Pyqt 截取特定屏幕区域

Question

我有这个用 pyqt 编写的应用程序。您可以在http://www.pasteall.org/62739/python查看源代码它会截取桌面的屏幕截图。我想知道的是如何让它也像窗口的截图工具一样拍摄屏幕上某个区域的屏幕截图（http://sjcblogs.sanjac.edu/its/files/2011/09/Snipping-Tool-selection-types1.jpg 和 gilsmethod.wpengine.netdna-cdn.com/images/snipping-tool-windows -73.png)。这个怎么写？

提前谢谢你！

Answer 1

你应该使用

img = QPixmap.grabWindow(QApplication.desktop().winId(), x, y, width, height)

pyqt 发行版有一个非常好的 python 示例，用于使用 pyqt 进行截图。该示例的 C++ 代码很容易转换为 Python，位于 http://doc.qt.io/qt-4.8/qt-desktop-screenshot-example.html

Answer 2

安装以下软件包：

pip install pillow opencv-python pyside2

运行以下代码：

import sys

from PySide2.QtCore import *
from PySide2.QtGui import *
from PySide2.QtWidgets import *

import numpy as np
import cv2
from PIL import ImageGrab

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        if not MainWindow.objectName():
            MainWindow.setObjectName(u"MainWindow")
        MainWindow.resize(1000, 1000)
        sizePolicy = QSizePolicy(QSizePolicy.Maximum, QSizePolicy.Maximum)
        sizePolicy.setHorizontalStretch(0)
        sizePolicy.setVerticalStretch(0)
        sizePolicy.setHeightForWidth(MainWindow.sizePolicy().hasHeightForWidth())
        MainWindow.setSizePolicy(sizePolicy)
        MainWindow.setMinimumSize(QSize(1000, 1000))
        MainWindow.setMaximumSize(QSize(16777215, 16777215))
        MainWindow.setTabShape(QTabWidget.Rounded)
        self.centralwidget = QWidget(MainWindow)
        self.centralwidget.setObjectName(u"centralwidget")
        sizePolicy1 = QSizePolicy(QSizePolicy.Preferred, QSizePolicy.Preferred)
        sizePolicy1.setHorizontalStretch(0)
        sizePolicy1.setVerticalStretch(0)
        sizePolicy1.setHeightForWidth(self.centralwidget.sizePolicy().hasHeightForWidth())
        self.centralwidget.setSizePolicy(sizePolicy1)
        self.centralwidget.setMinimumSize(QSize(1000, 1000))
        self.gridLayout = QGridLayout(self.centralwidget)
        self.gridLayout.setObjectName(u"gridLayout")
        self.pushButton_area = QPushButton(self.centralwidget)
        self.pushButton_area.setObjectName(u"pushButton_area")
        self.pushButton_area.setMinimumSize(QSize(800, 0))

        self.gridLayout.addWidget(self.pushButton_area, 0, 0, 1, 1)

        self.label = QLabel(self.centralwidget)
        self.label.setObjectName(u"label")
        sizePolicy2 = QSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding)
        sizePolicy2.setHorizontalStretch(0)
        sizePolicy2.setVerticalStretch(0)
        sizePolicy2.setHeightForWidth(self.label.sizePolicy().hasHeightForWidth())
        self.label.setSizePolicy(sizePolicy2)
        self.label.setMinimumSize(QSize(800, 800))
        self.label.setMaximumSize(QSize(4096, 4096))

        self.gridLayout.addWidget(self.label, 2, 0, 2, 1)

        self.pushButton_full = QPushButton(self.centralwidget)
        self.pushButton_full.setObjectName(u"pushButton_full")
        self.pushButton_full.setMinimumSize(QSize(800, 0))

        self.gridLayout.addWidget(self.pushButton_full, 1, 0, 1, 1)

        MainWindow.setCentralWidget(self.centralwidget)

        self.retranslateUi(MainWindow)

        QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        MainWindow.setWindowTitle(QCoreApplication.translate("MainWindow", u"Snipping Tool", None))
        MainWindow.setAccessibleName(QCoreApplication.translate("MainWindow", u"Snipping Tool", None))
        self.pushButton_area.setText(QCoreApplication.translate("MainWindow", u"Select Area", None))
        self.pushButton_full.setText(QCoreApplication.translate("MainWindow", u"Fullscreen", None))

