WIP "Smooth" freehand curve drawing Magic tool
https://sourceforge.net/p/tuxpaint/feature-requests/238/ h/t Pere for the suggestion Needs to support color, thickness (size controls), and have a round brush shape (anti-aliased would be nice, considering the objective is smoothness ;-) )
This commit is contained in:
Bill Kendrick
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353d572caa
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1 changed files with 386 additions and 0 deletions
386
magic/src/WIP/smooth.c
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magic/src/WIP/smooth.c
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/*
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smooth.c
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FIXME: WORK IN PROGRESS
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Smoothed-Line Magic Tool Plugin
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Tux Paint - A simple drawing program for children.
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Idea: Pere Pujal i Carabantes (https://sourceforge.net/p/tuxpaint/feature-requests/238/)
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Based on: calligraphy.c by Bill Kendrick
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Copyright (c) 2002-2023 by Bill Kendrick and others; see AUTHORS.txt
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bill@newbreedsoftware.com
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https://tuxpaint.org/
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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(See COPYING.txt)
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Last updated: May 16, 2023
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*/
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include "tp_magic_api.h"
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#include "SDL_image.h"
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#include "SDL_mixer.h"
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#include <math.h>
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static Mix_Chunk *smooth_snd;
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static int smooth_r, smooth_g, smooth_b;
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typedef struct
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{
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float x, y;
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} Point2D;
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#define MAX_CTRL_POINTS 4096
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static Point2D smooth_control_points[MAX_CTRL_POINTS];
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static int num_input_points, smooth_capture;
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/* Local Function Prototypes */
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static Point2D smooth_PointOnCubicBezier(Point2D * cp, float t);
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static void smooth_ComputeBezier(Point2D * cp, int numberOfPoints, Point2D * curve);
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static float smooth_dist(float x1, float y1, float x2, float y2);
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int smooth_init(magic_api * api, Uint32 disabled_features);
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Uint32 smooth_api_version(void);
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int smooth_get_tool_count(magic_api * api);
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SDL_Surface *smooth_get_icon(magic_api * api, int which);
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char *smooth_get_name(magic_api * api, int which);
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int smooth_get_group(magic_api * api, int which);
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char *smooth_get_description(magic_api * api, int which, int mode);
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static void smooth_linecb(void *ptr, int which, SDL_Surface * canvas, SDL_Surface * last, int x, int y);
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void smooth_drag(magic_api * api, int which, SDL_Surface * canvas,
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SDL_Surface * last, int ox, int oy, int x, int y, SDL_Rect * update_rect);
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void smooth_click(magic_api * api, int which, int mode,
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SDL_Surface * canvas, SDL_Surface * last, int x, int y, SDL_Rect * update_rect);
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void smooth_release(magic_api * api, int which, SDL_Surface * canvas,
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SDL_Surface * last, int x, int y, SDL_Rect * update_rect);
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void smooth_shutdown(magic_api * api);
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void smooth_set_color(magic_api * api, int which, SDL_Surface * canvas,
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SDL_Surface * last, Uint8 r, Uint8 g, Uint8 b, SDL_Rect * update_rect);
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int smooth_requires_colors(magic_api * api, int which);
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void smooth_switchin(magic_api * api, int which, int mode, SDL_Surface * canvas);
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void smooth_switchout(magic_api * api, int which, int mode, SDL_Surface * canvas);
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int smooth_modes(magic_api * api, int which);
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Uint8 smooth_accepted_sizes(magic_api * api, int which, int mode);
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Uint8 smooth_default_size(magic_api * api, int which, int mode);
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void smooth_set_size(magic_api * api, int which, int mode, SDL_Surface * canvas, SDL_Surface * last, Uint8 size,
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SDL_Rect * update_rect);
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int smooth_init(magic_api * api, Uint32 disabled_features ATTRIBUTE_UNUSED)
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{
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char fname[1024];
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snprintf(fname, sizeof(fname), "%ssounds/magic/rainbow.wav", api->data_directory); // FIXME
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smooth_snd = Mix_LoadWAV(fname);
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return (1);
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}
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Uint32 smooth_api_version(void)
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{
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return (TP_MAGIC_API_VERSION);
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}
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// Only one tool:
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int smooth_get_tool_count(magic_api * api ATTRIBUTE_UNUSED)
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{
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return (1);
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}
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// Load our icon:
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SDL_Surface *smooth_get_icon(magic_api * api, int which ATTRIBUTE_UNUSED)
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{
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char fname[1024];
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snprintf(fname, sizeof(fname), "%simages/magic/rainbow.png", api->data_directory); // FIXME
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return (IMG_Load(fname));
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}
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// Return our name, localized:
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char *smooth_get_name(magic_api * api ATTRIBUTE_UNUSED, int which ATTRIBUTE_UNUSED)
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{
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return (strdup(gettext_noop("Smooth")));
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}
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// Return our group
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int smooth_get_group(magic_api * api ATTRIBUTE_UNUSED, int which ATTRIBUTE_UNUSED)
