Android - JavaScript : touchstart event not fired until zoom or scroll the page

In my Android application, The user can browse some HTML pages using ViewPager, and the user can touch an element to highlight.

the problem is when trying to get the touch event using javascript using the following code, elementFromPoint returns null when navigate to new page, but after the user zoom the page or scroll on it, it works right.

I found that register of the touchstart event happens after zoom or scroll the page. so it works right after that although it is registered on $(document).ready()

        $(document).ready(function(){
            document.addEventListener("touchstart", touchstart, false);     
        });     

        function touchstart(e) {                              
            var x = e.targetTouches[0].clientX; 
            var y = e.targetTouches[0].clientY;                             
             el = document.elementFromPoint(x, y);  
            }

Thank you

Answers


write next code in your java code after calling javascript :

    myWebview.scrollTo(1, 0);
    myWebview.scrollTo(0, 0);

or use zoom in then zoom out

    myWebview.zoomIn();
    myWebview.zoomOut();

using Mohamed Abdel Latif's solution (obviously this is another lame WebView bug) below is what fixed it for me on Android 4.1.2. Note: I tested this on Android 4.4.2 and this hack-to-fix-a-bug isn't needed.

@Override
public void onCreate(Bundle savedInstanceState)
{

    final WebView myWebView = (WebView) findViewById(R.id.mywebview);
    myWebView.setHorizontalScrollBarEnabled(false);
    myWebView.getSettings().setJavaScriptEnabled(true);
    myWebView.loadDataWithBaseURL("file:///android_asset/", YOUR_HTML_GOES_HERE, "text/html", "utf-8", null);

    myWebView.setWebViewClient(new WebViewClient()
    {
        // overcome the ontouchstart registration bug !
        @Override
        public void onPageFinished(WebView view, String url)
        {
            super.onPageFinished(view, url);
            final WebView myWebView = (WebView) findViewById(R.id.mywebview);
            myWebview.scrollTo(1, 0);
            myWebview.scrollTo(0, 0);
        }
    });
}

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