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Commit 6e448088 authored by Mihai Popa's avatar Mihai Popa
Browse files

[Magnifier-36] Fix content clamping inside view 

We try to never display in the magnifier content that does not belong to
the magnified view. If the magnified view has one or more scrollable
containers, these have to be considered in order to find out the visible
portion of the view which is not masked by scrollable containers.

The previous logic for computing the visible region was wrong when one
of the containers was a ViewPager, whose getScrollX() returns the scroll
relative to all pages, rather than the currently visible one as the
logic was expecting. This CL replaces the old logic with a
View#getGlobalVisibleRect().

Bug: 74359490
Test: atest CtsWidgetTestCases:android.widget.cts.MagnifierTest
Change-Id: Ib6b63a35436aa691f29c13a0789688f23bfca9f1
parent 9009654c

core/java/android/widget/Magnifier.java

+6 −30
Original line number Diff line number Diff line
@@ -48,7 +48,6 @@ import android.view.SurfaceSession; 
import android.view.SurfaceView;

import android.view.ThreadedRenderer;

import android.view.View;

import android.view.ViewParent;

import android.view.ViewRootImpl;



import com.android.internal.R;
@@ -158,36 +157,13 @@ public final class Magnifier { 


        configureCoordinates(xPosInView, yPosInView);



        // Clamp the startX value to avoid magnifying content which does not belong to the magnified

        // view. This will not take into account overlapping views.

        // For this, we compute:

        // - zeroScrollXInSurface: this is the start x of mView, where this is not masked by a

        //                         potential scrolling container. For example, if mView is a

        //                         TextView contained in a HorizontalScrollView,

        //                         mViewCoordinatesInSurface will reflect the surface position of

        //                         the first text character, rather than the position of the first

        //                         visible one. Therefore, we need to add back the amount of

        //                         scrolling from the parent containers.

        // - actualWidth: similarly, the width of a View will be larger than its actually visible

        //                width when it is contained in a scrolling container. We need to use

        //                the minimum width of a scrolling container which contains this view.

        int zeroScrollXInSurface = mViewCoordinatesInSurface[0];

        int actualWidth = mView.getWidth();

        ViewParent viewParent = mView.getParent();

        while (viewParent instanceof View) {

            final View container = (View) viewParent;

            if (container.canScrollHorizontally(-1 /* left scroll */)

                    || container.canScrollHorizontally(1 /* right scroll */)) {

                zeroScrollXInSurface += container.getScrollX();

                actualWidth = Math.min(actualWidth, container.getWidth()

                        - container.getPaddingLeft() - container.getPaddingRight());

            }

            viewParent = viewParent.getParent();

        }



        final int startX = Math.max(zeroScrollXInSurface, Math.min(

        // Clamp the startX location to avoid magnifying content which does not belong

        // to the magnified view. This will not take into account overlapping views.

        final Rect viewVisibleRegion = new Rect();

        mView.getGlobalVisibleRect(viewVisibleRegion);

        final int startX = Math.max(viewVisibleRegion.left, Math.min(

                mCenterZoomCoords.x - mBitmapWidth / 2,

                zeroScrollXInSurface + actualWidth - mBitmapWidth));

                viewVisibleRegion.right - mBitmapWidth));

        final int startY = mCenterZoomCoords.y - mBitmapHeight / 2;



        if (xPosInView != mPrevPosInView.x || yPosInView != mPrevPosInView.y) {