paths.c

source code: Covert TXT to PDF

 
               switch (p->type) {
 
                   case LINETYPE:
                   case MOVETYPE:
                       break;
 
                   case CONICTYPE:
                   {
/*
The logic of this is that the new M point (stored relative to the new
beginning) is (M - C).  However, C ("dest") has already been reversed
So, we add "dest" instead of subtracting it:
*/
                       register struct conicsegment *cp = (struct conicsegment *) p;
 
                       cp->M.x += p->dest.x;  cp->M.y += p->dest.y;
                   }
                       break;
 
                   case BEZIERTYPE:
                   {
                       register struct beziersegment *bp = (struct beziersegment *) p;
 
                       bp->B.x += p->dest.x;  bp->B.y += p->dest.y;
                       bp->C.x += p->dest.x;  bp->C.y += p->dest.y;
                   }
                       break;
 
                   case HINTTYPE:
                   {
                       register struct hintsegment *hp = (struct hintsegment *) p;
 
                       hp->ref.x = -hp->ref.x;  hp->ref.y = -hp->ref.y;
                   }
                       break;
 
                   default:
                       abort("Reverse: bad path segment", 23);
               }
/*
We need to reverse the order of segments too, so we break this segment
off of the input path, and tack it on the front of the growing path
in 'r':
*/
               nextp = p->link;
               p->link = NULL;
               p->last = p;
               if (r != NULL)
                       CONCAT(p,r);  /* leaves result in 'p'... not what we want */
               r = p;
               p = nextp;    /* advance to next segment in input path        */
 
       } while (p != NULL);
 
       if (wasclosed)
               r = ClosePath(r);
 
       return(r);
}
 
/*
:h4.DropSubPath() - Drops the First Sub-Path Off a Path
 
This subroutine returns the remaining sub-path(s).  While doing so, it
breaks the input path after the first sub-path so that a pointer to
the original path now contains the first sub-path only.
*/
 
static struct segment *DropSubPath(p0)
       register struct segment *p0;  /* original path                        */
{
       register struct segment *p;  /* returned remainder here               */
 
       for (p = p0; p->link != NULL; p = p->link) {
               if (p->link->type == MOVETYPE)
                       break;
       }
 
       return(SplitPath(p0, p));
}
 
static struct segment *SplitPath(anchor, before)
       register struct segment *anchor;
       register struct segment *before;
{
       register struct segment *r;
 
       if (before == anchor->last)
               return(NULL);
 
       r = before->link;
       r->last = anchor->last;
       anchor->last = before;
       before->link = NULL;
 
       return(r);
}
 
 
/*
:h3.ReverseSubPaths() - Reverse the Direction of Sub-paths Within a Path
 
This user operator reverses the sub-paths in a path, but leaves the
'move' segments unchanged.  It builds on top of the subroutines
already established.
*/
 
struct segment *ReverseSubPaths(p)
       register struct segment *p;  /* input path                            */
{
       register struct segment *r;  /* reversed path will be created here    */
       register struct segment *nextp;  /* temporary variable used in loop   */
       int wasclosed;        /* flag; subpath was closed                     */
       register struct segment *nomove;  /* the part of sub-path without move segment */
       struct fractpoint delta;
 
       IfTrace1((MustTraceCalls),"ReverseSubPaths(%p)\n", p);
 
       if (p == NULL)
               return(NULL);
 
       ARGCHECK(!ISPATHANCHOR(p), "ReverseSubPaths: invalid path", p, NULL, (0), struct segment *);
 
       if (p->type == TEXTTYPE)
               p = CoerceText(p);
       if (p->type != MOVETYPE)
               p = JoinSegment(NULL, MOVETYPE, 0, 0, p);
 
       p = UniquePath(p);
 
       r = NULL;
 
       for (; p != NULL;) {
               nextp = DropSubPath(p);
               wasclosed = ISCLOSED(p->flag);
               if (wasclosed)
                       UnClose(p);
 
               nomove = SplitPath(p, p);
               r = Join(r, p);
 
