Why do narrowed joints need to be slower than others?

Question

I have a graphics problem when drawing lines in Flash Player, where two lines drawn on top of each other with different thicknesses do not align properly if I use other JointStyle than MITER . For effect images and for the graphic-oriented part of the question, see my post on doctype .

Nevertheless, there is a second angle in this task, namely: why should drawing “beveled” joints be much slower than others? This seems to be a problem since at least FP 8, but I could not find detailed information on what might be the problem. Is this just a common mistake that has not yet been fixed, or is there something inherently slower with respect to these joints? For example, they seem to have something to do with square roots, but I totally lack an understanding of what a joint thing of style is, technically. This is like some small details that a graphic designer might worry about.

I ask because I am wondering if I can do something to mitigate, eliminate, the problem.

Answer 1

There are several ways to combine two lines:

• none: free
• round: draw a circle for the width of the radius line / 2
• cap: fill in the gap between the lines
• miter: extrapolate lines and fill them

Mitra is the most expensive. If the lines meet at an external angle exceeding 90, they must be extrapolated, intersected and filled.

From the screenshots on your linked post, you don't need joints to draw a graph. Joints are important only with a large stroke width, and for drawing a graph, round or cap joints should be fine.

In flash rendering environments, pretty fast is simply the hardest compound to choose from.