在C
++中,这样一个方法可以返回一个值,该方法必须声明为,
Q_INVOKABLE并且
result在
@pyqtSlot装饰器中使用PyQt中的等效方法:
├── index.html└── main.py
main.py
from PyQt5 import QtCore, QtWidgets, QtWebEngineWidgets, QtWebChannelclass Backend(QtCore.QObject): @QtCore.pyqtSlot(int, **result=int** ) def getRef(self, x): print("inside getRef", x) return x + 5 @QtCore.pyqtSlot(int) def printRef(self, ref): print("inside printRef", ref)if __name__ == "__main__": import os import sys app = QtWidgets.QApplication(sys.argv) backend = Backend() view = QtWebEngineWidgets.QWebEngineView() channel = QtWebChannel.QWebChannel() view.page().setWebChannel(channel) channel.registerObject("backend", backend) current_dir = os.path.dirname(os.path.realpath(__file__)) filename = os.path.join(current_dir, "index.html") url = QtCore.QUrl.fromLocalFile(filename) view.load(url) view.resize(640, 480) view.show() sys.exit(app.exec_())
index.html
<!DOCTYPE html><html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <script type="text/javascript" src="qrc:///qtwebchannel/qwebchannel.js"></script> <script type="text/javascript"> var backend = null; var x = 5; window.onload = function() { new QWebChannel(qt.webChannelTransport, function(channel) { backend = channel.objects.backend; backend.getRef(x, function(pyval) { backend.printRef(pyval); }); }); } </script> </head></html>
更新:
通常,QtWebChannel只能传输可以从Qt端转换为QJsonObject的信息,而可以从javascript端传输可以转换为JSON的数据。
因此,有一些特殊情况:
- 整型
- 浮动
- 力量
list :如果支持发送和接收列表,但支持元素(如数字和字符串)以及字典和其他支持先前基本类型的列表,则可以发送和接收列表。
class Backend(QtCore.QObject):
@QtCore.pyqtSlot(result=list)
def return_list(self):
return [0.0, 1.5, ‘Hello’, [‘Stack’, 5.0], {‘a’: {‘b’: ‘c’}}]@QtCore.pyqtSlot(list)def print_list(self, l): print(l)
backend = channel.objects.backend;
backend.return_list(function(pyval) {
backend.print_list(pyval);
});
输出:
[0.0, 1.5, 'Hello', ['Stack', 5.0], {'a': {'b': 'c'}}]
字典 :
class Backend(QtCore.QObject):
@QtCore.pyqtSlot(result=”QJsonObject”)
def return_dict(self):
return {“a”: 1.5, “b”: {“c”: 2}, “d”: [1, “3”, “4”]}@QtCore.pyqtSlot("QJsonObject")def print_dict(self, ref): print(ref)
backend = channel.objects.backend;
backend.return_dict(function(pyval) {
backend.print_dict(pyval);
});
输出:
{'a': <PyQt5.QtCore.QJsonValue object at 0x7f3841d50150>, 'b': <PyQt5.QtCore.QJsonValue object at 0x7f3841d501d0>, 'd': <PyQt5.QtCore.QJsonValue object at 0x7f3841d50250>}
如您所见,返回了QJsonValue,因此获取信息可能很繁琐,因此在此解决方法是将它们打包在一个列表中:
class Backend(QtCore.QObject): @QtCore.pyqtSlot(result=list) def return_list(self): d = {"a": 1.5, "b": {"c": 2}, "d": [1, "3", "4"]} return [d] @QtCore.pyqtSlot(list) def print_list(self, ref): d, *_ = ref print(d)backend = channel.objects.backend;backend.return_list(function(pyval) { backend.print_list(pyval);});
输出:
{'a': 1.5, 'b': {'c': 2.0}, 'd': [1.0, '3', '4']}
UPDATe2:
传递信息的一种通用方法是使用JSON,即转换python或js对象,分别使用
json.dumps()和将其转换为字符串
JSON.stringify(),然后发送;当以python或js格式接收时,必须分别使用
json.loads()和转换字符串
JSON.parse():
class Backend(QtCore.QObject): @QtCore.pyqtSlot(str, result=str) def getRef(self, o): print("inside getRef", o) py_obj = json.loads(o) py_obj["c"] = ("Hello", "from", "Python") return json.dumps(py_obj) @QtCore.pyqtSlot(str) def printRef(self, o): py_obj = json.loads(o) print("inside printRef", py_obj)var backend = null;window.onload = function(){ new QWebChannel(qt.webChannelTransport, function(channel) { backend = channel.objects.backend; var x = {a: "1000", b: ["Hello", "From", "JS"]} backend.getRef(JSON.stringify(x), function(y) { js_obj = JSON.parse(y); js_obj["f"] = false; backend.printRef(JSON.stringify(js_obj)); }); });}inside getRef {"a":"1000","b":["Hello","From","JS"]}inside printRef {'a': '1000', 'b': ['Hello', 'From', 'JS'], 'c': ['Hello', 'from', 'Python'], 'f': False}
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