               PathDelta(nomove, &delta);
 
               nomove = ReverseSubPath(nomove);
               p->dest.x += delta.x;
               p->dest.y += delta.y;
               if (nextp != NULL) {
                       nextp->dest.x += delta.x;
                       nextp->dest.y += delta.y;
               }
               if (wasclosed) {
                       nomove = ClosePath(nomove);
                       nextp->dest.x -= delta.x;
                       nextp->dest.y -= delta.y;
               }
               r = Join(r, nomove);
               p = nextp;
 
       }
 
       return(r);
}
 
static int UnClose(p0)
       register struct segment *p0;
{
       register struct segment *p;
 
       for (p=p0; p->link->link != NULL; p=p->link) { ; }
 
       if (!LASTCLOSED(p->link->flag))
               abort("UnClose:  no LASTCLOSED", 24);
 
       Free(SplitPath(p0, p));
       p0->flag &= ~ISCLOSED(ON);
       return(0);
       
}
 
/*
:h2.Transforming and Putting Handles on Paths
 
:h3.PathTransform() - Transform a Path
 
Transforming a path involves transforming all the points.  In order
that closed paths do not become "unclosed" when their relative
positions are slightly changed due to loss of arithmetic precision,
all point transformations are in absolute coordinates.
 
(It might be better to reset the "absolute" coordinates every time a
move segment is encountered.  This would mean that we could accumulate
error from subpath to subpath, but we would be less likely to make
the "big error" where our fixed point arithmetic "wraps".  However, I
think I'll keep it this way until something happens to convince me
otherwise.)
 
The transform is described as a "space", that way we can use our
old friend the "iconvert" function, which should be very efficient.
*/
 
struct segment *PathTransform(p0, S)
       register struct segment *p0;    /* path to transform                  */
       register struct XYspace *S;     /* pseudo space to transform in       */
{
       register struct segment *p;   /* to loop through path with            */
       register fractpel newx,newy;  /* current transformed position in path */
       register fractpel oldx,oldy;  /* current untransformed position in path */
       register fractpel savex,savey;  /* save path delta x,y                */
 
       p0 = UniquePath(p0);
 
       newx = newy = oldx = oldy = 0;
 
       for (p=p0; p != NULL; p=p->link) {
 
               savex = p->dest.x;   savey = p->dest.y;
 
               (*S->iconvert)(&p->dest, S, p->dest.x + oldx, p->dest.y + oldy);
               p->dest.x -= newx;
               p->dest.y -= newy;
 
               switch (p->type) {
 
                   case LINETYPE:
                   case MOVETYPE:
                       break;
 
                   case CONICTYPE:
                   {
                       register struct conicsegment *cp = (struct conicsegment *) p;
 
                       (*S->iconvert)(&cp->M, S, cp->M.x + oldx, cp->M.y + oldy);
                       cp->M.x -= newx;
                       cp->M.y -= newy;
                       /*
                       * Note roundness doesn't change... linear transform
                       */
                       break;
                   }
 
 
                   case BEZIERTYPE:
                   {
                       register struct beziersegment *bp = (struct beziersegment *) p;
 
                       (*S->iconvert)(&bp->B, S, bp->B.x + oldx, bp->B.y + oldy);
                       bp->B.x -= newx;
                       bp->B.y -= newy;
                       (*S->iconvert)(&bp->C, S, bp->C.x + oldx, bp->C.y + oldy);
                       bp->C.x -= newx;
                       bp->C.y -= newy;
                       break;
                   }
 
                   case HINTTYPE:
                   {
                       register struct hintsegment *hp = (struct hintsegment *) p;
 
