[英]Transparent Circle at Middle of UIImageView IOS
我需要在中間位置使UIImageView透明(圓形)。
我應該能夠通過該中間圈看到UIImageView的子視圖...我嘗試了CAShapeLayer ..但是我看不到UIImageView的子視圖..請幫助我..抱歉我的英語....
CAShapeLayer *circleLayer = [CAShapeLayer layer];
// Give the layer the same bounds as your image view
[circleLayer setBounds:CGRectMake(100.0f, 100.0f, [((UIImageView *)view) bounds].size.width,
[((UIImageView *)view) bounds].size.height)];
// Position the circle anywhere you like, but this will center it
// In the parent layer, which will be your image view's root layer
[circleLayer setPosition:CGPointMake(100,
100)];
// Create a circle path.
UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:
CGRectMake(100.0f, 100.0f, 50.0f, 50.0f)];
// Set the path on the layer
[circleLayer setPath:[path CGPath]];
// Set the stroke color
[circleLayer setStrokeColor:[[UIColor redColor] CGColor]];
// Set the stroke line width
[circleLayer setLineWidth:2.0f];
// Add the sublayer to the image view's layer tree
[circleLayer setOpacity:0.5];
[[((UIImageView *)view) layer] addSublayer:circleLayer];
一種方法是這樣的。 我有一個包含主圖像的圖像視圖,還有另一個名為BlackCircle的圖像,它只是一個40x40的黑色圓圈(是我在Pixen應用中制作的)。 動作方法使主圖像在與黑圈重疊的地方變成透明,我將其放置在主圖像的中心:
@interface ViewController ()
@property (weak,nonatomic) IBOutlet UIImageView *imageView;
@end
@implementation ViewController
-(void)viewDidLoad {
[super viewDidLoad];
self.imageView.image = [UIImage imageNamed:@"House.tiff"];
self.imageView.backgroundColor = [UIColor clearColor];
}
-(IBAction)createAlphaClippedImage:(id)sender {
UIImage *circleImage = [UIImage imageNamed:@"BlackCircle.png"];
UIImage *mainImage = [UIImage imageNamed:@"House.tiff"];
UIGraphicsBeginImageContextWithOptions(mainImage.size, NO, 0.0);
CGRect imageRect = CGRectMake(0.0f, 0.0f, mainImage.size.width, mainImage.size.height);
CGRect centerCircleRect = CGRectMake(mainImage.size.width/2.0 - circleImage.size.width/2.0, mainImage.size.height/2.0 - circleImage.size.height/2.0,circleImage.size.width,circleImage.size.height);
[mainImage drawInRect:imageRect];
[circleImage drawInRect:centerCircleRect blendMode:kCGBlendModeXOR alpha:1.0];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
self.imageView.image = image;
}
與其嘗試使Imageview的一部分透明,不如通過將相應的alpha設置為0,使圖像在所需區域透明。
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