WebView: how to preserve the user's zoom settings across sessions?

Question

My app uses a WebView, and users sometimes adjust the zoom level to make the text larger. However the zoom level setting is lost when the Activity is closed and another one started.

I can't see how to get and set the zoom level programatically on WebView, can anyone suggest a way this could be done?

Jorgesys · Accepted Answer · 2010-06-03T01:06:00.570

its me Jorge from Grupo Reforma, this is my implementation using SharedPreferences..

static final  String PREFS_Zoom = "PREFS_Zoom";

 private String zoomlevel;
 private int Default_zoomlevel=100;

     @Override
     public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);

      mWebView = (WebView) findViewById(R.id.webview);        

      GetZoom();
      mWebView.setInitialScale(Default_zoomlevel);

      FrameLayout mContentView = (FrameLayout) getWindow().getDecorView().findViewById(android.R.id.content);
      View zoom = mWebView.getZoomControls();
      mContentView.addView(zoom, ZOOM_PARAMS);
      zoom.setVisibility(View.VISIBLE);

      WebSettings webSettings = mWebView.getSettings();
      webSettings.setSavePassword(false);
      webSettings.setSaveFormData(false);
      webSettings.setJavaScriptEnabled(true);
      webSettings.setSupportZoom(true);

      mWebView.loadUrl("http://www.elnorte.com");
    }



     private void GetZoom(){
      try{
       SharedPreferences settings = getSharedPreferences(PREFS_Zoom,0);
          zoomlevel = settings.getString("zoom_level","");     
       if (zoomlevel.length() >0)   
        Default_zoomlevel = Integer.parseInt(zoomlevel);               
       else
       Default_zoomlevel =100;
      }catch(Exception ex){
       Log.e("******ZOOM ! ", "Exception GetZoom()  ::"+ex.getMessage());          
      }
     }


     private void SaveZoom(){
      try{
       SharedPreferences settings = getSharedPreferences(PREFS_Zoom,0);            
       SharedPreferences.Editor editor = settings.edit();    
       Default_zoomlevel = (int) (mWebView.getScale() *100);
       editor.putString("zoom_level",""+ Default_zoomlevel);   
       editor.commit();
      }catch(Exception ex){
       Log.e("******ZOOM ! ", "Exception SaveZoom()  ::"+ex.getMessage());    
      }
     }


     public void finish() {  
      SaveZoom();
          super.finish();     
     }

I hope this help

one can use `editor.putInt()` and `editor.getInt()` instead of storing it as a string and parsing it back as an integer. Since the values are stored inside an XML - It probably does the parsing etc on it's own — Swaroop, Oct 11 '11 at 05:10

score 2 · Answer 2 · answered Feb 17 '12 at 16:43

The answer Jorge gave is spot on, except that SaveZoom ideally should not be called on finish() (which is when the activity is destroyed). A better zoom preference saving approach would be to extend the WebView's WebViewClient, and override onScaleChanged(). So continuing Jorge's onCreate method:

public void onCreate(Bundle savedInstanceState)
{

    ....

    class MyWebViewClient extends WebViewClient
    {
        @Override
        public void onScaleChanged(WebView wv, float oldScale, float newScale)
        {
            SaveZoom();
        }
    }

    mWebView.setWebViewClient(new MyWebViewClient());
}

Problem: onScaleChanged is not called when zooming by multi-touch gesture (Android bug). — Pointer Null, Jul 06 '12 at 13:19

score 1 · Answer 3 · answered Jun 02 '10 at 17:17

Perhaps you could try:

http://d.android.com/reference/android/webkit/WebSettings.html#setDefaultZoom(android.webkit.WebSettings.ZoomDensity)

&

http://d.android.com/reference/android/webkit/WebSettings.html#getDefaultZoom()

I haven't tried it myself but that looks like it might work

WebView: how to preserve the user's zoom settings across sessions?

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