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+/***********************************************************
+
+Copyright 1987, 1998 The Open Group
+
+Permission to use, copy, modify, distribute, and sell this software and its
+documentation for any purpose is hereby granted without fee, provided that
+the above copyright notice appear in all copies and that both that
+copyright notice and this permission notice appear in supporting
+documentation.
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+Except as contained in this notice, the name of The Open Group shall not be
+used in advertising or otherwise to promote the sale, use or other dealings
+in this Software without prior written authorization from The Open Group.
+
+
+Copyright 1987 by Digital Equipment Corporation, Maynard, Massachusetts.
+
+ All Rights Reserved
+
+Permission to use, copy, modify, and distribute this software and its
+documentation for any purpose and without fee is hereby granted,
+provided 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 Digital not be
+used in advertising or publicity pertaining to distribution of the
+software without specific, written prior permission.
+
+DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
+ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
+DIGITAL 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.
+
+******************************************************************/
+/* $Xorg: mizerline.c,v 1.4 2001/02/09 02:05:22 xorgcvs Exp $ */
+#include "X.h"
+
+#include "misc.h"
+#include "scrnintstr.h"
+#include "gcstruct.h"
+#include "windowstr.h"
+#include "pixmap.h"
+#include "mi.h"
+#include "miline.h"
+
+/*
+
+The bresenham error equation used in the mi/mfb/cfb line routines is:
+
+ e = error
+ dx = difference in raw X coordinates
+ dy = difference in raw Y coordinates
+ M = # of steps in X direction
+ N = # of steps in Y direction
+ B = 0 to prefer diagonal steps in a given octant,
+ 1 to prefer axial steps in a given octant
+
+ For X major lines:
+ e = 2Mdy - 2Ndx - dx - B
+ -2dx <= e < 0
+
+ For Y major lines:
+ e = 2Ndx - 2Mdy - dy - B
+ -2dy <= e < 0
+
+At the start of the line, we have taken 0 X steps and 0 Y steps,
+so M = 0 and N = 0:
+
+ X major e = 2Mdy - 2Ndx - dx - B
+ = -dx - B
+
+ Y major e = 2Ndx - 2Mdy - dy - B
+ = -dy - B
+
+At the end of the line, we have taken dx X steps and dy Y steps,
+so M = dx and N = dy:
+
+ X major e = 2Mdy - 2Ndx - dx - B
+ = 2dxdy - 2dydx - dx - B
+ = -dx - B
+ Y major e = 2Ndx - 2Mdy - dy - B
+ = 2dydx - 2dxdy - dy - B
+ = -dy - B
+
+Thus, the error term is the same at the start and end of the line.
+
+Let us consider clipping an X coordinate. There are 4 cases which
+represent the two independent cases of clipping the start vs. the
+end of the line and an X major vs. a Y major line. In any of these
+cases, we know the number of X steps (M) and we wish to find the
+number of Y steps (N). Thus, we will solve our error term equation.
+If we are clipping the start of the line, we will find the smallest
+N that satisfies our error term inequality. If we are clipping the
+end of the line, we will find the largest number of Y steps that
+satisfies the inequality. In that case, since we are representing
+the Y steps as (dy - N), we will actually want to solve for the
+smallest N in that equation.
+
