Issue 49

Selecting Objects, Part 1

Introduction

Many operations in MapViewer require first selecting an object or objects. Understanding the different ways to select objects is key to using MapViewer efficiently. This article will examine the basic ways to select objects. Part 2, in the next newsletter, will look at some more advanced object selection techniques.

The selection techniques discussed in this article are:

1. Clicking on objects in the map window
2. Clicking on objects in the Object Property Manager
3. Block Select
4. Selecting by object type
5. Inverting a selection
6. Select All
7. Deselecting objects

All of the methods of selecting objects apply only to objects on the active layer. If you have multiple layers, check the status bar or the layer manager to see which is active.

1 - Clicking on objects in the map window

The simplest way to select an object is to just click on it in the map window. However, this may not always select the object you want. To understand why, realize that each object is surrounded by an imaginary rectangle called a "bounding box".

An imaginary rectangle known as a "bounding box" surrounds each object.

Clicking anywhere within the bounding box selects the object. However, it is often the case that bounding boxes from multiple objects overlap.

Bounding boxes often overlap.

When clicking in the overlapped area, which object is selected depends on their order in the object hierarchy. Look for the green selection "handles" to tell which object is selected.

The green selection handles show which object is selected.

If an unintended object was selected, either click in a different location where there will be no overlap, or hold down the Control key while clicking on the same location to cycle through overlapping objects. Repeat the CTRL-click as needed until the green handles indicate the desired object is selected.

To select multiple objects in the map window, click on the first object, then hold down the SHIFT key while clicking on a second object. Repeat the SHIFT-click to add additional objects to the selection.

2 - Clicking on objects in the Object Property Manager

The Object Property Manager is normally displayed below the map window. It lists all of the objects in the active layer. Use View | Managers | Object Property Manager to enable it, if it is not currently being displayed.

The Object Property Manager lists the objects in the active layer.

Sometimes, it is easier to select objects in the Object Property Manager than in the map window, especially if the PID, SID, or attribute fields contain information that helps to determine which object is which. Click anywhere on an object's row, except on the light bulb icon, to select it. The row will be highlighted and the green selection handles will appear in the map window to indicate which object was selected.

The selection is indicated both in the Object Property Manager
and in the map window.

Use CTRL-click in the Object Property Manager to add a single additional object to the selection. Use SHIFT-click to add a range of adjacent rows.

Clicking on a column header (e.g., PID) in the Object Property Manager will allow you to sort the objects by that field. This could make it easier to find the right objects or could group similar objects together.

3 - Block Select

The Edit | Block Select command will let you select a group of objects in the map window by dragging a rectangle around them. A setting in File | Preferences determines whether the objects have to be fully contained by the selection rectangle or only partially within it.

The Block Select feature is available at all times, as long as you can start the rectangle outside of where any map objects reside. If you need to start the corner of the rectangle within the map, choose the command from the menu first. Otherwise, the click and drag operation will serve to select and move an object.

4 - Selecting by object type

The Edit | Select command will let you select objects by their type. For example, maybe you want to select all of the curve objects so that you can change their line color property to be blue instead of black.

Check one or more object types to select.

5 - Inverting a selection

The Edit | Invert Selection command will de-select currently selected objects and select all the previously unselected ones instead. This can be handy when you need to select most of the objects. Just select the few you don't want and then invert the selection.

6 - Select All

Use Edit | Select All to select all objects on the active layer. MapViewer uses the standard Windows CTRL-A shortcut for this command.

7 - Deselecting objects

To deselect all objects, just click on the map somewhere there are no objects or use the Edit | Deselect All command.

Individual objects can be removed from a group of selected objects the same way they were added to the selection. SHIFT-click on the object in the map window or CTRL-click on the object in the Object Property Manager.

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