Android get height of webview content once rendered

Question

I\'m trying to get the height of a webview once it has been rendered. It always returns null, I\'ve tried getHeight, getMeasuredHeight, getCo

Answer 1

I found this solution to be 100% reliable.

Subclass your WebView and there is a need to invoke javascript after the content has been loaded.

// callback made this way in order to get reliable html height and to avoid race conditions
    @SuppressLint("SetJavaScriptEnabled")
    override fun onPageFinished(view: WebView?, url: String?) {
        view?.let {
            it.settings.javaScriptEnabled = true
            it.addJavascriptInterface(WebAppInterface(it), "AndroidGetHeightFunction")
            it.loadUrl("javascript:AndroidGetHeightFunction.resize(document.body.scrollHeight)")
        }
    }

We can then get proper height and disable javascript in callback (for security and consistency):

inner class WebAppInterface(private val webView: WebView) {
    @JavascriptInterface
    fun resize(height: Float) {
        webView.post {
            heightMeasuredListener?.invoke(formatContentHeight(webView, height.toInt()))
            webView.settings.javaScriptEnabled = false
        }
    }
}

WebView must call post() as the code inside resize(...) is called in WebView thread!

After, make sure to scale your pixels to match density pixels!:

fun formatContentHeight(webView: WebView, height: Int): Int = Math.floor((height * webView.context.resources.displayMetrics.density).toDouble()).toInt()