如何确定HTML元素何时在Android WebView中获得焦点？

Question

I am trying to determine when a Text Field in a html page is focused from the Android WebView. Some notes: I do not own the web page so I can't add anything directly to the webpage.

What I have tried:

    webSettings.setJavaScriptEnabled(true);
    webSettings.setDomStorageEnabled(true);
    webView.addJavascriptInterface(new Object() {

        @JavascriptInterface
        public void displayScanButton() {
            WebViewActivity.this.runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Log.d("SCAN", "DISPLAY SCAN BUTTON");
                    toolbar.setVisibility(View.VISIBLE);
                }
            });
        }

        @JavascriptInterface
        public void hideScanButton() {
            WebViewActivity.this.runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Log.d("SCAN", "HIDE SCAN BUTTON");
                    toolbar.setVisibility(View.GONE);
                }
            });
        }
    }, "Android");

@Override
public void onPageFinished(WebView view, String url) {
    view.loadUrl("javascript:document.getElementById('tNewLabels').onfocus = Android.displayScanButton; document.getElementById('tNewLabels').onfocusout = Android.hideScanButton;");
}

I have a couple variations of that as well but that is what I currently have. It does not set onfocus for the input field.

Basically what I want is when the user clicks on the input field to type in text, I display my toolbar that I have attached to the keyboard for this specific element only. And when the user no longer has focus of the input field, hide the toolbar. I would think there would be a way since the WebView knows when to open up the keyboard and when to close it. Possibly a way to intercept this?

Thanks for any help.

Answer 1

Try this:

document.getElementById('tNewLabels').onfocus = function() { Android.displayScanButton(); };
document.getElementById('tNewLabels').onfocusout = function() { Android.hideScanButton(); };

For the Android-Java bridge to work, your function must have the interface object as the "this" variable. Assigning the function directly to the event strips it from its attachment to the interface object. I heard it used to work anyway in older versions of the WebView, but it no longer does.

And sorry for reviving an old question, you probably have already figured it out.