使用touch ios擦除imageView的背景颜色 [英] erase color of imageView's background color with touch ios

问题描述

我想这样做：我有一个带图像的imageView，我添加了另一个相同尺寸的图像视图和浅文本颜色背景。我需要清除/擦除上面图像的部分以进行擦除。因此，从该部分，下面的图像将是清楚的。我附加的图片
当我在屏幕上移动触摸时，该部分应该是清晰的。
任何帮助请

解决方案

创建一个Scratch-view类并将你的Scratch 透明图像在 initMethod 中，如： -

   - （id）initWithFrame：（CGRect）frame {
 
 self = [super initWithFrame：frame]; 
 if（self）{
 scratchable = [UIImage imageNamed：@scratchable.jpg]。CGImage; 
 width = CGImageGetWidth（可刮擦）; 
 height = CGImageGetHeight（可刮擦）; 
 self.opaque = NO; 
 CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceGray（）; 
 
 CFMutableDataRef pixels = CFDataCreateMutable（NULL，width * height）; 
 alphaPixels = CGBitmapContextCreate（CFDataGetMutableBytePtr（pixels），width，height，8，width，colorspace，kCGImageAlphaNone）; 
 provider = CGDataProviderCreateWithCFData（pixels）; 
 
 
 CGContextSetFillColorWithColor（alphaPixels，[UIColor blackColor] .CGColor）; 
 CGContextFillRect（alphaPixels，frame）; 
 
 CGContextSetStrokeColorWithColor（alphaPixels，[UIColor whiteColor] .CGColor）; 
 CGContextSetLineWidth（alphaPixels，20.0）; 
 CGContextSetLineCap（alphaPixels，kCGLineCapRound）; 
 
 CGImageRef mask = CGImageMaskCreate（width，height，8,8，width，provider，nil，NO）; 
 scratched = CGImageCreateWithMask（可刮，面具）; 
 
 CGImageRelease（mask）; 
 CGColorSpaceRelease（colorspace）; 
} 
返回自我; 
} 
  

并在Scratch

这个例子对你来说非常有用： -

https://github.com/oyiptong/CGScratch

I am trying to do like : I have one imageView with image and I add another Image view of same dimensions with light Text color background. And i need to clear / erase the portion of above image to erase. So that from that portion, below image will be clear. Image i attached And as i moved touch on screen, that portion should be clear. Any help please

解决方案

Create one Scratch-view class and put your Scratch transparent image in initMethod like:-

- (id)initWithFrame:(CGRect)frame {

    self = [super initWithFrame:frame];
    if (self) {
        scratchable = [UIImage imageNamed:@"scratchable.jpg"].CGImage;
        width = CGImageGetWidth(scratchable);
        height = CGImageGetHeight(scratchable);
        self.opaque = NO;
        CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceGray();

        CFMutableDataRef pixels = CFDataCreateMutable( NULL , width * height );
        alphaPixels = CGBitmapContextCreate( CFDataGetMutableBytePtr( pixels ) , width , height , 8 , width , colorspace , kCGImageAlphaNone );
        provider = CGDataProviderCreateWithCFData(pixels);


        CGContextSetFillColorWithColor(alphaPixels, [UIColor blackColor].CGColor);
        CGContextFillRect(alphaPixels, frame);

        CGContextSetStrokeColorWithColor(alphaPixels, [UIColor whiteColor].CGColor);
        CGContextSetLineWidth(alphaPixels, 20.0);
        CGContextSetLineCap(alphaPixels, kCGLineCapRound);

        CGImageRef mask = CGImageMaskCreate(width, height, 8, 8, width, provider, nil, NO);
        scratched = CGImageCreateWithMask(scratchable, mask);

        CGImageRelease(mask);
        CGColorSpaceRelease(colorspace);
    }
    return self;
}

and also create second view class for display image of background after Scratch

Bellow this example is much useful to you try with this:-

https://github.com/oyiptong/CGScratch

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