鼠标交互的设计模式 [英] Design pattern for mouse interaction

问题描述

我需要一些关于一般鼠标
交互的理想设计模式的意见。

I need some opinions on what is the "ideal" design pattern for a general mouse interaction.

这里是简化的问题。我有一个小的3D程序（QT和openGL）和
我使用鼠标进行交互。每个交互通常不仅仅是一个
的单一函数调用，它主要由最多3个函数调用（启动，执行，最终化）执行。
例如，相机旋转：这里初始函数调用将传递当前的第一个鼠标位置
，而执行功能调用将更新相机等。

Here the simplified problem. I have a small 3d program (QT and openGL) and I use the mouse for interaction. Every interaction is normally not only a single function call, it is mostly performed by up to 3 function calls (initiate, perform, finalize). For example, camera rotation: here the initial function call will deliver the current first mouse position, whereas the performing function calls will update the camera etc.

但是，对于只有几个交互，这些（MousePressEvent，MouseReleaseEvent MouseMoveEvent或MouseWheelEvent等）中的硬编码不是一件大事，但如果我想到一个更高级的程序（例如20个或更多的交互）那么需要一个适当的设计。

However, for only a couple of interactions, hardcoding these (inside MousePressEvent, MouseReleaseEvent MouseMoveEvent or MouseWheelEvent etc) is not a big deal, but if I think about a more advanced program (e.g 20 or more interactions) then a proper design is needed.

因此，你如何在QT中设计这样的交互。

Therefore, how would you design such a interactions inside QT.

我希望我的问题足够清楚，否则不要抱怨： - ）

I hope I made my problem clear enough, otherwise don't bother complain :-)

谢谢

推荐答案

我建议使用多态和工厂方法模式。这里有一个例子：

I suggest using polymorphism and the factory method pattern. Here's an example:

在我的Qt程序中，我有QGraphicsScenes和QGraphicsItems与mousePressEvent，mouseMoveEvent和mouseReleaseEvent，如下所示：

In my Qt program I have QGraphicsScenes and QGraphicsItems with mousePressEvent, mouseMoveEvent, and mouseReleaseEvent, which look like this:

void CustomItem::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
  // call factory method, which returns a subclass depending on where click occurred
  dragHandler = DragHandler::createDragHandler(event /* and other relevant stuff */);
}

void CustomItem::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
  dragHandler->onMouseMove(event);
}

void CustomItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
{
  dragHandler->onMouseRelease(event);
  delete dragHandler;
}

在这种特殊情况下的想法是，取决于我点击CustomItem的位置，鼠标按压，移动和释放将具有不同的功能。例如，如果我点击项目的边缘，拖动将调整大小，但如果我点击项目的中间，拖动将移动它。 DragHandler :: onMouseMove和DragHandler :: onMouseRelease是由子类重新实现的虚拟函数，以根据鼠标按下的位置提供我想要的特定功能。不需要DragHandler :: onMousePress，因为这基本上是构造函数。

The idea in this particular case is that depending on where I click on CustomItem, mouse pressing, moving, and releasing will have different functionality. For example, if I click on the edge of the item, dragging will resize it, but if I click in the middle of the item, dragging will move it. DragHandler::onMouseMove and DragHandler::onMouseRelease are virtual functions that are reimplemented by subclasses to provide the specific functionality I want depending on where the mouse press occurred. There's no need for DragHandler::onMousePress because that's basically the constructor.

这当然是一个比较具体的例子，可能不完全是你想要的，但它给了你一个想法如何使用多态来清理你的鼠标处理。

This is of course a rather specific example, and probably not exactly what you want, but it gives you an idea of how you can use polymorphism to clean up your mouse handling.

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