Android – WebView inside ViewPager or ScrollView – weird rendering bug on Android 3.0+

androidandroid-3.0-honeycombandroid-4.0-ice-cream-sandwichhardware-accelerationwebview

I have a ViewPager. Every page of the ViewPager is a ScrollView. The ScrollView contains a WebView and several other Views.

On Android 2.3 and older everything works fine but on 3.0+ there's a weird rendering issue:

The WebView should start right under the photo

When scrolling left / right in the ViewPager, there is also a very subtle rendering issue (which is present in Android 4.0 Gmail app too).

Best Answer

This might be related to hardwareAcceleration. Try specifically turning it off. You can do this

1) in the application tag inside your manifest (which will disable hardware acceleration throughout the app)

android:hardwareAccelerated="false"

OR 2) Disabling it for the problematic view in code:

myView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);

For more information, and to check if a WebView or a ListView handle hardware acceleration correct see this link

Related Solutions

Android – WebView “flashing” with white background if hardware acceleration is enabled (Android 3.0+)

I found the most effective fix for this, first mentioned here, was to set a transparent background color after the layout has been inflated:

webView.setBackgroundColor(Color.argb(1, 0, 0, 0));

Yes, it's a total hack, but it's the only solution I've found to work well without disabling hardware acceleration.

Note that this does not work through setting the background in XML.

This has been resolved in Jellybean, although some users have reported seeing this in KitKat. Check that you have not disabled hardware acceleration, and if the problem indeed disappears, you will probably want to wrap that code in a conditional statement to only target older devices:

if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
    webView.setBackgroundColor(Color.argb(1, 0, 0, 0));
}

Iphone – What sort of cleanup work should I do aside from dealloc in an iPhone app

For views, I typically release any UI widgets that were created from the NIB file in viewDidUnload. Any models or other objects I clean up in the viewController's dealloc.

Sometimes I have views that create a model (say a Dictionary of section names to section rows) from a primary data object. If I create/build an object in viewDidLoad I will release it in viewDidUnload (since my viewDidLoad will get called again when the time is right).

I believe that in SDK 3+ you don't have to typically worry about implementing didReceiveMemoryWarning directly as the new viewDidUnload method is the main place to do your view cleanup.

For normal objects (objects without special life cycles like a view controller has) I just release their member vars in the dealloc.

Best Answer

Related Solutions

Android – WebView “flashing” with white background if hardware acceleration is enabled (Android 3.0+)

Iphone – What sort of cleanup work should I do aside from dealloc in an iPhone app

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