How to view downloaded PDF inside android app?

Question

I am trying to view some pdf documents within my android app, which have been downloaded to the storage. I liked the idea of using Mozilla pdfjs library and so far I have tried this but no success.

webView.settings.javaScriptEnabled = true
webView.settings.loadWithOverviewMode = true
webView.settings.useWideViewPort = true
webView.settings.domStorageEnabled = true
webView.settings.allowFileAccessFromFileURLs = true
webView.settings.allowUniversalAccessFromFileURLs = true
webView.settings.mixedContentMode = WebSettings.MIXED_CONTENT_ALWAYS_ALLOW
webView.webViewClient = object : WebViewClient() {
    override fun onReceivedSslError(
        view: WebView?,
        handler: SslErrorHandler?,
        error: SslError?
    ) {
        handler?.proceed()
    }
}
webView.setWebChromeClient(object : WebChromeClient() {

    override fun onProgressChanged(view: WebView?, newProgress: Int) {
        super.onProgressChanged(view, newProgress)
        if (newProgress == 100) {
            showToast("Progress complete")
        }
    }
})
webView.setWebChromeClient(object : WebChromeClient() {
    override fun onProgressChanged(view: WebView?, newProgress: Int) {
        super.onProgressChanged(view, newProgress)
        if (newProgress == 100) {
            showToast("Progress complete")
        }
    }
})
val url = Uri.parse(Environment.getExternalStorageDirectory().toString() + "/CallE/TrainingPdf.pdf")
println(url)
val newUrl = "file:///android_asset/pdfjs/web/viewer.html?file=" + url
webView.loadUrl(newUrl)