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Diffstat (limited to 'src/libs/graphics/clipline.c')
| -rw-r--r-- | src/libs/graphics/clipline.c | 241 |
1 files changed, 241 insertions, 0 deletions
diff --git a/src/libs/graphics/clipline.c b/src/libs/graphics/clipline.c new file mode 100644 index 0000000..ab2d7dd --- /dev/null +++ b/src/libs/graphics/clipline.c @@ -0,0 +1,241 @@ +//Copyright Paul Reiche, Fred Ford. 1992-2002 + +/* + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + */ + +#include "gfxintrn.h" + +INTERSECT_CODE +_clip_line (const RECT *pClipRect, BRESENHAM_LINE *pLine) +{ + COORD p; + COORD x0, y0, xmin, ymin, xmax, ymax; + SIZE abs_delta_x, abs_delta_y; + INTERSECT_CODE intersect_code; + + xmin = pClipRect->corner.x; + ymin = pClipRect->corner.y; + xmax = pClipRect->corner.x + pClipRect->extent.width - 1; + ymax = pClipRect->corner.y + pClipRect->extent.height - 1; + if (pLine->first.x <= pLine->second.x) + pLine->end_points_exchanged = FALSE; + else + { + p = pLine->first.x; + pLine->first.x = pLine->second.x; + pLine->second.x = p; + + p = pLine->first.y; + pLine->first.y = pLine->second.y; + pLine->second.y = p; + + pLine->end_points_exchanged = TRUE; + } + + if (pLine->first.x > xmax || pLine->second.x < xmin || + (pLine->first.y > ymax && pLine->second.y > ymax) || + (pLine->first.y < ymin && pLine->second.y < ymin)) + return ((INTERSECT_CODE)0); + + intersect_code = INTERSECT_NOCLIP; + x0 = y0 = 0; + abs_delta_x = (pLine->second.x - pLine->first.x) << 1; + abs_delta_y = (pLine->second.y - pLine->first.y) << 1; + pLine->abs_delta_x = abs_delta_x; + pLine->abs_delta_y = abs_delta_y; + if (abs_delta_y == 0) + { + if (pLine->first.x < xmin) + { + pLine->first.x = xmin; + intersect_code |= INTERSECT_LEFT; + } + if (pLine->second.x > xmax) + { + pLine->second.x = xmax; + intersect_code |= INTERSECT_RIGHT; + } + } + else if (abs_delta_x == 0) + { + if (abs_delta_y < 0) + { + p = pLine->first.y; + pLine->first.y = pLine->second.y; + pLine->second.y = p; + + pLine->abs_delta_y = + abs_delta_y = -abs_delta_y; + } + + if (pLine->first.y < ymin) + { + pLine->first.y = ymin; + intersect_code |= INTERSECT_TOP; + } + if (pLine->second.y > ymax) + { + pLine->second.y = ymax; + intersect_code |= INTERSECT_BOTTOM; + } + } + else + { + COORD x1, y1; + + p = pLine->first.x; + x1 = pLine->second.x - p; + xmin = xmin - p; + xmax = xmax - p; + + p = pLine->first.y; + if (abs_delta_y > 0) + { + y1 = pLine->second.y - p; + ymin = ymin - p; + ymax = ymax - p; + } + else + { + y1 = p - pLine->second.y; + ymin = p - ymin; + ymax = p - ymax; + + p = ymin; + ymin = ymax; + ymax = p; + abs_delta_y = -abs_delta_y; + } + + if (abs_delta_x > abs_delta_y) + { + SIZE half_dx; + + half_dx = abs_delta_x >> 1; + if (x0 < xmin) + { + if ((y0 = (COORD)(((long)abs_delta_y * + (x0 = xmin) + half_dx) / abs_delta_x)) > ymax) + return ((INTERSECT_CODE)0); + intersect_code |= INTERSECT_LEFT; + } + if (x1 > xmax) + { + if ((y1 = (COORD)(((long)abs_delta_y * + (x1 = xmax) + half_dx) / abs_delta_x)) < ymin) + return ((INTERSECT_CODE)0); + intersect_code |= INTERSECT_RIGHT; + } + if (y0 < ymin) + { + if ((x0 = (COORD)(((long)abs_delta_x * + (y0 = ymin) - half_dx + (abs_delta_y - 1)) / + abs_delta_y)) > xmax) + return ((INTERSECT_CODE)0); + intersect_code |= INTERSECT_TOP; + intersect_code &= ~INTERSECT_LEFT; + } + if (y1 > ymax) + { + if ((x1 = (COORD)(((long)abs_delta_x * + ((y1 = ymax) + 1) - half_dx + (abs_delta_y - 1)) / + abs_delta_y) - 1) < xmin) + return ((INTERSECT_CODE)0); + intersect_code |= INTERSECT_BOTTOM; + intersect_code &= ~INTERSECT_RIGHT; + } + } + else + { + SIZE half_dy; + + half_dy = abs_delta_y >> 1; + if (y0 < ymin) + { + if ((x0 = (COORD)(((long)abs_delta_x * + (y0 = ymin) + half_dy) / abs_delta_y)) > xmax) + return ((INTERSECT_CODE)0); + intersect_code |= INTERSECT_TOP; + } + if (y1 > ymax) + { + if ((x1 = (COORD)(((long)abs_delta_x * + (y1 = ymax) + half_dy) / abs_delta_y)) < xmin) + return ((INTERSECT_CODE)0); + intersect_code |= INTERSECT_BOTTOM; + } + if (x0 < xmin) + { + if ((y0 = (COORD)(((long)abs_delta_y * + (x0 = xmin) - half_dy + (abs_delta_x - 1)) / + abs_delta_x)) > ymax) + return ((INTERSECT_CODE)0); + intersect_code |= INTERSECT_LEFT; + intersect_code &= ~INTERSECT_TOP; + } + if (x1 > xmax) + { + if ((y1 = (COORD)(((long)abs_delta_y * + ((x1 = xmax) + 1) - half_dy + (abs_delta_x - 1)) / + abs_delta_x) - 1) < ymin) + return ((INTERSECT_CODE)0); + intersect_code |= INTERSECT_RIGHT; + intersect_code &= ~INTERSECT_BOTTOM; + } + } + + pLine->second.x = pLine->first.x + x1; + pLine->first.x += x0; + if (pLine->abs_delta_y > 0) + { + pLine->second.y = pLine->first.y + y1; + pLine->first.y += y0; + } + else + { + INTERSECT_CODE y_code; + + pLine->second.y = pLine->first.y - y1; + pLine->first.y -= y0; + + y_code = (INTERSECT_CODE)(intersect_code + & (INTERSECT_TOP | INTERSECT_BOTTOM)); + if (y_code && y_code != (INTERSECT_TOP | INTERSECT_BOTTOM)) + intersect_code ^= (INTERSECT_TOP | INTERSECT_BOTTOM); + } + } + + if (!(intersect_code & INTERSECT_ALL_SIDES)) + { + if (abs_delta_x > abs_delta_y) + pLine->error_term = -(SIZE)(abs_delta_x >> 1); + else + pLine->error_term = -(SIZE)(abs_delta_y >> 1); + } + else + { + intersect_code &= ~INTERSECT_NOCLIP; + if (abs_delta_x > abs_delta_y) + pLine->error_term = (SIZE)((x0 * (long)abs_delta_y) - + (y0 * (long)abs_delta_x)) - (abs_delta_x >> 1); + else + pLine->error_term = (SIZE)((y0 * (long)abs_delta_x) - + (x0 * (long)abs_delta_y)) - (abs_delta_y >> 1); + } + + return (pLine->intersect_code = intersect_code); +} + |