CGMutablePath always starts at 0,0

Question

Learning to use a UIBezierPath path. I can draw a simple line within my UIView but the origin is always 0,0. What am I missing?

Simple Code:

CGMutablePathRef cgPath = CGPathCreateMutable();

UIBezierPath *aPath = [UIBezierPath bezierPath];

CGPathMoveToPoint(cgPath, NULL, 100, 100);
CGPathAddLineToPoint(cgPath, NULL, 200,200);

aPath.CGPath = cgPath;
aPath.usesEvenOddFillRule = YES;

CAShapeLayer *lines = [CAShapeLayer layer];
lines.path = aPath.CGPath;
lines.bounds = CGPathGetBoundingBox(lines.path);
lines.strokeColor = [UIColor whiteColor].CGColor;
lines.fillColor = [UIColor clearColor].CGColor; /*if you just want lines*/
lines.lineWidth = 3;

[self.UIView.layer addSublayer:lines];

CGPathRelease(cgPath);

I set my start point too 100,100 and draw a line to 200,200. But it always start somewhere around 0,0.

UPDATED CODE - But am I still mixing between UIBezierPath and CGPath?

static CGFloat thickness = 0.5;
static CGFloat shapeSizex = 300;
static CGFloat shapeSizey = 150;
static CGFloat xanchor = 20; // bottom-left corner x
static CGFloat yanchor = 180; // bottom-left corner y

UIBezierPath *axisPath = [UIBezierPath bezierPath];
[axisPath moveToPoint:CGPointMake(xanchor, yanchor-shapeSizey)];
[axisPath addLineToPoint:CGPointMake(xanchor, yanchor)];
[axisPath addLineToPoint:CGPointMake(xanchor+shapeSizex, yanchor)];

CAShapeLayer *lines = [CAShapeLayer layer];
lines.path = axisPath.CGPath;
lines.strokeColor = [UIColor whiteColor].CGColor;
lines.lineWidth = thickness;

[self.ChartViewOutlet.layer addSublayer:lines];

It does what I wanted which is to draw a graph axis.

Any particular reason you're using CGPath here? UIBezierPath has methods on it to do exactly the same thing without having to create a separate object. (Alternately you could do all of the work with CGPath, since you need it later; you definitely don't need both, though. Just set the fill rule on the CAShapeLayer; that's where it belongs if you need it, but it doesn't make any sense since you're not filling anyway.) — Rob Napier
I've update the code, it works but am I still mixing bewteen CGPath and UIBezierPath? — user5308141
Your updated code looks fine. You're using UIBezierPath and CGPath in the correct ways. I see you removed the bounds. Are you still having trouble? — Rob Napier
Hi. No all working fine now. Thanks for the help and advice... — user5308141

Rob Napier Rob Napier · Accepted Answer · 2015-09-15T14:21:31

Your problem is here:

lines.bounds = CGPathGetBoundingBox(lines.path);

You're redefined the layer to wrap around the path. So when you draw it, it's transformed to put the center of the drawn path in the center of the layer.

CGMutablePath always starts at 0,0

1 Answers