CALayer: Single pixel line looks like 2 pixels

Question

This is my code:

int columns 3;
int columnWidth = self.layer.bounds.size.width / 3;

for (int c = 1; c < columns; c++) {
    CALayer *layer  = [CALayer layer         


        

Answer 1

I went ahead and made an explanatory picture, in case it's helpful to anyone

The lower line on exact pixel coordinates and will look blurry... each half of the width of the line lies in a different row of pixels...

The upper line is offset by line_width/2.0 and will look sharp... it lies completely within a row of pixels.