diff options
Diffstat (limited to 'mi/mizerline.c')
| -rw-r--r-- | mi/mizerline.c | 960 |
1 files changed, 960 insertions, 0 deletions
diff --git a/mi/mizerline.c b/mi/mizerline.c new file mode 100644 index 000000000..2279cb822 --- /dev/null +++ b/mi/mizerline.c @@ -0,0 +1,960 @@ +/*********************************************************** + +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; +} |