Android "Web Access Plug-In" Technical FAQ

 

1. What is WebView?

WebView it is a widget built into android. Android using it to display html content

2. What is the Web Access Plug-in?

The Web Access Plug-In adds speech capabilities to WebView. It adds a local JavaScript server. By using one simple piece of JavaScript code, the Web Access Plug-In can be loaded into any web view

3. How we make WebView accessible through our Web Access Plug-In.

The Web Access Plug-In communicates with WebView using Content Providers. We have two Content Providers. One for serving JavaScript. The other is for accessing Android's TextToSpeech service. By serving JavaScript locally from the SD card, we enable developers and end- users to easily customize and further enhance the functionality of the scripts. The reason we isolates the JavaScript code on the SD card was to enable developers and users with the appropriate skills to customize and enhance the JavaScript. This capability eliminates the need modify and recompile Web Access.

By passing data to Android's TextToSpeech service via our Content Provider wrapper, and taking the string to be spoken inside the URI, we are able to seamlessly communicate with the Android's TextToSpeech service from JavaScript using standard JavaScript calls for opening web content. This approach has several distinct advantages.

  1. It requires no modification to the WebView code in the Android framework. So long as the HTML loaded in the WebView contains a reference to our Content Provider, our plug-in code will run.

  2. There is a precedence for allowing Android apps to tie in with the WebView via content providers. For example, "market://" links work from inside HTML.

  3. It works for the standard Browser as well as any application using a WebView, thanks to the previous two points.

  4. Because our plug-in is added to the WebView as a JavaScript tag with a SRC attribute that points to our JavaScript Content Provider, if the user does not have the plug-in installed, nothing bad happens. The WebView simply will not speak, but it will not crash. It simply treats our missing plug-in as nothing more than a resource that is unable to connect to (ie, it will ignore it without throwing errors.).

For developers to add accessibility into their own android apps using WebView, they simply need to include a simple JavaScript tag in their HTML webpage which loads the accessibility plug-in. While we are currently "always running" the Web Access JavaScript, once there is an established method established by Google for determining if a screen reader is running or not, it would be possible to use that method to decide whether or not to serve any scripts. This means there is no impact on anyone without a screen reader. For screenreader users, it will always do the right thing.

The main thing that needs to be done is for the Web Access JavaScript code to be run once inside the WebView. This can be accomplished either by a bookmarklet, or a Greasemonkey-like functionality inside of the web browsing client.

We have illustrated both approaches by automatically adding a bookmarklet to the standard Android Browser, as well as posting a compiled version of the Eyes-Free Project's Web Vox which is set to automatically run the Web Access script each time a page is loaded.

We hope that more browsers (including the standard Android Browser) will offer Greasemonkey-like capabilities in the near future. This would be a useful enhancement for all users, and it would make this approach to web accessibility more user-friendly.

We are currently working with Trace Research and Development Center on a Phase II of this project. Phase II will build a web browser, tailored to this approach, that uses gestures for moving through the page content. This would access enable the web for Android devices without a keyboard as well as remove the necessity for going into/out of browse mode.

The Android "Web Access Plug-In" was developed by Apps4Android, Inc.
as an open source donation to "Raising the Floor."

Apps4Android, Inc. is an IDEAL Group company.

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