AVScreenShack/AVScreenShackDocument.m

 
/*
     File: AVScreenShackDocument.m
 Abstract: Document, owns session, screen capture input, and movie file output
  Version: 2.0
 
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 */
 
#import "AVScreenShackDocument.h"
 
#import <AVFoundation/AVFoundation.h>
 
@interface AVScreenShackDocument ()
 
@property (weak) IBOutlet NSView *captureView;
 
- (IBAction)startRecording:(id)sender;
- (IBAction)stopRecording:(id)sender;
- (IBAction)setDisplayAndCropRect:(id)sender;
 
@end
 
 
@implementation AVScreenShackDocument
{
    CGDirectDisplayID           display;
    AVCaptureMovieFileOutput    *captureMovieFileOutput;
}
 
#pragma mark Capture
 
- (BOOL)createCaptureSession:(NSError **)outError
{
    /* Create a capture session. */
    self.captureSession = [[AVCaptureSession alloc] init];
    if ([self.captureSession canSetSessionPreset:AVCaptureSessionPresetHigh])
    {
        /* Specifies capture settings suitable for high quality video and audio output. */
        [self.captureSession setSessionPreset:AVCaptureSessionPresetHigh];
    }
    
    /* Add the main display as a capture input. */
    display = CGMainDisplayID();
    self.captureScreenInput = [[AVCaptureScreenInput alloc] initWithDisplayID:display];
    if ([self.captureSession canAddInput:self.captureScreenInput]) 
    {
        [self.captureSession addInput:self.captureScreenInput];
    } 
    else 
    {
        return NO;
    }
    
    /* Add a movie file output + delegate. */
    captureMovieFileOutput = [[AVCaptureMovieFileOutput alloc] init];
    [captureMovieFileOutput setDelegate:self];
    if ([self.captureSession canAddOutput:captureMovieFileOutput]) 
    {
        [self.captureSession addOutput:captureMovieFileOutput];
    } 
    else 
    {
        return NO;
    }
    
    /* Register for notifications of errors during the capture session so we can display an alert. */
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(captureSessionRuntimeErrorDidOccur:) name:AVCaptureSessionRuntimeErrorNotification object:self.captureSession];
    
    return YES;
}
 
/*
 AVCaptureVideoPreviewLayer is a subclass of CALayer that you use to display 
 video as it is being captured by an input device.
 
 You use this preview layer in conjunction with an AV capture session.
 */
-(void)addCaptureVideoPreview
{
    /* Create a video preview layer. */
    AVCaptureVideoPreviewLayer *videoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession];
    
    /* Configure it.*/
    [videoPreviewLayer setFrame:[[self.captureView layer] bounds]];
    [videoPreviewLayer setAutoresizingMask:kCALayerWidthSizable|kCALayerHeightSizable];
    
    /* Add the preview layer as a sublayer to the view. */
    [[self.captureView layer] addSublayer:videoPreviewLayer];
    /* Specify the background color of the layer. */
    [[self.captureView layer] setBackgroundColor:CGColorGetConstantColor(kCGColorBlack)];
}
 
/*
 An AVCaptureScreenInput's minFrameDuration is the reciprocal of its maximum frame rate.  This property
 may be used to request a maximum frame rate at which the input produces video frames.  The requested
 rate may not be achievable due to overall bandwidth, so actual frame rates may be lower.
 */
- (float)maximumScreenInputFramerate
{
    Float64 minimumVideoFrameInterval = CMTimeGetSeconds([self.captureScreenInput minFrameDuration]);
    return minimumVideoFrameInterval > 0.0f ? 1.0f/minimumVideoFrameInterval : 0.0;
}
 
/* Set the screen input maximum frame rate. */
- (void)setMaximumScreenInputFramerate:(float)maximumFramerate
{
    CMTime minimumFrameDuration = CMTimeMake(1, (int32_t)maximumFramerate);
    /* Set the screen input's minimum frame duration. */
    [self.captureScreenInput setMinFrameDuration:minimumFrameDuration];
}
 
