I'm working on a project where I'm reading in a file that contains a
list of coordinates that are used to define a stitch pattern for
embroidery machines. Think of those machines you see at the mall that
stitch names and logos on hats and t-shirts. To display the images, I
created a document based application that uses each coordinate to
build up a NSBezierPath and draw the image using NSBezierPath and
lineToPoint. It seems pretty straight forward but there are a few
wrinkles that are causing me problems so I thought I would ask for
help. I tried to find some answers online with no luck so I apologize
if this is basic stuff!
The first issue is the actual drawing of the lines. Since I'm trying
to represent stitch patterns, I want to be able to show layers such
that if one stitch crosses over another that there is some indication
of which line is over the other. Think of way the laces in your shoes
look, and that is the effect I am looking for. I thought I could solve
it by finding a way to stroke the line with an outline but I couldn't
figure out a way to do that. My first solution was to stroke the path
in black a couple extra pixels wide and then to stroke the path again
with a lighter color. This gave me a nice 3-D effect and was pretty
close to what I wanted but it wasn't quite perfect. The problem was in
the mitered ends. The stitches are typically back and forth with very
narrow angles and the outline only showed up on the edges, but I
really needed it to follow the full length of each stitch if that
makes sense. My next solution was to create a NSBezierPath for each
stitch. This solution gave me the look I wanted but I'm worried that
it is a very expensive solution. Since a design can be made up of
potentially tens of thousands of stitches I'm creating a huge amount
of NSBezierPaths which strikes me as a problem.
The next problem is that once I've got the design drawn, I want to be
able to zoom in and out and do other types of dynamic modifications of
the image. For example, I may want to show or hide individual colors
in the design. And of course, the image should be able to be scrolled
if it is too big for the window. I had originally used -readFromURL to
parse the file and store the line segments in my own internal
structure. I then used -drawRect of the NSView to build the
NSBezierPaths and draw the image. While this basically worked, I'm
pretty sure this is the wrong way to do it. For starters, I think I'm
recreating/drawing the image way too much by doing it in -drawRect.
Should I be doing my drawing in -initWithFrame instead? Also, I'm
struggling with zooming. Since I have all the x/y coordinates stored
in an internal structure, should I be recreating the path with an
appropriate scale factor? Or should I be trying to scale the created
image? If I had all of the image in a single path it would be easy to
transform it but how would I do it if I have thousands of paths?
Any help or suggestions would be greatly appreciated!
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