python - 从图像中选择区域，但可调整大小的 QRubberBand 不会调整大小

Question

我想从图像中选择一个区域并获取她的坐标。我已经搜索过，找到了这段代码，它创建了对象橡皮筋，但我无法调整它的大小..奇怪的是，在 linux (lubuntu) 上它可以工作，但在 macOS 上不行..我想要 macOS 上的橡皮筋版本这些“握把”很特别，在 macOS 中，这些握把都不会出现..还有一件事，可以通过右键单击选择来移动橡皮筋矩形，然后在图像上移动到任何我想要的位置，就像将图标移动到桌面。谢谢!

import sys
from PyQt5 import QtCore, QtGui, QtWidgets

class ResizableRubberBand(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(ResizableRubberBand, self).__init__(parent)
        self.setWindowFlags(QtCore.Qt.SubWindow)
        layout = QtWidgets.QHBoxLayout(self)
        layout.setContentsMargins(0, 0, 0, 0)
        layout.addWidget(
            QtWidgets.QSizeGrip(self), 0,
            QtCore.Qt.AlignLeft | QtCore.Qt.AlignTop)
        layout.addWidget(
            QtWidgets.QSizeGrip(self), 0,
            QtCore.Qt.AlignRight | QtCore.Qt.AlignBottom)
        self._band = QtWidgets.QRubberBand(
            QtWidgets.QRubberBand.Rectangle, self)
        self._band.show()
        self.show()

    def resizeEvent(self, event):
        size = QtCore.QSize(3, 4)
        size.scale(self.size(), QtCore.Qt.KeepAspectRatio)
        self.resize(size)
        self._band.resize(self.size())

class Window(QtWidgets.QWidget):
    def __init__(self):
        super(Window, self).__init__()
        self.button = QtWidgets.QPushButton('Show Rubber Band')
        self.button.clicked.connect(self.handleButton)
        self.label = QtWidgets.QLabel()
        self.label.setScaledContents(True)
        self.label.setPixmap(QtGui.QPixmap('image.JPG'))
        layout = QtWidgets.QVBoxLayout(self)
        layout.addWidget(self.label)
        layout.addWidget(self.button)

    def handleButton(self):
        self.band = ResizableRubberBand(self.label)
        self.band.setGeometry(50, 50, 150, 300)

if __name__ == '__main__':

    app = QtWidgets.QApplication(sys.argv)
    window = Window()
    window.setGeometry(800, 100, 600, 500)
    window.show()
    sys.exit(app.exec_())

Answer 1

你走在正确的道路上。 PyQt 使用事件处理程序来控制鼠标交互和调整事件大小。对于您的应用程序，调整夹点大小将调用 resizeEvent 并重新绘制更改的窗口涉及 paintEvent。同样，鼠标交互利用 mousePressEvent、mouseMoveEvent 和 mouseReleaseEvent 作为触发这些操作时调用的事件处理程序。本质上，对于您想要的每个交互，您必须实现该特定事件的处理程序。我使用PyQt4进行测试，但PyQt5应该是相同的。

import sys
from PyQt5 import QtCore, QtGui, QtWidgets
# from PyQt4 import QtCore, QtWidgets

class ResizableRubberBand(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(ResizableRubberBand, self).__init__(parent)

        self.draggable = True
        self.dragging_threshold = 5
        self.mousePressPos = None
        self.mouseMovePos = None
        self.borderRadius = 5

        self.setWindowFlags(QtCore.Qt.SubWindow)
        layout = QtWidgets.QHBoxLayout(self)
        layout.setContentsMargins(0, 0, 0, 0)
        layout.addWidget(
            QtWidgets.QSizeGrip(self), 0,
            QtCore.Qt.AlignLeft | QtCore.Qt.AlignTop)
        layout.addWidget(
            QtWidgets.QSizeGrip(self), 0,
            QtCore.Qt.AlignRight | QtCore.Qt.AlignBottom)
        self._band = QtWidgets.QRubberBand(
            QtWidgets.QRubberBand.Rectangle, self)
        self._band.show()
        self.show()

    def resizeEvent(self, event):
        self._band.resize(self.size())

    def paintEvent(self, event):
        # Get current window size
        window_size = self.size()
        qp = QtWidgets.QPainter()
        qp.begin(self)
        qp.setRenderHint(QtWidgets.QPainter.Antialiasing, True)
        qp.drawRoundedRect(0, 0, window_size.width(), window_size.height(),
                           self.borderRadius, self.borderRadius)
        qp.end()

    def mousePressEvent(self, event):
        if self.draggable and event.button() == QtCore.Qt.RightButton:
            self.mousePressPos = event.globalPos()                # global
            self.mouseMovePos = event.globalPos() - self.pos()    # local
        super(ResizableRubberBand, self).mousePressEvent(event)

    def mouseMoveEvent(self, event):
        if self.draggable and event.buttons() & QtCore.Qt.RightButton:
            globalPos = event.globalPos()
            moved = globalPos - self.mousePressPos
            if moved.manhattanLength() > self.dragging_threshold:
                # Move when user drag window more than dragging_threshold
                diff = globalPos - self.mouseMovePos
                self.move(diff)
                self.mouseMovePos = globalPos - self.pos()
        super(ResizableRubberBand, self).mouseMoveEvent(event)

    def mouseReleaseEvent(self, event):
        if self.mousePressPos is not None:
            if event.button() == QtCore.Qt.RightButton:
                moved = event.globalPos() - self.mousePressPos
                if moved.manhattanLength() > self.dragging_threshold:
                    # Do not call click event or so on
                    event.ignore()
                self.mousePressPos = None
        super(ResizableRubberBand, self).mouseReleaseEvent(event)

class Window(QtWidgets.QWidget):
    def __init__(self):
        super(Window, self).__init__()
        self.button = QtWidgets.QPushButton('Show Rubber Band')
        self.button.clicked.connect(self.handleButton)
        self.label = QtWidgets.QLabel()
        self.label.setScaledContents(True)
        self.label.setPixmap(QtGui.QPixmap('image.JPG'))
        layout = QtWidgets.QVBoxLayout(self)
        layout.addWidget(self.label)
        layout.addWidget(self.button)

    def handleButton(self):
        self.band = ResizableRubberBand(self.label)
        self.band.setGeometry(150, 150, 150, 150)

if __name__ == '__main__':

    app = QtWidgets.QApplication(sys.argv)
    window = Window()
    window.setGeometry(800, 100, 600, 500)
    window.show()
    sys.exit(app.exec_())