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Diffstat (limited to 'app/core/gimpcoords.c')
| -rw-r--r-- | app/core/gimpcoords.c | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/app/core/gimpcoords.c b/app/core/gimpcoords.c new file mode 100644 index 0000000..306f7f2 --- /dev/null +++ b/app/core/gimpcoords.c @@ -0,0 +1,248 @@ +/* GIMP - The GNU Image Manipulation Program + * Copyright (C) 1995 Spencer Kimball and Peter Mattis + * + * gimpcoords.c + * Copyright (C) 2002 Simon Budig <simon@gimp.org> + * + * 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 3 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, see <https://www.gnu.org/licenses/>. + */ + +#include "config.h" + +#include <glib-object.h> + +#include "libgimpmath/gimpmath.h" + +#include "core-types.h" + +#include "gimpcoords.h" + + +#define INPUT_RESOLUTION 256 + + +/* amul * a + bmul * b = ret_val */ + +void +gimp_coords_mix (const gdouble amul, + const GimpCoords *a, + const gdouble bmul, + const GimpCoords *b, + GimpCoords *ret_val) +{ + if (b) + { + ret_val->x = amul * a->x + bmul * b->x; + ret_val->y = amul * a->y + bmul * b->y; + ret_val->pressure = amul * a->pressure + bmul * b->pressure; + ret_val->xtilt = amul * a->xtilt + bmul * b->xtilt; + ret_val->ytilt = amul * a->ytilt + bmul * b->ytilt; + ret_val->wheel = amul * a->wheel + bmul * b->wheel; + ret_val->velocity = amul * a->velocity + bmul * b->velocity; + ret_val->direction = amul * a->direction + bmul * b->direction; + ret_val->extended = b->extended || a->extended; + } + else + { + ret_val->x = amul * a->x; + ret_val->y = amul * a->y; + ret_val->pressure = amul * a->pressure; + ret_val->xtilt = amul * a->xtilt; + ret_val->ytilt = amul * a->ytilt; + ret_val->wheel = amul * a->wheel; + ret_val->velocity = amul * a->velocity; + ret_val->direction = amul * a->direction; + ret_val->extended = a->extended; + } +} + + +/* (a+b)/2 = ret_average */ + +void +gimp_coords_average (const GimpCoords *a, + const GimpCoords *b, + GimpCoords *ret_average) +{ + gimp_coords_mix (0.5, a, 0.5, b, ret_average); +} + + +/* a + b = ret_add */ + +void +gimp_coords_add (const GimpCoords *a, + const GimpCoords *b, + GimpCoords *ret_add) +{ + gimp_coords_mix (1.0, a, 1.0, b, ret_add); +} + + +/* a - b = ret_difference */ + +void +gimp_coords_difference (const GimpCoords *a, + const GimpCoords *b, + GimpCoords *ret_difference) +{ + gimp_coords_mix (1.0, a, -1.0, b, ret_difference); +} + + +/* a * f = ret_product */ + +void +gimp_coords_scale (const gdouble f, + const GimpCoords *a, + GimpCoords *ret_product) +{ + gimp_coords_mix (f, a, 0.0, NULL, ret_product); +} + + +/* local helper for measuring the scalarproduct of two gimpcoords. */ + +gdouble +gimp_coords_scalarprod (const GimpCoords *a, + const GimpCoords *b) +{ + return (a->x * b->x + + a->y * b->y + + a->pressure * b->pressure + + a->xtilt * b->xtilt + + a->ytilt * b->ytilt + + a->wheel * b->wheel + + a->velocity * b->velocity + + a->direction * b->direction); +} + + +/* + * The "length" of the gimpcoord. + * Applies a metric that increases the weight on the + * pressure/xtilt/ytilt/wheel to ensure proper interpolation + */ + +gdouble +gimp_coords_length_squared (const GimpCoords *a) +{ + GimpCoords upscaled_a; + + upscaled_a.x = a->x; + upscaled_a.y = a->y; + upscaled_a.pressure = a->pressure * INPUT_RESOLUTION; + upscaled_a.xtilt = a->xtilt * INPUT_RESOLUTION; + upscaled_a.ytilt = a->ytilt * INPUT_RESOLUTION; + upscaled_a.wheel = a->wheel * INPUT_RESOLUTION; + upscaled_a.velocity = a->velocity * INPUT_RESOLUTION; + upscaled_a.direction = a->direction * INPUT_RESOLUTION; + + return gimp_coords_scalarprod (&upscaled_a, &upscaled_a); +} + + +gdouble +gimp_coords_length (const GimpCoords *a) +{ + return sqrt (gimp_coords_length_squared (a)); +} + +/* + * Distance via manhattan metric, an upper bound for the eucledian metric. + * used for e.g. bezier approximation + */ + +gdouble +gimp_coords_manhattan_dist (const GimpCoords *a, + const GimpCoords *b) +{ + gdouble dist = 0; + + dist += ABS (a->pressure - b->pressure); + dist += ABS (a->xtilt - b->xtilt); + dist += ABS (a->ytilt - b->ytilt); + dist += ABS (a->wheel - b->wheel); + dist += ABS (a->velocity - b->velocity); + dist += ABS (a->direction - b->direction); + + dist *= INPUT_RESOLUTION; + + dist += ABS (a->x - b->x); + dist += ABS (a->y - b->y); + + return dist; +} + +gboolean +gimp_coords_equal (const GimpCoords *a, + const GimpCoords *b) +{ + return (a->x == b->x && + a->y == b->y && + a->pressure == b->pressure && + a->xtilt == b->xtilt && + a->ytilt == b->ytilt && + a->wheel == b->wheel && + a->velocity == b->velocity && + a->direction == b->direction); + + /* Extended attribute was omitted from this comparison deliberately, + * it describes the events origin, not its value + */ +} + +/* helper for calculating direction of two gimpcoords. */ + +gdouble +gimp_coords_direction (const GimpCoords *a, + const GimpCoords *b) +{ + gdouble direction; + gdouble delta_x, delta_y; + + delta_x = a->x - b->x; + delta_y = a->y - b->y; + + if ((delta_x == 0) && (delta_y == 0)) + { + direction = a->direction; + } + else if (delta_x == 0) + { + if (delta_y > 0) + direction = 0.25; + else + direction = 0.75; + } + else if (delta_y == 0) + { + if (delta_x < 0) + direction = 0.0; + else + direction = 0.5; + } + else + { + direction = atan ((- 1.0 * delta_y) / delta_x) / (2 * G_PI); + + if (delta_x > 0.0) + direction = direction + 0.5; + + if (direction < 0.0) + direction = direction + 1.0; + } + + return direction; +} |