Properties Implementation Design and Details

Introduction

Properties are a convenient way to associate additional information with edges and vertices. For example, one might want to have all edges contain a weight. A single property can be displayed inside a vertex which will resize appropriately or next to an edge. No properties need be displayed.

Structure

There are 4 main components to the Properties structure:

Prop
The Prop Class is simply a container object consisting of the property's name and value.
PropVector
The PropVector extends a regular Vector. It is a sorted list of Properties (by name). A simple insertion sort is used. This is not particularly efficient, but since properties will not be getting much larger than 2 or 3 items, it should not become an issue. PropVector also includes a method to merge two PropVectors (reconcile).
PropMan
This is the actual property manager. Every Vertex and Edge contains a PropMan. The PropMan contains the PropVector of properties for this property, keeps track of the current property to display (if any), and makes sure that the property window (PropWin) stays in a consistant state. Any time a property is added, deleted, or changed, the PropMan closes the PropWin. This is to avoid past problems with Property Windows that stop responding when updated in place. Hopefully, this is a bug in the current AWT and windows can be kept open in later versions of Zarbiff.
PropWin
This is the Property Window. When displayed it looks like:

You can directly alter the values of the properties from this window by editing the text fields. You can also set which property (perhaps none) to display using the check boxes along the left edge. Clicking "DONE" will save the state of the Property. Anytime the window is forced closed, it will also save the current state. Destroying the PropWin from the menu, however, will not save the current changes.

PropWin contains the class PropPanel. Inside the physical Property Window, there is a PropPanel for each Property. The PropPanel is just a panel containing a label for the peroperty name, and a textfield that is initialized to the property value.

Before the property window is closed, the PropMan gets a PropVector containing the current values from the PropWin and makes it it's own. This vector is generated by the PropWin iterating through each of the PropPanels, getting their respective Props. At closing time, the PropMan also gets the value of the current selected property.

Adding/Deleteing

All of the adding and deleting of properties is done in filters which act on the set of highlighted vertices/edges. There are also filters for seting and selecting the highlighted. In the case in which properties are inconsistant (i.e. two selected vertices have different properties) the two are merged for displaying purposes, but the actual property lists are not altered. For example, if you try to select a property that doesn't exist in all vertices, the property will be selected in the vertices that have it and the others will be unchanged.

Undo

The PropMan includes a link to the Undo Manager. Adding, deleting, and selecting are fully undoable. At this time setting the value of a property is not undoable.

Properties Implementation Design and Details

Introduction

Structure

Prop

PropVector

PropMan

PropWin

Adding/Deleteing

Undo