Android: How to get scroll position when displaying document files in webview by using gview of Google

Question

I am using gview of Google Docs to display document files but I cannot get scroll position as well as set scroll offset to force document view jump to any positions.

Here is my code:

String url = "https://dl.dropbox.com/s/8wubzwsbcafqxmt/GMAT-Vocabulary-List.pdf?dl=0";
webView.loadUrl("https://docs.google.com/viewer?url=" + url + "&embedded=true");

public boolean onTouchEvent(final MotionEvent event) {
    if (event.getAction() == MotionEvent.ACTION_MOVE) {
        int xPos = webView.getScrollX();
        int yPos = webview.getScrollY();
        Log.d("Scroll", "xPos = " + xPos + ";yPos = " + yPos);
    }
    return false;
}

The logcat is always like this: "xPos = 0;yPos = 0".

And nothing happens when I set webView position like this:

webView.setScrollY(1000);

I have no idea why!

I searched and tried many solutions but this problem is still not resolved. Could you please show me some ways to resolve this problem.

Thank you in advance!