在Qt中捕获拖动取消事件 [英] Catching drag cancel event in Qt

问题描述

在Qt中捕获应用程序范围事件时遇到一些困难。

我的目的是捕获某些GUI应用程序中的每个用户操作。当然，我已经改写了 QApplication :: notify 处理程序并处理不同类型的应用程序范围事件。像这样：

  bool CoolApplication :: notify（QObject * obj，QEvent * e）
 {
 switch（e-> type（））{
 case QEvent :: MouseButtonPress：
 case QEvent :: MouseButtonRelease：
 //处理鼠标
 break; 
 
 case QEvent :: Wheel：
 //处理轮
 break; 
 
 case QEvent :: KeyPress：
 case QEvent :: KeyRelease：
 //处理键盘等
 break; 
默认值：
 break; 
} 
 
 return QApplication :: notify（obj，e）; 
} 
  

这样工作得很好，直到用户开始拖放操作。鼠标按下事件处理得很好，它在我的处理程序，捕捉生活是美丽的。当我尝试在Windows上捕获鼠标释放事件时，问题就开始了。

当输入拖动操作时，鼠标和键盘事件不再由QApplication :: notify处理。它是可能的catch事件，当它是成功的（我可以添加 case QEvent :: Drop 分支到我的处理程序），但如何捕获忽略删除或取消删除与Esc ？似乎不可能直接做，也许我可以捕获拖动事件循环终止事件或类似的东西？

编辑：
一次又一次的关注我需要捕获应用程序范围的事件，而不是

请尝试此

  code> bool QtCoreApplication :: notify（QObject * obj，QEvent * e）
 {
 switch（e-> type（））{
 case QEvent :: QDropEvent：
 QDropEvent * dropEvent =（QDropEvent *）e; 
 dropEvent-> keyboardModifiers（）; // keys pressed 
 dropEvent-> dropAction（）; // drop result 
 break; 
 
 return QApplication :: notify（obj，e）; 
} 
  

I'm experiencing some difficulties with catching application-scope events in Qt.

My purpose is to catch every user action in some GUI application. Of course I've overrided QApplication::notify handler and processing different types of application-scope events there. Something like that:

bool CoolApplication::notify(QObject *obj, QEvent *e)
{
    switch (e->type()) {
    case QEvent::MouseButtonPress:
    case QEvent::MouseButtonRelease:
        // Handle mouse
        break;

    case QEvent::Wheel:
        // Handle wheel
        break;

    case QEvent::KeyPress:
    case QEvent::KeyRelease:
        // Handle keyboard and so on
        break;
    default:
        break;
    }

    return QApplication::notify(obj, e);
}

That works pretty well until user starts drag-and-drop operation. Mouse press event is handled well, it is catched in my handler, life is beautiful there. The problems start when I try to catch mouse release event on Windows.

When entering drag operation mouse and keyboard events are no longer handled by QApplication::notify. It is possible to catch drop event when it was successfull (I can add case QEvent::Drop branch into my handler), but how to catch ignored drop or canceling drop with Esc? It seems impossible to be done directly, maybe I can catch drag event loop termination event or something like that? Or even maybe someone knows a direct way to do it?

Edit: Once more turning the attention that I need to catch application-scope event, not the widget one

解决方案

Please, try this

bool QtCoreApplication::notify(QObject *obj, QEvent *e)
    {
        switch (e->type()) {
        case QEvent::QDropEvent:
            QDropEvent* dropEvent = (QDropEvent*)e;
            dropEvent->keyboardModifiers(); // keys pressed
            dropEvent->dropAction(); // Drop result
        break;

        return QApplication::notify(obj, e);
    }

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