Immediately get UIImage after UIImagepickercontroller -(void)takePicture

Question

I have a cameraOverlay with it's own camera button and I use the takePicture method when they press the camera button and use the delegate method

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo: (NSDictionary *)info{
    [CommonClass AddToStack:@"ReviewController:imagePickerController"];
    PhotoOverlay *overlay = (PhotoOverlay*)picker.cameraOverlayView;
    [overlay setupImage:[info objectForKey:UIImagePickerControllerOriginalImage]];
}

the setupImage: method just does sets the image for a UIImageView I have on the overlay

the problem with this is that there is a 0.3 second gap between the takePicture and the imagepicker delegate method so it looks really weird. I've seen apps transition immediately from pressing the camera to the final view when using a custom overlay.

has anybody encountered this?

Answer 1

The way to get the instant image is by doing a screenshot of the screen and using that image first, then call the takePicture and replace it with the screenshot when it's ready (the screenshot is a lower resolution than the actual image).

Here is my snippet:

-(void)CameraPressedTake
{
extern CGImageRef UIGetScreenImage();
PhotoOverlay *overlay = (PhotoOverlay*)cameraPicker.cameraOverlayView;

CGImageRef cgoriginal = UIGetScreenImage();

float width = 320.0;
float height = 480.0-[overlay myHeight];
//if it's retina...
if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)] && [[UIScreen mainScreen] scale] == 2) {
    width = 2*width;
    height = 2*height;
}
CGImageRef cgimg = CGImageCreateWithImageInRect(cgoriginal, CGRectMake(0, 0, width, height));            
UIImage *viewImage = [UIImage imageWithCGImage:cgimg];
[overlay setupImage:viewImage];
CGImageRelease(cgoriginal);                
CGImageRelease(cgimg);
[cameraPicker takePicture];
}