iPhone занимает увеличенную реальность скриншот с AVCaptureVideoPreviewLayer

Question

У меня есть небольшое приложение дополненной реальности, которое я разрабатываю, и хотел бы знать, как сохранить скриншот того, что пользователь видит с нажатием кнопки или таймера.

Приложение работает, накладывая прямую трансляцию камеры над другим UIView. Я могу сохранить скриншоты с помощью кнопки питания + кнопка «домой», они сохраняются в кадре камеры. Однако Apple не будет отображать AVCaptureVideoPreviewLayer, даже если я попрошу окно сохранить себя. Он создаст прозрачную часть холста, где находится слой предварительного просмотра.

Каким образом можно использовать приложение дополненной реальности для сохранения скриншотов, в том числе прозрачности и подсмотров?

//displaying a live preview on one of the views 
    -(void)startCapture 
{ 
     captureSession = [[AVCaptureSession alloc] init]; 
     AVCaptureDevice *audioCaptureDevice = nil; 

     //   AVCaptureDevice *audioCaptureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]; 

     NSArray *videoDevices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo]; 

     for (AVCaptureDevice *device in videoDevices) { 

      if(useFrontCamera){ 
       if (device.position == AVCaptureDevicePositionFront) { 
        //FRONT-FACING CAMERA EXISTS 
        audioCaptureDevice = device; 
        break; 
       } 
      }else{ 
       if (device.position == AVCaptureDevicePositionBack) { 
        //Rear-FACING CAMERA EXISTS 
        audioCaptureDevice = device; 
        break; 
       } 
      } 

     } 


     NSError *error = nil; 
     AVCaptureDeviceInput *audioInput = [AVCaptureDeviceInput deviceInputWithDevice:audioCaptureDevice error:&error]; 
     if (audioInput) { 
      [captureSession addInput:audioInput]; 
     } 
     else { 
      // Handle the failure. 
     } 


if([captureSession canAddOutput:captureOutput]){ 
captureOutput = [[AVCaptureVideoDataOutput alloc] init]; 
    [captureOutput setAlwaysDiscardsLateVideoFrames:YES]; 
    [captureOutput setSampleBufferDelegate:self queue:queue]; 
    [captureOutput setVideoSettings:videoSettings]; 

    dispatch_release(queue); 
}else{ 
//handle failure 
} 

     previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:captureSession]; 
     UIView *aView = arOverlayView; 
     previewLayer.frame =CGRectMake(0,0, arOverlayView.frame.size.width,arOverlayView.frame.size.height); // Assume you want the preview layer to fill the view. 

     [aView.layer addSublayer:previewLayer]; 
     [captureSession startRunning]; 


} 

//ask the entire window to draw itself in a graphics context. This call will not render 

// AVCaptureVideoPreviewLayer. Он должен быть заменен представлением UIImageView или GL. // см следующий код для создания динамического обновления UIImageView - (Недействительными) saveScreenshot {

UIGraphicsBeginImageContext(appDelegate.window.bounds.size); 

    [appDelegate.window.layer renderInContext:UIGraphicsGetCurrentContext()]; 

    UIImage *screenshot = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 

    UIImageWriteToSavedPhotosAlbum(screenshot, self, 
            @selector(image:didFinishSavingWithError:contextInfo:), nil); 


} 


//image saved to camera roll callback 
- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error 
    contextInfo:(void *)contextInfo 
{ 
    // Was there an error? 
    if (error != NULL) 
    { 
     // Show error message... 
     NSLog(@"save failed"); 

    } 
    else // No errors 
    { 
     NSLog(@"save successful"); 
     // Show message image successfully saved 
    } 
} 

Вот код для создания образа:

// вам нужно добавить контроллер представления в качестве делегировать на выходе камеры, чтобы получать уведомления о buffereed данных

-(void)activateCameraFeed 
{ 
//this is the code responsible for capturing feed for still image processing 
dispatch_queue_t queue = dispatch_queue_create("com.AugmentedRealityGlamour.ImageCaptureQueue", NULL); 

    captureOutput = [[AVCaptureVideoDataOutput alloc] init]; 
    [captureOutput setAlwaysDiscardsLateVideoFrames:YES]; 
    [captureOutput setSampleBufferDelegate:self queue:queue]; 
    [captureOutput setVideoSettings:videoSettings]; 

    dispatch_release(queue); 