# Refer to https://github.com/harupy/snipping-tool
class SnippingWidget(QWidget):
    is_snipping = False

    def __init__(self, parent=None, app=None):
        super(SnippingWidget, self).__init__()
        self.parent = parent
        self.setWindowFlags(Qt.WindowStaysOnTopHint)

        self.screen = app.primaryScreen()
        self.setGeometry(0, 0, self.screen.size().width(), self.screen.size().height())
        self.begin = QPoint()
        self.end = QPoint()
        self.onSnippingCompleted = None

    def fullscreen(self):
        img = ImageGrab.grab(bbox=(0, 0, self.screen.size().width(), self.screen.size().height()))

        try:
            img = cv2.cvtColor(np.array(img), cv2.COLOR_RGB2BGR)
        except:
            img = None
            
        if self.onSnippingCompleted is not None:
            self.onSnippingCompleted(img)

    def start(self):
        SnippingWidget.is_snipping = True
        self.setWindowOpacity(0.3)
        QApplication.setOverrideCursor(QCursor(Qt.CrossCursor))
        self.show()

    def paintEvent(self, event):
        if SnippingWidget.is_snipping:
            brush_color = (128, 128, 255, 100)
            lw = 3
            opacity = 0.3
        else:
            self.begin = QPoint()
            self.end = QPoint()
            brush_color = (0, 0, 0, 0)
            lw = 0
            opacity = 0

        self.setWindowOpacity(opacity)
        qp = QPainter(self)
        qp.setPen(QPen(QColor('black'), lw))
        qp.setBrush(QColor(*brush_color))
        rect = QRectF(self.begin, self.end)
        qp.drawRect(rect)

    def mousePressEvent(self, event):
        self.begin = event.pos()
        self.end = self.begin
        self.update()

    def mouseMoveEvent(self, event):
        self.end = event.pos()
        self.update()

    def mouseReleaseEvent(self, event):
        SnippingWidget.is_snipping = False
        QApplication.restoreOverrideCursor()
        x1 = min(self.begin.x(), self.end.x())
        y1 = min(self.begin.y(), self.end.y())
        x2 = max(self.begin.x(), self.end.x())
        y2 = max(self.begin.y(), self.end.y())

        self.repaint()
        QApplication.processEvents()
        img = ImageGrab.grab(bbox=(x1, y1, x2, y2))

        try:
            img = cv2.cvtColor(np.array(img), cv2.COLOR_RGB2BGR)
        except:
            img = None
            
        if self.onSnippingCompleted is not None:
            self.onSnippingCompleted(img)

        self.close()

class MainWindow(QMainWindow):
    useQThread = True

    def __init__(self):
        super(MainWindow, self).__init__()
        self.ui = Ui_MainWindow()
        self.ui.setupUi(self)
        self.setAcceptDrops(True)

        self.snippingWidget = SnippingWidget(app=QApplication.instance())
        self.snippingWidget.onSnippingCompleted = self.onSnippingCompleted
        self.ui.pushButton_area.clicked.connect(self.snipArea)
        self.ui.pushButton_full.clicked.connect(self.snipFull)

        self._pixmap = None

    def onSnippingCompleted(self, frame):
        self.setWindowState(Qt.WindowActive)
        if frame is None:
            return 

        image = QImage(frame, frame.shape[1], frame.shape[0], frame.strides[0], QImage.Format_RGB888)
        pixmap = QPixmap.fromImage(image)
        self._pixmap = self.resizeImage(pixmap)
        self.ui.label.setPixmap(self._pixmap)

    def snipArea(self):
        self.setWindowState(Qt.WindowMinimized)
        self.snippingWidget.start()    

    def snipFull(self):
        self.setWindowState(Qt.WindowMinimized)
        self.snippingWidget.fullscreen()    

    def dragEnterEvent(self, event):
        event.acceptProposedAction()

    def dropEvent(self, event):
        urls = event.mimeData().urls()
        filename = urls[0].toLocalFile()
        self.loadFile(filename)
        self.decodeFile(filename)
        event.acceptProposedAction()

    def resizeImage(self, pixmap):
        lwidth = self.ui.label.width()
        pwidth = pixmap.width()
        lheight = self.ui.label.height()
        pheight = pixmap.height()

        wratio = pwidth * 1.0 / lwidth
        hratio = pheight * 1.0 / lheight

        if pwidth > lwidth or pheight > lheight:
            if wratio > hratio:
                lheight = pheight / wratio
            else:
                lwidth = pwidth / hratio

            scaled_pixmap = pixmap.scaled(lwidth, lheight)
            return scaled_pixmap
        else:
            return pixmap

    def showMessageBox(self, title, content):
        msgBox = QMessageBox()
        msgBox.setWindowTitle(title)
        msgBox.setText(content)
        msgBox.exec_()

    def closeEvent(self, event):
    
        msg = "Close the app?"
        reply = QMessageBox.question(self, 'Message', 
                        msg, QMessageBox.Yes, QMessageBox.No)

        if reply == QMessageBox.Yes:
            event.accept()
        else:
            event.ignore()

def main():
    app = QApplication(sys.argv)
    window = MainWindow()
    window.show()
    sys.exit(app.exec_())

if __name__ == '__main__':
    main()