Filter4Cam 實作: 4. 新增相機相關方法

since: 2012/02/28
update: 2012/02/28
reference: 1. The iOS 5 Developer's Cookbook
                   2. I touchs: Filter4Cam 學習之 Getting Raw Video Data

A. 開啓 ViewController.h 檔案, 修改如下:
....
//@add
#import "Filter4CamHelper.h"

//@add:Cameras defined
enum {
    kCameraNone = -1, // 無相機
    kCameraFront,        // 前置相機
    kCameraBack,         // 後置相機
} availableCameras;

//@interface ViewController : GLKViewController
//@update
@interface ViewController : GLKViewController <AVCaptureVideoDataOutputSampleBufferDelegate>
{
....
    // AVCaptureSession: Used to coordinate the flow of data from
    //                                     AV input devices to outputs.
    AVCaptureSession *session;
   
    BOOL isUsingFrontCamera;
}

//@add
@property (strong, nonatomic) EAGLContext *glContext;
@property (strong, nonatomic) CIContext *coreImageContext;
@property (strong, nonatomic) GLKView *glView;
@property (strong) AVCaptureSession *session;
@property (assign) BOOL isUsingFrontCamera;

//@add for Render
- (void)establishRender; // establish Render

//@add for Camera
- (void)establishCamera:(uint)whichCamera; // 建立相機 Session
- (void)startRunningSession;                              // 啟動相機 Session
- (void)stopRunningSession;                              // 停止相機 Session

//@add for test
- (void)helperTest;

-----------------------------------------------------------------------------------

B. 開啓 ViewController.m 檔案, 修改如下:
@implementation ViewController

//@add
@synthesize glContext = _glContext;
@synthesize coreImageContext = _coreImageContext;
@synthesize glView = _glView;
@synthesize session = _session;
@synthesize isUsingFrontCamera = _isUsingFrontCamera;
....
#pragma mark Camera
//@add:啟動相機 Session
- (void)startRunningSession
{
    if (self.session.running) return;
    [self.session startRunning];
}

//@add:停止相機 Session
- (void)stopRunningSession
{
    [self.session stopRunning];
}

//@add:建立相機 Session
- (void)establishCamera:(uint)whichCamera
{
    NSError *error;
   
    // Is a camera available
    if (![Filter4CamHelper numberOfCameras]) return;
   
    // 設置相機輸入: 建立 session 並設定. 在這邊設定 session 為 640 pixels 寬,
    //              480 pixels 高. 還有其他的選項, 包括 720 pixels 跟 1080 pixels.
    //              Core Image 的解析度越高, 效能就越低. 一個單一簡單的濾鏡就能夠來
    //              處理高解析度.   

    // Create a session
    self.session = [[AVCaptureSession alloc] init];
   
    // begin
    [self.session beginConfiguration];
    [self.session setSessionPreset:AVCaptureSessionPreset640x480];   
   
   
    // 輸入設備: 假如要指定前置或後置相機, 需要呼叫 devicesWithMediaType, 
    //          它會回傳一個設備的陣列. 若要取得前置相機, 可在
    //          AVCaptureDevicePosition 屬性中, 重複地在陣列中尋找
    //          AVCaptureDevicePositionFront.
    //
   
    // Choose camera
    self.isUsingFrontCamera = NO;
    if ((whichCamera == kCameraFront) && [Filter4CamHelper frontCameraAvailable])
    {
        self.isUsingFrontCamera = YES;
    }
   
    // 設定輸入設備
    // Retrieve the selected camera
    //
    // 使用預設的設備:
    // AVCaptureDevice *device = [AVCaptureDevice
    //                               defaultDeviceWithMediaType:AVMediaTypeVideo];
    //
    AVCaptureDevice *device = self.isUsingFrontCamera ? [Filter4CamHelper frontCamera] : [Filter4CamHelper backCamera];
   
    // Create the capture input
    AVCaptureDeviceInput *captureInput = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];

    if (!captureInput)
    { 
        NSLog(@"Error establishing device input: %@", error);
        return;
    }
   
    [self.session addInput:captureInput];
   
    /*********************************************************************/
   
    // 設定輸出: 並忽略較慢的影格(frames). 如果需要記錄改變的地方,
    //                    可以設定輸入資料的顏色格式.
    //                 
   
    // 設定輸出設備
    AVCaptureVideoDataOutput *captureOutput = [[AVCaptureVideoDataOutput alloc] init];

    [captureOutput setAlwaysDiscardsLateVideoFrames:YES];   
   
    // Establish settings
    NSDictionary *settings = [NSDictionary dictionaryWithObject:[NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA] forKey:(NSString *)kCVPixelBufferPixelFormatTypeKey];
   
    [captureOutput setVideoSettings:settings];
   
   
    /*********************************************************************/
   
    // 設定 delegate: 它將會收到回傳(callback)的每個 frame,
    //                            並且設為主要的駐列(queue).
    //                  
   
    // Create capture output
    [captureOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()];
    [self.session addOutput:captureOutput];
   
    // 完成設定
    //
   
    // commit
    [self.session commitConfiguration];
} 

#pragma mark Implementation Delegate Method

//@add implementation method for
//  <AVCaptureVideoDataOutputSampleBufferDelegate>
// 將接收到由傳送者(delivers)所回傳(callback) 的原始像素資料(raw pixel data).
-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
    //@TODO
}