Various ways to get the height of a Webview on Android. Nothing really works on all cases

WebViewHeight.kt

import android.view.ViewTreeObserver
import android.webkit.JavascriptInterface
import android.webkit.WebView
import android.webkit.WebViewClient

// Try 1

private fun getHeightFromDocumentBodyScrollHeight(webView: WebView, setHeight: (Int)->Unit) {
    webView.webViewClient = object : WebViewClient() {
        override fun onPageFinished(view: WebView?, url: String?) {
            view?.let {
                it.settings.javaScriptEnabled = true
                it.addJavascriptInterface(WebAppInterface(it, setHeight), "AndroidGetHeightFunction")
                it.loadUrl("javascript:AndroidGetHeightFunction.resize(document.body.scrollHeight)")
            }
        }
    }
}

class WebAppInterface(private val webView: WebView, val setHeight: (Int)->Unit) {
    @JavascriptInterface
    fun resize(height: Float) {
        webView.post {
            val h = Math.floor((height * webView.context.resources.displayMetrics.density).toDouble()).toInt()
            setHeight(h)
            webView.settings.javaScriptEnabled = false
        }
    }
}

// Try 2

private val heightWebViewJSScript = "(function() {var pageHeight = 0;function findHighestNode(nodesList) { for (var i = nodesList.length - 1; i >= 0; i--) {if (nodesList[i].scrollHeight && nodesList[i].clientHeight) {var elHeight = Math.max(nodesList[i].scrollHeight, nodesList[i].clientHeight);pageHeight = Math.max(elHeight, pageHeight);}if (nodesList[i].childNodes.length) findHighestNode(nodesList[i].childNodes);}}findHighestNode(document.documentElement.childNodes); return pageHeight;})()"
private fun getHeightWithJavascriptEvaluation(webView: WebView, setHeight: (Int)->Unit) {
    webView.settings.javaScriptEnabled = true
    webView.webViewClient = object : WebViewClient() {
        override fun onPageFinished(view: WebView, url: String) {
            webView.evaluateJavascript(heightWebViewJSScript) { height ->
                val h = Math.floor((height.toInt() * webView.context.resources.displayMetrics.density).toDouble()).toInt()
                setHeight(h)
                webView.settings.javaScriptEnabled = false
            }
        }
    }
}

// Try 3

private fun getHeightWithViewTreeObserver(webView: WebView, setHeight: (Int)->Unit) {
        webView.viewTreeObserver.addOnPreDrawListener(object : ViewTreeObserver.OnPreDrawListener {
            override fun onPreDraw(): Boolean {
                val height = webView.measuredHeight
                if (height != 0) {
                    val h = Math.floor((height * webView.context.resources.displayMetrics.density).toDouble()).toInt()
                    setHeight(height)
                    webView.viewTreeObserver.removeOnPreDrawListener(this)
                }
                return false
            }
        })
}

// Try 4

private fun getHeightWithLayoutChangeListener(webView: WebView, setHeight: (Int)->Unit) {
    webView.addOnLayoutChangeListener{ _, _, _, _, _, _, _, _, _ ->
        setHeight(webView.contentHeight)
    }
}

Hey @antonis ,
I have came across this code-snippet as I was also struggling with the dynamic webview height issue, when expandable/collapse view is being used in webview.
Your approach, by multiplying height to "webView.context.resources.displayMetrics.density" is helped me to resolve this issue.

However, I am curious to know that, you wrote in the beginning that, "Nothing really works on all cases", so wondering, about which cases you identified where you found your tried approaches are not working.

Thank you for reaching out @DhavalsShah :)

I was also struggling with the dynamic webview height issue

Sorry to hear that this is still an issue on Android :(
It's been a while since I've tried this and I don't remember the details. From what I recall in some use cases I was getting erroneous values (eg zero) and retried an alternative approach within the code. Tbh I don't consider the above a solid approach and it's more like a hack.