I have an application with a CardScrollView as activity.
Ok Glass => My App => Ok Glass => Next Page
Or OK Glass => Previous Page
Would it be possible to skip the second "Ok Glass" ?
The best would be to let the Voice Command always activated but I don't know if it's possible.
It is currently not possible to trigger contextual voice commands without the "ok glass" cue: the main reasons are to prevent false positive and narrow down the window when the microphone is listening for commands.
I actually did this for my Glass app. Take a look here: https://github.com/RIVeR-Lab/google_glass_driver/tree/master/android/RobotManager/src/com/riverlab/robotmanager
You are going to be interested in the VoiceRecognitionThread, Vocabulary, and MessageListActivity.
The functionality you described is implemented in both MessageListActivity and VoiceRecognitionThread.
The vocabulary is just support for multi-layered commands. You only need to worry about it if you plan on using voice commands that could branch off to other commands. For example, in my application I was controlling a robot. Commands could look like "drive forward" "drive forward quickly" "drive forward now" or "drive forward quickly delay five". You can see examples in the xml files here: https://github.com/RIVeR-Lab/google_glass_driver/tree/master/test
Hope this helps!
