()",
            "",
            "Images (*.png *.jpeg *.jpg *.bmp *.gif)",
        )
        if fileName:
            pixmap = QtGui.QPixmap(fileName)
            if pixmap.isNull():
                QtWidgets.QMessageBox.information(
                    self, "Image Viewer", "Cannot load %s." % fileName
                )
                return

            self.view.setPixmap(pixmap)

            self.printAct.setEnabled(True)
            self.fitToWindowAct.setEnabled(True)
            self.updateActions()

            if not self.fitToWindowAct.isChecked():
                pass
                # self.imageLabel.adjustSize()

    def print_(self):
        dialog = QtPrintSupport.QPrintDialog(self.printer, self)
        if dialog.exec_():
            pixmap = self.view.pixmap_item.pixmap()
            painter = QtGui.QPainter(self.printer)
            rect = painter.viewport()
            size = pixmap.size()
            size.scale(rect.size(), QtCore.Qt.KeepAspectRatio)
            painter.setViewport(rect.x(), rect.y(), size.width(), size.height())
            painter.setWindow(pixmap.rect())
            painter.drawPixmap(0, 0, pixmap)

    def fitToWindow(self):
        if self.fitToWindowAct.isChecked():
            self.view.fitToWindow()
        else:
            self.view.resetZoom()
        self.updateActions()

    def about(self):
        QtWidgets.QMessageBox.about(
            self,
            "About Image Viewer",
            "<p>The <b>Image Viewer</b> example shows how to combine "
            "QLabel and QScrollArea to display an image. QLabel is "
            "typically used for displaying text, but it can also display "
            "an image. QScrollArea provides a scrolling view around "
            "another widget. If the child widget exceeds the size of the "
            "frame, QScrollArea automatically provides scroll bars.</p>"
            "<p>The example demonstrates how QLabel's ability to scale "
            "its contents (QLabel.scaledContents), and QScrollArea's "
            "ability to automatically resize its contents "
            "(QScrollArea.widgetResizable), can be used to implement "
            "zooming and scaling features.</p>"
            "<p>In addition the example shows how to use QPainter to "
            "print an image.</p>",
        )

    def createActions(self):
        self.openAct = QtWidgets.QAction(
            "&Open...", self, shortcut="Ctrl+O", triggered=self.open
        )
        self.printAct = QtWidgets.QAction(
            "&Print...", self, shortcut="Ctrl+P", enabled=False, triggered=self.print_
        )
        self.exitAct = QtWidgets.QAction(
            "E&xit", self, shortcut="Ctrl+Q", triggered=self.close
        )
        self.zoomInAct = QtWidgets.QAction(
            "Zoom &In (25%)",
            self,
            shortcut="Ctrl++",
            enabled=False,
            triggered=self.view.zoomIn,
        )
        self.zoomOutAct = QtWidgets.QAction(
            "Zoom &Out (25%)",
            self,
            shortcut="Ctrl+-",
            enabled=False,
            triggered=self.view.zoomOut,
        )
        self.normalSizeAct = QtWidgets.QAction(
            "&Normal Size",
            self,
            shortcut="Ctrl+S",
            enabled=False,
            triggered=self.view.resetZoom,
        )
        self.fitToWindowAct = QtWidgets.QAction(
            "&Fit to Window",
            self,
            enabled=False,
            checkable=True,
            shortcut="Ctrl+F",
            triggered=self.fitToWindow,
        )
        self.aboutAct = QtWidgets.QAction("&About", self, triggered=self.about)
        self.aboutQtAct = QtWidgets.QAction(
            "About &Qt", self, triggered=QtWidgets.qApp.aboutQt
        )

    def createMenus(self):
        self.fileMenu = QtWidgets.QMenu("&File", self)
        self.fileMenu.addAction(self.openAct)
        self.fileMenu.addAction(self.printAct)
        self.fileMenu.addSeparator()
        self.fileMenu.addAction(self.exitAct)

        self.viewMenu = QtWidgets.QMenu("&View", self)
        self.viewMenu.addAction(self.zoomInAct)
        self.viewMenu.addAction(self.zoomOutAct)
        self.viewMenu.addAction(self.normalSizeAct)
        self.viewMenu.addSeparator()
        self.viewMenu.addAction(self.fitToWindowAct)

        self.helpMenu = QtWidgets.QMenu("&Help", self)
        self.helpMenu.addAction(self.aboutAct)
        self.helpMenu.addAction(self.aboutQtAct)

        self.menuBar().addMenu(self.fileMenu)
        self.menuBar().addMenu(self.viewMenu)
        self.menuBar().addMenu(self.helpMenu)

    def updateActions(self):
        self.zoomInAct.setEnabled(not self.fitToWindowAct.isChecked())
        self.zoomOutAct.setEnabled(not self.fitToWindowAct.isChecked())
        self.normalSizeAct.setEnabled(not self.fitToWindowAct.isChecked())


if __name__ == "__main__":
    import sys
    from PyQt5.QtWidgets import QApplication

    app = QApplication(sys.argv)
    imageViewer = QImageViewer()
    imageViewer.show()
    sys.exit(app.exec_())