/* Add a display as an input to the capture session. */
-(void)addDisplayInputToCaptureSession:(CGDirectDisplayID)newDisplay cropRect:(CGRect)cropRect
{
    /* Indicates the start of a set of configuration changes to be made atomically. */
    [self.captureSession beginConfiguration];
    
    /* Is this display the current capture input? */
    if ( newDisplay != display ) 
    {
        /* Display is not the current input, so remove it. */
        [self.captureSession removeInput:self.captureScreenInput];
        AVCaptureScreenInput *newScreenInput = [[AVCaptureScreenInput alloc] initWithDisplayID:newDisplay];
        
        self.captureScreenInput = newScreenInput;
        if ( [self.captureSession canAddInput:self.captureScreenInput] )
        {
            /* Add the new display capture input. */
            [self.captureSession addInput:self.captureScreenInput];
        }
        [self setMaximumScreenInputFramerate:[self maximumScreenInputFramerate]];
    }
    /* Set the bounding rectangle of the screen area to be captured, in pixels. */
    [self.captureScreenInput setCropRect:cropRect];
    
    /* Commits the configuration changes. */
    [self.captureSession commitConfiguration];
}
 
 
/* Informs the delegate when all pending data has been written to the output file. */
- (void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error
{
    if (error) 
    {
        [self presentError:error];
        return;
    }
    
    [[NSWorkspace sharedWorkspace] openURL:outputFileURL];
}
 
- (BOOL)captureOutputShouldProvideSampleAccurateRecordingStart:(AVCaptureOutput *)captureOutput
{
    // We don't require frame accurate start when we start a recording. If we answer YES, the capture output
    // applies outputSettings immediately when the session starts previewing, resulting in higher CPU usage
    // and shorter battery life.
    return NO;
}
 
#pragma mark NSDocument
 
/* Initializes a AVScreenShackDocument document. */
- (id)initWithType:(NSString *)typeName error:(NSError **)outError
{
    self = [super initWithType:typeName error:outError];
    
    if (self) 
    {        
        BOOL success = [self createCaptureSession:outError];
        if (!success) 
        {
            return nil;
        }
    }
    
    return self;
}
 
- (void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self name:AVCaptureSessionRuntimeErrorNotification object:self.captureSession];
}
 
- (NSString *)windowNibName
{
    /* 
       Override returning the nib file name of the document.
     
       If you need to use a subclass of NSWindowController or if your document supports multiple NSWindowControllers, 
       you should remove this method and override -makeWindowControllers instead.
     */
    
    return @"AVScreenShackDocument";
}
 
- (void)windowControllerDidLoadNib:(NSWindowController *)aController
{
    [super windowControllerDidLoadNib:aController];
    
    [self addCaptureVideoPreview];
 
    /* Start the capture session running. */
    [self.captureSession startRunning];
 
    [[aController window] setContentBorderThickness:75.f forEdge:NSMinYEdge];
    [[aController window] setMovableByWindowBackground:YES];
}
 
/* Called when the document is closed. */
- (void)close
{
    /* Stop the capture session running. */
    [self.captureSession stopRunning];
    
    [super close];
}
 
/* AVScreenShackDocument does not support saving. */
-(BOOL)isDocumentEdited
{
    return NO;
}
 
#pragma mark Crop Rect
 
#define kShadyWindowLevel   (NSDockWindowLevel + 1000)
 
/* Draws a crop rect on the display. */
- (void)drawMouseBoxView:(DrawMouseBoxView*)view didSelectRect:(NSRect)rect
{
    /* Map point into global coordinates. */
    NSRect globalRect = rect;
    NSRect windowRect = [[view window] frame];
    globalRect = NSOffsetRect(globalRect, windowRect.origin.x, windowRect.origin.y);
    globalRect.origin.y = CGDisplayPixelsHigh(CGMainDisplayID()) - globalRect.origin.y;
    CGDirectDisplayID displayID = display;
    uint32_t matchingDisplayCount = 0;
    /* Get a list of online displays with bounds that include the specified point. */
    CGError e = CGGetDisplaysWithPoint(NSPointToCGPoint(globalRect.origin), 1, &displayID, &matchingDisplayCount);
    if ((e == kCGErrorSuccess) && (1 == matchingDisplayCount)) 
    {
        /* Add the display as a capture input. */
        [self addDisplayInputToCaptureSession:displayID cropRect:NSRectToCGRect(rect)];
    }
    
    for (NSWindow* w in [NSApp windows])
    {
        if ([w level] == kShadyWindowLevel)
            [w close];
    }
    [[NSCursor currentCursor] pop];
}
 
/* 
 Called when the user sets a Crop Rect for the display.
 