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{
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return MAGIC_TYPE_PAINTING;
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}
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// Return our description, localized:
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char *smooth_get_description(magic_api * api ATTRIBUTE_UNUSED,
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int which ATTRIBUTE_UNUSED, int mode ATTRIBUTE_UNUSED)
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{
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return (strdup(gettext_noop("Click and drag the mouse around to draw in freehand; it will be smoothed when you let go.")));
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}
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static void smooth_linecb(void *ptr, int which ATTRIBUTE_UNUSED,
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SDL_Surface * canvas, SDL_Surface * last ATTRIBUTE_UNUSED, int x, int y)
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{
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magic_api *api = (magic_api *) ptr;
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SDL_Rect dest;
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dest.x = x;
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dest.y = y;
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dest.w = 2;
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dest.h = 2;
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SDL_FillRect(canvas, &dest, 0);
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}
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void smooth_drag(magic_api * api, int which ATTRIBUTE_UNUSED,
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SDL_Surface * canvas,
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SDL_Surface * last ATTRIBUTE_UNUSED, int ox, int oy, int x, int y, SDL_Rect * update_rect)
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{
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if (num_input_points < MAX_CTRL_POINTS) {
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smooth_capture = (smooth_capture + 1) % 4;
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if (smooth_capture == 1) {
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num_input_points++;
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smooth_control_points[num_input_points].x = x;
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smooth_control_points[num_input_points].y = y;
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}
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api->line((void *)api, which, canvas, last, ox, oy, x, y, 1, smooth_linecb);
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}
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if (ox > x)
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{
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int tmp = ox;
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ox = x;
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x = tmp;
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}
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if (oy > y)
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{
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int tmp = oy;
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oy = y;
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y = tmp;
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}
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// FIXME
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update_rect->x = ox - 16;
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update_rect->y = oy - 16;
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update_rect->w = (x + 16) - update_rect->x;
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update_rect->h = (y + 16) - update_rect->y;
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api->playsound(smooth_snd, (x * 255) / canvas->w, 255); // FIXME
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}
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void smooth_click(magic_api * api ATTRIBUTE_UNUSED,
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int which ATTRIBUTE_UNUSED, int mode ATTRIBUTE_UNUSED,
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SDL_Surface * canvas ATTRIBUTE_UNUSED,
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SDL_Surface * last ATTRIBUTE_UNUSED, int x, int y, SDL_Rect * update_rect ATTRIBUTE_UNUSED)
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{
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num_input_points = 0;
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smooth_control_points[num_input_points].x = x;
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smooth_control_points[num_input_points].y = y;
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smooth_capture = 0;
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api->playsound(smooth_snd, (x * 255) / canvas->w, 255); // FIXME
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}
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void smooth_release(magic_api * api ATTRIBUTE_UNUSED,
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int which ATTRIBUTE_UNUSED,
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SDL_Surface * canvas,
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SDL_Surface * last,
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int x, int y, SDL_Rect * update_rect)
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{
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Point2D *curve;
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int p, i, n_points;
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for (p = 0; p < 4; p++) {
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num_input_points++;
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smooth_control_points[num_input_points].x = x;
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smooth_control_points[num_input_points].y = y;
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}
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SDL_BlitSurface(last, NULL, canvas, NULL);
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for (p = 0; p < num_input_points - 3; p += 3) {
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n_points = smooth_dist(smooth_control_points[p + 0].x,
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smooth_control_points[p + 0].y,
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smooth_control_points[p + 1].x,
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smooth_control_points[p + 1].y) +
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smooth_dist(smooth_control_points[p + 1].x,
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smooth_control_points[p + 1].y,
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smooth_control_points[p + 2].x,
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smooth_control_points[p + 2].y) +
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smooth_dist(smooth_control_points[p + 2].x,
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smooth_control_points[p + 2].y,
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smooth_control_points[p + 3].x,
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smooth_control_points[p + 3].y);
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if (n_points == 0)
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continue; // No-op; not any points to plot
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curve = (Point2D *) malloc(sizeof(Point2D) * n_points);
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smooth_ComputeBezier(smooth_control_points + p, n_points, curve);
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for (i = 0; i < n_points - 1; i++)
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{
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api->line((void *)api, which, canvas, last, curve[i].x, curve[i].y, curve[i + 1].x, curve[i + 1].y, 1, smooth_linecb);
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}
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free(curve);
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api->update_progress_bar();
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}
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api->playsound(smooth_snd, (x * 255) / canvas->w, 255); // FIXME
