camera programming in black berry

my following code returns null ,

byte[开发者_StackOverflow] image1 = _videoControl.getSnapshot(null);

any suggestion please

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Few important moments about VideoControl.getSnapshot method:

• some manufacturers may not implement getSnapshot() method;
• the viewfinder must actually be visible on the screen prior to calling getSnapShot();
• if you attempt to take pictures too quickly, however, getSnapShot() may return null. The camera requires time to clear out its buffer and prepare for the next shot;
• you may check MMAPI System Property for "video.snapshot.encodings" before capturing:

if (System.getProperty("video.snapshot.encodings") == null) {
        // getSnapshot() is not supported
}

You may read this chapter from book "Advanced BlackBerry Development": http://books.google.com/books?id=F4Qu-lpoVncC&pg=PA53&lpg=PA53#v=onepage&q&f=false

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Since VideoControl.getSnapshot method is not supported by all devices I'd recommend to use another approach. You can start the native BB Camera app with this line of code:

Invoke.invokeApplication(Invoke.APP_TYPE_CAMERA, new CameraArguments());

and then using the FileSystemJournalListener catch the taken image.

The BB SDK on your PC contains samples. Search for 'fileexplorerdemo' sample to see the rest of details.