I'm trying to get the absolute screen pixel coordinates of the top left corner of a view. However, all methods I can find such as getLeft() and getRight() don't work as they all seem to be relative to the parent of the view, thus giving me 0. What is the proper way to do this?

If it helps, this is for a 'put the picture back in order' game. I want the user to be able to draw a box to select multiple pieces. My assumption is that the easiest way to do that is to getRawX() and getRawY() from the MotionEvent and then compare those values against the top left corner of the layout holding the pieces. Knowing the size of the pieces, I can then determine how many pieces have been selected. I realise I can use getX() and getY() on the MotionEvent, but as that returns a relative position that makes determining which pieces were selected more difficult. (Not impossible, I know, but it seems unnecessarily complicated).

Edit: This is the code I used to try to get the size of the holding container, as per one of the questions. TableLayout is the table which holds all the puzzle pieces.

TableLayout tableLayout = (TableLayout) findViewById(R.id.tableLayout);
Log.d(LOG_TAG, "Values " + tableLayout.getTop() + tableLayout.getLeft());

Edit 2: Here is the code I've tried, following more of the suggested answers.

public int[] tableLayoutCorners = new int[2];
(...)

TableLayout tableLayout = (TableLayout) findViewById(R.id.tableLayout);
tableLayout.requestLayout();
Rect corners = new Rect();
tableLayout.getLocalVisibleRec开发者_如何学编程t(corners);
Log.d(LOG_TAG, "Top left " + corners.top + ", " + corners.left + ", " + corners.right
            + ", " + corners.bottom);

cells[4].getLocationOnScreen(tableLayoutCorners);
Log.d(LOG_TAG, "Values " + tableLayoutCorners[0] + ", " + tableLayoutCorners[1]);

This code was added after all the initialisation is done. The image has been divided up into a array of ImageViews (the cells[] array) contained within a TableLayout. Cells[0] is the top left ImageView, and I picked cells[4] as it's somewhere in the middle and most definitely should not have coordinates of (0,0).

The code shown above still gives me all 0s in the logs, which I really don't understand because the various puzzle pieces are correctly displayed. (I tried public int for tableLayoutCorners and default visibility, both giving the same result.)

I don't know if this is significant, but the ImageViews are originally not given a size. The size of the ImageViews is determined during the initialisation automatically by the View when I give it an image to display. Could this contribute to their values being 0, even though that logging code is after they have been given an image and have automatically resized themselves? To potentially counter that, I added the code tableLayout.requestLayout() as shown above, but that didn't help.

Use View.getLocationOnScreen() and/or getLocationInWindow().

The accepted answer didn't actually tell how to get the location, so here is a little more detail. You pass in an int array of length 2 and the values are replaced with the view's (x, y) coordinates (of the top, left corner).

int[] location = new int[2];
myView.getLocationOnScreen(location);
int x = location[0];
int y = location[1];

Notes

• Replacing getLocationOnScreen with getLocationInWindow should give the same results in most cases (see this answer). However, if you are in a smaller window like a Dialog or custom keyboard, then use you will need to choose which one better suits your needs.
• You will get (0,0) if you call this method in onCreate because the view has not been laid out yet. You can use a ViewTreeObserver to listen for when the layout is done and you can get the measured coordinates. (See this answer.)

First you have to get the localVisible rectangle of the view

For eg:

Rect rectf = new Rect();

//For coordinates location relative to the parent
anyView.getLocalVisibleRect(rectf);

//For coordinates location relative to the screen/display
anyView.getGlobalVisibleRect(rectf);

Log.d("WIDTH        :", String.valueOf(rectf.width()));
Log.d("HEIGHT       :", String.valueOf(rectf.height()));
Log.d("left         :", String.valueOf(rectf.left));
Log.d("right        :", String.valueOf(rectf.right));
Log.d("top          :", String.valueOf(rectf.top));
Log.d("bottom       :", String.valueOf(rectf.bottom));

Hope this will help

Using a global layout listener has always worked well for me. It has the advantage of being able to remeasure things if the layout is changed, e.g. if something is set to View.GONE or child views are added/removed.

public void onCreate(Bundle savedInstanceState)
{
     super.onCreate(savedInstanceState);

     // inflate your main layout here (use RelativeLayout or whatever your root ViewGroup type is
     LinearLayout mainLayout = (LinearLayout ) this.getLayoutInflater().inflate(R.layout.main, null); 

     // set a global layout listener which will be called when the layout pass is completed and the view is drawn
     mainLayout.getViewTreeObserver().addOnGlobalLayoutListener(
       new ViewTreeObserver.OnGlobalLayoutListener() {
          public void onGlobalLayout() {
               //Remove the listener before proceeding
               if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                    mainLayout.getViewTreeObserver().removeOnGlobalLayoutListener(this);
               } else {
                    mainLayout.getViewTreeObserver().removeGlobalOnLayoutListener(this);
               }

               // measure your views here
          }
       }
     );

     setContentView(mainLayout);
 }

First Way:

In Kotlin we can create a simple extension for view:

fun View.getLocationOnScreen(): Point
{
    val location = IntArray(2)
    this.getLocationOnScreen(location)
    return Point(location[0],location[1])
}

And simply get coordinates:

val location = yourView.getLocationOnScreen()
val absX = location.x
val absY = location.y

Second Way:

The Second way is more simple :

fun View.absX(): Int
{
    val location = IntArray(2)
    this.getLocationOnScreen(location)
    return location[0]
}

fun View.absY(): Int
{
    val location = IntArray(2)
    this.getLocationOnScreen(location)
    return location[1]
}

and simply get absolute X by view.absX() and Y by view.absY()

Following Romain Guy's comment, here's how I fixed it. Hopefully it'll help anyone else who also had this problem.