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update_rect->x = 0;
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update_rect->y = 0;
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update_rect->w = canvas->w;
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update_rect->h = canvas->h;
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}
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void smooth_shutdown(magic_api * api ATTRIBUTE_UNUSED)
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{
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if (smooth_snd != NULL)
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Mix_FreeChunk(smooth_snd);
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}
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void smooth_set_color(magic_api * api, int which ATTRIBUTE_UNUSED, SDL_Surface * canvas ATTRIBUTE_UNUSED,
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SDL_Surface * last ATTRIBUTE_UNUSED, Uint8 r, Uint8 g, Uint8 b,
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SDL_Rect * update_rect ATTRIBUTE_UNUSED)
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{
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if (smooth_r == r && smooth_g == g && smooth_b == b)
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return;
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smooth_r = r;
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smooth_g = g;
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smooth_b = b;
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}
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int smooth_requires_colors(magic_api * api ATTRIBUTE_UNUSED, int which ATTRIBUTE_UNUSED)
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{
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return 1;
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}
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/*
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Code to generate a cubic Bezier curve
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*/
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/*
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cp is a 4 element array where:
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cp[0] is the starting point, or P0 in the above diagram
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cp[1] is the first control point, or P1 in the above diagram
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cp[2] is the second control point, or P2 in the above diagram
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cp[3] is the end point, or P3 in the above diagram
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t is the parameter value, 0 <= t <= 1
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*/
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static Point2D smooth_PointOnCubicBezier(Point2D * cp, float t)
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{
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float ax, bx, cx;
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float ay, by, cy;
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float tSquared, tCubed;
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Point2D result;
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/* calculate the polynomial coefficients */
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cx = 3.0 * (cp[1].x - cp[0].x);
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bx = 3.0 * (cp[2].x - cp[1].x) - cx;
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ax = cp[3].x - cp[0].x - cx - bx;
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cy = 3.0 * (cp[1].y - cp[0].y);
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by = 3.0 * (cp[2].y - cp[1].y) - cy;
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ay = cp[3].y - cp[0].y - cy - by;
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/* calculate the curve point at parameter value t */
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tSquared = t * t;
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tCubed = tSquared * t;
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result.x = (ax * tCubed) + (bx * tSquared) + (cx * t) + cp[0].x;
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result.y = (ay * tCubed) + (by * tSquared) + (cy * t) + cp[0].y;
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return result;
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}
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/*
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ComputeBezier fills an array of Point2D structs with the curve
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points generated from the control points cp. Caller must
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allocate sufficient memory for the result, which is
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<sizeof(Point2D) numberOfPoints>
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*/
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static void smooth_ComputeBezier(Point2D * cp, int numberOfPoints, Point2D * curve)
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{
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float dt;
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int i;
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dt = 1.0 / (numberOfPoints - 1);
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for (i = 0; i < numberOfPoints; i++)
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curve[i] = smooth_PointOnCubicBezier(cp, i * dt);
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}
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static float smooth_dist(float x1, float y1, float x2, float y2)
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{
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float d;
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d = (sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1)));
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return d;
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}
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void smooth_switchin(magic_api * api ATTRIBUTE_UNUSED,
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int which ATTRIBUTE_UNUSED, int mode ATTRIBUTE_UNUSED, SDL_Surface * canvas ATTRIBUTE_UNUSED)
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{
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}
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void smooth_switchout(magic_api * api ATTRIBUTE_UNUSED,
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int which ATTRIBUTE_UNUSED, int mode ATTRIBUTE_UNUSED, SDL_Surface * canvas ATTRIBUTE_UNUSED)
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{
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}
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int smooth_modes(magic_api * api ATTRIBUTE_UNUSED, int which ATTRIBUTE_UNUSED)
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{
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return (MODE_PAINT);
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}
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Uint8 smooth_accepted_sizes(magic_api * api ATTRIBUTE_UNUSED, int which ATTRIBUTE_UNUSED,
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int mode ATTRIBUTE_UNUSED)
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{
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return 0;
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}
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Uint8 smooth_default_size(magic_api * api ATTRIBUTE_UNUSED, int which ATTRIBUTE_UNUSED, int mode ATTRIBUTE_UNUSED)
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{
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return 0;
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}
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void smooth_set_size(magic_api * api ATTRIBUTE_UNUSED, int which ATTRIBUTE_UNUSED, int mode ATTRIBUTE_UNUSED,
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SDL_Surface * canvas ATTRIBUTE_UNUSED, SDL_Surface * last ATTRIBUTE_UNUSED,
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Uint8 size ATTRIBUTE_UNUSED, SDL_Rect * update_rect ATTRIBUTE_UNUSED)
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{
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}
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