Android Webview rem units scale way to large for boxes - android

EDIT: This bug is Webview overriding the default minimum font size.
In my example, Webview sets the minimum font-size to 8px somewhere. The solution is below :)
Android Webview rem units scale way to large.
All rem units appear 8 times too large and out of place in Android Webview.
The only rem tag that works correctly is font-size:30rem; for text. Everything else
seems to scale way to large. i.e. 100rem = 800px # 1.0px scale.
Strangely, after I pass 8.0px while scaling, the box starts to enlarge.
This example works on every browser that supports rem units except Webview.
Anyone have an idea?
Online Example: http://digitalknob.com/rem.html
JSFiddle Example: https://jsfiddle.net/aquawicket/71p49ag9/
Android Example: http://digitalknob.com/remTest.apk
I've tried mWebView.getSettings().setLoadWithOverviewMode(true);
I've tried mWebView.getSettings().setUseWideViewPort(true);
I've tried < meta name="viewport" content="width=device-width, user-scalable=no" /> and other variations.
I've tried loading a default user style sheet.
rem.html
<!DOCTYPE html>
<html style="font-size:1.0px;">
<head>
</head>
<body style="font-size:16em;">
<button style="position:absolute;width:100px;height:100px;font-size:60px;" onclick="ScaleDown()">-</button>
<button style="position:absolute;left:110px;width:100px;height:100px;font-size:60px;" onclick="ScaleUp()">+</button>
<a id="text" style="position:absolute;top:20px;left:220px;font-size:60px;">1.0px</a>
<!-- FIXME: rem units appear 8 times too large and out of place in Android Webview.
The only rem tag that works correctly is font-size:30rem;
This html file works as expexted on all other browsers. -->
<div style="position:absolute;top:115px;width:100rem;height:100rem;background-color:green;">
<a style="position:relative;top:30rem;left:16rem;font-size:30rem;">Scale</a>
</div>
<script>
var scale = window.devicePixelRatio;
Update_Scale();
function ScaleDown(){
scale -= 0.5;
Update_Scale();
}
function ScaleUp(){
scale += 0.5;
Update_Scale();
}
function Update_Scale(){
document.documentElement.style.fontSize = parseFloat(scale).toFixed(1)+"px";
document.getElementById("text").innerHTML = parseFloat(scale).toFixed(1)+"px";
}
</script>
</body>
</html>
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="digitalknob.remTest"
android:installLocation="auto"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:targetSdkVersion="19" android:minSdkVersion="19"></uses-sdk>
<uses-permission android:name="android.permission.INTERNET"/>
<application android:label="remTest"
android:icon="#mipmap/icon"
android:theme="#android:style/Theme.NoTitleBar.Fullscreen">
<activity android:name="digitalknob.remTest.WebviewActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
WebviewActivity.java
package digitalknob.remTest;
import android.app.Activity;
import android.os.Bundle;
import android.webkit.WebView;
public class WebviewActivity extends Activity {
private WebView mWebView;
#Override protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.webview);
mWebView=(WebView)findViewById(R.id.webview_webview);
mWebView.setWebContentsDebuggingEnabled(true); //Debuggable in Chrome
mWebView.getSettings().setJavaScriptEnabled(true);
mWebView.getSettings().setLoadWithOverviewMode(true);
mWebView.getSettings().setUseWideViewPort(true);
mWebView.loadUrl("http://digitalknob.com/rem.html");
}
#Override public void onBackPressed(){
System.exit(0);
}
}
webview.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<WebView
android:id="#+id/webview_webview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>
</RelativeLayout>

I found that setting the following webview settings will act as a workaround for this bug.
mWebView.getSettings().setMinimumFontSize(1);
mWebView.getSettings().setMinimumLogicalFontSize(1);
setMinimumFontSize
These settings really should only be honored for actual text display, not rem based positioning/sizing. This must but an android webview bug.

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MyBrowser.loadUrl("file:///android_asset/index.html");
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and also make sure in XML. your web view's height and width should be match_parent
WebView MyBrowser = (WebView) findViewById(R.id.mybrowser);
WebSettings webSettings = MyBrowser.getSettings();
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<iframe width="560" height="315" src="http://www.youtube.com/embed/hH9Kx06oO_0" frameborder="0" allowfullscreen></iframe>
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thanks.
Laurent
For embedded video, the app needs surfacetexture class. This requrires android:hardwareAccelerated="true" to be set to true.
according to http://developer.android.com/guide/topics/manifest/supports-screens-element.html, android:anyDensity="false" should not be set to false.
fullscreen video uses surfaceview, surfaceview has no requirement on hardware acceleration.
Youtube Recently released player for android :
https://developers.google.com/youtube/android/player/

edit div tag in a webview

I'm trying to make an Android app with a webview in which I have an html page. This one contains a "div" tag with the contentEditable property set to true.
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PhoneGap : 1.5.0, Android : 2.3.4
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but it's not working. I have a window with width = 320px, but it should be 480px.
When I Googled this problem, I found this:
Add these 2 line to onCreate():
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ActivityThread.performLaunchActivity(ActivityThread$ActivityRecord, Intent) line: 2496
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try this code:
Activity file:
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getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN |
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I've answered my fix here: https://stackoverflow.com/a/28755743/4612666
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JavaScript Alert in Android WebView working only at first time

I am new to Stack Exchange and Andorid development.
I am working on Android webview. I have the following code in my activity class.
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<uses-permission android:name="android.permission.INTERNET" />
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<!DOCTYPE html>
<html>
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webView.setWebViewClient(new WebViewClient());
webView.setWebChromeClient(new WebChromeClient());
Used these on my code and then my alert() worked pefectly
This is a very old question, but I recently encountered the same problem and would like to share the solution to anyone who come across this later.
You will need to assign a custom WebChromeClient to your WebView to handle the alert.
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alertDialog.show()
//Here AlertDialog is just an example. You can also simply show a Toast.
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}
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You need to call either JsResult.confirm() or JsResult.cancel() to notify your WebView whether the user confirmed or canceled the alert dialog. Otherwise, the WebView would assume an alert dialog is still showing(blocking the UI) and won't allow a new one to be shown.

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