C++ QQuickItem:如何在项目大小更改时触发函数 [英] C++ QQuickItem: How to trigger a function on item size change

问题描述

我在 C++ 中有一个 QQuickItem，它在 QML 应用程序中实例化.如果我的 QQuickItem 的 width 属性发生变化，我想在 C++ 端触发一个自定义函数.

I have a QQuickItem in C++ which is instantiated in a QML application. I want to trigger a custom function on the c++ side if the width property of my QQuickItem changes.

在 QML 中，我会做 onWidthChanged: { my code}.我怎样才能在 C++ 方面做到这一点?

In QML I would do onWidthChanged: { my code}. How can I do this on the c++ side?

推荐答案

如果您想响应自定义 QQuickItem 中的大小更改，请重新实现 geometryChanged() 函数.这样做的好处是不会为每个创建额外的信号槽连接项，如果您要连接到 widthChanged()/heightChanged() 信号，这将是必需的.

If you want to respond to size changes in a custom QQuickItem, reimplement the geometryChanged() function. This has the benefit of not creating extra signal-slot connections for each item, as would be necessary if you were to connect to the widthChanged()/heightChanged() signals.

这是在 Qt Quick Controls 2 中重新实现的示例.

Here's an example of it being reimplemented in Qt Quick Controls 2.

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