How would I draw something like this in Core Graphics

Question

I want to be able to draw using this as my stroke. How would I do this as efficient as possible, and on the fly drawing, I was thinking CGPatternRef, but I really don't know how to do that.

Edit: It does not need to warp to the path. I just coultn't fix that issue in Illustrator.

Answer 1

This looks like a job for OpenGL. CoreGraphics doesn't offer any simple way that I know of to warp the stars according to their proximity to a path.

Answer 2

You could try importing your Illustrator document into this application: Opacity, and then doing an "Export as source code".

See here: http://likethought.com/opacity/workflow/ for more information.

Answer 3

Does the Apple doc help?

See the section in Quartz 2D Programming Guide, How Patterns Work, or Patterns in general.

Here is how to draw a start (from the above docs), PSIZE is the star size:

static void MyDrawStencilStar (void *info, CGContextRef myContext)
{
    int k;
    double r, theta;

    r = 0.8 * PSIZE / 2;
    theta = 2 * M_PI * (2.0 / 5.0); // 144 degrees

    CGContextTranslateCTM (myContext, PSIZE/2, PSIZE/2);

    CGContextMoveToPoint(myContext, 0, r);
    for (k = 1; k < 5; k++) {
        CGContextAddLineToPoint (myContext,
                    r * sin(k * theta),
                    r * cos(k * theta));
    }
    CGContextClosePath(myContext);
    CGContextFillPath(myContext);
}

Just add the curve transformation and at each point draw the star.

Here is a simple C code to calculate points on cubic bezier curve.