版本记录

前言

GPUImage是直接利用显卡实现视频或者图像处理的技术。感兴趣可以看上面几篇文章。
1. GPUImage解析（一） —— 基本概览（一）
2. GPUImage解析（二） —— 基本概览（二）
3. GPUImage解析（三） —— 基本概览（三）
4. GPUImage解析（四） —— 安装方法及框架介绍
5. GPUImage解析（五） —— 框架中的几个基类
6. GPUImage解析（六） —— 一个简单的实例（一）

功能要求

利用GPUImage进行视频采集，利用GPUImageVideoCamera进行输入，并采取其中的一种滤镜进行处理，然后利用GPUImageView显示在界面上。

功能实现

下面我们就直接看代码。

#import "JJGPUImageCameraVC.h"
#import "GPUImage.h"

@interface JJGPUImageCameraVC ()

@property (nonatomic, strong) GPUImageView *gpuImageView;
@property (nonatomic, strong) GPUImageVideoCamera *gpuVideoCamera;

@end

@implementation JJGPUImageCameraVC

#pragma mark - Override Base Function

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    self.view.backgroundColor = [UIColor whiteColor];
    
    [self setupUI];
    [self setupCamera];
}

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    
    self.navigationController.navigationBarHidden = YES;
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    
    self.navigationController.navigationBarHidden = NO;
}

#pragma mark - Object Private Function

- (void)setupUI
{
    self.gpuImageView = [[GPUImageView alloc] init];
    self.gpuImageView.frame = self.view.frame;
    [self.view addSubview:self.gpuImageView];
}

- (void)setupCamera
{
    //videoCamera
    self.gpuVideoCamera = [[GPUImageVideoCamera alloc] initWithSessionPreset:AVCaptureSessionPreset1280x720 cameraPosition:AVCaptureDevicePositionBack];
    //GPUImageView填充模式
    self.gpuImageView.fillMode = kGPUImageFillModePreserveAspectRatioAndFill;
    //滤镜
    GPUImageSepiaFilter *filter = [[GPUImageSepiaFilter alloc] init];
    [self.gpuVideoCamera addTarget:filter];
    [filter addTarget:self.gpuImageView];
    
    //Start camera capturing, 里面封装的是AVFoundation的session的startRunning
    [self.gpuVideoCamera startCameraCapture];
    
    //屏幕方向的检测
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(orientationDidChange:) name:UIDeviceOrientationDidChangeNotification object:nil];
}

#pragma mark - Action && Notification

- (void)orientationDidChange:(NSNotification *)noti
{
    UIInterfaceOrientation *orientation = (UIInterfaceOrientation)[UIDevice currentDevice].orientation;
    self.gpuVideoCamera.outputImageOrientation = orientation;
    self.gpuImageView.frame = self.view.frame;
}

@end

这里有几个枚举需要说一下：

• GPUImageFillModeType：该枚举用于定义GPUImageView的填充模式。

typedef enum {
    // Stretch to fill the full view, which may distort the image outside of its normal aspect ratio
    kGPUImageFillModeStretch,       

    // Maintains the aspect ratio of the source image, adding bars of the specified background color              
    kGPUImageFillModePreserveAspectRatio,    

    // Maintains the aspect ratio of the source image, zooming in on its center to fill the view      
    kGPUImageFillModePreserveAspectRatioAndFill     
} GPUImageFillModeType;

• AVCaptureDevicePosition：该枚举是AVFoundation框架里面的，用于定义图像视频采集方向的，下面看一下这个枚举。

/*!
 @enum AVCaptureDevicePosition
 @abstract
 Constants indicating the physical position of an AVCaptureDevice's hardware on the system.
 
 @constant AVCaptureDevicePositionUnspecified
 Indicates that the device's position relative to the system hardware is unspecified.
 @constant AVCaptureDevicePositionBack
 Indicates that the device is physically located on the back of the system hardware.
 @constant AVCaptureDevicePositionFront
 Indicates that the device is physically located on the front of the system hardware.
 */
typedef NS_ENUM(NSInteger, AVCaptureDevicePosition) {
    AVCaptureDevicePositionUnspecified         = 0,
    AVCaptureDevicePositionBack                = 1,
    AVCaptureDevicePositionFront               = 2
} NS_AVAILABLE(10_7, 4_0) __TVOS_PROHIBITED;

功能验证

下面看一下这个功能效果。

后记

未完，待续~~~