Display

Iristick smart glasses have a small display on the right side, located on a movable arm. The following table shows the display resolution for various Iristick models. Applications should however be able to handle other display sizes.

Models	Resolution
G1 / G2	428 × 240
H1	640 × 400

By default, the display mirrors the content of the phone screen. This behavior can be overridden to either show custom UI with standard Android widgets and layouts, or to draw directly to the underlying surface.

Tip

Please read the Getting Started guide for a discussion on the default behavior of the display.

Example code

The Clock Display Example provided in the SDK package shows how to draw standard UI elements on the display. It uses a TextView to show a clock.

The Bubbles Display Example shows how to directly draw on the display using the 2D drawing API of the Canvas class. It shows a bunch of colored bubbles floating around on the display.

Opening the display

Before any drawing can occur, the display must first be opened. The Headset objects provides two methods for this: openDisplay() results in a Display object for drawing Android widgets; openDisplaySurface() results in a Surface for direct drawing.

@Override
public void onHeadsetConnected(@NonNull Headset headset) {
    headset.openDisplay(new DisplayListener() {
        @Override
        public void onDisplayOpened(@NonNull Display display) {
            /* This method is called when the display is opened and ready
             * for use.
             */
        }

        @Override
        public void onDisplaySurfaceOpened(@NonNull Surface surface,
                                           int width, int height,
                                           int density) {
            /* This method would have been called instead of onDisplayOpened
             * if we had opened the display with openDisplaySurface().
             */
        }

        @Override
        public void onDisplayClosed(int reason) {
            /* This method is called when the display is closed.
             * It is also called instead of the above two methods if the
             * display could not be opened.
             */
        }
    }, null);
}

When you no longer need the display, you can close it with a call to the closeDisplay() method of the Headset object.

Note

The display can only be opened by one application at the same time. Trying to open the display while another app is drawing on it, will result in an error (if the requesting app has lower priority) or closing the display in the other app (if the requesting app has higher priority, e.g., it is in foreground).

Likewise, it is not possible to open the display twice. You have to close it first before you can reopen it.

Drawing standard widgets

To show a window with standard UI elements on the Iristick display, subclass the Presentation class. A Presentation is a special kind of dialog window that displays its content on a secondary display. Presentation automatically adapt resources to the dimensions and density of the secondary display.

class MyPresentation extends Presentation {
    MyPresentation(@NonNull Context outerContext, @NonNull Display display) {
        super(outerContext, display);

        /* Prevent widgets on the display from stealing focus. */
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE);
    }

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.presentation_screen);
        /* Perform any initialization here, such as retrieving widgets
         * with findViewById().
         */
    }

    @Override
    public void onStop() {
        /* Called when the presentation is dismissed. Do cleanup here. */
        super.onStop();
    }
}

The presentation is closely linked to the display on which it shows its contents. It requires a Display object representing the secondary display as an argument to its constructor. You can get this object by opening the display with the openDisplay() method of the Headset object. When opening the display was successful, the onDisplayOpened() of your display listener is called. You can create and show your presentation there.

@Override
public void onDisplayOpened(@NonNull Display display) {
    new MyPresentation(this, display).show();
}

Presentations are automatically dismissed when the display is closed.

Note

You must use the Context provided by the presentation for layouts and views shown in the presentation and the regular activity context or fragment context for layouts and views shown on the screen of the phone. This ensures proper scaling of the views and text. You can get the presentation's context with the presentation's getContext() method.

Drawing directly on the display

To directly draw on the display bypassing the Android view hierarchy, open the display with openDisplaySurface() to get a Surface object representing the raw display surface. Surface objects can be used at multiple places in the Android API. For example, one can call lockCanvas() to use the Canvas 2D drawing API.