//......configure audio feed, add inputs and outputs 

} 

//buffer delegate callback 
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection 
{ 
    if (ignoreImageStream) 
     return; 
     [self performImageCaptureFrom:sampleBuffer]; 

} 

Создание UIImage:

- (void) performImageCaptureFrom:(CMSampleBufferRef)sampleBuffer 
{ 
    CVImageBufferRef imageBuffer; 

    if (CMSampleBufferGetNumSamples(sampleBuffer) != 1) 
     return; 
    if (!CMSampleBufferIsValid(sampleBuffer)) 
     return; 
    if (!CMSampleBufferDataIsReady(sampleBuffer)) 
     return; 

    imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); 

    if (CVPixelBufferGetPixelFormatType(imageBuffer) != kCVPixelFormatType_32BGRA) 
     return; 

    CVPixelBufferLockBaseAddress(imageBuffer,0); 

    uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer); 
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer); 
    size_t width = CVPixelBufferGetWidth(imageBuffer); 
    size_t height = CVPixelBufferGetHeight(imageBuffer); 

    CGImageRef newImage = nil; 

    if (cameraDeviceSetting == CameraDeviceSetting640x480) 
    { 
     CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 
     CGContextRef newContext = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst); 
     newImage = CGBitmapContextCreateImage(newContext); 
     CGColorSpaceRelease(colorSpace); 
     CGContextRelease(newContext); 
    } 
    else 
    { 
     uint8_t *tempAddress = malloc(640 * 4 * 480); 
     memcpy(tempAddress, baseAddress, bytesPerRow * height); 
     baseAddress = tempAddress; 
     CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 
     CGContextRef newContext = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipFirst); 
     newImage = CGBitmapContextCreateImage(newContext); 
     CGContextRelease(newContext); 
     newContext = CGBitmapContextCreate(baseAddress, 640, 480, 8, 640*4, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst); 
     CGContextScaleCTM(newContext, (CGFloat)640/(CGFloat)width, (CGFloat)480/(CGFloat)height); 
     CGContextDrawImage(newContext, CGRectMake(0,0,640,480), newImage); 
     CGImageRelease(newImage); 
     newImage = CGBitmapContextCreateImage(newContext); 
     CGColorSpaceRelease(colorSpace); 
     CGContextRelease(newContext); 
     free(tempAddress); 
    } 

    if (newImage != nil) 
    { 

//modified for iOS5.0 with ARC  
    tempImage = [[UIImage alloc] initWithCGImage:newImage scale:(CGFloat)1.0 orientation:cameraImageOrientation]; 
    CGImageRelease(newImage); 

//this call creates the illusion of a preview layer, while we are actively switching images created with this method 
     [self performSelectorOnMainThread:@selector(newCameraImageNotification:) withObject:tempImage waitUntilDone:YES]; 
    } 

    CVPixelBufferUnlockBaseAddress(imageBuffer,0); 
} 

обновление интерфейса с UIView, который на самом деле может быть оказанной в графическом контексте:

- (void) newCameraImageNotification:(UIImage*)newImage 
{ 
    if (newImage == nil) 
     return; 

     [arOverlayView setImage:newImage]; 
//or do more advanced processing of the image 
} 

Answer 1

Если Вы желаете сделать снимок того, что на экране, это то, что я делаю в одном из моих приложения для камеры. Я не дотронулся до этого кода за долгое время, так что теперь может быть лучший вариант 5.0, но он прочный с более чем 1 миллионом загрузок. Существует функция для захвата экрана, и один на основе UIView для захвата экрана Open/GLES1:

// 
// ScreenCapture.m 
// LiveEffectsCam 
// 
// Created by John Carter on 10/8/10. 
// 

#import "ScreenCapture.h" 

#import <QuartzCore/CABase.h> 
#import <QuartzCore/CATransform3D.h> 
#import <QuartzCore/CALayer.h> 
#import <QuartzCore/CAScrollLayer.h> 

