zuoyebang/tongxin/ThirdPartyLib/MessageDisplayKit/Classes/Common/XHCaptureHelper.m

//
//  XHCaptureHelper.m
//  MessageDisplayExample
//
//  Created by 曾 宪华 on 14-5-25.
//  Copyright (c) 2014年 曾宪华 开发团队(http://iyilunba.com ) 本人QQ:543413507 本人QQ群（142557668）. All rights reserved.
//

#import "XHCaptureHelper.h"

@interface XHCaptureHelper ()

@property (nonatomic, copy) DidOutputSampleBufferBlock didOutputSampleBuffer;

@property (nonatomic, strong) dispatch_queue_t captureSessionQueue;

@property (nonatomic, strong) AVCaptureVideoPreviewLayer *captureVideoPreviewLayer;
@property (nonatomic, strong) AVCaptureSession *captureSession;
@property (nonatomic, strong) AVCaptureDeviceInput *captureInput;
@property (nonatomic, strong) AVCaptureVideoDataOutput *captureOutput;

@end

@implementation XHCaptureHelper

- (void)setDidOutputSampleBufferHandle:(DidOutputSampleBufferBlock)didOutputSampleBuffer {
    self.didOutputSampleBuffer = didOutputSampleBuffer;
}

- (void)showCaptureOnView:(UIView *)preview {
    dispatch_async(self.captureSessionQueue, ^{
        [self.captureSession startRunning];
        
        dispatch_async(dispatch_get_main_queue(), ^{
            self.captureVideoPreviewLayer.frame = preview.bounds;
            [preview.layer addSublayer:self.captureVideoPreviewLayer];
        });
    });
}

#pragma mark - Propertys

- (AVCaptureSession *)captureSession {
    if (!_captureSession) {
        _captureSession = [[AVCaptureSession alloc] init];
        
        AVCaptureDevice *inputDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
        
        _captureInput = [AVCaptureDeviceInput deviceInputWithDevice:inputDevice error:nil];
        if ([_captureSession canAddInput:self.captureInput])
            [self.captureSession addInput:self.captureInput];
        
        _captureOutput = [[AVCaptureVideoDataOutput alloc] init];
        _captureOutput.alwaysDiscardsLateVideoFrames = YES;
        [_captureOutput setSampleBufferDelegate:self queue:self.captureSessionQueue];
        NSString *key = (NSString *)kCVPixelBufferPixelFormatTypeKey;
        NSNumber *value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];
        NSDictionary *videoSettings = [NSDictionary dictionaryWithObject:value forKey:key];
        [_captureOutput setVideoSettings:videoSettings];
        [self.captureSession addOutput:self.captureOutput];
        
        NSString* preset = 0;
        if (NSClassFromString(@"NSOrderedSet") && // Proxy for "is this iOS 5" ...
            [UIScreen mainScreen].scale > 1 &&
            [inputDevice
             supportsAVCaptureSessionPreset:AVCaptureSessionPresetiFrame960x540]) {
                preset = AVCaptureSessionPresetiFrame960x540;
            }
        if (!preset) {
            preset = AVCaptureSessionPresetMedium;
        }
        self.captureSession.sessionPreset = preset;
    }
    return _captureSession;
}

- (AVCaptureVideoPreviewLayer *)captureVideoPreviewLayer {
    if (!_captureVideoPreviewLayer) {
        _captureVideoPreviewLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.captureSession];
        _captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    }
    return _captureVideoPreviewLayer;
}

#pragma mark - Life Cycle

- (id)init {
    self = [super init];
    if (self) {
        _captureSessionQueue = dispatch_queue_create("com.HUAJIE.captureSessionQueue", 0);
    }
    return self;
}

- (void)dealloc {
    _captureSessionQueue = nil;
    _captureVideoPreviewLayer = nil;
    
    if (![_captureSession canAddOutput:self.captureOutput])
        [_captureSession removeOutput:self.captureOutput];
    self.captureOutput = nil;
    
    [_captureSession stopRunning];
    _captureSession = nil;   
}

#pragma mark - AVCaptureVideoDataOutputSampleBuffer Delegate

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
    if (self.didOutputSampleBuffer) {
        self.didOutputSampleBuffer(sampleBuffer);
    }
}

@end