如何使用UIBezierPath裁剪图像？

Question

I want to get the image from the UIBezierpath closed path(See the image). I draw the image on the UIView using drawRect method and also draw the lines are using the drawRect method. How can I get the particular closed path image? Please help me. Thanks in advance.

This code used for draw the bezierpath.

UIBezierPath *aPath = [UIBezierPath bezierPath];
for (NSString *pointString in pointArray) {
    if ([pointArray indexOfObject:pointString] == 0)
        [aPath moveToPoint:CGPointFromString(pointString)];
    else
        [aPath addLineToPoint:CGPointFromString(pointString)];
}
[aPath closePath];

Answer 1

You can use a shapeLayer for that. Something like,

UIBezierPath *aPath = [UIBezierPath bezierPath];
for (NSString *pointString in pointArray) {
    if ([pointArray indexOfObject:pointString] == 0)
        [aPath moveToPoint:CGPointFromString(pointString)];
    else
        [aPath addLineToPoint:CGPointFromString(pointString)];
}
[aPath closePath];

CAShapeLayer *shapeLayer = [CAShapeLayer layer];
shapeLayer.path = aPath.CGPath;
[view.layer setMask:shapeLayer];//or make it as [imageview.layer setMask:shapeLayer]; 
//and add imageView as subview of whichever view you want. draw the original image
//on the imageview in that case

To get it as an image,

UIGraphicsBeginImageContext(view.bounds.size);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

image should have the corresponding image.

Answer 2

Well, there are a couple of things that you have to take in notice.

1. Are you passing your UIImageView instead of your UIView?
2. If you are, did you enable your image view for touch handling?
3. Subclass your UIImageView and use drawrect() for handling that stuff for you.

If you want only a portion of the image (like the cat), then you need to submask your image according to UIBezierPath.

Updated

The following is a complete working example, change it to your requirements.

ViewController.h:

@interface ViewController : UIViewController
{
  UIBezierPath *aPath;
}
@property (nonatomic,retain) NSMutableArray *pathArray;
@property (nonatomic,retain) NSMutableDictionary *dic;
@property (nonatomic,retain) IBOutlet UIImageView *imgView;

@end

ViewController.m:

@interface ViewController ()
 - (IBAction)Crop:(id)sender;
@end

@implementation ViewController
@synthesize pathArray,dic,imgView;
- (void)viewDidLoad
 {
   [super viewDidLoad];

 }
 - (void) setClippingPath:(UIBezierPath *)clippingPath : (UIImageView *)imgView;
{

    NSLog(@"Mask Paths %@",clippingPath);

    CAShapeLayer *maskLayer = [CAShapeLayer layer];
    maskLayer.frame = self.imgView.frame;
    maskLayer.path = [clippingPath CGPath];
    maskLayer.fillColor = [[UIColor whiteColor] CGColor];
    maskLayer.backgroundColor = [[UIColor clearColor] CGColor];


    self.imgView.layer.mask = maskLayer;



}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
 {

   UITouch *mytouch=[[touches allObjects] objectAtIndex:0];
   self->aPath = [[UIBezierPath alloc]init];
   [aPath moveToPoint:[mytouch locationInView:imgView]];

}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
 {

  UITouch *mytouch=[[touches allObjects] objectAtIndex:0];
  [aPath addLineToPoint:[mytouch locationInView:imgView
                       ]];

 }
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
 {

 }
- (IBAction)Crop:(id)sender
 {
  [self setClippingPath:aPath :imgView];
 }

Answer 3

For Swift try this : ZImageCropper

ZImageCropper is using following things as core part:

• UIBezierPath
• UITouch Events
• CAShapeLayer
• CoreGraphics

Answer 4

use this pod ios-helpers

- (UIImage *)imageWithStrokeColor: (UIColor *)stroke_color andFillColor: (UIColor *)fill_color {

    // adjust bounds to account for extra space needed for lineWidth
    CGFloat width = self.bounds.size.width + self.lineWidth * 2;
    CGFloat height = self.bounds.size.height + self.lineWidth * 2;
    CGRect bounds = CGRectMake(self.bounds.origin.x, self.bounds.origin.y, width, height);

    // create a view to draw the path in
    UIView *view = [[UIView alloc] initWithFrame:bounds];

    // begin graphics context for drawing
    UIGraphicsBeginImageContextWithOptions(view.frame.size, NO, [[UIScreen mainScreen] scale]);

    // configure the view to render in the graphics context
    [view.layer renderInContext:UIGraphicsGetCurrentContext()];

    // get reference to the graphics context
    CGContextRef context = UIGraphicsGetCurrentContext();

