Develop Reference

Intercept Touch events in Android

How do I intercept touch events in Android, ensuring that the existing touch workflow is not impacted. Basically I want to add some touch visualizer so as to know where the user is touching on the screen whereby ensuring that if the user is trying to scroll the tableview, touch visualizer is shown as the user drags his finger but also the tableview scrolls with ease.
In iOS, there is one method sendEvent of class UIWindow does this exactly. Not sure if Android has anything similar.
Thanks

Override Activity.dispatchTouchEvent() and do your touch handling there. Always return super.dispatchTouchEvent() to make sure it gets handled the normal way after your logic executes.
#Override
public boolean dispatchTouchEvent(MotionEvent event) {
/* your code here */
return super.dispatchTouchEvent(event);
}

http://developer.android.com/reference/android/view/View.OnTouchListener.html have alook at this link. It is pretty straight forward. Google it there is lots of example on it.
yourview.setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
return false;
}
});

Developing for Google Glass with HTML5 (beginner)

I'm new to programming for Google Glass. I really like the cards possibilities (https://glass-python-starter-demo.appspot.com/) and it's great that I can submit HTML.
Because the project I'm working on (for which I would like to use Glass) is an online platform, I would like to be able to work from the website. As I found out, I can detect (from the user agent) that Glass is being used (http://www.googleglass.gs/quick-tip-google-glass-web-browser-user-agent/)
So, now my question in two parts.
1) Can I create an Android app that's actually a 'browser without a toolbar' so that I can direct directly to a webpage, but that functions as an app so that I can have it in the menu (after: "ok Glass")?
2) Can I use voice commands in the above app?
PS:
I know this is a beginner question, but -with exception from the Glass Cards option- it's hard to find a starting point for this.

So if I understand you correctly, you want to do this following:
1) Create an app that is basically just a browser.
2) Have the link that opens be to your website where the app is actually contained.
3) Use voice commands to control this app.
All to bypass having to code in java/xml so you can code in the language you know better and then run it online, and just have one line of code creating the browser in the actual app code.
Yes, you can create an app that is just a browser.
Yes, you can have it link to your website and then have it stay there.
I think that it will be much harder for you to interact with the website. The default browser controls are tap to click, hold 2 fingers down and move your head to move "mouse" around the current screen, slide up and down to scroll.
If you want to control the app, you'd have to implement your own gesturedetector, override the default actions taken each time you do something, and then for each action send something to your website to let it know that you just did something.
You could use voice recognition for controls as well.
Either way, you'll need a gesturedetector to override the default controls for the browser if you decide to use the standard one. Here is what you'd need for that:
At the very top, you'll have
private GestureDetector gestureDetector;
Then in your onCreate method, you'll need to create your gestureDetector. I like to have a method to create it farther down. It is just cleaner that way for me.
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
gestureDetector = createGestureDetector(this);
}
And then the method to actually create the GestureDetector:
private GestureDetector createGestureDetector(Context context) {
GestureDetector gestureDetectorTemp = new GestureDetector(context, new GestureDetector.OnGestureListener() {
#Override
public boolean onDown(MotionEvent motionEvent) {
return false;
}
#Override
public void onShowPress(MotionEvent motionEvent) {
return false;
}
#Override
public boolean onSingleTapUp(MotionEvent motionEvent) {
//communicate to the website that you tapped, and have it handle the tap
Log.v("APP_TAG","Someone tapped me!");
return false;
}
#Override
public boolean onScroll(MotionEvent motionEvent, MotionEvent motionEvent2, float distanceX, float distanceY) {
return false;
}
#Override
public void onLongPress(MotionEvent motionEvent) {
return false;
}
#Override
public boolean onFling(MotionEvent motionEvent, MotionEvent motionEvent2, float v, float v2) { //fling = a single slide
return false;
}
});
return gestureDetectorTemp;
}
Notice that each method that was overriden has a "return false" in it. The boolean you are returning represents whether or not the event is to be consumed.
In other words, if you look at onSingleTapUp, we have a Log.v that will print out "Someone tapped me!" when you tap the screen. By returning false, you are letting whatever else was going to occur based on a tao (in the case of a browser, a "click" of the mouse) occur. If you return true, nothing else will occur. The event won't be reported to the other default methods. So to nullify all of the default controls of the browser, you would just change all of the return statements there to "return true", indicating that the event was consumed and that no further action is necessary!
I hope that helped a bit. If you goal is to completely bypass the entire android coding platform and just develop in the browser and then link the app to the browser, I don't think you'll be able to do it completely just because of the nature of Glass. There is no touch screen with lots of different buttons and a keyboard, etc. You'll need to do at least some glass development to get it to work.

