Qt VirtualKeyboard C++集成与实现（解决模态对话框键盘失效问题）

一. Qt 模态对话框

先让我们来看看对话框的几种特性:

1.Qt::NonModa

The window is not modal and does not block input to other windows.

2.Qt::WindowModal

The window is modal to a single window hierarchy and blocks input to its parent window, all grandparent windows, and all siblings of its parent and grandparent windows.

3.Qt::ApplicationModal

The window is modal to the application and blocks input to all windows.

可以看出，比较常用的exec()方法显示的对话框是属于第三种：Qt::ApplicationModal，这种对话框无法接受除了自身之外的任何其他对象的输入，而第二种 Qt::WindowModal 是可以接受 QApplication 的输入，所以我们只需将其改为第二种即可。

二. 实现

我们只需在显示键盘之前添加如下代码:

if(qGuiApp->focusWindow()->isModal())
    qGuiApp->focusWindow()->setModality(Qt::WindowModal);