SWT: A Developer's Notebook

Positioning the Text Field

When building a GUI, you need to have precise control over the positioning of every widget that makes up the interface. In SWT, there are two ways to specify the size and position of a widget within a container. The first approach is to use the setBounds() or setLocation( ) methods that are part of the super class for every widget.

How do I do that?

In the TextFieldExample class, the Text widget is positioned with this:

text1.setBounds(10,10,100,20);

Placing a text field in a particular location on the window is simply a matter of adjusting the first two parameters, which represent the x and y coordinates of the upper lefthand corner of the text field with respect to the upper lefthand corner of the shell’s workspace area (the area below the title bar and menu).

Note

A toolbar that is displayed on the shell takes up room beginning in the upper left-hand corner of the workspace area, so you must account for the height of the toolbar in calculating where to place a widget.

The first setBounds( ) parameter moves the text field’s position to the right as the parameter’s value increases, while the second parameter moves the field’s position closer to the bottom of the window as the value increases. Aligning widgets along their lefthand side is a matter of specifying the same value in the first parameter passed to setBounds( ). Example 5-2 demonstrates how to align two Text widgets along their lefthand sides, with the result shown in Figure 5-3.

Example 5-2. Aligning ...