+Case 1: X major, starting X coordinate moved by M steps
+
+ -2dx <= 2Mdy - 2Ndx - dx - B < 0
+ 2Ndx <= 2Mdy - dx - B + 2dx 2Ndx > 2Mdy - dx - B
+ 2Ndx <= 2Mdy + dx - B N > (2Mdy - dx - B) / 2dx
+ N <= (2Mdy + dx - B) / 2dx
+
+Since we are trying to find the smallest N that satisfies these
+equations, we should use the > inequality to find the smallest:
+
+ N = floor((2Mdy - dx - B) / 2dx) + 1
+ = floor((2Mdy - dx - B + 2dx) / 2dx)
+ = floor((2Mdy + dx - B) / 2dx)
+
+Case 1b: X major, ending X coordinate moved to M steps
+
+Same derivations as Case 1, but we want the largest N that satisfies
+the equations, so we use the <= inequality:
+
+ N = floor((2Mdy + dx - B) / 2dx)
+
+Case 2: X major, ending X coordinate moved by M steps
+
+ -2dx <= 2(dx - M)dy - 2(dy - N)dx - dx - B < 0
+ -2dx <= 2dxdy - 2Mdy - 2dxdy + 2Ndx - dx - B < 0
+ -2dx <= 2Ndx - 2Mdy - dx - B < 0
+ 2Ndx >= 2Mdy + dx + B - 2dx 2Ndx < 2Mdy + dx + B
+ 2Ndx >= 2Mdy - dx + B N < (2Mdy + dx + B) / 2dx
+ N >= (2Mdy - dx + B) / 2dx
+
+Since we are trying to find the highest number of Y steps that
+satisfies these equations, we need to find the smallest N, so
+we should use the >= inequality to find the smallest:
+
+ N = ceiling((2Mdy - dx + B) / 2dx)
+ = floor((2Mdy - dx + B + 2dx - 1) / 2dx)
+ = floor((2Mdy + dx + B - 1) / 2dx)
+
+Case 2b: X major, starting X coordinate moved to M steps from end
+
+Same derivations as Case 2, but we want the smallest number of Y
+steps, so we want the highest N, so we use the < inequality:
+
+ N = ceiling((2Mdy + dx + B) / 2dx) - 1
+ = floor((2Mdy + dx + B + 2dx - 1) / 2dx) - 1
+ = floor((2Mdy + dx + B + 2dx - 1 - 2dx) / 2dx)
+ = floor((2Mdy + dx + B - 1) / 2dx)
+
+Case 3: Y major, starting X coordinate moved by M steps
+
+ -2dy <= 2Ndx - 2Mdy - dy - B < 0
+ 2Ndx >= 2Mdy + dy + B - 2dy 2Ndx < 2Mdy + dy + B
+ 2Ndx >= 2Mdy - dy + B N < (2Mdy + dy + B) / 2dx
+ N >= (2Mdy - dy + B) / 2dx
+
+Since we are trying to find the smallest N that satisfies these
+equations, we should use the >= inequality to find the smallest:
+
+ N = ceiling((2Mdy - dy + B) / 2dx)
+ = floor((2Mdy - dy + B + 2dx - 1) / 2dx)
+ = floor((2Mdy - dy + B - 1) / 2dx) + 1
+
+Case 3b: Y major, ending X coordinate moved to M steps
+
+Same derivations as Case 3, but we want the largest N that satisfies
+the equations, so we use the < inequality:
+
+ N = ceiling((2Mdy + dy + B) / 2dx) - 1
+ = floor((2Mdy + dy + B + 2dx - 1) / 2dx) - 1
+ = floor((2Mdy + dy + B + 2dx - 1 - 2dx) / 2dx)
+ = floor((2Mdy + dy + B - 1) / 2dx)
+
+Case 4: Y major, ending X coordinate moved by M steps
+
+ -2dy <= 2(dy - N)dx - 2(dx - M)dy - dy - B < 0
+ -2dy <= 2dxdy - 2Ndx - 2dxdy + 2Mdy - dy - B < 0
+ -2dy <= 2Mdy - 2Ndx - dy - B < 0
+ 2Ndx <= 2Mdy - dy - B + 2dy 2Ndx > 2Mdy - dy - B
+ 2Ndx <= 2Mdy + dy - B N > (2Mdy - dy - B) / 2dx
+ N <= (2Mdy + dy - B) / 2dx
+
+Since we are trying to find the highest number of Y steps that
+satisfies these equations, we need to find the smallest N, so
+we should use the > inequality to find the smallest:
+
+ N = floor((2Mdy - dy - B) / 2dx) + 1
+
+Case 4b: Y major, starting X coordinate moved to M steps from end
+
+Same analysis as Case 4, but we want the smallest number of Y steps
+which means the largest N, so we use the <= inequality:
+
+ N = floor((2Mdy + dy - B) / 2dx)
+
+Now let's try the Y coordinates, we have the same 4 cases.
