iPhone4 iOS take screenshot of the view without NavBar and TabBar? - objective-c

Question

I got this code to be able to take a screenshot of the view.
UIGraphicsBeginImageContext(scrollView.bounds.size);
[scrollView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSData * data = UIImagePNGRepresentation(image);
However, even if I set the context to be 320x480, parts of the scroll view are still not shown. The view that the scrollview manages can perfectly fit within the 320x480 frame, but parts of it are covered by the status bar, navBar and TabBar.
I would like to take full screen (320x480) screenshot of the view with the parts of the view, covered by status bar, TabBar and NavBar visible. Any pointers on how to do this?
An extra question, which may be related: the resulting image is using x1 scale, and looks very blurry on the retina display, which scales takes a larger image and scales it down. This means I'll need to render the 640x960 screenshot to reproduce the original crisp quality. How would I go about doing that?
Thank you!

Answer 1

I found the following on this site: http://www.icodeblog.com/2009/07/27/1188/
UIGraphicsBeginImageContext(YourView.frame.size);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil);
You may also want to check out this (Apple's example of how to make a screenshot): http://developer.apple.com/library/ios/#qa/qa1703/_index.html

Answer 2

First make a screenshot of the whole screen:
// Create a graphics context with the target size
// On iOS 4 and later, use UIGraphicsBeginImageContextWithOptions to take the scale into consideration
// On iOS prior to 4, fall back to use UIGraphicsBeginImageContext
CGSize imageSize = [[UIScreen mainScreen] bounds].size;
if (NULL != UIGraphicsBeginImageContextWithOptions)
UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0.0);
else
UIGraphicsBeginImageContext(imageSize);
CGContextRef context = UIGraphicsGetCurrentContext();
// Iterate over every window from back to front
for (UIWindow *window in [[UIApplication sharedApplication] windows])
{
if (![window respondsToSelector:#selector(screen)] || [window screen] == [UIScreen mainScreen])
{
// -renderInContext: renders in the coordinate space of the layer,
// so we must first apply the layer's geometry to the graphics context
CGContextSaveGState(context);
// Center the context around the window's anchor point
CGContextTranslateCTM(context, [window center].x, [window center].y);
// Apply the window's transform about the anchor point
CGContextConcatCTM(context, [window transform]);
// Offset by the portion of the bounds left of and above the anchor point
CGContextTranslateCTM(context,
-[window bounds].size.width * [[window layer] anchorPoint].x,
-[window bounds].size.height * [[window layer] anchorPoint].y);
// Render the layer hierarchy to the current context
[[window layer] renderInContext:context];
// Restore the context
CGContextRestoreGState(context);
}
}
// Retrieve the screenshot image
UIImage *screenshot = UIGraphicsGetImageFromCurrentImageContext();
Then crop it to the right size
CGImageRef subImageRef = CGImageCreateWithImageInRect(screenshot.CGImage, rect);
CGRect smallBounds = CGRectMake(0, 64, 320, 372); //You should remove the hard coded numbers
UIGraphicsBeginImageContext(smallBounds.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextDrawImage(context, smallBounds, subImageRef);
UIImage* cropped = [UIImage imageWithCGImage:subImageRef];
UIGraphicsEndImageContext();