#import <OpenGLES/EAGL.h> 
#import <OpenGLES/ES1/gl.h> 
#import <OpenGLES/ES1/glext.h> 
#import <QuartzCore/QuartzCore.h> 
#import <OpenGLES/EAGLDrawable.h> 


@implementation ScreenCapture 

+ (UIImage *) GLViewToImage:(GLView *)glView 
{ 
    UIImage *glImage = [GLView snapshot:glView]; // returns an autoreleased image 
    return glImage; 
} 

+ (UIImage *) GLViewToImage:(GLView *)glView withOverlayImage:(UIImage *)overlayImage 
{ 
    UIImage *glImage = [GLView snapshot:glView]; // returns an autoreleased image 

    // Merge Image and Overlay 
    // 
    CGRect imageRect = CGRectMake((CGFloat)0.0, (CGFloat)0.0, glImage.size.width*glImage.scale, glImage.size.height*glImage.scale); 
    CGImageRef overlayCopy = CGImageCreateCopy(overlayImage.CGImage); 
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 
    CGContextRef context = CGBitmapContextCreate(NULL, (int)glImage.size.width*glImage.scale, (int)glImage.size.height*glImage.scale, 8, (int)glImage.size.width*4*glImage.scale, colorSpace, kCGImageAlphaPremultipliedLast); 
    CGContextDrawImage(context, imageRect, glImage.CGImage); 
    CGContextDrawImage(context, imageRect, overlayCopy); 
    CGImageRef newImage = CGBitmapContextCreateImage(context); 
    UIImage *combinedViewImage = [[[UIImage alloc] initWithCGImage:newImage] autorelease]; 
    CGImageRelease(newImage); 
    CGImageRelease(overlayCopy); 
    CGContextRelease(context); 
    CGColorSpaceRelease(colorSpace); 

    return combinedViewImage; 
} 

+ (UIImage *) UIViewToImage:(UIView *)view withOverlayImage:(UIImage *)overlayImage 
    { 
    UIImage *viewImage = [ScreenCapture UIViewToImage:view]; // returns an autoreleased image 

    // Merge Image and Overlay 
    // 
    CGRect imageRect = CGRectMake((CGFloat)0.0, (CGFloat)0.0, viewImage.size.width*viewImage.scale, viewImage.size.height*viewImage.scale); 
    CGImageRef overlayCopy = CGImageCreateCopy(overlayImage.CGImage); 
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 
    CGContextRef context = CGBitmapContextCreate(NULL, (int)viewImage.size.width*viewImage.scale, (int)viewImage.size.height*viewImage.scale, 8, (int)viewImage.size.width*4*viewImage.scale, colorSpace, kCGImageAlphaPremultipliedLast); 
    CGContextDrawImage(context, imageRect, viewImage.CGImage); 
    CGContextDrawImage(context, imageRect, overlayCopy); 
    CGImageRef newImage = CGBitmapContextCreateImage(context); 
    UIImage *combinedViewImage = [[[UIImage alloc] initWithCGImage:newImage] autorelease]; 
    CGImageRelease(newImage); 
    CGImageRelease(overlayCopy); 
    CGContextRelease(context); 
    CGColorSpaceRelease(colorSpace); 

    return combinedViewImage; 
} 



+ (UIImage *) UIViewToImage:(UIView *)view 
{ 
    // 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; 
    CGSize imageSize = CGSizeMake((CGFloat)480.0, (CGFloat)640.0);  // camera image size 

    if (NULL != UIGraphicsBeginImageContextWithOptions) 
     UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0); 
    else 
     UIGraphicsBeginImageContext(imageSize); 

    CGContextRef context = UIGraphicsGetCurrentContext(); 

    // Start with the view... 
    // 
    CGContextSaveGState(context); 
    CGContextTranslateCTM(context, [view center].x, [view center].y); 
    CGContextConcatCTM(context, [view transform]); 
    CGContextTranslateCTM(context,-[view bounds].size.width * [[view layer] anchorPoint].x,-[view bounds].size.height * [[view layer] anchorPoint].y); 
    [[view layer] renderInContext:context]; 
    CGContextRestoreGState(context); 

