+++ /dev/null
-/* $XConsortium: curves.c,v 1.4 92/07/07 17:14:55 gildea Exp $ */
-/* Copyright International Business Machines,Corp. 1991 */
-/* All Rights Reserved */
-
-/* License to use, copy, modify, and distribute this software */
-/* and its documentation for any purpose and without fee is */
-/* hereby granted, provided that licensee provides a license to */
-/* IBM, Corp. to use, copy, modify, and distribute derivative */
-/* works and their documentation for any purpose and without */
-/* fee, that the above copyright notice appear in all copies */
-/* and that both that copyright notice and this permission */
-/* notice appear in supporting documentation, and that the name */
-/* of IBM not be used in advertising or publicity pertaining to */
-/* distribution of the software without specific, written prior */
-/* permission. */
-
-/* IBM PROVIDES THIS SOFTWARE "AS IS", WITHOUT ANY WARRANTIES */
-/* OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING, BUT NOT */
-/* LIMITED TO ANY IMPLIED WARRANTIES OF MERCHANTABILITY, */
-/* FITNESS FOR A PARTICULAR PURPOSE, AND NONINFRINGEMENT OF */
-/* THIRD PARTY RIGHTS. THE ENTIRE RISK AS TO THE QUALITY AND */
-/* PERFORMANCE OF THE SOFTWARE, INCLUDING ANY DUTY TO SUPPORT */
-/* OR MAINTAIN, BELONGS TO THE LICENSEE. SHOULD ANY PORTION OF */
-/* THE SOFTWARE PROVE DEFECTIVE, THE LICENSEE (NOT IBM) ASSUMES */
-/* THE ENTIRE COST OF ALL SERVICING, REPAIR AND CORRECTION. IN */
-/* NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR */
-/* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING */
-/* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF */
-/* CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT */
-/* OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS */
-/* SOFTWARE. */
-/*
-:h1.CURVES Module - Stepping Beziers
-
-This module is responsible for "rasterizing"
-third order curves. That is, it changes the high level curve
-specification into a list of pels that that curve travels
-through.
-
-:h3.Include Files
-
-Include files needed:
-*/
-
-#include "objects.h"
-#include "spaces.h"
-#include "paths.h"
-#include "regions.h"
-#include "curves.h"
-#include "lines.h"
-#include "arith.h"
-
-
-/*
-:h3.Functions Provided to Other Modules
-
-External entry points:
-*/
-/*SHARED LINE(S) ORIGINATED HERE*/
-
-/*
-Note that "stepping" and "flattening" are so similiar that they use the
-same routine. When the "region" parameter is NULL, that is a flag that
-we are flattening instead of stepping.
-*/
-/*
-:h2.Bezier Third Order Curves
-*/
-/*
-:h3.The "bezierinfo" Structure
-
-This structure is used to store information used when we subdivide
-Bezier curves.
-*/
-
-struct bezierinfo {
- struct region *region; /* the region being built or NULL */
- struct fractpoint last; /* not used yet; maybe could save some work */
- struct fractpoint origin; /* the origin of the bezier */
-} ;
-
-/*
- Checking for termination of the subdivision process:
- This is the stupidest test in the world, just check if the coordinatewise
- distance from an end control point to the next control point is less than
- one half pel. If so, we must be done.
- This returns 1 if the subdivision is terminated and 0 if you still need
- to subdivide.
-*/
-
-static int BezierTerminationTest(xa,ya,xb,yb,xc,yc,xd,yd)
-fractpel xa,ya,xb,yb,xc,yc,xd,yd;
-{
- fractpel dmax;
- dmax = ABS(xa - xb);
- dmax = MAX(dmax,ABS(ya - yb));
- dmax = MAX(dmax,ABS(xd - xc));
- dmax = MAX(dmax,ABS(yd - yc));
- if(dmax > FPHALF)
- return(0); /* not done yet */
- else
- return(1); /* done */
-}
-
-/*
-:h3.StepBezierRecurse() - The Recursive Logic in StepBezier()
-
-The recursion involves dividing the control polygon into two smaller
-control polygons by finding the midpoints of the lines. This idea is
-described in any graphics text book and its simplicity is what caused
-Bezier to define his curves as he did. If the input region 'R' is NULL,
-the result is a path that is the 'flattened' curve; otherwise StepBezier
-returns nothing special.
