Given a coordinate relative to the descendant, find the coordinate in a parent view's coordinates. - Android User Interface

Android examples for User Interface:View Parent

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Description

Given a coordinate relative to the descendant, find the coordinate in a parent view's coordinates.

Demo Code


//package com.java2s;

import android.view.View;

import java.util.ArrayList;

public class Main {
    /**//from  w  w w. ja  v a  2s.c om
     * Given a coordinate relative to the descendant, find the coordinate in a parent view's
     * coordinates.
     *
     * @param descendant        The descendant to which the passed coordinate is relative.
     * @param root              The root view to make the coordinates relative to.
     * @param coord             The coordinate that we want mapped.
     * @param includeRootScroll Whether or not to account for the scroll of the descendant:
     *                          sometimes this is relevant as in a child's coordinates within the descendant.
     * @return The factor by which this descendant is scaled relative to this DragLayer. Caution
     * this scale factor is assumed to be equal in X and Y, and so if at any point this
     * assumption fails, we will need to return a pair of scale factors.
     */
    public static float getDescendantCoordRelativeToParent(View descendant,
            View root, int[] coord, boolean includeRootScroll) {
        ArrayList<View> ancestorChain = new ArrayList<View>();

        float[] pt = { coord[0], coord[1] };

        View v = descendant;
        while (v != root && v != null) {
            ancestorChain.add(v);
            v = (View) v.getParent();
        }
        ancestorChain.add(root);

        float scale = 1.0f;
        int count = ancestorChain.size();
        for (int i = 0; i < count; i++) {
            View v0 = ancestorChain.get(i);
            // For TextViews, scroll has a meaning which relates to the text position
            // which is very strange... ignore the scroll.
            if (v0 != descendant || includeRootScroll) {
                pt[0] -= v0.getScrollX();
                pt[1] -= v0.getScrollY();
            }

            v0.getMatrix().mapPoints(pt);
            pt[0] += v0.getLeft();
            pt[1] += v0.getTop();
            scale *= v0.getScaleX();
        }

        coord[0] = (int) Math.round(pt[0]);
        coord[1] = (int) Math.round(pt[1]);
        return scale;
    }
}

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