with fw 2.2 i was able to get a screenshot using the private method _createCGImageRefRepresentationInFrame of UIWindow. In 3.0 doesn't exist anymore.
I used that method with the PLCameraView over a window to take a small video just by get as much screenshot as possible. Now i tried with the CALayer of the PLPreviewView and -renderInContext: method, but it always render the view as it has the iris closed.
How can i take a screenshot of what the cameraView is showing?
Thanks
Marco
Try for following code snippet to get
CGImageRef imageRef = [[UIApplication sharedApplication] _createDefaultImageSnapshot];
UIImage* img = [UIImage imageWithCGImage:imageRef];
//Now you can save it the way you want
//May as following
//oops yes this image is just the screenshot so better take care of unwanted image side
//So cut crap out from the image captured
UIImageWriteToSavedPhotosAlbum(img, nil, nil, nil);
Related
So, I know how to take a screenshot with UIKit:
UIWindow *window = [[[UIApplication sharedApplication] delegate] window];
UIGraphicsBeginImageContext(window.bounds.size);
[window.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
And I know how to take a screenshot with OpenGL
// Some preparation to read pixels into a buffer
glReadPixels(0,0,backingWidth, backingHeight, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
// Some code to massage the raw pixel data into an image
My app mixes OpenGL and UIKit, so any screenshot taken with just one method doesn't look right.
What's the best way to either
a) Composit the two images together or
b) Take a screenshot that can capture both OpenGL and UIKit together
This is a similar post which has some answers. Apparently you can use either UIGetScreenImage, or glReadPixels to do this task. Hope that helps!
I'm trying to emulate the animation seen in the default camera app, where a snapshot of the cameras viewfinder is animated into the corner of the apps display.
The AVCaptureVideoPreviewLayer object that holds the key to solving this problem isn't very open to these requirements: trying to create a copy of it in a new layer with ..
- (id)initWithLayer:(id)layer
.. returns an empty layer, without the image snapshot, so clearly there is some deeper magic going on here.
Your clues/boos are most welcome.
M.
facing the same woes, from a slightly different angle.
Here are possible solutions, that none are too great IMO:
You can add to an AVCaptureSession both an AVCaptureStillImageOutput and an AVCaptureVideoDataOutput. When you set the sessionPreset to AVCaptureSessionPresetHigh you'll start getting frames by the API, and when you switch to AVCaptureSessionPresetPhoto you can take real images. So right before taking the picture, you can switch to video, get a frame, and then return to camera. Major caveat is that it takes a "long" time (couple of seconds) for the camera to switch between the video camera and picture camera.
Another option would be to use only the camera output (AVCaptureStillImageOutput), and use UIGetScreenImage to get a screen capture of the phone. You could then crop out the controls and leave only the image. This gets complicated if you're showing UI controls over the image. Also, according to this post, Apple started rejecting apps that use this function (it was always iffy).
Aside from these I also tried playing with AVCaptureVideoPreviewLayer. There's this post to save a UIView or CALayer to a UIImage. But it all produces clear or white images. I tried accessing the layer, the view's layer, the superlayer, the presentationLayer, the modelLayer, but to no avail. I guess the data in AVCaptureVideoPreviewLayer is very internal, and not really part of the regular layer infrastructure.
Hope this helps,
Oded.
I think you should add an AVCaptureVideoDataOutput to the current session with:
AVCaptureVideoDataOutput *videoOutput = [[AVCaptureVideoDataOutput alloc] init];
videoOutput.videoSettings = #{ (NSString *)kCVPixelBufferPixelFormatTypeKey : #(kCVPixelFormatType_32BGRA) };
[session addOutput:videoOutput];
dispatch_queue_t queue = dispatch_queue_create("MyQueue", NULL);
[videoOutput setSampleBufferDelegate:self queue:queue];
dispatch_release(queue);
Then, implement the delegate method below to get your image snapshot:
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
UIImage *image = [self imageFromSampleBuffer:sampleBuffer];
// Add your code here that uses the image.
dispatch_async(dispatch_get_main_queue(), ^{
_imageView.image = image;
});
}
This will consume memory and reduce the performance of the app. To improve, you can also optimize your AVCaptureVideoDataOutput with:
videoOutput.minFrameDuration = CMTimeMake(1, 15);
You can also use alwaysDiscardsLateVideoFrames.
there are 2 ways to grab frames of the preview.. AVCaptureVideoDataOutput & AVCaptureStillImageOutput :)
is your capture session is setup to grab video frames, then make your layer with the cgimage from a chosen frame. if it's setup for stills, wait until getting your still image and make your layer from a scaled down version of that cgimage. if you don't have an output on your session yet, you'll have to add one i think.
Starting in iOS 7, you can use UIView::snapshotViewAfterScreenUpdates to snapshot the UIView wrapping your AVCaptureVideoPreviewLayer. This is not the same as UIGetScreenImage, which will get your app rejected.
UIView *snapshot = [self.containerView snapshotViewAfterScreenUpdates:YES];
Recall the old-school way of turning a view into an image. For some reason it worked on everything except for camera previews:
UIGraphicsBeginImageContextWithOptions(self.containerView.bounds.size, NO, [UIScreen mainScreen].scale);
[self.containerView drawViewHierarchyInRect:self.containerView.bounds afterScreenUpdates:YES];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
I'd like to get the image that is being displayed on the UIImagePickerController when user uses the camera. And when I get I want to process the image and display instead of regular camera view.
But the problem is when I want to get the camera view, the image is just a black rectangle.