    // ...then repeat for every subview from back to front 
    // 
    for (UIView *subView in [view subviews]) 
    { 
     if ([subView respondsToSelector:@selector(screen)]) 
      if ([(UIWindow *)subView screen] == [UIScreen mainScreen]) 
       continue; 

     CGContextSaveGState(context); 
     CGContextTranslateCTM(context, [subView center].x, [subView center].y); 
     CGContextConcatCTM(context, [subView transform]); 
     CGContextTranslateCTM(context,-[subView bounds].size.width * [[subView layer] anchorPoint].x,-[subView bounds].size.height * [[subView layer] anchorPoint].y); 
     [[subView layer] renderInContext:context]; 
     CGContextRestoreGState(context); 
    } 

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); // autoreleased image 

    UIGraphicsEndImageContext(); 

    return image; 
} 

+ (UIImage *) snapshot:(GLView *)eaglview 
{ 
    NSInteger x = 0; 
    NSInteger y = 0; 
    NSInteger width = [eaglview backingWidth]; 
    NSInteger height = [eaglview backingHeight]; 
    NSInteger dataLength = width * height * 4; 

    NSUInteger i; 
    for (i=0; i<100; i++) 
    { 
     glFlush(); 
     CFRunLoopRunInMode(kCFRunLoopDefaultMode, (float)1.0/(float)60.0, FALSE); 
    } 

    GLubyte *data = (GLubyte*)malloc(dataLength * sizeof(GLubyte)); 

    // Read pixel data from the framebuffer 
    // 
    glPixelStorei(GL_PACK_ALIGNMENT, 4); 
    glReadPixels(x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, data); 

    // Create a CGImage with the pixel data 
    // If your OpenGL ES content is opaque, use kCGImageAlphaNoneSkipLast to ignore the alpha channel 
    // otherwise, use kCGImageAlphaPremultipliedLast 
    // 
    CGDataProviderRef ref = CGDataProviderCreateWithData(NULL, data, dataLength, NULL); 
    CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB(); 
    CGImageRef iref = CGImageCreate(width, height, 8, 32, width * 4, colorspace, kCGBitmapByteOrder32Big | kCGImageAlphaPremultipliedLast, ref, NULL, true, kCGRenderingIntentDefault); 

    // OpenGL ES measures data in PIXELS 
    // Create a graphics context with the target size measured in POINTS 
    // 
    NSInteger widthInPoints; 
    NSInteger heightInPoints; 

    if (NULL != UIGraphicsBeginImageContextWithOptions) 
    { 
     // On iOS 4 and later, use UIGraphicsBeginImageContextWithOptions to take the scale into consideration 
     // Set the scale parameter to your OpenGL ES view's contentScaleFactor 
     // so that you get a high-resolution snapshot when its value is greater than 1.0 
     // 
     CGFloat scale = eaglview.contentScaleFactor; 
     widthInPoints = width/scale; 
     heightInPoints = height/scale; 
     UIGraphicsBeginImageContextWithOptions(CGSizeMake(widthInPoints, heightInPoints), NO, scale); 
    } 
    else 
    { 
     // On iOS prior to 4, fall back to use UIGraphicsBeginImageContext 
     // 
     widthInPoints = width; 
     heightInPoints = height; 
     UIGraphicsBeginImageContext(CGSizeMake(widthInPoints, heightInPoints)); 
    } 

    CGContextRef cgcontext = UIGraphicsGetCurrentContext(); 

    // UIKit coordinate system is upside down to GL/Quartz coordinate system 
    // Flip the CGImage by rendering it to the flipped bitmap context 
    // The size of the destination area is measured in POINTS 
    // 
    CGContextSetBlendMode(cgcontext, kCGBlendModeCopy); 
    CGContextDrawImage(cgcontext, CGRectMake(0.0, 0.0, widthInPoints, heightInPoints), iref); 

    // Retrieve the UIImage from the current context 
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); // autoreleased image 

    UIGraphicsEndImageContext(); 

    // Clean up 
    free(data); 
    CFRelease(ref); 
    CFRelease(colorspace); 
    CGImageRelease(iref); 

    return image; 
} 

@end