                       (*S->iconvert)(&hp->ref, S, hp->ref.x + oldx, hp->ref.y + oldy);
                       hp->ref.x -= newx;
                       hp->ref.y -= newy;
                       (*S->iconvert)(&hp->width, S, hp->width.x, hp->width.y);
                       /* Note: width is not relative to origin */
                       break;
                   }
 
                   case TEXTTYPE:
                   {
                        XformText(p,S);
                        break;
                   }
 
                   default:
                       IfTrace1(TRUE,"path = %p\n", p);
                       abort("PathTransform:  invalid segment", 25);
               }
               oldx += savex;
               oldy += savey;
               newx += p->dest.x;
               newy += p->dest.y;
       }
       return(p0);
}
 
/*
:h3.PathDelta() - Return a Path's Ending Point
*/
 
void PathDelta(p, pt)
       register struct segment *p; /* input path                             */
       register struct fractpoint *pt; /* pointer to x,y to set              */
{
       struct fractpoint mypoint;  /* I pass this to TextDelta               */
       register fractpel x,y;  /* working variables for path current point   */
 
       for (x=y=0; p != NULL; p=p->link) {
               x += p->dest.x;
               y += p->dest.y;
               if (p->type == TEXTTYPE) {
                       TextDelta(p, &mypoint);
                       x += mypoint.x;
                       y += mypoint.y;
               }
       }
 
       pt->x = x;
       pt->y = y;
}
 
/*
:h3.BoundingBox() - Produce a Bounding Box Path
 
This function is called by image code, when we know the size of the
image in pels, and need to get a bounding box path that surrounds it.
The starting/ending handle is in the lower right hand corner.
*/
struct segment *BoundingBox(h, w)
       register pel h,w;     /* size of box                                  */
{
       register struct segment *path;
 
       path = PathSegment(LINETYPE, -TOFRACTPEL(w), 0);
       path = JoinSegment(NULL, LINETYPE, 0, -TOFRACTPEL(h), path);
       path = JoinSegment(NULL, LINETYPE, TOFRACTPEL(w), 0, path);
       path = ClosePath(path);
 
       return(path);
}
 
/*
:h2.Querying Locations and Paths
 
:h3.QueryLoc() - Return the X,Y of a Locition
*/
 
void QueryLoc(P, S, xP, yP)
       register struct segment *P;  /* location to query, not consumed       */
       register struct XYspace *S;  /* XY space to return coordinates in     */
       register DOUBLE *xP,*yP;  /* coordinates returned here                */
{
       IfTrace4((MustTraceCalls),"QueryLoc(P=%p, S=%p, (%f, %f))\n",
                                            P, S, *xP, *yP);
       if (!ISLOCATION(P)) {
               ArgErr("QueryLoc: first arg not a location", P, NULL);
               return;
       }
       if (S->type != SPACETYPE) {
               ArgErr("QueryLoc: second arg not a space", S, NULL);
               return;
       }
       UnConvert(S, &P->dest, xP, yP);
}
/*
:h3.QueryPath() - Find Out the Type of Segment at the Head of a Path
 
This is a very simple routine that looks at the first segment of a
path and tells the caller what it is, as well as returning the control
point(s) of the path segment.  Different path segments have different
number of control points.  If the caller knows that the segment is
a move segment, for example, he only needs to pass pointers to return
one control point.
*/
 
void QueryPath(path, typeP, Bp, Cp, Dp, fP)
       register struct segment *path;  /* path to check                      */
       register int *typeP;  /* return the type of path here                 */
       register struct segment **Bp;  /* return location of first point      */
       register struct segment **Cp;  /* return location of second point     */
       register struct segment **Dp;  /* return location of third point      */
       register DOUBLE *fP;  /* return Conic sharpness                       */
{
       register int coerced = FALSE;  /* did I coerce a text path?           */
 
       IfTrace3((MustTraceCalls), "QueryPath(%p, %p, %p, ...)\n",
                                             path, typeP, Bp);
       if (path == NULL) {
               *typeP = -1;
               return;