 First dims the display, then allows the user specify a rectangular
 area of the display to capture.
*/
- (IBAction)setDisplayAndCropRect:(id)sender
{
    for (NSScreen* screen in [NSScreen screens]) 
    {
        NSRect frame = [screen frame];
        NSWindow * window = [[NSWindow alloc] initWithContentRect:frame styleMask:NSBorderlessWindowMask backing:NSBackingStoreBuffered defer:NO];
        [window setBackgroundColor:[NSColor blackColor]];
        [window setAlphaValue:.5];
        [window setLevel:kShadyWindowLevel];
        [window setReleasedWhenClosed:YES];
        DrawMouseBoxView* drawMouseBoxView = [[DrawMouseBoxView alloc] initWithFrame:frame];
        drawMouseBoxView.delegate = self;
        [window setContentView:drawMouseBoxView];
        [window makeKeyAndOrderFront:self];
    }
    
    [[NSCursor crosshairCursor] push];
}
 
- (void)captureSessionRuntimeErrorDidOccur:(NSNotification *)notification
{
    NSError *error = [[notification userInfo] objectForKey:AVCaptureSessionErrorKey];
    if ([error localizedDescription]) {
        if ([error localizedFailureReason]) {
            NSRunAlertPanel(@"AVScreenShack Alert", 
                            [NSString stringWithFormat:@"%@\n\n%@", [error localizedDescription], [error localizedFailureReason]],
                            nil, nil, nil);
        }
        else {
            NSRunAlertPanel(@"AVScreenShack Alert", 
                            [NSString stringWithFormat:@"%@", [error localizedDescription]],
                            nil, nil, nil);
        }
    }
    else {
        NSRunAlertPanel(@"AVScreenShack Alert", 
                        @"An unknown error occured",
                        nil, nil, nil);
    }
}
 
#pragma mark Start/Stop Button Actions
 
/* Called when the user presses the 'Start' button to start a recording. */
- (IBAction)startRecording:(id)sender
{
    NSLog(@"Minimum Frame Duration: %f, Crop Rect: %@, Scale Factor: %f, Capture Mouse Clicks: %@, Capture Mouse Cursor: %@, Remove Duplicate Frames: %@",
          CMTimeGetSeconds([self.captureScreenInput minFrameDuration]),
          NSStringFromRect(NSRectFromCGRect([self.captureScreenInput cropRect])),
          [self.captureScreenInput scaleFactor],
          [self.captureScreenInput capturesMouseClicks] ? @"Yes" : @"No",
          [self.captureScreenInput capturesCursor] ? @"Yes" : @"No",
          [self.captureScreenInput removesDuplicateFrames] ? @"Yes" : @"No");
    
    char *tempNameBytes = tempnam([[@"~/Desktop/" stringByStandardizingPath] fileSystemRepresentation], "AVScreenShack_");
    NSString *tempName = [[NSString alloc] initWithBytesNoCopy:tempNameBytes length:strlen(tempNameBytes) encoding:NSUTF8StringEncoding freeWhenDone:YES];
    
    /* Starts recording to a given URL. */
    [captureMovieFileOutput startRecordingToOutputFileURL:[NSURL fileURLWithPath:[tempName stringByAppendingPathExtension:@"mov"]] recordingDelegate:self];
}
 
/* Called when the user presses the 'Stop' button to stop a recording. */
- (IBAction)stopRecording:(id)sender
{
    [captureMovieFileOutput stopRecording];
}
 
@end