+
+Case 5: X major, starting Y coordinate moved by N steps
+
+ -2dx <= 2Mdy - 2Ndx - dx - B < 0
+ 2Mdy >= 2Ndx + dx + B - 2dx 2Mdy < 2Ndx + dx + B
+ 2Mdy >= 2Ndx - dx + B M < (2Ndx + dx + B) / 2dy
+ M >= (2Ndx - dx + B) / 2dy
+
+Since we are trying to find the smallest M, we use the >= inequality:
+
+ M = ceiling((2Ndx - dx + B) / 2dy)
+ = floor((2Ndx - dx + B + 2dy - 1) / 2dy)
+ = floor((2Ndx - dx + B - 1) / 2dy) + 1
+
+Case 5b: X major, ending Y coordinate moved to N steps
+
+Same derivations as Case 5, but we want the largest M that satisfies
+the equations, so we use the < inequality:
+
+ M = ceiling((2Ndx + dx + B) / 2dy) - 1
+ = floor((2Ndx + dx + B + 2dy - 1) / 2dy) - 1
+ = floor((2Ndx + dx + B + 2dy - 1 - 2dy) / 2dy)
+ = floor((2Ndx + dx + B - 1) / 2dy)
+
+Case 6: X major, ending Y coordinate moved by N steps
+
+ -2dx <= 2(dx - M)dy - 2(dy - N)dx - dx - B < 0
+ -2dx <= 2dxdy - 2Mdy - 2dxdy + 2Ndx - dx - B < 0
+ -2dx <= 2Ndx - 2Mdy - dx - B < 0
+ 2Mdy <= 2Ndx - dx - B + 2dx 2Mdy > 2Ndx - dx - B
+ 2Mdy <= 2Ndx + dx - B M > (2Ndx - dx - B) / 2dy
+ M <= (2Ndx + dx - B) / 2dy
+
+Largest # of X steps means smallest M, so use the > inequality:
+
+ M = floor((2Ndx - dx - B) / 2dy) + 1
+
+Case 6b: X major, starting Y coordinate moved to N steps from end
+
+Same derivations as Case 6, but we want the smallest # of X steps
+which means the largest M, so use the <= inequality:
+
+ M = floor((2Ndx + dx - B) / 2dy)
+
+Case 7: Y major, starting Y coordinate moved by N steps
+
+ -2dy <= 2Ndx - 2Mdy - dy - B < 0
+ 2Mdy <= 2Ndx - dy - B + 2dy 2Mdy > 2Ndx - dy - B
+ 2Mdy <= 2Ndx + dy - B M > (2Ndx - dy - B) / 2dy
+ M <= (2Ndx + dy - B) / 2dy
+
+To find the smallest M, use the > inequality:
+
+ M = floor((2Ndx - dy - B) / 2dy) + 1
+ = floor((2Ndx - dy - B + 2dy) / 2dy)
+ = floor((2Ndx + dy - B) / 2dy)
+
+Case 7b: Y major, ending Y coordinate moved to N steps
+
+Same derivations as Case 7, but we want the largest M that satisfies
+the equations, so use the <= inequality:
+
+ M = floor((2Ndx + dy - B) / 2dy)
+
+Case 8: Y major, ending Y coordinate moved by N steps
+
+ -2dy <= 2(dy - N)dx - 2(dx - M)dy - dy - B < 0
+ -2dy <= 2dxdy - 2Ndx - 2dxdy + 2Mdy - dy - B < 0
+ -2dy <= 2Mdy - 2Ndx - dy - B < 0
+ 2Mdy >= 2Ndx + dy + B - 2dy 2Mdy < 2Ndx + dy + B
+ 2Mdy >= 2Ndx - dy + B M < (2Ndx + dy + B) / 2dy
+ M >= (2Ndx - dy + B) / 2dy
+
+To find the highest X steps, find the smallest M, use the >= inequality:
+
+ M = ceiling((2Ndx - dy + B) / 2dy)
+ = floor((2Ndx - dy + B + 2dy - 1) / 2dy)
+ = floor((2Ndx + dy + B - 1) / 2dy)
+
+Case 8b: Y major, starting Y coordinate moved to N steps from the end
+
+Same derivations as Case 8, but we want to find the smallest # of X
+steps which means the largest M, so we use the < inequality:
+
+ M = ceiling((2Ndx + dy + B) / 2dy) - 1
+ = floor((2Ndx + dy + B + 2dy - 1) / 2dy) - 1
+ = floor((2Ndx + dy + B + 2dy - 1 - 2dy) / 2dy)
+ = floor((2Ndx + dy + B - 1) / 2dy)
+
+So, our equations are:
+
+ 1: X major move x1 to x1+M floor((2Mdy + dx - B) / 2dx)
+ 1b: X major move x2 to x1+M floor((2Mdy + dx - B) / 2dx)
+ 2: X major move x2 to x2-M floor((2Mdy + dx + B - 1) / 2dx)
+ 2b: X major move x1 to x2-M floor((2Mdy + dx + B - 1) / 2dx)
+
+ 3: Y major move x1 to x1+M floor((2Mdy - dy + B - 1) / 2dx) + 1
+ 3b: Y major move x2 to x1+M floor((2Mdy + dy + B - 1) / 2dx)
+ 4: Y major move x2 to x2-M floor((2Mdy - dy - B) / 2dx) + 1
+ 4b: Y major move x1 to x2-M floor((2Mdy + dy - B) / 2dx)
+
+ 5: X major move y1 to y1+N floor((2Ndx - dx + B - 1) / 2dy) + 1
+ 5b: X major move y2 to y1+N floor((2Ndx + dx + B - 1) / 2dy)
+ 6: X major move y2 to y2-N floor((2Ndx - dx - B) / 2dy) + 1
+ 6b: X major move y1 to y2-N floor((2Ndx + dx - B) / 2dy)
+
+ 7: Y major move y1 to y1+N floor((2Ndx + dy - B) / 2dy)
+ 7b: Y major move y2 to y1+N floor((2Ndx + dy - B) / 2dy)
+ 8: Y major move y2 to y2-N floor((2Ndx + dy + B - 1) / 2dy)
+ 8b: Y major move y1 to y2-N floor((2Ndx + dy + B - 1) / 2dy)
+
+We have the following constraints on all of the above terms:
+
+ 0 < M,N <= 2^15 2^15 can be imposed by miZeroClipLine
+ 0 <= dx/dy <= 2^16 - 1
+ 0 <= B <= 1
+
+The floor in all of the above equations can be accomplished with a
+simple C divide operation provided that both numerator and denominator
+are positive.
