我正在开发一个应用程序,我通过代码绘制 UIView 并用 UIColor 填充它。接下来我要加载一个 mask.png 文件(没有透明度,只有黑色和白色)并屏蔽 UIView 以更改其视觉外观。
知道怎么做吗?
// Create your mask layer
CALayer* maskLayer = [CALayer layer];
maskLayer.frame = CGRectMake(0,0,yourMaskWidth ,yourMaskHeight);
maskLayer.contents = (__bridge id)[[UIImage imageNamed:@"yourMaskImage.png"] CGImage];
// Apply the mask to your uiview layer
yourUIView.layer.mask = maskLayer;
记得导入 QuartzCore 并添加框架
#import <QuartzCore/QuartzCore.h>
这很容易,但我在任何地方都找不到答案!
iOS 8 引入了maskView
允许您使用备用视图来提供遮罩图像的属性。在斯威夫特:
if let maskImage = UIImage(named: "MaskImage") {
myView.maskView = UIImageView(image: maskImage)
}
请注意,您需要提供实际具有透明度的图像;带有白色部分(用于不透明)和黑色部分(用于透明)的图像将不起作用。
您也许可以使用 CGContextClipToMask:
-(void) drawRect:(CGRect)dirty {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState( context );
CGContextClipToMask( context , [self bounds] , [self maskImage] );
[super drawRect:dirty]; // or draw your color manually
CGContextRestoreGState( context );
}
我用上面的代码创建了一个类别:
UIView+ImageMask.h:
#import <UIKit/UIKit.h>
@interface UIView (ImageMask)
- (void) maskWithImage:(UIImage*) mask;
- (void) maskWithImage:(UIImage*)mask size:(CGSize)maskSize;
- (void) removeMask;
@end
UIView+ImageMask.m:
#import <QuartzCore/QuartzCore.h>
#import "UIView+ImageMask.h"
@implementation UIView (ImageMask)
- (void) maskWithImage:(UIImage*) mask {
[self maskWithImage:mask size:mask.size];
}
- (void) maskWithImage:(UIImage*)mask size:(CGSize)maskSize {
CALayer* maskLayer = [CALayer layer];
maskLayer.frame = CGRectMake(0, 0, maskSize.size.width, maskSize.size.height);
maskLayer.contents = (__bridge id)[mask CGImage];
// Apply the mask to your uiview layer
self.layer.mask = maskLayer;
}
- (void) removeMask {
self.layer.mask = nil;
}
@end
谢谢提请,
结束了这个功能:
- (UIImage*) maskImage:(UIView *)image withMask:(UIImage *)maskImage {
UIGraphicsBeginImageContext(image.bounds.size);
[image.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGImageRef maskRef = maskImage.CGImage;
CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef),
CGImageGetHeight(maskRef),
CGImageGetBitsPerComponent(maskRef),
CGImageGetBitsPerPixel(maskRef),
CGImageGetBytesPerRow(maskRef),
CGImageGetDataProvider(maskRef), NULL, false);
CGImageRef masked = CGImageCreateWithMask([viewImage CGImage], mask);
return [UIImage imageWithCGImage:masked];
}
斯威夫特 2.0
将 UIImage 和蒙版图像传递给此函数,您将获得蒙版图像作为 UIImage。
func maskImage(image:UIImage, mask:(UIImage))->UIImage{
let imageReference = image.CGImage
let maskReference = mask.CGImage
let imageMask = CGImageMaskCreate(CGImageGetWidth(maskReference),
CGImageGetHeight(maskReference),
CGImageGetBitsPerComponent(maskReference),
CGImageGetBitsPerPixel(maskReference),
CGImageGetBytesPerRow(maskReference),
CGImageGetDataProvider(maskReference), nil, true)
let maskedReference = CGImageCreateWithMask(imageReference, imageMask)
let maskedImage = UIImage(CGImage:maskedReference!)
return maskedImage
}