Qt| control qscrollbar display position

stay Qt Middle control QScrollBar The display position of ？ Some people will think when such a function will be used ？

In general , Most of the functions used scroll the scroll bar to the bottom . In many cases QScrollArea The application of .

function ：

1： rolling QScrollArea Control in real time QScrollBar The location of

2： Appoint QScrollBar The display position of

According to the above two functions , Let's introduce ！

1： Get... In real time QScrollBar Scroll position

A lot of times , When we scroll, we want to know how much the page scrolls , But you can't get ！

Is to rewrite QScrollArea Do you ？

I tried to rewrite QWidget::wheelEvent, But there are too many rewrites , Maintenance is also troublesome , therefore , This method resolutely gives up ！

In that case , Let's change our thinking ！

because QScrollArea There are vertical scroll bars and horizontal scroll bars , So why don't we use scroll bar messages ？

hypothesis , The current display is the vertical scroll bar ,QScrollArea in widget We don't know where to roll , however , We know where the scroll bar scrolls , According to the change of the scroll bar , Try to get QScrollBar The location of .

First , We need to define the response message slot function .

This is important , Many people just don't know which message to use , Only when the news is confirmed, the following problems will be solved ！

connect(ui.scrollArea->verticalScrollBar(), &QScrollBar::valueChanged, ui.widget, &QScrollAreaWidget::ChangedScrollBarData);


explain ：

ui.widget yes QScrollArea Used in widget.

The corresponding class is ：QScrollAreaWidget

The response function is ：ChangedScrollBarData

In function ChangedScrollBarData The parameter in is the real-time display position of the scroll bar .

See here , Do you think it's easy to find out suddenly ！

2： Appoint QScrollBar The display position of

This function is even simpler , We just need to set the scroll length of the scroll bar .

hypothesis , We're going to scroll bar , One half of the scroll bar .

//1： Get the total length of the scroll bar
int nTotalValue = ui.scrollArea->verticalScrollBar->value();
//2： Set the position of the scroll bar in half .
int nNewLoaction = nTotalValue*0.5;
ui.scrollArea->verticalScrollBar->setvalue(nNewLocation);


Someone will say , Only QSCrollArea Will you use the setting method of the scroll bar ？

NO！ As long as there is a scroll bar control in your control, you can ~

I am a good citizen of China st, a C++ Development program yuan ~