I was indeed trying to get the positions of the views before they had been laid out on the screen but it wasn't at all obvious that was happening. Those lines had been placed after the initilisation code ran, so I assumed everything was ready. However, this code was still in onCreate(); by experimenting with Thread.sleep() I discovered that the layout is not actually finalised until after onCreate() all the way to onResume() had finished executing. So indeed, the code was trying to run before the layout had finished being positioned on the screen. By adding the code to an OnClickListener (or some other Listener) the correct values were obtained because it could only be fired after the layout had finished.

The line below was suggested as a community edit:

please use onWindowfocuschanged(boolean hasFocus)

You can get a View's coordinates using getLocationOnScreen() or getLocationInWindow()

Afterwards, x and y should be the top-left corner of the view. If your root layout is smaller than the screen (like in a Dialog), using getLocationInWindow will be relative to its container, not the entire screen.

Java Solution

int[] point = new int[2];
view.getLocationOnScreen(point); // or getLocationInWindow(point)
int x = point[0];
int y = point[1];

NOTE: If value is always 0, you are likely changing the view immediately before requesting location.

To ensure view has had a chance to update, run your location request after the View's new layout has been calculated by using view.post:

view.post(() -> {
    // Values should no longer be 0
    int[] point = new int[2];
    view.getLocationOnScreen(point); // or getLocationInWindow(point)
    int x = point[0];
    int y = point[1];
});

~~

Kotlin Solution

val point = IntArray(2)
view.getLocationOnScreen(point) // or getLocationInWindow(point)
val (x, y) = point

NOTE: If value is always 0, you are likely changing the view immediately before requesting location.

To ensure view has had a chance to update, run your location request after the View's new layout has been calculated by using view.post:

view.post {
    // Values should no longer be 0
    val point = IntArray(2)
    view.getLocationOnScreen(point) // or getLocationInWindow(point)
    val (x, y) = point
}

I recommend creating an extension function for handling this:

// To use, call:
val (x, y) = view.screenLocation

val View.screenLocation get(): IntArray {
    val point = IntArray(2)
    getLocationOnScreen(point)
    return point
}

And if you require reliability, also add:

view.screenLocationSafe { x, y -> Log.d("", "Use $x and $y here") }

fun View.screenLocationSafe(callback: (Int, Int) -> Unit) {
    post {
        val (x, y) = screenLocation
        callback(x, y)
    }
}

Just in addition to the above answers, for the question where and when you should call getLocationOnScreen?

For any information that is related to the view, will be available only after the view has been laid out(created) on the screen. So to get the location put your code inside view.post(Runnable) which is called after view has been laid out, like this:

view.post(new Runnable() {
            @Override
            public void run() {

               // This code will run when view created and rendered on screen

               // So as the answer to this question, you can put the code here
               int[] location = new int[2];
               myView.getLocationOnScreen(location);
               int x = location[0];
               int y = location[1];
            }
        });  

My utils function for get view location, it will return a Point object with x value and y value

public static Point getLocationOnScreen(View view){
    int[] location = new int[2];
    view.getLocationOnScreen(location);
    return new Point(location[0], location[1]);
}

Using

Point viewALocation = getLocationOnScreen(viewA);

Get Both View Position and Dimension on screen

val viewTreeObserver: ViewTreeObserver = videoView.viewTreeObserver;

    if (viewTreeObserver.isAlive) {
        viewTreeObserver.addOnGlobalLayoutListener(object : ViewTreeObserver.OnGlobalLayoutListener {
            override fun onGlobalLayout() {
                //Remove Listener
                videoView.viewTreeObserver.removeOnGlobalLayoutListener(this);
                
                //View Dimentions
                viewWidth = videoView.width;
                viewHeight = videoView.height;

                //View Location
                val point = IntArray(2)
                videoView.post {
                    videoView.getLocationOnScreen(point) // or getLocationInWindow(point)
                    viewPositionX = point[0]
                    viewPositionY = point[1]
                }

            }
        });
    }

binding.ivStory.setOnTouchListener(object : View.OnTouchListener{
        override fun onTouch(p0: View?, event: MotionEvent?): Boolean {
            val x = event?.x
            vak y = event?.y

            when (event!!.action) {
                MotionEvent.ACTION_UP ->

                if (x != null) {
                   //Do your stuff                    }

                MotionEvent.ACTION_DOWN  -> {

                }
            }
            return true
        }

    })

This is the Kotlin way of getting coordinates of screen view when you touch the screen. Make sure you handle both Action UP and DOWN or it may cause multiple click/touch.