    // reverse the y-axis to match the opengl coordinate space
    CGContextScaleCTM(context, 1, -1);
    CGContextTranslateCTM(context, 0, -view.bounds.size.height);

    // translate matrix so that path will be centered in bounds
    CGContextTranslateCTM(context, -(bounds.origin.x - self.lineWidth), -(bounds.origin.y - self.lineWidth));

    // stroke color
    [stroke_color setStroke];
    [self stroke];

    //fill color
    [fill_color setFill];
    [self fill];

    // get an image of the graphics context
    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();

    // end the context
    UIGraphicsEndImageContext();

    return viewImage;
}

Answer 5

If you're drawing everything in code just use - addClip , ie:

UIBezierPath *aPath = [UIBezierPath bezierPath];
for (NSString *pointString in pointArray) {
    if ([pointArray indexOfObject:pointString] == 0)
        [aPath moveToPoint:CGPointFromString(pointString)];
    else
        [aPath addLineToPoint:CGPointFromString(pointString)];
}
[aPath closePath];


CGContextSaveGState(context);
{
    [aPath addClip];
    // draw image
    [aPath stroke];
}
CGContextRestoreGState(context);

Answer 6

iDev's answer is excellent, but if you need transparent background, then except UIGraphicsBeginImageContext(view.bounds.size); you should use

UIGraphicsBeginImageContextWithOptions(view.bounds.size, NO, 1.0);

By default image context is created with opaque == YES, so you have to change it to NO.

Answer 7

this works for me...

UIBezierPath *path = ....//your path
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef    context    = CGBitmapContextCreate(nil, frame.size.width, frame.size.height, 8, 4*frame.size.width, colorSpace, (CGBitmapInfo)kCGImageAlphaPremultipliedFirst);

CGContextAddPath(context, path.CGPath);
CGContextClip(context);
CGContextDrawImage(context, frame, image.CGImage);

[UIImage imageWithCGImage:CGBitmapContextCreateImage(context)];

Answer 8

// This Work 100%

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

mouseSwiped = NO;
UITouch *touch = [touches anyObject];
lastPoint = [touch locationInView:self.view];
megView = [[UIImageView alloc]initWithFrame:CGRectMake(lastPoint.x , lastPoint.y , k_POINT_WIDTH , k_POINT_WIDTH )];
//[megView setImage:[UIImage imageNamed:@"b_image22.png"]];
[megView setContentMode:UIViewContentModeScaleToFill];
megView.alpha = 2;
//megView.layer.backgroundColor = [UIColor whiteColor].CGColor;
//megView.layer.cornerRadius = megView.frame.size.width / 2;
megView.clipsToBounds = YES;
[self.main_uiview addSubview:megView];


self.bezierPath = [UIBezierPath bezierPath];
[self.bezierPath moveToPoint:lastPoint];

}

  // Touchmove method


 - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {

mouseSwiped = YES;
UITouch *touch = [touches anyObject];
CGPoint currentPoint = [touch locationInView:self.view];
UIGraphicsBeginImageContext(self.main_uiview.frame.size);
[self.bg_imageview.image drawInRect:CGRectMake(0, 0, self.main_uiview.frame.size.width, self.main_uiview.frame.size.height)];
megView.frame = CGRectMake( currentPoint.x - k_POINT_WIDTH/2 , currentPoint.y - k_POINT_WIDTH/2 , k_POINT_WIDTH , k_POINT_WIDTH );
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextStrokePath(UIGraphicsGetCurrentContext());


CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red,green ,blue, 0.20);
CGContextSetBlendMode(UIGraphicsGetCurrentContext(), kCGBlendModeCopy);
  self.bg_imageview.image = UIGraphicsGetImageFromCurrentImageContext();
  [self.bg_imageview setAlpha:opacity];

 UIGraphicsEndImageContext();

 lastPoint = currentPoint;

[self.bezierPath addLineToPoint:lastPoint];

}

 // TouchEnd Method


   - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event

{

[megView removeFromSuperview];

}

      // Image Crop Method


    -(UIImage *)croppedImage
   {
UIImage *myImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[self.bezierPath closePath];
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.0, 0.0, 0.0, 0.0);
_b_image = self.bg_imageview.image;
CGSize imageSize = _b_image.size;
CGRect imageRect = CGRectMake(0, 0, imageSize.width, imageSize.height);
UIGraphicsBeginImageContextWithOptions(imageSize, NO, [[UIScreen mainScreen] scale]);
[self.bezierPath addClip];
[_b_image drawInRect:imageRect];

UIImage *croppedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return croppedImage;

}