+
+Since dx,dy >= 0 and since moving an X coordinate implies that dx != 0
+and moving a Y coordinate implies dy != 0, we know that the denominators
+are all > 0.
+
+For all lines, (-B) and (B-1) are both either 0 or -1, depending on the
+bias. Thus, we have to show that the 2MNdxy +/- dxy terms are all >= 1
+or > 0 to prove that the numerators are positive (or zero).
+
+For X Major lines we know that dx > 0 and since 2Mdy is >= 0 due to the
+constraints, the first four equations all have numerators >= 0.
+
+For the second four equations, M > 0, so 2Mdy >= 2dy so (2Mdy - dy) >= dy
+So (2Mdy - dy) > 0, since they are Y major lines. Also, (2Mdy + dy) >= 3dy
+or (2Mdy + dy) > 0. So all of their numerators are >= 0.
+
+For the third set of four equations, N > 0, so 2Ndx >= 2dx so (2Ndx - dx)
+>= dx > 0. Similarly (2Ndx + dx) >= 3dx > 0. So all numerators >= 0.
+
+For the fourth set of equations, dy > 0 and 2Ndx >= 0, so all numerators
+are > 0.
+
+To consider overflow, consider the case of 2 * M,N * dx,dy + dx,dy. This
+is bounded <= 2 * 2^15 * (2^16 - 1) + (2^16 - 1)
+ <= 2^16 * (2^16 - 1) + (2^16 - 1)
+ <= 2^32 - 2^16 + 2^16 - 1
+ <= 2^32 - 1
+Since the (-B) and (B-1) terms are all 0 or -1, the maximum value of
+the numerator is therefore (2^32 - 1), which does not overflow an unsigned
+32 bit variable.
+
+*/
+
+#define MIOUTCODES(outcode, x, y, xmin, ymin, xmax, ymax) \
+{\
+ if (x < xmin) outcode |= OUT_LEFT;\
+ if (x > xmax) outcode |= OUT_RIGHT;\
+ if (y < ymin) outcode |= OUT_ABOVE;\
+ if (y > ymax) outcode |= OUT_BELOW;\
+}
+
+/* Bit codes for the terms of the 16 clipping equations defined below. */
+
+#define T_2NDX (1 << 0)
+#define T_2MDY (0) /* implicit term */
+#define T_DXNOTY (1 << 1)
+#define T_DYNOTX (0) /* implicit term */
+#define T_SUBDXORY (1 << 2)
+#define T_ADDDX (T_DXNOTY) /* composite term */
+#define T_SUBDX (T_DXNOTY | T_SUBDXORY) /* composite term */
+#define T_ADDDY (T_DYNOTX) /* composite term */
+#define T_SUBDY (T_DYNOTX | T_SUBDXORY) /* composite term */
+#define T_BIASSUBONE (1 << 3)
+#define T_SUBBIAS (0) /* implicit term */
+#define T_DIV2DX (1 << 4)
+#define T_DIV2DY (0) /* implicit term */
+#define T_ADDONE (1 << 5)
+
+/* Bit masks defining the 16 equations used in miZeroClipLine. */
+
+#define EQN1 (T_2MDY | T_ADDDX | T_SUBBIAS | T_DIV2DX)
+#define EQN1B (T_2MDY | T_ADDDX | T_SUBBIAS | T_DIV2DX)
+#define EQN2 (T_2MDY | T_ADDDX | T_BIASSUBONE | T_DIV2DX)
+#define EQN2B (T_2MDY | T_ADDDX | T_BIASSUBONE | T_DIV2DX)
+
+#define EQN3 (T_2MDY | T_SUBDY | T_BIASSUBONE | T_DIV2DX | T_ADDONE)
+#define EQN3B (T_2MDY | T_ADDDY | T_BIASSUBONE | T_DIV2DX)
+#define EQN4 (T_2MDY | T_SUBDY | T_SUBBIAS | T_DIV2DX | T_ADDONE)
+#define EQN4B (T_2MDY | T_ADDDY | T_SUBBIAS | T_DIV2DX)
+
+#define EQN5 (T_2NDX | T_SUBDX | T_BIASSUBONE | T_DIV2DY | T_ADDONE)
+#define EQN5B (T_2NDX | T_ADDDX | T_BIASSUBONE | T_DIV2DY)
+#define EQN6 (T_2NDX | T_SUBDX | T_SUBBIAS | T_DIV2DY | T_ADDONE)
+#define EQN6B (T_2NDX | T_ADDDX | T_SUBBIAS | T_DIV2DY)
+
+#define EQN7 (T_2NDX | T_ADDDY | T_SUBBIAS | T_DIV2DY)
