Mac Forum / Programming / Mac Programming / December 2006

It's late, but let me give it a try:

- could it be that your lines overlap, so the wide lines obscure the
narrow ones?

- remember to draw on the pixel boundaries.

patrick

Use:

if ((k==0)||(k==10)) {
   [[NSColor yellowColor] set];
   [lineToDraw setLineWidth:3.0];
} else if ((k==3)||(k==6)) {
   [[NSColor redColor] set];
   [lineToDraw setLineWidth:2.0];
} else {
   [[NSColor blackColor] set];
   [lineToDraw setLineWidth:1.0];
}

And you'll see the where the problem lies. (really your loop code is to
difficult to understand...)

patrick

First, better variable names would help. Partly when you're asking for
help and partly when you're coming back to the code 2 years from now.

Second, I don't see you allocating lineToDraw. If you're really not
doing that, rather than having just omitted it from the posted code, I
think that's the major problem.

Third, if you're just drawing straight lines, NSBezierPath has a class
method that strokes a line from one point to another. There's also a
class method to impose a line width for subsequent drawing commands.

Fourth, k loops from 0 to 9, but you've got a line of code looking for
it to be 10. You probably want that to be a 9 so that last line will
have a width of 3 instead of 1.

What I was doing wrong here was assuming I was drawing the lines one
at a time, with whatever characteristics I set most recently.

But what really happens is that the characteristics are set for *all*
lines drawn using lineToDraw. In other words, I need a different line
object for each line thickness, color, etc.

This code works the way it should:

   int i,j,k,l;
   NSBezierPath *thinLine, *avgLine, *thickLine;
   NSPoint theMarker;

   thinLine = [[NSBezierPath alloc] init];
   avgLine = [[NSBezierPath alloc] init];
   thickLine = [[NSBezierPath alloc] init];

   [[NSColor blackColor] set];
   
   [thinLine setLineWidth:1.0];
   [avgLine setLineWidth:2.0];
   [thickLine setLineWidth:3.0];

   for (i=0;i<2;i++)
       for (j=0;j<3;j++)
       {
          for (k=0;k<10;k++)
          {
              if ((k==0)||(k==9))
              {    
                  theMarker.x = 320*i+30*k+20;
                  theMarker.y = 320*j+30;
                  [thickLine moveToPoint:theMarker];
                  theMarker.x = 320*i+30*k+20;
                  theMarker.y = 320*(j+1)-20;
                  [thickLine lineToPoint:theMarker];
              }
              else if ((k==3)||(k==6))
              {  
                  theMarker.x = 320*i+30*k+20;
                  theMarker.y = 320*j+30;
                  [avgLine moveToPoint:theMarker];
                  theMarker.x = 320*i+30*k+20;
                  theMarker.y = 320*(j+1)-20;
                  [avgLine lineToPoint:theMarker];
              }
              else
              {  
                  theMarker.x = 320*i+30*k+20;
                  theMarker.y = 320*j+30;
                  [thinLine moveToPoint:theMarker];
                  theMarker.x = 320*i+30*k+20;
                  theMarker.y = 320*(j+1)-20;
                  [thinLine lineToPoint:theMarker];
              }
           }
        }

   [thinLine stroke];
   [avgLine stroke];
   [thickLine stroke];