CODEWITHSUNDEEP
javascriptandroidios
user2122422
user2122422

Reputation: 103

How to find out if WebView is displayed/onscreen/visible using JavaScript

I have a webpage that "plays a video" using sprite sheets. The page is mobile-optimized, so it can get loaded into Android and iOS WebViews. I'd like to know is when the page is visible so only after that I can play the video. I don't want users to catch the video mid-stream because the WebView lags in presenting itself.

I can see some developers might wait until the whole page has finished pulling in all the assets from the page before making it visible to the user. So, I don't want the "video" to start before that time. I can't rely on window.onload because that event fires even when the WebView isn't onscreen or visible.

How can I accomplish this from the client side, with some JavaScript, preferably?

[Edit] To be clear, I'm implying that I don't have any control over the native WebView. You can load web pages into a WebView that isn't onscreen and push the view or add it to the on-screen layout at a later time. My issue is that when my webpage's URL is loaded into a WebView, I can't tell when the WebView comes onscreen.

Upvotes: 7

Views: 2303

Answers (3)

Mathew
Mathew

Reputation: 1798

Take a look at the Safari Web Content Guide. Scroll down to the Supported Events table. I am thinking (or hoping) that the pageshow event will do what you are hoping for. There is also the focus event.

Looks like using these events for mobile Safari would be as easy as

<body onpageshow="onPageShow();">

I am less familiar with Android, but I will look into it real quick.

EDIT: The onpageshow solution should work the same way in Android 2.2 and above as it does in iOS 4.0 and above. As for whether it works the way you need it to, I am not entirely sure. Let me know!

Upvotes: 3

omid
omid

Reputation: 772

you can use phonegap library: 

document.addEventListener("deviceready", onDeviceReady, false);

function onDeviceReady() {
    // Now safe to use the PhoneGap API
}

phonegap is very good for handle events and more action in webview.

Upvotes: 1

Ashish Agarwal
Ashish Agarwal

Reputation: 14925

It is not possible to control the webview using JavaScript. If its not too late to change the design of the app, using native APIs will give you more control of the webview.

You could insert a timeout in the webpage before loading the video. It might be worth a shot.

Upvotes: 1

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