+#define EQN7B (T_2NDX | T_ADDDY | T_SUBBIAS | T_DIV2DY)
+#define EQN8 (T_2NDX | T_ADDDY | T_BIASSUBONE | T_DIV2DY)
+#define EQN8B (T_2NDX | T_ADDDY | T_BIASSUBONE | T_DIV2DY)
+
+/* miZeroClipLine
+ *
+ * returns: 1 for partially clipped line
+ * -1 for completely clipped line
+ *
+ */
+int
+miZeroClipLine(xmin, ymin, xmax, ymax,
+ new_x1, new_y1, new_x2, new_y2,
+ adx, ady,
+ pt1_clipped, pt2_clipped, octant, bias, oc1, oc2)
+ int xmin, ymin, xmax, ymax;
+ int *new_x1, *new_y1, *new_x2, *new_y2;
+ int *pt1_clipped, *pt2_clipped;
+ unsigned int adx, ady;
+ int octant;
+ unsigned int bias;
+ int oc1, oc2;
+{
+ int swapped = 0;
+ int clipDone = 0;
+ CARD32 utmp;
+ int clip1, clip2;
+ int x1, y1, x2, y2;
+ int x1_orig, y1_orig, x2_orig, y2_orig;
+ int xmajor;
+ int negslope, anchorval;
+ unsigned int eqn;
+
+ x1 = x1_orig = *new_x1;
+ y1 = y1_orig = *new_y1;
+ x2 = x2_orig = *new_x2;
+ y2 = y2_orig = *new_y2;
+
+ clip1 = 0;
+ clip2 = 0;
+
+ xmajor = IsXMajorOctant(octant);
+ bias = ((bias >> octant) & 1);
+
+ while (1)
+ {
+ if ((oc1 & oc2) != 0) /* trivial reject */
+ {
+ clipDone = -1;
+ clip1 = oc1;
+ clip2 = oc2;
+ break;
+ }
+ else if ((oc1 | oc2) == 0) /* trivial accept */
+ {
+ clipDone = 1;
+ if (swapped)
+ {
+ SWAPINT_PAIR(x1, y1, x2, y2);
+ SWAPINT(clip1, clip2);
+ }
+ break;
+ }
+ else /* have to clip */
+ {
+ /* only clip one point at a time */
+ if (oc1 == 0)
+ {
+ SWAPINT_PAIR(x1, y1, x2, y2);
+ SWAPINT_PAIR(x1_orig, y1_orig, x2_orig, y2_orig);
+ SWAPINT(oc1, oc2);
+ SWAPINT(clip1, clip2);
+ swapped = !swapped;
+ }
+
+ clip1 |= oc1;
+ if (oc1 & OUT_LEFT)
+ {
+ negslope = IsYDecreasingOctant(octant);
+ utmp = xmin - x1_orig;
+ if (utmp <= 32767) /* clip based on near endpt */
+ {
+ if (xmajor)
+ eqn = (swapped) ? EQN2 : EQN1;
+ else
+ eqn = (swapped) ? EQN4 : EQN3;
+ anchorval = y1_orig;
+ }
+ else /* clip based on far endpt */
+ {
+ utmp = x2_orig - xmin;
+ if (xmajor)
+ eqn = (swapped) ? EQN1B : EQN2B;
+ else
+ eqn = (swapped) ? EQN3B : EQN4B;
+ anchorval = y2_orig;
+ negslope = !negslope;
+ }
+ x1 = xmin;
+ }
+ else if (oc1 & OUT_ABOVE)
+ {
+ negslope = IsXDecreasingOctant(octant);
+ utmp = ymin - y1_orig;
+ if (utmp <= 32767) /* clip based on near endpt */
+ {
+ if (xmajor)
+ eqn = (swapped) ? EQN6 : EQN5;
+ else
+ eqn = (swapped) ? EQN8 : EQN7;
+ anchorval = x1_orig;
+ }
+ else /* clip based on far endpt */
+ {
+ utmp = y2_orig - ymin;
+ if (xmajor)
+ eqn = (swapped) ? EQN5B : EQN6B;
+ else
+ eqn = (swapped) ? EQN7B : EQN8B;
+ anchorval = x2_orig;
+ negslope = !negslope;
+ }
+ y1 = ymin;
+ }
+ else if (oc1 & OUT_RIGHT)
+ {
+ negslope = IsYDecreasingOctant(octant);
+ utmp = x1_orig - xmax;
+ if (utmp <= 32767) /* clip based on near endpt */
+ {
+ if (xmajor)
+ eqn = (swapped) ? EQN2 : EQN1;
+ else
+ eqn = (swapped) ? EQN4 : EQN3;
+ anchorval = y1_orig;
+ }
+ else /* clip based on far endpt */
+ {
+ /*
+ * Technically since the equations can handle
+ * utmp == 32768, this overflow code isn't
+ * needed since X11 protocol can't generate
+ * a line which goes more than 32768 pixels
+ * to the right of a clip rectangle.
