zebra barcode printer in vb.net Download at in Objective-C

Print Data Matrix 2d barcode in Objective-C Download at

Let s start with the terminology: what exactly does accessibility mean In short, accessibility is about ensuring that your software can be used by the widest possible range of users, regardless of any sensory impairments they may have. It means providing tools and design features within your software that allow users who are visually impaired, have limited mobility, or have hearing difficulties to get just as highquality a user experience as any other users. The main topics to consider are display factors and keyboard operation.

Support for users with restricted vision in desktop applications comes down to a number of fairly simple rules: Avoid using combinations of color that are difficult to see for users with limited vision. If you stick to the standard color combinations used in Xcode, you won t go far wrong. Maintain a good level of contrast between text and backgrounds. Don t rely on color alone as a source of information in your interface. Users with color blindness, for example, may not be able to distinguish between certain colors. Avoid unusual typefaces or text effects such as shadows that may detract from readability. Use titles for all controls where possible so that it is clear what a control is for (and also to help with VoiceOver control, as you will see shortly).

Your application should allow the user to control its functions with the keyboard. This means ensuring that you can use the keyboard to navigate and control the application. You can control the tab order to make a logical progression around the user interface, and can bind crucial controls and menu items to keyboard combinations. There is a wide range of reserved key combinations for keyboard navigation: these are listed in the Developer Documentation article Accessibility Keyboard Shortcuts. While doing so, you should ensure that you don t subvert any existing key combinations: this is as much a usability consideration as an accessibility consideration: your user will have an existing Mac experience that convinces her that, say, C is used to copy content, so if your application does something quite different you will definitely have an unhappy user! You should also look closely at system key combinations that are used in accessibility support tools such as VoiceOver or Mouse Keys. VoiceOver uses the Control and

Option keys together with keys such as the arrow keys, K, C, R, D, M, U, H, and the spacebar. If you think your users are likely to use VoiceOver, then you obviously need to avoid using these key combinations for any other purpose. Mouse Keys allows you to use the keyboard to move the mouse around. There are some predefined keys for moving in different directions, and for clicking, holding and releasing the mouse button (see Table 14 1). The main concern is to not risk using these keys for navigation purposes in your application.

Up Down Left Right Diagonal NE Diagonal SE Diagonal NW Diagonal SW Button click Button hold Button release

8 2 4 6 9 3 7 1 5 0 .

(Equivalent Without a Numeric Keypad)

Xcode includes a tool that helps you to design accessible software: Accessibility Verifier (the Xcode Developer Tools installation also includes an Accessibility Inspector, but personally I find Accessibility Verifier the more useful of the two tools). Let s take a look at both of these tools now with the DailyJournal application. First, open the Xcode project for the DailyJournal application and Build and Run. Then find and run Accessibility Verifier (it s in /Developer/Applications/Utilities/Accessibility Tools/). Once open, choose DailyJournal from the popup and click the Verify button. After a brief pause you will see the report (see Figure 14 5):