Qt: replaceWidget的使用误区

曾经遇到过类似问题。当时一个同事使用replaceWidget，导致窗口有一小块区域始终无法点击。将控件自定义QSS，进而看到存在一个莫名其妙的小控件。具体原因的定位本人未参与，只记得好像是使用这个API导致。

本人一般倾向于控件提升方式自定义控件，所以并没有尝试过这个函数。此次由于程序实现需要，不得不使用replaceWidget。开始一直没问题。直到某一天，再次使用时，某个子窗口也出现无法点击的问题。同样是自定义qss，dumpObjectTree等方式，发现原先被替换的控件还在，再查看文档，才想起来以前那位同事遇到的问题。

文档内容：

Searches for widget from and replaces it with widget to if found. Returns the layout item that contains the widget from on success. Otherwise nullptr is returned. If options contains Qt::FindChildrenRecursively (the default), sub-layouts are searched for doing the replacement. Any other flag in options is ignored.
Notice that the returned item therefore might not belong to this layout, but to a sub-layout.
The returned layout item is no longer owned by the layout and should be either deleted or inserted to another layout. The widget from is no longer managed by the layout and may need to be deleted or hidden. The parent of widget from is left unchanged.
This function works for the built-in Qt layouts, but might not work for custom layouts.
This function was introduced in Qt 5.2.

所以，正确的写法应该是：

auto pLayoutItem = layout()->replaceWidget(ui.wndContain, ***);
if (pLayoutItem != nullptr)
{
delete pLayoutItem;
delete ui.wndContain;
}

转载请注明来源，谢谢。

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