From 3562e78743202e43aec8727005182a2558117eca Mon Sep 17 00:00:00 2001 From: marha Date: Sun, 28 Jun 2009 22:07:26 +0000 Subject: Checked in the following released items: xkeyboard-config-1.4.tar.gz ttf-bitstream-vera-1.10.tar.gz font-alias-1.0.1.tar.gz font-sun-misc-1.0.0.tar.gz font-sun-misc-1.0.0.tar.gz font-sony-misc-1.0.0.tar.gz font-schumacher-misc-1.0.0.tar.gz font-mutt-misc-1.0.0.tar.gz font-misc-misc-1.0.0.tar.gz font-misc-meltho-1.0.0.tar.gz font-micro-misc-1.0.0.tar.gz font-jis-misc-1.0.0.tar.gz font-isas-misc-1.0.0.tar.gz font-dec-misc-1.0.0.tar.gz font-daewoo-misc-1.0.0.tar.gz font-cursor-misc-1.0.0.tar.gz font-arabic-misc-1.0.0.tar.gz font-winitzki-cyrillic-1.0.0.tar.gz font-misc-cyrillic-1.0.0.tar.gz font-cronyx-cyrillic-1.0.0.tar.gz font-screen-cyrillic-1.0.1.tar.gz font-xfree86-type1-1.0.1.tar.gz font-adobe-utopia-type1-1.0.1.tar.gz font-ibm-type1-1.0.0.tar.gz font-bitstream-type1-1.0.0.tar.gz font-bitstream-speedo-1.0.0.tar.gz font-bh-ttf-1.0.0.tar.gz font-bh-type1-1.0.0.tar.gz font-bitstream-100dpi-1.0.0.tar.gz font-bh-lucidatypewriter-100dpi-1.0.0.tar.gz font-bh-100dpi-1.0.0.tar.gz font-adobe-utopia-100dpi-1.0.1.tar.gz font-adobe-100dpi-1.0.0.tar.gz font-util-1.0.1.tar.gz font-bitstream-75dpi-1.0.0.tar.gz font-bh-lucidatypewriter-75dpi-1.0.0.tar.gz font-adobe-utopia-75dpi-1.0.1.tar.gz font-bh-75dpi-1.0.0.tar.gz bdftopcf-1.0.1.tar.gz font-adobe-75dpi-1.0.0.tar.gz mkfontscale-1.0.6.tar.gz openssl-0.9.8k.tar.gz bigreqsproto-1.0.2.tar.gz xtrans-1.2.2.tar.gz resourceproto-1.0.2.tar.gz inputproto-1.4.4.tar.gz compositeproto-0.4.tar.gz damageproto-1.1.0.tar.gz zlib-1.2.3.tar.gz xkbcomp-1.0.5.tar.gz freetype-2.3.9.tar.gz pthreads-w32-2-8-0-release.tar.gz pixman-0.12.0.tar.gz kbproto-1.0.3.tar.gz evieext-1.0.2.tar.gz fixesproto-4.0.tar.gz recordproto-1.13.2.tar.gz randrproto-1.2.2.tar.gz scrnsaverproto-1.1.0.tar.gz renderproto-0.9.3.tar.gz xcmiscproto-1.1.2.tar.gz fontsproto-2.0.2.tar.gz xextproto-7.0.3.tar.gz xproto-7.0.14.tar.gz libXdmcp-1.0.2.tar.gz libxkbfile-1.0.5.tar.gz libfontenc-1.0.4.tar.gz libXfont-1.3.4.tar.gz libX11-1.1.5.tar.gz libXau-1.0.4.tar.gz libxcb-1.1.tar.gz xorg-server-1.5.3.tar.gz --- xorg-server/mi/mizerclip.c | 635 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 635 insertions(+) create mode 100644 xorg-server/mi/mizerclip.c (limited to 'xorg-server/mi/mizerclip.c') diff --git a/xorg-server/mi/mizerclip.c b/xorg-server/mi/mizerclip.c new file mode 100644 index 000000000..b167c5475 --- /dev/null +++ b/xorg-server/mi/mizerclip.c @@ -0,0 +1,635 @@ +/*********************************************************** + +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. + +******************************************************************/ +#ifdef HAVE_DIX_CONFIG_H +#include +#endif + +#include + +#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. + +*/ + +/* 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 + * + */ +_X_EXPORT 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 = 0; + int clip1, clip2; + int x1, y1, x2, y2; + int x1_orig, y1_orig, x2_orig, y2_orig; + int xmajor; + int negslope = 0, anchorval = 0; + unsigned int eqn = 0; + + 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; +} -- cgit v1.2.3