Ivor Horton's Beginning Visual C++ 2012

DELETING AND MOVING ELEMENTS

Being able to delete shapes is a fundamental requirement in a drawing program. The document object already has the facility for deleting a sketch element but you still have to decide on the user interface mechanism for this. How are you going to select the element you want to delete? Of course, after you decide on a mechanism for selecting an element, this will apply equally well to selecting an element to move it. This suggests that you can treat moving and deleting elements as related problems. But first, let’s consider how you might initiate move and delete operations in the user interface.

A neat way of providing these functions would be to have a context menu popup at the cursor position when you click the right mouse button. You could then include Move and Delete as items on the menu. A pop-up menu that works like this is a very handy facility in lots of situations.

NOTE Context menus are also referred to as pop-up menus or as shortcut menus.

How should the context menu work? The standard way is that the user moves the mouse over a particular element that is displayed and right-clicks it. This selects the element and pops up a menu containing a list of menu items offering actions that can be performed on that element. The element provides the context for the menu. Naturally, different elements can have different context menus. You have seen this in action in the IDE for Visual C++. When you right-click a class name in Class View, you get ...