我正在尝试像这样使用遮罩遮盖一个图像:
请问你能帮我吗？
我正在使用以下代码：
- (void) viewDidLoad {
UIImage *OrigImage = [UIImage imageNamed:@"dogs.png"];
UIImage *mask = [UIImage imageNamed:@"mask.png"];
UIImage *maskedImage = [self maskImage:OrigImage withMask:mask];
myUIIMage.image = maskedImage;
}
#import <QuartzCore/QuartzCore.h>
// remember to include Framework as well
CALayer *mask = [CALayer layer];
mask.contents = (id)[[UIImage imageNamed:@"mask.png"] CGImage];
mask.frame = CGRectMake(0, 0, yourImageView.frame.size.width, yourImageView.frame.size.height);
yourImageView.layer.mask = mask;
yourImageView.layer.masksToBounds = YES;
let mask = CALayer()
mask.contents = UIImage(named: "right_challenge_bg")?.cgImage as Any
mask.frame = CGRect(x: 0, y: 0, width: leftBGImage.frame.size.width, height: leftBGImage.frame.size.height)
leftBGImage.layer.mask = mask
leftBGImage.layer.masksToBounds = true
viewDidLoad中，但什么也没有发生！ - iOS.Lover这个教程使用带有两个参数的方法：image和maskImage，当你调用该方法时必须设置这些参数。例如，如果该方法在同一个类中且图片在你的捆绑包中，则调用示例可能如下：
注意 - 令人惊讶的是，这些图片甚至不必是相同大小的。
...
UIImage *image = [UIImage imageNamed:@"dogs.png"];
UIImage *mask = [UIImage imageNamed:@"mask.png"];
// result of the masking method
UIImage *maskedImage = [self maskImage:image withMask:mask];
...
- (UIImage*) maskImage:(UIImage *)image withMask:(UIImage *)maskImage {
CGImageRef maskRef = maskImage.CGImage;
CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef),
CGImageGetHeight(maskRef),
CGImageGetBitsPerComponent(maskRef),
CGImageGetBitsPerPixel(maskRef),
CGImageGetBytesPerRow(maskRef),
CGImageGetDataProvider(maskRef), NULL, false);
CGImageRef maskedImageRef = CGImageCreateWithMask([image CGImage], mask);
UIImage *maskedImage = [UIImage imageWithCGImage:maskedImageRef];
CGImageRelease(mask);
CGImageRelease(maskedImageRef);
// returns new image with mask applied
return maskedImage;
}
在您提供了代码之后，我已经添加了一些数字作为参考注释。您仍然有两个选择。整个东西是一个方法，在某个地方进行调用。您不需要在其中创建图像：这将使该方法的可重用性降为零。
要使您的代码运行，请更改方法头（1.）为
- (UIImage *)maskImageMyImages {
然后将2.中的变量名改为：
UIImage *maskImage = [UIImage imageNamed:@"mask.png"];
这个方法会返回经过遮罩处理的图像，因此您需要在某个位置调用该方法。 您能否展示一下您调用该方法的代码？
UIImage *image的代码？因为在-(UIimage *) maskeImage中编译器会报重定义错误！ - iOS.Lover我创建了一个@IBDesignable，这样您就可以立即在Storyboard上看到效果。
import UIKit
@IBDesignable
class UIImageViewWithMask: UIImageView {
var maskImageView = UIImageView()
@IBInspectable
var maskImage: UIImage? {
didSet {
maskImageView.image = maskImage
updateView()
}
}
// This updates mask size when changing device orientation (portrait/landscape)
override func layoutSubviews() {
super.layoutSubviews()
updateView()
}
func updateView() {
if maskImageView.image != nil {
maskImageView.frame = bounds
mask = maskImageView
}
}
}
我尝试了使用CALayer和CGImageCreateWithMask两种代码，但都没有对我起作用
但是我发现问题在于PNG文件格式，而不是代码!! 所以只是分享我的发现!
