My Tree Control

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Introduction

Many programmers rely on CTreeCtrl to help them view their applications. But the trouble they encounter is, always making sure that the tree is displaying their data correctly. This could be very annoying, writing it all in the dialog.

Background

Well, my tree isn't so nice looking, it really looks like an ordinary tree. But.. it stores items!! It is a template. If you are using my tree, the tree becomes the manager of the application instead of being managed.

If you haven't figured it yet, when you insert a new item, you also insert an item of your own you want to store. If it is a struct, let it be. If it is a class, that's fine too. If it is an abstract class pointed by a smart pointer, you made what really this tree is designed for. Beginners - I recommend reading about smart pointers, and reading about the Factory design pattern. I use "Loki" library for smart pointers.

My application uses this tree to store many items. Using an abstract class as the stored item, I specify what an item it is only when creating it.

Then, if I choose from the menu what action to do on an item, the right action happens depending on the item with in the tree. When an item is deleted, it destroys the item stored. You can specify in the destructor of an item what it should do on deletion. I use smart pointers, so my items are deleted only when that last item pointed to by the smart pointer is deleted. This design avoids unwanted annoying code, any code that makes adding new tree items complicated, and mostly making annoying stupid bugs.

Using the code

Simply create a tree control with the MFC wizard. Add a tree to a dialog, add a member. Include "myTreeCtrl.h" and change the type of the member to:

CMyTreeCtrl< UrItem> m_Tree

That's it! You have your new tree.

GetStorageItem would give you a pointer to the item inside. In addition, I added a very troublesome recursive code to get all items, all items by level, and a code that moves items - the first image you insert in CImageList should be an arrow of some sort, and also there is a code that transfers items to be children of other items.

There is something that sends messages on move, transfer and delete, but I don't use it in my main application. There is also a function to set the maximum hierarchy length.

All this code is based on the MFC example of CTreeCtrl. It uses STL to store items.

My tester application doesn't use all those features, most of them are in use in my commercial applications which aren't here. But it is simple to use.

I'd be happy to receive your comments. If you find a bug, I'd like to know about it.

Bunniez rulez.