Developing LabVIEW Applications for the Visually Impaired

LabVIEW offers several options for creating applications for the visually impaired user. This document describes these options, as well as capabilities of various operating systems that you can use when developing an application for the visually impaired.

Adjusting Font Size in LabVIEW

A simple way to improve program usability for the visually imparied is to increase the size of text that appears in the program. LabVIEW includes three different categories of fonts that you can modify from the Fonts Options Page. Select Tools»Options to display the Options dialog box and select Fonts from the Category list to display this page. Select Application Font, Dialog Font, or System Font from the pull-down menu at the top of the page and click the Font Style button to modify the style of the selected font. Note that changes do not take effect until the next time you start LabVIEW.


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The three font types in the pull-down menu refer to different types of text in the LabVIEW environment. Application Font refers to object labels and comments on the front panel and block diagram, as well as the text within text boxes. Dialog Font refers to text in dialog boxes, such as the text on the Fonts Options Page. System Font refers to the text on toolbars and the labels of palettes and subpalettes. You also can change the font size for an individual item from the pull-down menu at the top of the front panel or block diagram.

Resizing Controls and Indicators

You can resize controls and indicators on the front panel, including graphs, to make them larger and easier to see. If resized objects take up too much space on the front panel, use a tab control to make only one subset of the objects visible at a time.

Scaling the Front Panel

Use the front panel scaling abilities of LabVIEW to create a front panel with controls and indicators that scale as you make the window larger or smaller. Enable this feature from the VI Properties dialog box. Select File»VI Properties to show this dialog box. Select Window Size from the pull-down menu and place a checkmark in the Scale all objects on front panel as the window resizes checkbox to enable scaling. You also can set a minimum panel size to prevent a user from making the front panel window too small. For best results, design your front panel at the minimum size and click the Set to Current Window Size button to ensure the front panel cannot decrease in size from how you design it.


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Capturing User Events

With Event Structures, available in the LabVIEW Full Development System, versions 6.1 and later, you can programmatically capture user events and use them to trigger certain responses from LabVIEW. For example, you can set up an event that speaks the name of an object or displays a large text box describing the object when it detects the mouse hovering over that object. Use an Event Structure that watches for the Mouse Enter and Mouse Leave events (LabVIEW 7.0 and later) to perform the actions just described. Refer to the LabVIEW Help for more information on how to use Event Structures, or see the link below.

See Also:
Event-Driven Programming in LabVIEW

Leveraging Windows Capabilities

The Microsoft Windows operating system provides several utilities and features that you can use in tandem with LabVIEW to make applications more usable for the visually impaired. The Windows Accessibility Wizard allows you to modify such things as font size, scroll bar size, icon size, and cursor size for the entire operating system. You can access the wizard from the Windows start menu. The wizard walks you through the process of modifying the OS user interface.

You also can use the Magnifier in Windows to magnify specific parts of the screen for easier viewing.

National Instruments also has developed VIs that use the Microsoft Speech functionality. You can use these VIs with the Event Structure previously described to desing a program that speaks a description of an object when the mouse hovers over the item. Refer to the link below for these VIs and a description of how to use them.

See Also:
Text to Speech Using Microsoft Speech SDK 5.1

Leveraging MacOS Capabilities

National Instruments also has developed VIs that use speech functionality on the MacOS. Refer to the link belowthese VIs and a description of how to use them.

See Also:
Speech Synthesis with LabVIEW

Related Links:
Start and Stop Buttons for Visually Impaired Users or for Touch Screen Applications

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