QML 对象的动态实例化?

本文介绍了QML 对象的动态实例化?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我想在 QML 中绘制许多矩形.Rectangulars (x,y) 的坐标将在 C++ 中计算，并且需要传递给 QML.

I want to draw many Rectangular's inside a QML. The coordinates for Rectangulars (x,y) will be calculated inside C++, and need to be passed to QML.

我试图寻找 ListView 或 Column 或 Row 元素(使用中继器)，但这些似乎都不能解决问题，因为元素的排列方式类似于表格"......我面临缺乏有关此类案例的网络示例.

I tried to look for ListView or Column or Row elements (with Repeater), but non of this seems to solve the problem, because the elements are arranged like in 'tables'... I faced the lack of information on the web examples on such case.

更具体地说:1. 如何将矩形的多个坐标传递给 QML?(什么数据结构)2. 我应该使用什么机制来显示它们?

To be more specific: 1. How to pass many coordinates for my Rectangular's to QML? (what data structure) 2. What mechanism should I use to display them?

推荐答案

您可以简单地:

import QtQuick 2.0 Rectangle { id: root height: 500 width: 500 property string sc: 'import QtQuick 2.0; Rectangle {width: 20; height: 20; color: "red"; Component.onCompleted: {x = Math.random() * parent.width; y = Math.random() * parent.height;}}' Component.onCompleted: { for (var i = 0; i < 10; ++i) Qt.createQmlObject(sc, root, 'obj' + i); } }

此代码将创建指定数量的矩形并将它们随机放置在父矩形上.

This code will create the specified number of rectangles and position them randomly over the parent rectangle.

如果需要在 C++ 中生成位置，则必须创建自定义 C++ 元素，这是一个基本示例:

If generating the position in C++ is a necessity, you will have to create a custom C++ element, here is a basic example:

class Positioner : public QObject { Q_OBJECT public: explicit Positioner(QObject *parent = 0) : QObject(parent) {} public slots: QPointF getPosition() { return QPoint(qrand() % 500, qrand() % 500); } };

在 main.cpp 中注册:

Register it in main.cpp:

qmlRegisterType<Positioner>("TestComponent", 1, 0, "Positioner");

最后使用它，这次我们使用Positioner的getPosition() C++槽:

And finally use it, this time we use the Positioner's getPosition() C++ slot:

import QtQuick 2.0 import TestComponent 1.0 Rectangle { id: root height: 500 width: 500 Positioner {id: myPositioner} property string sc: 'import QtQuick 2.0; Rectangle {width: 20; height: 20; color: "red"; Component.onCompleted: {var pos = myPositioner.getPosition(); x = pos.x; y = pos.y;}}' Component.onCompleted: { for (var i = 0; i < 10; ++i) Qt.createQmlObject(sc, root, 'obj' + i); } }

您还可以使用现有的 QML 文件代替字符串，这样更方便一些，因为您可以自动完成.那将是您的 TestItem 组件，只是为了好玩，它的实例会在单击时自行删除:

You can also use an existing QML file instead of a string, which is a little more convenient, since you get autocomplete. That would be your TestItem component and just for fun, its instances will delete themselves when clicked:

import QtQuick 2.0 Rectangle { width: 100 height: 100 color: "black" MouseArea { anchors.fill: parent onClicked: parent.destroy() } Component.onCompleted: { var pos = myPositioner.getPosition() x = pos.x y = pos.y } }

在你的主 QML 文件中实例化它:

And in your main QML file you instantiate it:

var component = Qt.createComponent("TestItem.qml") component.createObject(root)

如果您不想在 QML 中实例化定位器，而是在 QML 中实例化和使用单个对象，您可以执行以下操作(在 main.cpp 中):

In case you don't want to instantiate a Positioner in QML and instead instantiate and use a single object in QML, you can do the following (in main.cpp):

Positioner p; view.rootContext()->setContextProperty("sPositioner", &p);

并在 QML 中使用:

And use in QML:

var pos = sPositioner.getPosition()