Getting View s coordinates relative to the root layout

Question

Can I get a View s x and y position relative to the root layout of my Activity in Android

User · Answer

I wrote myself two utility methods that seem to work in most conditions, handling scroll, translation and scaling, but not rotation. I did this after trying to use offsetDescendantRectToMyCoords() in the framework, which had inconsistent accuracy. It worked in some cases but gave wrong results in others.

"point" is a float array with two elements (the x & y coordinates), "ancestor" is a viewgroup somewhere above the "descendant" in the tree hierarchy.

First a method that goes from descendant coordinates to ancestor:

public static void transformToAncestor(float[] point, final View ancestor, final View descendant) {
    final float scrollX = descendant.getScrollX();
    final float scrollY = descendant.getScrollY();
    final float left = descendant.getLeft();
    final float top = descendant.getTop();
    final float px = descendant.getPivotX();
    final float py = descendant.getPivotY();
    final float tx = descendant.getTranslationX();
    final float ty = descendant.getTranslationY();
    final float sx = descendant.getScaleX();
    final float sy = descendant.getScaleY();

    point[0] = left + px + (point[0] - px) * sx + tx - scrollX;
    point[1] = top + py + (point[1] - py) * sy + ty - scrollY;

    ViewParent parent = descendant.getParent();
    if (descendant != ancestor && parent != ancestor && parent instanceof View) {
        transformToAncestor(point, ancestor, (View) parent);
    }
}

Next the inverse, from ancestor to descendant:

public static void transformToDescendant(float[] point, final View ancestor, final View descendant) {
    ViewParent parent = descendant.getParent();
    if (descendant != ancestor && parent != ancestor && parent instanceof View) {
        transformToDescendant(point, ancestor, (View) parent);
    }

    final float scrollX = descendant.getScrollX();
    final float scrollY = descendant.getScrollY();
    final float left = descendant.getLeft();
    final float top = descendant.getTop();
    final float px = descendant.getPivotX();
    final float py = descendant.getPivotY();
    final float tx = descendant.getTranslationX();
    final float ty = descendant.getTranslationY();
    final float sx = descendant.getScaleX();
    final float sy = descendant.getScaleY();

    point[0] = px + (point[0] + scrollX - left - tx - px) / sx;
    point[1] = py + (point[1] + scrollY - top - ty - py) / sy;
}

User · Answer

No need to calculate it manually   Just use getGlobalVisibleRect like so   Rect myViewRect   new Rect    myView getGlobalVisibleRect myViewRect   float x   myViewRect left  float y   myViewRect top    Also note that for the centre coordinates  rather than something like       float two    float  2 float cx   myViewRect left   myView getWidth     two  float cy   myViewRect top   myView getHeight     two    You can just do   float cx   myViewRect exactCenterX    float cy   myViewRect exactCenterY

User · Answer

You can use       view getLocationOnScreen int   location       to get location of your view correctly   But there is a catch if you use it before layout has been inflated you will get wrong position   Solution to this problem is adding ViewTreeObserver like this  -  Declare globally the array to store x y position of your view       int   img coordinates   new int 2     and then add ViewTreeObserver on your parent layout to get callback for layout  inflation and only then fetch position of view otherwise you will get wrong x y coordinates       set a global layout listener which will be called when the layout pass is completed and the view is drawn             parentViewGroup getViewTreeObserver   addOnGlobalLayoutListener                      new ViewTreeObserver OnGlobalLayoutListener                             public void onGlobalLayout                                   Remove the listener before proceeding                             if  Build VERSION SDK INT  gt   Build VERSION CODES JELLY BEAN                                    parentViewGroup getViewTreeObserver   removeOnGlobalLayoutListener this                                 else                                   parentViewGroup getViewTreeObserver   removeGlobalOnLayoutListener this                                                                 measure your views here                             fab getLocationOnScreen img coordinates                                                                    and then use it like this  xposition   img coordinates 0   yposition    img coordinates 1

User · Answer

The Android API already provides a method to achieve that  Try this   Rect offsetViewBounds   new Rect      returns the visible bounds childView getDrawingRect offsetViewBounds      calculates the relative coordinates to the parent parentViewGroup offsetDescendantRectToMyCoords childView  offsetViewBounds     int relativeTop   offsetViewBounds top  int relativeLeft   offsetViewBounds left    Here is the doc

User · Answer

Please use view getLocationOnScreen int   location    see Javadocs   The answer is in the integer array  x   location 0  and y   location 1

User · Answer

I just found the answer here  It says  It is possible to retrieve the location of a view by invoking the methods getLeft   and getTop    The former returns the left  or X  coordinate of the rectangle representing the view  The latter returns the top  or Y  coordinate of the rectangle representing the view  These methods both return the location of the view relative to its parent  For instance  when getLeft   returns 20  that means the view is located 20 pixels to the right of the left edge of its direct parent   so use   view getLeft       to get the location of X from left to right view getRight        to get the location of Y from right to left

User · Answer

View rootLayout   view getRootView   findViewById android R id content    int   viewLocation   new int 2    view getLocationInWindow viewLocation    int   rootLocation   new int 2   rootLayout getLocationInWindow rootLocation    int relativeLeft   viewLocation 0  - rootLocation 0   int relativeTop    viewLocation 1  - rootLocation 1     First I get the root layout then calculate the coordinates difference with the view  You can also use the getLocationOnScreen   instead of getLocationInWindow

User · Answer

This is one solution  though since APIs change over time and there may be other ways of doing it  make sure to check the other answers   One claims to be faster  and another claims to be easier   private int getRelativeLeft View myView        if  myView getParent      myView getRootView            return myView getLeft        else         return myView getLeft     getRelativeLeft  View  myView getParent        private int getRelativeTop View myView        if  myView getParent      myView getRootView            return myView getTop        else         return myView getTop     getRelativeTop  View  myView getParent         Let me know if that works   It should recursively just add the top and left positions from each parent container  You could also implement it with a Point if you wanted

User · Answer

Incase someone is still trying to figure this out  This is how you get the center X and Y of the view       int pos     new int 2       view getLocationOnScreen pos       int centerX   pos 0    view getMeasuredWidth     2      int centerY   pos 1    view getMeasuredHeight     2

User · Answer

You can use the following the get the difference between parent and the view you interested in  private int getRelativeTop View view        final View parent    View  view getParent        int   parentLocation   new int 2       int   viewLocation   new int 2        view getLocationOnScreen viewLocation       parent getLocationOnScreen parentLocation        return viewLocation 1  - parentLocation 1      Dont forget to call it after the view is drawn   timeIndicator getViewTreeObserver   addOnGlobalLayoutListener    - gt            final int relativeTop   getRelativeTop timeIndicator

[android] Getting View's coordinates relative to the root layout

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