+ */
+ utmp = xmax - x2_orig;
+ if (xmajor)
+ eqn = (swapped) ? EQN1B : EQN2B;
+ else
+ eqn = (swapped) ? EQN3B : EQN4B;
+ anchorval = y2_orig;
+ negslope = !negslope;
+ }
+ x1 = xmax;
+ }
+ else if (oc1 & OUT_BELOW)
+ {
+ negslope = IsXDecreasingOctant(octant);
+ utmp = y1_orig - ymax;
+ if (utmp <= 32767) /* clip based on near endpt */
+ {
+ if (xmajor)
+ eqn = (swapped) ? EQN6 : EQN5;
+ else
+ eqn = (swapped) ? EQN8 : EQN7;
+ anchorval = x1_orig;
+ }
+ else /* clip based on far endpt */
+ {
+ /*
+ * Technically since the equations can handle
+ * utmp == 32768, this overflow code isn't
+ * needed since X11 protocol can't generate
+ * a line which goes more than 32768 pixels
+ * below the bottom of a clip rectangle.
+ */
+ utmp = ymax - y2_orig;
+ if (xmajor)
+ eqn = (swapped) ? EQN5B : EQN6B;
+ else
+ eqn = (swapped) ? EQN7B : EQN8B;
+ anchorval = x2_orig;
+ negslope = !negslope;
+ }
+ y1 = ymax;
+ }
+
+ if (swapped)
+ negslope = !negslope;
+
+ utmp <<= 1; /* utmp = 2N or 2M */
+ if (eqn & T_2NDX)
+ utmp = (utmp * adx);
+ else /* (eqn & T_2MDY) */
+ utmp = (utmp * ady);
+ if (eqn & T_DXNOTY)
+ if (eqn & T_SUBDXORY)
+ utmp -= adx;
+ else
+ utmp += adx;
+ else /* (eqn & T_DYNOTX) */
+ if (eqn & T_SUBDXORY)
+ utmp -= ady;
+ else
+ utmp += ady;
+ if (eqn & T_BIASSUBONE)
+ utmp += bias - 1;
+ else /* (eqn & T_SUBBIAS) */
+ utmp -= bias;
+ if (eqn & T_DIV2DX)
+ utmp /= (adx << 1);
+ else /* (eqn & T_DIV2DY) */
+ utmp /= (ady << 1);
+ if (eqn & T_ADDONE)
+ utmp++;
+
+ if (negslope)
+ utmp = -utmp;
+
+ if (eqn & T_2NDX) /* We are calculating X steps */
+ x1 = anchorval + utmp;
+ else /* else, Y steps */
+ y1 = anchorval + utmp;
+
+ oc1 = 0;
+ MIOUTCODES(oc1, x1, y1, xmin, ymin, xmax, ymax);
+ }
+ }
+
+ *new_x1 = x1;
+ *new_y1 = y1;
+ *new_x2 = x2;
+ *new_y2 = y2;
+
+ *pt1_clipped = clip1;
+ *pt2_clipped = clip2;
+
+ return clipDone;
+}
+
+
+/* Draw lineSolid, fillStyle-independent zero width lines.
+ *
+ * Must keep X and Y coordinates in "ints" at least until after they're
+ * translated and clipped to accomodate CoordModePrevious lines with very
+ * large coordinates.
+ *
+ * Draws the same pixels regardless of sign(dx) or sign(dy).
+ *
+ * Ken Whaley
+ *
+ */
+
+/* largest positive value that can fit into a component of a point.
+ * Assumes that the point structure is {type x, y;} where type is
+ * a signed type.