-*/
-static struct segment *StepBezierRecurse(I,xA,yA,xB,yB,xC,yC,xD,yD)
- struct bezierinfo *I; /* Region under construction or NULL */
- fractpel xA,yA; /* A control point */
- fractpel xB,yB; /* B control point */
- fractpel xC,yC; /* C control point */
- fractpel xD,yD; /* D control point */
-
-{
- if (BezierTerminationTest(xA,yA,xB,yB,xC,yC,xD,yD))
- {
- if (I->region == NULL)
- return(PathSegment(LINETYPE, xD - xA, yD - yA));
- else
- StepLine(I->region, I->origin.x + xA, I->origin.y + yA,
- I->origin.x + xD, I->origin.y + yD);
- }
- else
- {
- fractpel xAB,yAB;
- fractpel xBC,yBC;
- fractpel xCD,yCD;
- fractpel xABC,yABC;
- fractpel xBCD,yBCD;
- fractpel xABCD,yABCD;
-
- xAB = xA + xB; yAB = yA + yB;
- xBC = xB + xC; yBC = yB + yC;
- xCD = xC + xD; yCD = yC + yD;
-
- xABC = xAB + xBC; yABC = yAB + yBC;
- xBCD = xBC + xCD; yBCD = yBC + yCD;
-
- xABCD = xABC + xBCD; yABCD = yABC + yBCD;
-
- xAB >>= 1; yAB >>= 1;
- xBC >>= 1; yBC >>= 1;
- xCD >>= 1; yCD >>= 1;
- xABC >>= 2; yABC >>= 2;
- xBCD >>= 2; yBCD >>= 2;
- xABCD >>= 3; yABCD >>= 3;
-
- if (I->region == NULL)
- {
- return( Join(
- StepBezierRecurse(I, xA, yA, xAB, yAB, xABC, yABC, xABCD, yABCD),
- StepBezierRecurse(I, xABCD, yABCD, xBCD, yBCD, xCD, yCD, xD, yD)
- )
- );
- }
- else
- {
- StepBezierRecurse(I, xA, yA, xAB, yAB, xABC, yABC, xABCD, yABCD);
- StepBezierRecurse(I, xABCD, yABCD, xBCD, yBCD, xCD, yCD, xD, yD);
- }
- }
- /*NOTREACHED*/
-}
-
-/*
-:h3.TOOBIG() - Macro to Test if a Coordinate is Too Big to Bezier SubDivide Normally
-
-Intermediate values in the Bezier subdivision are 8 times bigger than
-the starting values. If this overflows, a 'long', we are in trouble:
-*/
-
-#define BITS (sizeof(long)*8)
-#define HIGHTEST(p) (((p)>>(BITS-4)) != 0) /* includes sign bit */
-#define TOOBIG(xy) ((xy < 0) ? HIGHTEST(-xy) : HIGHTEST(xy))
-
-/*
-:h3.StepBezier() - Produce Run Ends for a Bezier Curve
-
-This is the entry point called from outside the module.
-*/
-
-struct segment *StepBezier(R, xA, yA, xB, yB, xC, yC, xD, yD)
- struct region *R; /* Region under construction or NULL */
- fractpel xA,yA; /* A control point */
- fractpel xB,yB; /* B control point */
- fractpel xC,yC; /* C control point */
- fractpel xD,yD; /* D control point */
-{
- struct bezierinfo Info;
-
- Info.region = R;
- Info.origin.x = xA;
- Info.origin.y = yA;
-
- xB -= xA;
- xC -= xA;
- xD -= xA;
- yB -= yA;
- yC -= yA;
- yD -= yA;
-
- if ( TOOBIG(xB) || TOOBIG(yB) || TOOBIG(xC) || TOOBIG(yC)
- || TOOBIG(xD) || TOOBIG(yD) )
- abort("Beziers this big not yet supported");
-
- return(StepBezierRecurse(&Info,
- (fractpel) 0, (fractpel) 0, xB, yB, xC, yC, xD, yD));
-}
-
projects / rdpsrv / blobdiff