Change how SlidingDrawer responds to trackball or cursor

Question

(Please note that the behavior described in this question only appeared because of something else seemingly unrelated we were doing. See the accepted answer.)

We have an Android activity with a GridView and a SlidingDrawer inside of a RelativeLayout. The way this activity responds to the trackball (or cursor keys) is rather odd. The focus will move among the items in the GridView, but whenever the cursor moves in a direction "out" of the GridView. (e.g. up when at the top, left when already at the leftmost item) the sliding drawer opens or shut. Notably, the focus stays on the same item in the GridView---it does not move to the sliding drawer.

With a trackball this is particularly horrible, as spinning the trackball past your real destination will cause the sliding drawer to repeatedly open and close.

We've determined that we can turn off the trackball entirely by overriding onTrackballEvent(). We'd prefer to have the trackball and cursor work normally on the GridView but not cause the sliding drawer to open or close. In principle we'd also like the trackball to focus on the various contents of the sliding drawer when it is open.

How?

score 3 · Answer 1 · answered Dec 01 '11 at 20:56

You may consider creating custom views extending GridView and SlidingDrawer and using custom implementations of onInterceptTouchEvent and onTouchEvent for the GridView and a custom implementation just for onInterceptTouchEvent for the SlidingDrawer. You may not need to implement a custom SlidingDrawer depending on what user interactions may be triggered on the handle

for your custom GridView, give it an interface maybe defined like this:

public interface MyGridViewListener {
    public boolean shouldPreventScroll();
}

return if your custom SlidingDrawer is opened. this returned value will be used to determine if actions should be performed(for onInterceptTouchEvent and onTouchEvent methods) on the GridView. So when the SlidingDrawer is opened, actions performed on the GridView will not trigger anything on the SlidingDrawer.

Activity:

MyGridView gridView = (MyGridView) findViewById(R.id.gridView);
gridView.setMyGridViewListener(new MyGridViewListener() {
    @Override
    public boolean shouldPreventScroll() {
        return slidingDrawer.isOpened();
    }
});

MyCustomGridView: shouldIntercept will be called whenever some touch/track event happens on the GridView.

private boolean shouldIntercept() {
    boolean shouldIntercept = false;
    if(myGridViewListener != null) {
        shouldIntercept = myGridViewListener.shouldPreventScroll();
    }
    return shouldIntercept;
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
    return shouldIntercept() ? true : super.onInterceptTouchEvent(ev);
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
    return shouldIntercept() ? true : super.onTouchEvent(ev);
}
@Override
public boolean onTrackballEvent(MotionEvent event) {
    return shouldIntercept() ? true : super.onTrackballEvent(event);
}
public MyGridViewListener getMyGridViewListener() {
    return myGridViewListener;
}
public void setMyGridViewListener(
        MyGridViewListener myGridViewListener) {
    this.myGridViewListener = myGridViewListener;
}

I hope this points you in a right direction or at least helps

Useful ideas. It gave me the idea to override `open()` in a custom `SlidingDrawer` and emit a stack trace, which led to the solution described in the accepted answer. — Robert Tupelo-Schneck, Dec 08 '11 at 18:28

triggs · Answer 2 · 2011-12-01T22:03:40.990

While playing around with a custom sliding drawer I set the layout of the handle to some odd value, something like

handle.layout(0, 0,0, 0);

to make the handle disappear but dragging a finger from the side of the screen would still open the sliding drawer, which is what I didn't want, so I set

handle.layout(10000, 10000, 10000, 10000);

which moved it way outside the viewable area and the drawer could no longer be pulled out manually by dragging from the side of the screen. After looking at the source code its teh position of the handle that determines the sliding of the drawer, get rid of the handle and it should solve your problem.

If you need to open/close the drawer call animateOpen()/animateClose()

Robert Tupelo-Schneck · Accepted Answer · 2011-12-08T18:33:14.703

As it turned out, we caused this problem by an unrelated bit of foolishness. We wanted the MENU key to open and close the SlidingDrawer. We did this by overriding onPrepareOptionsMenu():

public boolean onPrepareOptionsMenu (Menu menu) {
    slidingDrawer.animateToggle();
    return true;
}

This works fine; but it turns out it can be called when the menu is not about to be opened. In particular, if the Activity uses setDefaultKeyMode(DEFAULT_KEYS_SHORTCUT), then an unhandled key event will end up accessing the menu. This includes trackball motion off the edge of the screen.

The less dumb way to get the desired behavior is

public boolean onKeyUp(int keyCode, KeyEvent event) {
    if(keyCode==KeyEvent.KEYCODE_MENU) {
        slidingDrawer.animateToggle();
    }
    return super.onKeyUp(keyCode,event);
}

Meanwhile, we can get the trackball to move within the SlidingDrawer when it is open by setting up a SlidingDrawer.OnDrawerOpenListener which calls

slidingDrawer.getContent().requestFocus();

Finally it seems like a good idea to call

slidingDrawer.getHandle().setFocusable(false);

Change how SlidingDrawer responds to trackball or cursor

3 Answers3