我在5.12.2上使用了一些带有QML的javascript库。它们中的一些像Proj4JS一样工作。但是当我在QML中使用geographiclib.js库时,我得到了错误。如何将JavaScript库导入到QML中?
main.qml:
import QtQuick 2.12
import QtQuick.Window 2.12
import "geographiclib.js" as MyGeo
Window {
visible: true
width: 640
height: 480
Component.onCompleted: {
var Geodesic = MyGeo.GeographicLib.Geodesic,
DMS = MyGeo.GeographicLib.DMS,
geod = Geodesic.WGS84;
var r = geod.Inverse(23, 22, 44, 29);
console.log("distance is: ", r.s12.toFixed(3) + " m")
}
}
错误:
qrc:/geographiclib.js:3081: ReferenceError: window is not defined
qrc:/main.qml:9: TypeError: Cannot read property 'Geodesic' of undefined
发布于 2019-04-07 18:24:27
要做到这一点,最简单的方法是让GeographicLib
在全球范围内可用:
在geographiclib.js文件的末尾,更改
window.GeographicLib = geo;
至
this.GeographicLib = geo;
然后你可以直接使用:
main.qml:
import QtQuick 2.12
import QtQuick.Window 2.12
import "geographiclib.js" as ThenItWillBeAvailableGlobally
Window {
visible: true
width: 640
height: 480
Component.onCompleted: {
var Geodesic = GeographicLib.Geodesic,
DMS = GeographicLib.DMS,
geod = Geodesic.WGS84;
var r = geod.Inverse(23, 22, 44, 29);
console.log("distance is: ", JSON.stringify(r))
}
}
结果是:
qml: distance is: {"lat1":23,"lat2":44,"lon1":22,"lon2":29,"a12":21.754466225665134,"s12":2416081.7576307985,"azi1":13.736139413215236,"azi2":17.669059640534535}
如果您根本不想更改geographiclib.js文件,则可以使用以下命令添加全局窗口对象,例如:
window.js:
this.window = this;
然后使用:
import QtQuick 2.12
import QtQuick.Window 2.12
import "window.js" as ThenWindowWillBeAvailableGlobally
import "geographiclib.js" as ThenGeographicLibWillBeAvailableGlobally
Window {
visible: true
width: 640
height: 480
Component.onCompleted: {
var Geodesic = GeographicLib.Geodesic,
DMS = GeographicLib.DMS,
geod = Geodesic.WGS84;
var r = geod.Inverse(23, 22, 44, 29);
console.log("distance is: ", JSON.stringify(r))
}
}
如果您不想添加任何全局变量,但您愿意编辑geographiclib.js文件,那么您可以将第68行移动到文件的顶部:
var GeographicLib = {};
/*
* Geodesic routines from GeographicLib translated to JavaScript. See
* https://geographiclib.sourceforge.io/html/js/
} else {
/******** otherwise just pollute our global namespace ********/
window.GeographicLib = geo;
}
});
至
} else if (typeof window === 'object') {
/******** otherwise just pollute our global namespace ********/
window.GeographicLib = geo;
}
});
然后你的main.qml就能正常工作了。
https://stackoverflow.com/questions/55531885
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