CODEWITHSUNDEEP
iphoneipadcore-graphics
juliet
juliet

Reputation: 175

how to check CGMutablePathRef is null or not

i have a CGMutablePathRef object called path, i want to know, how can i know path is null, it means i didn't use 

CGPathAddLineToPoint(path, NULL, point.x, point.y);

or

CGPathMoveToPoint(path, NULL, startPoint.x, startPoint.y);

to push points into path.

Upvotes: 2

Views: 429

Answers (2)

kennytm
kennytm

Reputation: 523284

To check whether a path is NULL, use the ==/!= operator.

if (path != NULL)
  CGPathAddLineToPoint(path, NULL, point.x, point.y);

To check whether a path contains no nothing, use CGPathIsEmpty.

if (!CGPathIsEmpty(path))
  CGPathAddLineToPoint(path, NULL, point.x, point.y);

To check whether a path's point has been moved, use CGPathGetCurrentPoint and compare with (0, 0).

if (!CGPointEqualToPoint(CGPathGetCurrentPoint(path), CGPointZero))
  CGPathAddLineToPoint(path, NULL, point.x, point.y);

Of course this cannot distinguish between a truly empty path and a path that someone called CGPathMoveToPoint(path, NULL, 0, 0) on it.

(Actually, why you need to care? Just create a new path if you want an empty one.)

Upvotes: 2

justin
justin

Reputation: 104698

a CGMutablePathRef is a pointer, so all you have to do to test this is:

if (NULL != path) {
  CGPathAddLineToPoint(path, NULL, point.x, point.y);
}

Upvotes: 0

Related Questions