Filter4Cam 學習之 Saving a Photo

since: 2012/01/07
update: 2012/01/07
reference: Saving a Photo With AVFoundation and Core Image | Indie Ambitions

A.調整 UI
   1. 接續之前的專案, 點選 MainStoryboard.storyboard 檔案, 加入一個 button,
       並對應到 -(void)snap:(id)sender 方法. 

   2. 接著, 新增一個 slider, 並對應到 sldr IBOutlet.
       這是可用來調整濾鏡的(在此尚未實作)

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B. 修改 ViewController.h
     新增一個 CIImage 實體變數.
@interface ViewController : GLKViewController <AVCaptureVideoDataOutputSampleBufferDelegate>
{
    //@add
    AVCaptureSession *session;
   
    CIContext *coreImageContext;
    EAGLContext *context;
    GLuint _renderBuffer;
    IBOutlet UISlider *sldr;
    //@add
    CIImage *ciimg;
}

//@add
@property (strong, nonatomic) EAGLContext *context;

- (IBAction)snap:(id)sender;

@end

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C. 將照片儲存到相簿
    1. 將 AssetsLibrary framework 加入專案中.
    2. 修改 ViewController.h 檔案, 如下:
....
#import <ImageIO/ImageIO.h>
//@add
#import <AssetsLibrary/AssetsLibrary.h>
....

    3. 開啓 ViewController.m 檔案, 修改如下:
- (IBAction)snap:(id)sender {
    //@add
    CGImageRef cgimg = [coreImageContext createCGImage:ciimg fromRect:[ciimg extent]];

    ALAssetsLibrary *lib = [[ALAssetsLibrary alloc] init];

    [lib writeImageToSavedPhotosAlbum:cgimg metadata:nil completionBlock:^(NSURL *assetURL, NSError *error) {
        CGImageRelease(cgimg);
    }];
}

   // 將 CIImage *image 都改成 ciimg
-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
   
    CVPixelBufferRef pixelBuffer = (CVPixelBufferRef)CMSampleBufferGetImageBuffer(sampleBuffer);
   
    //CIImage *image = [CIImage imageWithCVPixelBuffer:pixelBuffer];
    //@update
    ciimg = [CIImage imageWithCVPixelBuffer:pixelBuffer];
   
    //@add filter
    /*
    image = [CIFilter filterWithName:@"CIFalseColor" keysAndValues:
             kCIInputImageKey, image,
             @"inputColor0", [CIColor colorWithRed:0.0 green:0.2 blue:0.0],
             @"inputColor1", [CIColor colorWithRed:0.0 green:0.0 blue:1.0],
             nil].outputImage;
    */
    //@update
    ciimg = [CIFilter filterWithName:@"CIFalseColor" keysAndValues:
             kCIInputImageKey, ciimg,
             @"inputColor0", [CIColor colorWithRed:0.0 green:0.2 blue:0.0],
             @"inputColor1", [CIColor colorWithRed:0.0 green:0.0 blue:1.0], nil].outputImage;
   
    //[coreImageContext drawImage:image atPoint:CGPointZero fromRect:[image extent] ];
    //@update
    [coreImageContext drawImage:ciimg atPoint:CGPointZero fromRect:[ciimg extent] ];
   
    [self.context presentRenderbuffer:GL_RENDERBUFFER];
}

    4. 編譯並執行

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D. 調整方向
   1. 修改 ViewController.m 檔案如下

-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
   
    CVPixelBufferRef pixelBuffer = (CVPixelBufferRef)CMSampleBufferGetImageBuffer(sampleBuffer);
   
    ciimg = [CIImage imageWithCVPixelBuffer:pixelBuffer];
   
    //update: orientation
    UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation];
    CGAffineTransform t;
    if (orientation == UIDeviceOrientationPortrait) {
        t = CGAffineTransformMakeRotation(-M_PI / 2);
    } else if (orientation == UIDeviceOrientationPortraitUpsideDown) {
        t = CGAffineTransformMakeRotation(M_PI / 2);
    } else if (orientation == UIDeviceOrientationLandscapeRight) {
        t = CGAffineTransformMakeRotation(M_PI);
    } else {
        t = CGAffineTransformMakeRotation(0);
    }
   
    ciimg = [ciimg imageByApplyingTransform:t];
   
    //@add filter
    ciimg = [CIFilter filterWithName:@"CIFalseColor" keysAndValues:
             kCIInputImageKey, ciimg,
             @"inputColor0", [CIColor colorWithRed:0.0 green:0.2 blue:0.0],
             @"inputColor1", [CIColor colorWithRed:0.0 green:0.0 blue:1.0], nil].outputImage;
   
    [coreImageContext drawImage:ciimg atPoint:CGPointZero fromRect:[ciimg extent] ];
   
    [self.context presentRenderbuffer:GL_RENDERBUFFER];
}

   2. 編譯並執行

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E. 滑動(Slider)
  1. 修改 ViewController.m 檔案如下:
//@add
-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
   ....
   //@add filter
    /*
    ciimg = [CIFilter filterWithName:@"CIFalseColor" keysAndValues:
             kCIInputImageKey, ciimg,
             @"inputColor0", [CIColor colorWithRed:0.0 green:0.2 blue:0.0],
             @"inputColor1", [CIColor colorWithRed:0.0 green:0.0 blue:1.0], nil].outputImage;
     */

    //@add filter & slider
    ciimg = [CIFilter filterWithName:@"CIFalseColor" keysAndValues:
             kCIInputImageKey, ciimg,
             @"inputColor0", [CIColor colorWithRed:0.0 green:sldr.value blue:0.0],
             @"inputColor1", [CIColor colorWithRed:0.0 green:sldr.value blue:1.0], nil].outputImage;
   
    [coreImageContext drawImage:ciimg atPoint:CGPointZero fromRect:[ciimg extent] ];
   
    [self.context presentRenderbuffer:GL_RENDERBUFFER];
}

  2. 編譯並執行