[英]Qt layouts, difference between passing and not passing QWidget as parent
I have created a simple QHBoxLayout
(horizontal) that is pushed to the bottom of the QVBoxLayout
(Vertical) and it contains two buttons. 我创建了一个简单的
QHBoxLayout
(水平),将其推到QVBoxLayout
(垂直)的底部,它包含两个按钮。 See code: 看到代码:
QWidget* create_ver_and_horizontal_box() {
QWidget* temp = new QWidget();
// Add buttons to the horizontal box
QHBoxLayout* hbox = new QHBoxLayout();
QPushButton *ok = new QPushButton("OK");
QPushButton *cancel = new QPushButton("Cancel");
hbox->addWidget(ok);
hbox->addWidget(cancel);
// Create a vertical box and add the horizontal box to
// the end of it
QVBoxLayout* vbox = new QVBoxLayout();
vbox->addStretch(1);
vbox->addLayout(hbox);
// set the layout and return
temp->setLayout(vbox);
return temp;
}
and the resulting UI is the following. 最终的用户界面如下。
But when I add the QWidget temp
to be the parent of the QHBoxLayout, like so: 但是,当我将QWidget
temp
添加为QHBoxLayout的父级时,如下所示:
// Add buttons to the horizontal box
QHBoxLayout* hbox = new QHBoxLayout(temp);
I want to understand what is going on here. 我想了解这里发生了什么。 And in which cases I want the QWidget to be the parent of a layout or any other QWidget(s) and in which cases I don't the containing QWidget to be the parent of the containing QWidgets.
在某些情况下,我希望QWidget成为布局或任何其他QWidget的父项,在那种情况下,我不让包含QWidget的人成为包含QWidget的父项。 For example, I could've added temp to be the parent of the two Push buttons but I didn't.
例如,我可以将temp添加为两个“按钮”的父级,但我没有。 What is the implication of not adding vs adding.
不添加与添加的含义是什么。
Thanks, 谢谢,
QHBoxLayout* hbox = new QHBoxLayout(temp);
is equivalent to 相当于
QHBoxLayout* hbox = new QHBoxLayout();
temp->setLayout(hbox);
Ie you are making the horizontal layout responsible for temp
. 也就是说,您正在制作负责
temp
的水平布局。
The call to setLayout(vbox)
should have generated a runtime warning message, that temp
already has a layout, hinting at that. 对
setLayout(vbox)
的调用应该已经生成了运行时警告消息,该temp
消息已经具有布局,以进行提示。
Since you want the vertical layout to be responsible for that widget, either keep the temp->setLayout(vbox)
or pass temp
to the constructor of QVBoxLayout
. 由于您希望垂直布局负责该小部件,因此请保留
temp->setLayout(vbox)
或将temp
传递给QVBoxLayout
的构造QVBoxLayout
。
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