Drawing a line with a shadow, but you only need to keep the shadow. IOS

Question

I am trying to draw a line with a shadow, but I do not want to hold a line, but only a shadow.

I tried to set the color of the line stroke, but when I do this, the shadow also disappears.

The following code creates 2 lines, I only want to keep the shadow, because it looks more beautiful, and the pixel does not look like a line.

Is it possible?

CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 2.0); CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.0, 0.0, 0.0, 1.0); CGContextSetShouldAntialias(UIGraphicsGetCurrentContext(), YES); CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGFloat components[4] = {0.0, 0.0, 0.0, 1.0}; CGColorRef shadowColor = CGColorCreate(colorSpace, components); CGContextSetShadowWithColor(UIGraphicsGetCurrentContext(), CGSizeMake(10,10), 4.0, shadowColor); 

Thanks.

Answer 1

So, you cannot do this directly, because the shadow reflects the path, so if you make the path transparent, the shadow will also be transparent. There are some workarounds that I can come up with (depending on what you are doing), but one sneaky way is to just draw a shadow far enough below the path that you can just draw, basically by erasing it. For example, if the background is white, this will accomplish what you want:

 - (void)drawRect:(CGRect)rect { CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetRGBStrokeColor(context, 0.0, 0.0, 0.0, 1.0); CGContextSetLineWidth(context, 10.0); CGContextMoveToPoint(context, 10.0, 30.0); CGContextAddLineToPoint(context, 310.0, 30.0); CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGFloat components[4] = {0.0, 0.0, 0.0, 1.0}; CGColorRef shadowColor = CGColorCreate(colorSpace, components); CGContextSetShadowWithColor(context, CGSizeMake(0.0f,20.0f), 4.0, shadowColor); CGContextStrokePath(context); CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0); CGContextSetLineWidth(context, 10.0); CGContextMoveToPoint(context, 10.0, 30.0); CGContextAddLineToPoint(context, 310.0, 30.0); CGContextStrokePath(context); } 

hope this helps.

Answer 2

why don't you just draw your line like a shadow. Do not create a shadow, but instead draw a black line with an alpha letter of 25. or less, and sweep it to where you expect the shadow to be.