Develop Reference

How to add tap listener to the displayed image and bind XY axis to the image

I would like to display an .jpg image into the screen and add Listener to this image which will can detect the location of tap on that image. I would like to bind XY axis to the image.
Example:
To display an image I should use:
private ImageView imgView;
imgView = (ImageView) findViewById(R.id.imageViewId);
imgView.setImageBitmap(BitmapFactory.decodeFile("pathToImageFile"));
To add listener to the image
iv.setOnClickListener(clickListener);
But how to define that listener which will detect the click coordinates (x,y) but the coordinates should be binded to the image not to the screen.

ImgeView.setOnTouchListener(new OnTouchListener(){
#Override
public boolean onTouch(View v, MotionEvent event) {
switch(event.getAction()){
case MotionEvent.ACTION_DOWN:
//Finger placed on screen
event.getX();
event.getY();
break;
case MotionEvent.ACTION_MOVE:
//Finger is moving
event.getX();
event.getY();
break;
case MotionEvent.ACTION_POINTER_DOWN:
//Second finger is touching screen
break;
}
return false;
}
});

How do I detect if a user has touched any part of the screen other than the inside of an EditText?

I am guessing this means making the whole screen touchable. How exactly is that done?
and secondly calculating if an X,Y is within the EditText.

override the onTouchEvent in the activity you want to implement this....and get the X, Y co-ordinates using event.getX() and event.getY()
#Override
public boolean onTouchEvent(MotionEvent event) {
int x = (int)event.getX();
int y = (int)event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
case MotionEvent.ACTION_MOVE:
case MotionEvent.ACTION_UP:
}
return false;
}
but i suggest you must search thoroughly before posting a question.

Is there a way in android to get the area (a collection of points) of my finger

Is there a way in android to get the area (a collection of points) of my finger when i touch the screen. Usually, the return is one point location. I need to get the several points which can represent the area of my touching. Any one knows? Thnaks

Just use View class's onTouchEvent() or implements OnTouchListener in your activity and get the X and Y co-ordinates like,
This is View class's OnTouchEvent()..
#Override
public boolean onTouchEvent(MotionEvent ev) {
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
float x = ev.getX();
float y = ev.getY();
break;
}
case MotionEvent.ACTION_MOVE: {
float mLastTouchX = x;
float mLastTouchY = y;
break;
}
case MotionEvent.ACTION_UP: {
break;
}
case MotionEvent.ACTION_CANCEL: {
break;
}
case MotionEvent.ACTION_POINTER_UP: {
break;
}
}
return true;
}
EDIT:
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final TextView textView = (TextView)findViewById(R.id.textView);
// this is the view on which you will listen for touch events
final View touchView = findViewById(R.id.touchView);
touchView.setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
textView.setText("Touch coordinates : " +
String.valueOf(event.getX()) + "x" + String.valueOf(event.getY()));
return true;
}
});
}
For more details Android - View.

Does it have to be the real shape of the finger? Otherwise you could calculate a circle around the center of the touch.

I believe this is not possible in the touch's coordinate along with it's area. It's natively unsupported by Android API.
Ref:
http://developer.android.com/guide/topics/ui/ui-events.html
http://developer.android.com/reference/android/gesture/package-summary.html

Unfortunately not. I ran in to this a while ago - you could try normalising the data over several 'frames'. May be worth trying to figure out why you need an exact point, or set of points, and find another way of doing it.

Allowing rectangle to be clickable - android

I wrote a View with canvas, which contains many rectangles. I want these rectangles to be used as a button which will open a new activity. How can I do it?

You need to be careful with Suri Sahani example, onTouchEvent is called on any action qualified as a touch event, meaning press, release, movement gesture, etc(Android Event Listener Documentation). To use the onTouchEvent properly you need to check the MotionEvent type.
List<Rect> retangles;//Assume these have been drawn in your draw method.
#Override
public boolean onTouchEvent(MotionEvent event) {
int touchX = event.getX();
int touchY = event.getY();
switch(event){
case MotionEvent.ACTION_DOWN:
System.out.println("Touching down!");
for(Rect rect : rectangles){
if(rect.contains(touchX,touchY)){
System.out.println("Touched Rectangle, start activity.");
Intent i = new Intent(<your activity info>);
startActivity(i);
}
}
break;
case MotionEvent.ACTION_UP:
System.out.println("Touching up!");
break;
case MotionEvent.ACTION_MOVE:
System.out.println("Sliding your finger around on the screen.");
break;
}
return true;
}

In your onTouchEvent() just capture the x and y values and you can use the contains(int x, int y) method in the Rect class. If contains(x, y) returns true, then the touch was inside the rectangle and then just create the intent and start the new activity.

Drag and drop the textview on imageview?

can any one help me how to drag and drop the text view on entire image view. i found from this drag n drop textview in android here the text view is static, in my app textview and image view's are dynamically change. `#Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
// Remember our initial down event location.
startX = event.getRawX();
startY = event.getRawY();
break;
case MotionEvent.ACTION_MOVE:
float x = event.getRawX();
float y = event.getRawY();
// Calculate move update. This will happen many times
// during the course of a single movement gesture.
scrollByX = x - startX; //move update x increment
scrollByY = y - startY; //move update y increment
startX = x; //reset initial values to latest
startY = y;
invalidate(); //force a redraw
break;
}
return true; //done with this event so consume it
}
i wright this code, but it's not working properly.

You can always change the image and text of existing view programatically using setText sort of methods.
There are many drag and drop tutrials if you google it. strongly suggest you try them out.
Basically what you do is implement a OnTouchListener on the TextView like
textview.setOntouchListener(listen);
OnTouchListener onThumbTouch = new OnTouchListener()
{
#Override
public boolean onTouch(View v, MotionEvent event)
{
switch(v.getId())
{
case R.id.slider_thumb_id:
{
switch(event.getAction())
{
case MotionEvent.ACTION_MOVE:
{
}
case MotionEvent.ACTION_UP:
{
}
}
break;
}
}
return true;
}
};
Here from the event attribute you get the value of x and y and the touch event and
use that to alter the position of the textview. I did it by add add/subtracting the margin values.
EDIT:
This is what I did to update the position of my view
Look event.getRawY(); is going to give you the distance from the parent view. So if I get event.getRawY() = 50. I know I need the text view to be 50 pixels from the top.
LinearLayout.LayoutParams iconParams = (LinearLayout.LayoutParams)
v.getLayoutParams();
iconParams.topMargin = 50;
v.setLayoutParams(iconParams);
So now the view that i selected is 50 px from the top of the parent view.