Android: how to check if a View inside of ScrollView is visible?

Question

I have a ScrollView which holds a series of Views. I would like to be able to determine if a view is currently visible (if any part of it is curre

Answer 1

public static int getVisiblePercent(View v) {
        if (v.isShown()) {
            Rect r = new Rect();
            v.getGlobalVisibleRect(r);
            double sVisible = r.width() * r.height();
            double sTotal = v.getWidth() * v.getHeight();
            return (int) (100 * sVisible / sTotal);
        } else {
            return -1;
        }
    }

Answer 2

Use View#getHitRect instead of View#getDrawingRect on the view you're testing. You can use View#getDrawingRect on the ScrollView instead of calculating explicitly.

Code from View#getDrawingRect:

 public void getDrawingRect(Rect outRect) {
        outRect.left = mScrollX;
        outRect.top = mScrollY;
        outRect.right = mScrollX + (mRight - mLeft);
        outRect.bottom = mScrollY + (mBottom - mTop);
 }

Code from View#getHitRect:

public void getHitRect(Rect outRect) {
        outRect.set(mLeft, mTop, mRight, mBottom);
}

Answer 3

This works:

Rect scrollBounds = new Rect();
scrollView.getHitRect(scrollBounds);
if (imageView.getLocalVisibleRect(scrollBounds)) {
    // Any portion of the imageView, even a single pixel, is within the visible window
} else {
    // NONE of the imageView is within the visible window
}

Answer 4

If you want to detect that the view is FULLY visible:

private boolean isViewVisible(View view) {
    Rect scrollBounds = new Rect();
    mScrollView.getDrawingRect(scrollBounds);

    float top = view.getY();
    float bottom = top + view.getHeight();

    if (scrollBounds.top < top && scrollBounds.bottom > bottom) {
        return true;
    } else {
        return false;
    }
}

Answer 5

I you want to detect if your View is fully visible, try with this method:

private boolean isViewVisible(View view) {
    Rect scrollBounds = new Rect();
    mScrollView.getDrawingRect(scrollBounds);
    float top = view.getY();
    float bottom = top + view.getHeight();
    if (scrollBounds.top < top && scrollBounds.bottom > bottom) {
        return true; //View is visible.
    } else {
        return false; //View is NOT visible.
    }
}

Strictly speaking you can get the visibility of a view with:

if (myView.getVisibility() == View.VISIBLE) {
    //VISIBLE
} else {
    //INVISIBLE
}

The posible constant values of the visibility in a View are:

VISIBLE This view is visible. Use with setVisibility(int) and android:visibility.

INVISIBLE This view is invisible, but it still takes up space for layout purposes. Use with setVisibility(int) and android:visibility.

GONE This view is invisible, and it doesn't take any space for layout purposes. Use with setVisibility(int) and android:visibility.

Answer 6

I ended up implementing a combination of two of the Java answers ( @bill-mote https://stackoverflow.com/a/12428154/3686125 and @denys-vasylenko https://stackoverflow.com/a/25528434/3686125 ) in my project as a set of Kotlin extensions, which support either standard vertial ScrollView or HorizontalScrollView controls.

I just tossed these in a Kotlin file named Extensions.kt, no class, just methods.

I used these to determine which item to snap to when a user stops scrolling in various scrollviews in my project:

fun View.isPartiallyOrFullyVisible(horizontalScrollView: HorizontalScrollView) : Boolean {
    val scrollBounds = Rect()
    horizontalScrollView.getHitRect(scrollBounds)
    return getLocalVisibleRect(scrollBounds)
}

fun View.isPartiallyOrFullyVisible(scrollView: ScrollView) : Boolean {
    val scrollBounds = Rect()
    scrollView.getHitRect(scrollBounds)
    return getLocalVisibleRect(scrollBounds)
}

fun View.isFullyVisible(horizontalScrollView: HorizontalScrollView) : Boolean {
    val scrollBounds = Rect()
    horizontalScrollView.getDrawingRect(scrollBounds)
    val left = x
    val right = left + width
    return scrollBounds.left < left && scrollBounds.right > right
}

fun View.isFullyVisible(scrollView: ScrollView) : Boolean {
    val scrollBounds = Rect()
    scrollView.getDrawingRect(scrollBounds)
    val top = y
    val bottom = top + height
    return scrollBounds.top < top && scrollBounds.bottom > bottom
}

fun View.isPartiallyVisible(horizontalScrollView: HorizontalScrollView) : Boolean = isPartiallyOrFullyVisible(horizontalScrollView) && !isFullyVisible(horizontalScrollView)
fun View.isPartiallyVisible(scrollView: ScrollView) : Boolean = isPartiallyOrFullyVisible(scrollView) && !isFullyVisible(scrollView)

Example usage, iterating through scrollview's LinearLayout children and logging outputs:

val linearLayoutChild: LinearLayout = getChildAt(0) as LinearLayout
val scrollView = findViewById(R.id.scroll_view) //Replace with your scrollview control or synthetic accessor
for (i in 0 until linearLayoutChild.childCount) {
    with (linearLayoutChild.getChildAt(i)) {
        Log.d("ScrollView", "child$i left=$left width=$width isPartiallyOrFullyVisible=${isPartiallyOrFullyVisible(scrollView)} isFullyVisible=${isFullyVisible(scrollView)} isPartiallyVisible=${isPartiallyVisible(scrollView)}")
    }
}