objective-c - 使用内部阴影的 UILabel 中的发光效果

Question

我正在尝试为UILabel实现这种发光效果，如下所示：

我有子类UILabel，并创建了一个自定义标签类，它添加了一个外部阴影。

编辑：这是我在自定义标签类中用于外部阴影/发光的代码：

- (void)drawTextInRect:(CGRect)rect {
UIColor *insideColor;
UIColor *blurColor;
CGContextRef ctx = UIGraphicsGetCurrentContext();

insideColor =[UIColor colorWithRed:255/255.0 green:255/255.0 blue:191/255.0 alpha:1];
blurColor =[UIColor orangeColor];    


    CGContextSetFillColorWithColor(ctx, insideColor.CGColor);
    CGContextSetShadowWithColor(ctx, CGSizeMake(0, 0), self.glowAmount, blurColor.CGColor);
    CGContextSetTextDrawingMode(ctx, kCGTextFillStroke);

    [self.text drawInRect:self.bounds withFont:self.font lineBreakMode:self.lineBreakMode alignment:self.textAlignment];
}

但这给了我以下结果

如您所见，由于缺少内部阴影，因此缺少所需的效果。谁能建议如何实现这一目标？

谢谢！

Answer 1

我在 UILabel 中提到了 Steven XM 对 Inner Shadow 的回答。这是一个很大的帮助。

这是我为实现结果所做的工作，但我想知道这是否可以更优化？

-(void)setInnerGlowWithColor:(UIColor *)shadowColor fillColor:(UIColor *)insideColor inRect:(CGRect)rect 
{

    UIFont *font = self.font;
   // UIFont *font = [UIFont fontWithName:@"HelveticaNeue-Bold" size:17];
    CGSize fontSize = [self.text sizeWithFont:font];


    /****    Following are the steps to create an inside shadow ****/

    // STEP 1 :  Create a  image mask of your text.

        CGImageRef mask = [self createMaskWithSize:rect.size shape:^{
        [[UIColor blackColor] setFill];
        CGContextFillRect(UIGraphicsGetCurrentContext(), rect);
        [[UIColor whiteColor] setFill];
        // custom shape goes here
        [self.text drawAtPoint:CGPointMake((self.bounds.size.width/2)-(fontSize.width/2), 0) withFont:font];
        }];


    // STEP 2 : Invert that mask.

        CGImageRef cutoutRef = CGImageCreateWithMask([self blackSquareOfSize:rect.size].CGImage, mask);
        CGImageRelease(mask);

        UIImage *cutout = [UIImage imageWithCGImage:cutoutRef scale:[[UIScreen mainScreen] scale] orientation:UIImageOrientationUp];
        CGImageRelease(cutoutRef);  



     // STEP 3 : Use this inverted mask to draw a shadow around the inside edges of the text.

        CGImageRef shadedMask = [self createMaskWithSize:rect.size shape:^{
        [[UIColor whiteColor] setFill];
        CGContextFillRect(UIGraphicsGetCurrentContext(), rect);
        //****************For inner shadow/glow
        NSLog(@"in custom label---->  %f",self.glowAmount);
        CGContextSetShadowWithColor(UIGraphicsGetCurrentContext(), CGSizeMake(0, 0), self.glowAmount, shadowColor.CGColor);
        [cutout drawAtPoint:CGPointZero];
        }];


    // STEP 4 : Create negative image

        UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0);
        [shadowColor setFill];
        // custom shape goes here
        [self.text drawAtPoint:CGPointMake((self.bounds.size.width/2)-(fontSize.width/2), 0) withFont:font];
        UIImage *negative = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext(); 


    // STEP 5 : Create the shadow image

        CGImageRef innerShadowRef = CGImageCreateWithMask(negative.CGImage, shadedMask);
        CGImageRelease(shadedMask);
        UIImage *innerShadow = [UIImage imageWithCGImage:innerShadowRef scale:[[UIScreen mainScreen] scale] orientation:UIImageOrientationUp];
        CGImageRelease(innerShadowRef);


    // STEP 6 : Draw actual text

        [insideColor setFill];
        [self.text drawAtPoint:CGPointMake((self.bounds.size.width/2)-(fontSize.width/2), 0) withFont:font];  


    // STEP 7 : Finally apply the shadow image   

        [innerShadow drawAtPoint:CGPointZero];

}


- (UIImage*)blackSquareOfSize:(CGSize)size {
    UIGraphicsBeginImageContextWithOptions(size, NO, 0);  
    [[UIColor blackColor] setFill];
    CGContextFillRect(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, size.width, size.height));
    UIImage *blackSquare = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return blackSquare;
}


- (CGImageRef)createMaskWithSize:(CGSize)size shape:(void (^)(void))block {
    UIGraphicsBeginImageContextWithOptions(size, NO, 0);  
    block();
    CGImageRef shape = [UIGraphicsGetImageFromCurrentImageContext() CGImage];
    UIGraphicsEndImageContext();  
    CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(shape),
                                        CGImageGetHeight(shape),
                                        CGImageGetBitsPerComponent(shape),
                                        CGImageGetBitsPerPixel(shape),
                                        CGImageGetBytesPerRow(shape),
                                        CGImageGetDataProvider(shape), NULL, false);
    return mask;
}