Using MotionEventCompat in android

I'm looking for an example of how to use MotionEventCompat in Android. I'm using API level 10, which doesn't support if a finger is 'hovering' or 'dragging' onto a view. I need to detect this, preferably from the view itself. Here's some code snippets regarding how I'm trying to use this:
**my class:**
import android.support.v4.view.MotionEventCompat;
public class GridButton extends View
overriding onTouchEvent:
#Override
public boolean onTouchEvent(MotionEvent event) {
super.onTouchEvent(event);
switch (event.getAction() & MotionEventCompat.ACTION_MASK) {
case (MotionEvent.ACTION_DOWN): {
set_active(true);
return true;
}
case (MotionEventCompat.ACTION_HOVER_ENTER): {
set_active(true);
break;
}
}
return false;
}
I based the MotionEventCompat.ACTION_MASK off an example I found somewhere, but it doesn't trigger my code for set_active().
Any help on using this would be appreciated. There's very little about this on the web.

Hover events are sent when the device supports a mouse or touchpad. When the cursor hovers over a view these events are sent to onGenericMotionEvent, not onTouchEvent. They won't help you detect a finger that isn't touching the surface of a capacitive touchscreen or a finger that touched down in a different position and then slid over the view in question. They will never be sent on an API 10 (Android 2.3) device.

Disable parts of the touch screen in android

So I was trying to disable the screen for an app I am making for a brief period using this
#Override
public boolean onTouchEvent(MotionEvent pMotioneEvent) {
if(pMotioneEvent.getY() < TestSprite.getY()){
return false;
}else{
return true;
}
}
but this seems to have no effect. I read around and it seems like in general its a bad idea to disable the touch screen, but I'm still curious to know if there is a way.
Thanks

You could try
requestDisallowInterceptTouchEvent

If you want to check for touchevents in a certain area of your screen, you might want to put this in a View and set a touchEvent Listener to it.

Android: ScrollView 'setOnScrollListener' (like ListView)

I want to do something when the user has scrolled >90% down, so I thought I could just add a onScrollListener like I would in a ListView. Unfortunatly, ScrollView doesn't seem to have a similar method. Is there any way I can do what I want; getting a notification when the user scrolls approx 90% down?
Thanks,
Erik

This is what I end up doing to know if the user was interacting with my ScrollView or not:
findViewById(R.id.scrollview).setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_SCROLL:
case MotionEvent.ACTION_MOVE:
setScrollState(OnScrollListener.SCROLL_STATE_FLING);
break;
case MotionEvent.ACTION_DOWN:
setScrollState(OnScrollListener.SCROLL_STATE_TOUCH_SCROLL);
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
setScrollState(OnScrollListener.SCROLL_STATE_IDLE);
break;
}
return false;
}
});

You can try extending ScrollView and overriding View#onScrollChanged and the doing your checks there. You have to extend ScrollView since onScrollChanged is a protected method.

You can implement an onTouchListener and use the getScrollX and getScrollY callbacks of the view

If you want a scrolling view that works like a listview, may I suggest trying out a horizontal listView library:
https://github.com/sephiroth74/HorizontalVariableListView
it's based on the original ListView, and it works very well.
it has its OnScrollListener , and even though the website says it supports Android 2.3 and above, I think it should work from API 7 and above (and with some tweaks even older).