+ */
+#define MAX_COORDINATE ((1 << (((sizeof(DDXPointRec) >> 1) << 3) - 1)) - 1)
+
+#define MI_OUTPUT_POINT(xx, yy)\
+{\
+ if ( !new_span && yy == current_y)\
+ {\
+ if (xx < spans->x)\
+ spans->x = xx;\
+ ++*widths;\
+ }\
+ else\
+ {\
+ ++Nspans;\
+ ++spans;\
+ ++widths;\
+ spans->x = xx;\
+ spans->y = yy;\
+ *widths = 1;\
+ current_y = yy;\
+ new_span = FALSE;\
+ }\
+}
+
+void
+miZeroLine(pDraw, pGC, mode, npt, pptInit)
+ DrawablePtr pDraw;
+ GCPtr pGC;
+ int mode; /* Origin or Previous */
+ int npt; /* number of points */
+ DDXPointPtr pptInit;
+{
+ int Nspans, current_y;
+ DDXPointPtr ppt;
+ DDXPointPtr pspanInit, spans;
+ int *pwidthInit, *widths, list_len;
+ int xleft, ytop, xright, ybottom;
+ int new_x1, new_y1, new_x2, new_y2;
+ int x, y, x1, y1, x2, y2, xstart, ystart;
+ int oc1, oc2;
+ int result;
+ int pt1_clipped, pt2_clipped = 0;
+ Bool new_span;
+ int signdx, signdy;
+ int clipdx, clipdy;
+ int width, height;
+ int adx, ady;
+ int octant;
+ unsigned int bias = miGetZeroLineBias(pDraw->pScreen);
+ int e, e1, e2, e3; /* Bresenham error terms */
+ int length; /* length of lines == # of pixels on major axis */
+
+ xleft = pDraw->x;
+ ytop = pDraw->y;
+ xright = pDraw->x + pDraw->width - 1;
+ ybottom = pDraw->y + pDraw->height - 1;
+
+ if (!pGC->miTranslate)
+ {
+ /* do everything in drawable-relative coordinates */
+ xleft = 0;
+ ytop = 0;
+ xright -= pDraw->x;
+ ybottom -= pDraw->y;
+ }
+
+ /* it doesn't matter whether we're in drawable or screen coordinates,
+ * FillSpans simply cannot take starting coordinates outside of the
+ * range of a DDXPointRec component.
+ */
+ if (xright > MAX_COORDINATE)
+ xright = MAX_COORDINATE;
+ if (ybottom > MAX_COORDINATE)
+ ybottom = MAX_COORDINATE;
+
+ /* since we're clipping to the drawable's boundaries & coordinate
+ * space boundaries, we're guaranteed that the larger of width/height
+ * is the longest span we'll need to output
+ */
+ width = xright - xleft + 1;
+ height = ybottom - ytop + 1;
+ list_len = (height >= width) ? height : width;
+ pspanInit = (DDXPointPtr)ALLOCATE_LOCAL(list_len * sizeof(DDXPointRec));
+ pwidthInit = (int *)ALLOCATE_LOCAL(list_len * sizeof(int));
+ if (!pspanInit || !pwidthInit)
+ return;
+
+ Nspans = 0;
+ new_span = TRUE;
+ spans = pspanInit - 1;
+ widths = pwidthInit - 1;
+ ppt = pptInit;
+
+ xstart = ppt->x;
+ ystart = ppt->y;
+ if (pGC->miTranslate)
+ {
+ xstart += pDraw->x;
+ ystart += pDraw->y;
+ }
+
+ /* x2, y2, oc2 copied to x1, y1, oc1 at top of loop to simplify
+ * iteration logic
+ */
+ x2 = xstart;
+ y2 = ystart;
+ oc2 = 0;
+ MIOUTCODES(oc2, x2, y2, xleft, ytop, xright, ybottom);
+
+ while (--npt > 0)
+ {
+ if (Nspans > 0)
+ (*pGC->ops->FillSpans)(pDraw, pGC, Nspans, pspanInit,
+ pwidthInit, FALSE);
+ Nspans = 0;
+ new_span = TRUE;
+ spans = pspanInit - 1;
+ widths = pwidthInit - 1;
+
+ x1 = x2;
+ y1 = y2;
+ oc1 = oc2;
+ ++ppt;
+
+ x2 = ppt->x;
+ y2 = ppt->y;
+ if (pGC->miTranslate && (mode != CoordModePrevious))
+ {
+ x2 += pDraw->x;
+ y2 += pDraw->y;
+ }
+ else if (mode == CoordModePrevious)
+ {
+ x2 += x1;
+ y2 += y1;
+ }
+
+ oc2 = 0;
+ MIOUTCODES(oc2, x2, y2, xleft, ytop, xright, ybottom);
+
+ CalcLineDeltas(x1, y1, x2, y2, adx, ady, signdx, signdy, 1, 1, octant);