Here's my code:
UIView *cameraView = [[[[[[imagePicker.view subviews] objectAtIndex:0]
subviews] objectAtIndex: 0]
subviews] objectAtIndex: 0];
UIGraphicsBeginImageContext( CGSizeMake(320, 427) );
[cameraView.layer renderInContext: UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
imageToDisplay.image = [PixelProcessing processImage: viewImage]; //In this case the image is black
//imageToDisplay.image = viewImage; //In this case the image is black too
//imageToDisplay.image = [UIImage imageNamed: #"icon.png"]; //In this case image is being displayed properly
What am I doing wrong?
Thanks.
This one is also working quite good. Use it when the camera preview is open:
UIImage *viewImage = [[(id)objc_getClass("PLCameraController")
performSelector:#selector(sharedInstance)]
performSelector:#selector(_createPreviewImage)];
But as far as I found out it brings the same results than the following solution which takes a 'screenshot' of the current screen:
extern CGImageRef UIGetScreenImage();
CGImageRef cgoriginal = UIGetScreenImage();
CGImageRef cgimg = CGImageCreateWithImageInRect(cgoriginal, rect);
UIImage *viewImage = [UIImage imageWithCGImage:cgimg];
CGImageRelease(cgoriginal);
CGImageRelease(cgimg);
A problem I didn't still find a fix for is, how can one get the camera image very fast without any overlays?
The unofficial call is:
UIGetScreenImage()
which you declare above the #implementation as:
extern CGImageRef UIGetScreenImage();
There may be a documented way to do this in 3.1, but I'm not sure. If not, please please file a Radar with Apple asking them to make some kind of screen grab access public!!!
That uses your same AppleID you log in to the iPhone development portal with.
Update: This call is not yet documented, but Apple explicitly has given the OK to use it with App Store apps.
at least for now, there's no way to do this. (certainly no official documented way, and as far as I know nobody's figured out an unofficial way either.)
the camera preview data is being drawn by the OS in some way that bypasses the normal graphics methods.
I need to capture a screen shot of a video playing in mpmovieplayer controller, but all I get is a red screen (I made the coverView with red background and 0.5 alpha).
Here is the code:
NSArray *windows = [[UIApplication sharedApplication] windows];
if ([windows count] > 1)
{
UIWindow *moviePlayerWindow = [[UIApplication sharedApplication] keyWindow];
UIView *coverView = [[UIView alloc] initWithFrame:moviePlayerWindow.bounds];
[mainController.moviePlayer pause]; //Without that it won't work either!
coverView.backgroundColor = [UIColor redColor];
coverView.alpha = 0.5;
[moviePlayerWindow addSubview:coverView];
UIGraphicsBeginImageContext(coverView.bounds.size);
[coverView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *screenShot;
screenShot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(screenShot, self, nil, nil);
}
Any ideas???
Thanks
I was curious about his myself. I believe there are similar issues with taking screenshots of OpenGL stuff too.
If you look at this blog post http://getsetgames.com/2009/07/30/5-ways-to-take-screenshots-of-your-iphone-app/, they have a method that works for an EAGLView, it might be worth giving it a go for your issue.
Follow up to the question:
Recently I have a project that requires the functionality that was asked in this thread again, and I am glad to say there is already an apple provided solution to this. I am posting this so that people that visit this thread can get an answer.
MPMoviePlayerController now has a method that return a UIImage of the moment you want to capture.
- (UIImage *)thumbnailImageAtTime:(NSTimeInterval)playbackTime timeOption:(MPMovieTimeOption)option
Just put in the playbackTime you want to capture, and bingo, UIImage.
Looking at your codes, I would like to advise that you should look for an alternative method of getting the image rather than from the mpmovieplayer itself. The reason being that the method you are using is a private framework code, and second, getting screenshots off a video is highly prone to crashes.
Instead of getting a screenshot from the video, how about tagging the video beforehand? The codes looks highly vulnerable to an app rejection by apple.
Sounds like you're taking a shot of the video overlay mask
http://en.wikipedia.org/wiki/Hardware_overlay
I am looking for a way to capture a screenshot on the iPhone with the top status bar included, I am currently using the following code:
UIGraphicsBeginImageContext(self.view.bounds.size); //self.view.window.frame.size
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil);
The above code sucessfully takes a screenshot of the iPhone UIView but does not include the top status bar (In its place is just a blank 20px space).
As of iOS 7, you can do this without the use of private APIs using
UIView *screenshotView = [[UIScreen mainScreen] snapshotViewAfterScreenUpdates:NO];
See my answer to this question:
Moving status bar in iOS 7
You can get the entire contents of the screen by calling the private API UIGetScreenImage. See my previous answer to a similar question for details.
As of Oct 8, 2009, the use of UIGetScreenImage got my app rejected! :( I would not advise using it. I believe Apple is trying to clean up all the apps and make them conform to the new 3.x OS/APIs. I'm looking for an alternative. If anyone has any suggestions. The video API?
Instead of using private API, why not render the entire UIWindow into the image context? It might be enough to replace self.view with self.view.window in your code.
You can also get the current window(s) as a property of the [UIApplication sharedApplication] instance. It's possible the status bar is on a separate window layer and maybe you'll have to render the windows in order.
Something like this:
UIGraphicsBeginImageContext(self.view.window.frame.size);
for (UIWindow *window in [[UIApplication sharedApplication] windows]) {
[window.layer renderInContext:UIGraphicsGetCurrentContext()];
}
UIImage *screenshotImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil);
At any rate, you probably don't need to resort to private API.