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Diffstat (limited to 'plug-ins/selection-to-path/spline.h')
| -rw-r--r-- | plug-ins/selection-to-path/spline.h | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/plug-ins/selection-to-path/spline.h b/plug-ins/selection-to-path/spline.h new file mode 100644 index 0000000..3daa9cc --- /dev/null +++ b/plug-ins/selection-to-path/spline.h @@ -0,0 +1,124 @@ +/* spline.h: manipulate the spline representation. + * + * Copyright (C) 1992 Free Software Foundation, Inc. + * + * 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, 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/>. + */ + +#ifndef SPLINE_H +#define SPLINE_H + +#include <stdio.h> +#include "bounding-box.h" +#include "types.h" + + +/* Third degree is the highest we deal with. */ +typedef enum +{ + LINEAR = 1, QUADRATIC = 2, CUBIC = 3 +} polynomial_degree; + + +/* A Bezier spline can be represented as four points in the real plane: + a starting point, ending point, and two control points. The + curve always lies in the convex hull defined by the four points. It + is also convenient to save the divergence of the spline from the + straight line defined by the endpoints. */ +typedef struct +{ + real_coordinate_type v[4]; /* The control points. */ + polynomial_degree degree; + real linearity; +} spline_type; + +#define START_POINT(spl) ((spl).v[0]) +#define CONTROL1(spl) ((spl).v[1]) +#define CONTROL2(spl) ((spl).v[2]) +#define END_POINT(spl) ((spl).v[3]) +#define SPLINE_DEGREE(spl) ((spl).degree) +#define SPLINE_LINEARITY(spl) ((spl).linearity) + + +/* Return a spline structure. */ +extern spline_type new_spline (void); + +/* Print a spline on the given file. */ +extern void print_spline (FILE *, spline_type); + +/* Evaluate SPLINE at the given T value. */ +extern real_coordinate_type evaluate_spline (spline_type spline, real t); + +/* Each outline in a character is typically represented by many + splines. So, here is a list structure for that: */ +typedef struct +{ + spline_type *data; + unsigned length; +} spline_list_type; + +/* An empty list will have length zero (and null data). */ +#define SPLINE_LIST_LENGTH(s_l) ((s_l).length) + +/* The address of the beginning of the array of data. */ +#define SPLINE_LIST_DATA(s_l) ((s_l).data) + +/* The element INDEX in S_L. */ +#define SPLINE_LIST_ELT(s_l, index) (SPLINE_LIST_DATA (s_l)[index]) + +/* The last element in S_L. */ +#define LAST_SPLINE_LIST_ELT(s_l) \ + (SPLINE_LIST_DATA (s_l)[SPLINE_LIST_LENGTH (s_l) - 1]) + +/* The previous and next elements to INDEX in S_L. */ +#define NEXT_SPLINE_LIST_ELT(s_l, index) \ + SPLINE_LIST_ELT (s_l, ((index) + 1) % SPLINE_LIST_LENGTH (s_l)) +#define PREV_SPLINE_LIST_ELT(s_l, index) \ + SPLINE_LIST_ELT (s_l, index == 0 \ + ? SPLINE_LIST_LENGTH (s_l) - 1 \ + : index - 1) + +/* Construct and destroy new `spline_list_type' objects. */ +extern spline_list_type *new_spline_list (void); +extern spline_list_type *init_spline_list (spline_type); +extern void free_spline_list (spline_list_type *); + +/* Append the spline S to the list S_LIST. */ +extern void append_spline (spline_list_type *s_list, spline_type s); + +/* Append the elements in list S2 to S1, changing S1. */ +extern void concat_spline_lists (spline_list_type *s1, spline_list_type s2); + + +/* Each character is in general made up of many outlines. So here is one + more list structure. */ +typedef struct +{ + spline_list_type *data; + unsigned length; +} spline_list_array_type; + +/* Turns out we can use the same definitions for lists of lists as for + just lists. But we define the usual names, just in case. */ +#define SPLINE_LIST_ARRAY_LENGTH SPLINE_LIST_LENGTH +#define SPLINE_LIST_ARRAY_DATA SPLINE_LIST_DATA +#define SPLINE_LIST_ARRAY_ELT SPLINE_LIST_ELT +#define LAST_SPLINE_LIST_ARRAY_ELT LAST_SPLINE_LIST_ELT + +/* The usual routines. */ +extern spline_list_array_type new_spline_list_array (void); +extern void free_spline_list_array (spline_list_array_type *); +extern void append_spline_list (spline_list_array_type *, spline_list_type); + +#endif /* not SPLINE_H */ |