+
+ if (adx > ady)
+ {
+ e1 = ady << 1;
+ e2 = e1 - (adx << 1);
+ e = e1 - adx;
+ length = adx; /* don't draw endpoint in main loop */
+
+ FIXUP_ERROR(e, octant, bias);
+
+ new_x1 = x1;
+ new_y1 = y1;
+ new_x2 = x2;
+ new_y2 = y2;
+ pt1_clipped = 0;
+ pt2_clipped = 0;
+
+ if ((oc1 | oc2) != 0)
+ {
+ result = miZeroClipLine(xleft, ytop, xright, ybottom,
+ &new_x1, &new_y1, &new_x2, &new_y2,
+ adx, ady,
+ &pt1_clipped, &pt2_clipped,
+ octant, bias, oc1, oc2);
+ if (result == -1)
+ continue;
+
+ length = abs(new_x2 - new_x1);
+
+ /* if we've clipped the endpoint, always draw the full length
+ * of the segment, because then the capstyle doesn't matter
+ */
+ if (pt2_clipped)
+ length++;
+
+ if (pt1_clipped)
+ {
+ /* must calculate new error terms */
+ clipdx = abs(new_x1 - x1);
+ clipdy = abs(new_y1 - y1);
+ e += (clipdy * e2) + ((clipdx - clipdy) * e1);
+ }
+ }
+
+ /* draw the segment */
+
+ x = new_x1;
+ y = new_y1;
+
+ e3 = e2 - e1;
+ e = e - e1;
+
+ while (length--)
+ {
+ MI_OUTPUT_POINT(x, y);
+ e += e1;
+ if (e >= 0)
+ {
+ y += signdy;
+ e += e3;
+ }
+ x += signdx;
+ }
+ }
+ else /* Y major line */
+ {
+ e1 = adx << 1;
+ e2 = e1 - (ady << 1);
+ e = e1 - ady;
+ length = ady; /* don't draw endpoint in main loop */
+
+ SetYMajorOctant(octant);
+ FIXUP_ERROR(e, octant, bias);
+
+ new_x1 = x1;
+ new_y1 = y1;
+ new_x2 = x2;
+ new_y2 = y2;
+ pt1_clipped = 0;
+ pt2_clipped = 0;
+
+ if ((oc1 | oc2) != 0)
+ {
+ result = miZeroClipLine(xleft, ytop, xright, ybottom,
+ &new_x1, &new_y1, &new_x2, &new_y2,
+ adx, ady,
+ &pt1_clipped, &pt2_clipped,
+ octant, bias, oc1, oc2);
+ if (result == -1)
+ continue;
+
+ length = abs(new_y2 - new_y1);
+
+ /* if we've clipped the endpoint, always draw the full length
+ * of the segment, because then the capstyle doesn't matter
+ */
+ if (pt2_clipped)
+ length++;
+
+ if (pt1_clipped)
+ {
+ /* must calculate new error terms */
+ clipdx = abs(new_x1 - x1);
+ clipdy = abs(new_y1 - y1);
+ e += (clipdx * e2) + ((clipdy - clipdx) * e1);
+ }
+ }
+
+ /* draw the segment */
+
+ x = new_x1;
+ y = new_y1;
+
+ e3 = e2 - e1;
+ e = e - e1;
+
+ while (length--)
+ {
+ MI_OUTPUT_POINT(x, y);
+ e += e1;
+ if (e >= 0)
+ {
+ x += signdx;
+ e += e3;
+ }
+ y += signdy;
+ }
+ }
+ }
+
+ /* only do the capnotlast check on the last segment
+ * and only if the endpoint wasn't clipped. And then, if the last
+ * point is the same as the first point, do not draw it, unless the
+ * line is degenerate
+ */
+ if ( (! pt2_clipped) && (pGC->capStyle != CapNotLast) &&
+ (((xstart != x2) || (ystart != y2)) || (ppt == pptInit + 1)))
+ {
+ MI_OUTPUT_POINT(x, y);
+ }
+
+ if (Nspans > 0)
+ (*pGC->ops->FillSpans)(pDraw, pGC, Nspans, pspanInit,
+ pwidthInit, FALSE);
+
+ DEALLOCATE_LOCAL(pwidthInit);
+ DEALLOCATE_LOCAL(pspanInit);
+}
+
+void
+miZeroDashLine(dst, pgc, mode, nptInit, pptInit)
+DrawablePtr dst;
+GCPtr pgc;
+int mode;
+int nptInit; /* number of points in polyline */
+DDXPointRec *pptInit; /* points in the polyline */
+{
+ /* XXX kludge until real zero-width dash code is written */
+ pgc->lineWidth = 1;
+ miWideDash (dst, pgc, mode, nptInit, pptInit);
+ pgc->lineWidth = 0;
+}
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