如果你想使用
- (UIImage*) maskImage:(UIImage *)image withMask:(UIImage *)maskImage
你必须使用没有 alpha 通道的 24 位 PNG。
如果你想要使用 CALayer mask，你必须使用 (24 位或 8 位) 带有 alpha 通道的 PNG，其中 PNG 的透明部分将作为遮罩来遮盖图像（对于平滑渐变 alpha mask，请使用带有 alpha 通道的 24 位 PNG）。
- (UIImage*) maskImage:(UIImage *)image withMask:(UIImage *)maskImage {
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGImageRef maskImageRef = [maskImage CGImage];
// create a bitmap graphics context the size of the image
CGContextRef mainViewContentContext = CGBitmapContextCreate (NULL, maskImage.size.width, maskImage.size.height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast);
CGColorSpaceRelease(colorSpace);
if (mainViewContentContext==NULL)
return NULL;
CGFloat ratio = 0;
ratio = maskImage.size.width/ image.size.width;
if(ratio * image.size.height < maskImage.size.height) {
ratio = maskImage.size.height/ image.size.height;
}
CGRect rect1 = {{0, 0}, {maskImage.size.width, maskImage.size.height}};
CGRect rect2 = {{-((image.size.width*ratio)-maskImage.size.width)/2 , -((image.size.height*ratio)-maskImage.size.height)/2}, {image.size.width*ratio, image.size.height*ratio}};
CGContextClipToMask(mainViewContentContext, rect1, maskImageRef);
CGContextDrawImage(mainViewContentContext, rect2, image.CGImage);
// Create CGImageRef of the main view bitmap content, and then
// release that bitmap context
CGImageRef newImage = CGBitmapContextCreateImage(mainViewContentContext);
CGContextRelease(mainViewContentContext);
UIImage *theImage = [UIImage imageWithCGImage:newImage];
CGImageRelease(newImage);
// return the image
return theImage;
}
这对我起作用。
SWIFT 3 XCODE 8.1
func maskImage(image: UIImage, withMask maskImage: UIImage) -> UIImage {
let maskRef = maskImage.cgImage
let mask = CGImage(
maskWidth: maskRef!.width,
height: maskRef!.height,
bitsPerComponent: maskRef!.bitsPerComponent,
bitsPerPixel: maskRef!.bitsPerPixel,
bytesPerRow: maskRef!.bytesPerRow,
provider: maskRef!.dataProvider!,
decode: nil,
shouldInterpolate: false)
let masked = image.cgImage!.masking(mask!)
let maskedImage = UIImage(cgImage: masked!)
// No need to release. Core Foundation objects are automatically memory managed.
return maskedImage
}
// 供使用
testImage.image = maskImage(image: UIImage(named: "OriginalImage")!, withMask: UIImage(named: "maskImage")!)
这是已经被接受的解决方案的Swift版本：
func maskImage(image: UIImage, withMask maskImage: UIImage) -> UIImage {
let maskRef = maskImage.CGImage
let mask = CGImageMaskCreate(
CGImageGetWidth(maskRef),
CGImageGetHeight(maskRef),
CGImageGetBitsPerComponent(maskRef),
CGImageGetBitsPerPixel(maskRef),
CGImageGetBytesPerRow(maskRef),
CGImageGetDataProvider(maskRef),
nil,
false)
let masked = CGImageCreateWithMask(image.CGImage, mask)
let maskedImage = UIImage(CGImage: masked)!
// No need to release. Core Foundation objects are automatically memory managed.
return maskedImage
}
万一有人需要的话。
对我来说，它完美地正常工作。
WBMaskedImageView *imgView = [[WBMaskedImageView alloc] initWithFrame:frame];
imgView.originalImage = [UIImage imageNamed:@"original_image.png"];
imgView.maskImage = [UIImage imageNamed:@"mask_image.png"];