ios学习--camera zoom with slider

设置preview zoom的方式：

// create a uiview subclass for showing the camera feed 
 UIView *previewView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 430)]; 
 [[self view] addSubview:previewView]; 
 
 CGRect layerRect = CGRectMake(0, 0, 320, 430); 
 [[self avCaptureVideoPreviewLayer] setBounds:layerRect]; 
 
 [[self  previewLayer] setPosition:CGPointMake(CGRectGetMidX(layerRect), CGRectGetMidY(layerRect))]; 
 
 // add the video previewview layer to the preview view 
 [[previewView layer] addSublayer:[self avCaptureVideoPreviewLayer]]; 

// zoom the preview view using core graphics 
 [previewView setTransform:CGAffineTransformMakeScale(2.0, 2.0 )]; 

设置preview zoom的方式：

- (void)handlePinchGesture:(UIPinchGestureRecognizer *)gestureRecognizer { 
 
    if([gestureRecognizer state] == UIGestureRecognizerStateBegan) { 
        // Reset the last scale, necessary if there are multiple objects with different scales 
        lastScale = [gestureRecognizer scale]; 
    } 
 
    if ([gestureRecognizer state] == UIGestureRecognizerStateBegan ||  
        [gestureRecognizer state] == UIGestureRecognizerStateChanged) { 
 
        CGFloat currentScale = [[[gestureRecognizer view].layer valueForKeyPath:@"transform.scale"] floatValue]; 
 
        // Constants to adjust the max/min values of zoom 
        const CGFloat kMaxScale = 2.0; 
        const CGFloat kMinScale = 1.0; 
 
        CGFloat newScale = 1 -  (lastScale - [gestureRecognizer scale]);  
        newScale = MIN(newScale, kMaxScale / currentScale);    
        newScale = MAX(newScale, kMinScale / currentScale); 
        CGAffineTransform transform = CGAffineTransformScale([[gestureRecognizer view] transform], newScale, newScale); 
        [gestureRecognizer view].transform = transform; 
 
        lastScale = [gestureRecognizer scale];  // Store the previous scale factor for the next pinch gesture call   
    } 
} 

 

图片后处理：

 if (cameraZoom > 1.0)  
 { 
        // save the images original size 
        CGSize orgSize = [image size];   
 
        // resize the image to the zoom scale   
        image = [image resizedImage:CGSizeMake(image.size.width * cameraZoom, image.size.height *cameraZoom) interpolationQuality:kCGInterpolationNone];            
 
        // now calculate the offset x and offset y 
        CGFloat offsetX = ( image.size.width / 2 ) - (orgSize.width /2) ; 
        CGFloat offsetY =  ( image.size.height / 2 ) - (orgSize.height /2); 
 
         // crop the image from the offset position to the original width and height 
         image = [image croppedImage:CGRectMake(offsetX, offsetY, orgSize.width, orgSize.height)]; 
    } 
 
 
    UIButton *imgBtn = (UIButton *)[self.view viewWithTag:500]; 
    [imgBtn setImage:image forState:UIControlStateNormal]; 

}