From 6f7443f938b95b5a5b4b66f5e2f8f93415d888b3 Mon Sep 17 00:00:00 2001 From: James Bursa Date: Mon, 18 Feb 2008 20:47:03 +0000 Subject: Linear gradients, part 1. svn path=/trunk/libsvgtiny/; revision=3861 --- svgtiny_gradient.c | 517 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 517 insertions(+) create mode 100644 svgtiny_gradient.c (limited to 'svgtiny_gradient.c') diff --git a/svgtiny_gradient.c b/svgtiny_gradient.c new file mode 100644 index 0000000..8317cea --- /dev/null +++ b/svgtiny_gradient.c @@ -0,0 +1,517 @@ +/* + * This file is part of Libsvgtiny + * Licensed under the MIT License, + * http://opensource.org/licenses/mit-license.php + * Copyright 2008 James Bursa + */ + +#define _GNU_SOURCE /* for strndup */ +#include +#include +#include "svgtiny.h" +#include "svgtiny_internal.h" + +#define GRADIENT_DEBUG + +static svgtiny_code svgtiny_parse_linear_gradient(xmlNode *linear, + struct svgtiny_parse_state *state); +static float svgtiny_parse_gradient_offset(const char *s); +static void svgtiny_path_bbox(float *p, unsigned int n, + float *x0, float *y0, float *x1, float *y1); + + +/** + * Find a gradient by id and parse it. + */ + +void svgtiny_find_gradient(const char *id, struct svgtiny_parse_state *state) +{ + fprintf(stderr, "svgtiny_find_gradient: id \"%s\"\n", id); + + state->linear_gradient_stop_count = 0; + + xmlNode *gradient = svgtiny_find_element_by_id( + (xmlNode *) state->document, id); + fprintf(stderr, "gradient %p\n", gradient); + if (!gradient) { + fprintf(stderr, "gradient \"%s\" not found\n", id); + return; + } + + fprintf(stderr, "gradient name \"%s\"\n", gradient->name); + if (strcmp((const char *) gradient->name, "linearGradient") == 0) { + svgtiny_parse_linear_gradient(gradient, state); + } +} + + +/** + * Parse a element node. + * + * http://www.w3.org/TR/SVG11/pservers#LinearGradients + */ + +svgtiny_code svgtiny_parse_linear_gradient(xmlNode *linear, + struct svgtiny_parse_state *state) +{ + xmlAttr *href = xmlHasProp(linear, (const xmlChar *) "href"); + if (href && href->children->content[0] == '#') + svgtiny_find_gradient((const char *) href->children->content + + 1, state); + + unsigned int i = 0; + for (xmlNode *stop = linear->children; stop; stop = stop->next) { + float offset = -1; + svgtiny_colour color = svgtiny_TRANSPARENT; + + if (stop->type != XML_ELEMENT_NODE) + continue; + if (strcmp((const char *) stop->name, "stop") != 0) + continue; + + for (xmlAttr *attr = stop->properties; attr; + attr = attr->next) { + const char *name = (const char *) attr->name; + const char *content = + (const char *) attr->children->content; + if (strcmp(name, "offset") == 0) + offset = svgtiny_parse_gradient_offset(content); + else if (strcmp(name, "stop-color") == 0) + svgtiny_parse_color(content, &color, state); + else if (strcmp(name, "style") == 0) { + const char *s; + char *value; + if ((s = strstr(content, "stop-color:"))) { + s += 11; + while (*s == ' ') + s++; + value = strndup(s, strcspn(s, "; ")); + svgtiny_parse_color(value, &color, + state); + free(value); + } + } + } + + if (offset != -1 && color != svgtiny_TRANSPARENT) { + fprintf(stderr, "stop %g %x\n", offset, color); + state->gradient_stop[i].offset = offset; + state->gradient_stop[i].color = color; + i++; + } + + if (i == svgtiny_MAX_STOPS) + break; + } + + if (i) + state->linear_gradient_stop_count = i; + + return svgtiny_OK; +} + + +float svgtiny_parse_gradient_offset(const char *s) +{ + int num_length = strspn(s, "0123456789+-."); + const char *unit = s + num_length; + float n = atof((const char *) s); + + if (unit[0] == 0) + ; + else if (unit[0] == '%') + n /= 100.0; + else + return -1; + + if (n < 0) + n = 0; + if (1 < n) + n = 1; + return n; +} + + +/** + * Add a path with a linear gradient fill to the svgtiny_diagram. + */ + +svgtiny_code svgtiny_add_path_linear_gradient(float *p, unsigned int n, + struct svgtiny_parse_state *state) +{ + /* determine object bounding box */ + float object_x0, object_y0, object_x1, object_y1; + svgtiny_path_bbox(p, n, &object_x0, &object_y0, &object_x1, &object_y1); + #ifdef GRADIENT_DEBUG + fprintf(stderr, "object bbox: (%g %g) (%g %g)\n", + object_x0, object_y0, object_x1, object_y1); + #endif + + /* compute gradient vector */ + float gradient_x0 = 0, gradient_y0 = 0, + gradient_x1 = 1, gradient_y1 = 0.7, + gradient_dx, gradient_dy; + gradient_x0 = object_x0 + gradient_x0 * (object_x1 - object_x0); + gradient_y0 = object_y0 + gradient_y0 * (object_y1 - object_y0); + gradient_x1 = object_x0 + gradient_x1 * (object_x1 - object_x0); + gradient_y1 = object_y0 + gradient_y1 * (object_y1 - object_y0); + gradient_dx = gradient_x1 - gradient_x0; + gradient_dy = gradient_y1 - gradient_y0; + #ifdef GRADIENT_DEBUG + fprintf(stderr, "gradient vector: (%g %g) => (%g %g)\n", + gradient_x0, gradient_y0, gradient_x1, gradient_y1); + #endif + + /* show theoretical gradient strips for debugging */ + /*unsigned int strips = 10; + for (unsigned int z = 0; z != strips; z++) { + float f0, fd, strip_x0, strip_y0, strip_dx, strip_dy; + f0 = (float) z / (float) strips; + fd = (float) 1 / (float) strips; + strip_x0 = gradient_x0 + f0 * gradient_dx; + strip_y0 = gradient_y0 + f0 * gradient_dy; + strip_dx = fd * gradient_dx; + strip_dy = fd * gradient_dy; + fprintf(stderr, "strip %i vector: (%g %g) + (%g %g)\n", + z, strip_x0, strip_y0, strip_dx, strip_dy); + + float *p = malloc(13 * sizeof p[0]); + if (!p) + return svgtiny_OUT_OF_MEMORY; + p[0] = svgtiny_PATH_MOVE; + p[1] = strip_x0 + (strip_dy * 3); + p[2] = strip_y0 - (strip_dx * 3); + p[3] = svgtiny_PATH_LINE; + p[4] = p[1] + strip_dx; + p[5] = p[2] + strip_dy; + p[6] = svgtiny_PATH_LINE; + p[7] = p[4] - (strip_dy * 6); + p[8] = p[5] + (strip_dx * 6); + p[9] = svgtiny_PATH_LINE; + p[10] = p[7] - strip_dx; + p[11] = p[8] - strip_dy; + p[12] = svgtiny_PATH_CLOSE; + svgtiny_transform_path(p, 13, state); + struct svgtiny_shape *shape = svgtiny_add_shape(state); + if (!shape) { + free(p); + return svgtiny_OUT_OF_MEMORY; + } + shape->path = p; + shape->path_length = 13; + shape->fill = svgtiny_TRANSPARENT; + shape->stroke = svgtiny_RGB(0, 0xff, 0); + state->diagram->shape_count++; + }*/ + + /* compute points on the path for triangle vertices */ + unsigned int steps = 10; + float x0, y0, x1, y1; + float gradient_norm_squared = gradient_dx * gradient_dx + + gradient_dy * gradient_dy; + struct grad_point { + float x, y, r; + }; + struct grad_point *pts = malloc(n * steps * sizeof pts[0]); + if (!pts) + return svgtiny_OUT_OF_MEMORY; + unsigned int pts_count = 0; + float min_r = 1000; + unsigned int min_pt = 0; + for (unsigned int j = 0; j != n; ) { + switch ((int) p[j]) { + case svgtiny_PATH_MOVE: + x0 = p[j + 1]; + y0 = p[j + 2]; + j += 3; + break; + case svgtiny_PATH_LINE: + case svgtiny_PATH_CLOSE: + if (((int) p[j]) == svgtiny_PATH_LINE) { + x1 = p[j + 1]; + y1 = p[j + 2]; + j += 3; + } else { + x1 = p[1]; + y1 = p[2]; + j++; + } + fprintf(stderr, "line: "); + for (unsigned int z = 0; z != steps; z++) { + float f, x, y, r; + f = (float) z / (float) steps; + x = x0 + f * (x1 - x0); + y = y0 + f * (y1 - y0); + r = ((x - gradient_x0) * gradient_dx + + (y - gradient_y0) * gradient_dy) / + gradient_norm_squared; + fprintf(stderr, "(%g %g [%g]) ", x, y, r); + pts[pts_count].x = x; + pts[pts_count].y = y; + pts[pts_count].r = r; + if (r < min_r) { + min_r = r; + min_pt = pts_count; + } + pts_count++; + } + fprintf(stderr, "\n"); + x0 = x1; + y0 = y1; + break; + case svgtiny_PATH_BEZIER: + fprintf(stderr, "bezier: "); + for (unsigned int z = 0; z != steps; z++) { + float t, x, y, r; + t = (float) z / (float) steps; + x = (1-t) * (1-t) * (1-t) * x0 + + 3 * t * (1-t) * (1-t) * p[j + 1] + + 3 * t * t * (1-t) * p[j + 3] + + t * t * t * p[j + 5]; + y = (1-t) * (1-t) * (1-t) * y0 + + 3 * t * (1-t) * (1-t) * p[j + 2] + + 3 * t * t * (1-t) * p[j + 4] + + t * t * t * p[j + 6]; + r = ((x - gradient_x0) * gradient_dx + + (y - gradient_y0) * gradient_dy) / + gradient_norm_squared; + fprintf(stderr, "(%g %g [%g]) ", x, y, r); + pts[pts_count].x = x; + pts[pts_count].y = y; + pts[pts_count].r = r; + if (r < min_r) { + min_r = r; + min_pt = pts_count; + } + pts_count++; + } + fprintf(stderr, "\n"); + x0 = p[j + 5]; + y0 = p[j + 6]; + j += 7; + break; + default: + assert(0); + } + } + fprintf(stderr, "pts_count %i, min_pt %i, min_r %.3f\n", + pts_count, min_pt, min_r); + + unsigned int stop_count = state->linear_gradient_stop_count; + assert(2 <= stop_count); + unsigned int current_stop = 0; + float last_stop_r = 0; + float current_stop_r = state->gradient_stop[0].offset; + int red0, green0, blue0, red1, green1, blue1; + red0 = red1 = svgtiny_RED(state->gradient_stop[0].color); + green0 = green1 = svgtiny_GREEN(state->gradient_stop[0].color); + blue0 = blue1 = svgtiny_BLUE(state->gradient_stop[0].color); + unsigned int t, a, b; + t = min_pt; + a = (min_pt + 1) % pts_count; + b = min_pt == 0 ? pts_count - 1 : min_pt - 1; + while (a != b) { + float mean_r = (pts[t].r + pts[a].r + pts[b].r) / 3; + fprintf(stderr, "triangle: t %i %.3f a %i %.3f b %i %.3f " + "mean_r %.3f\n", + t, pts[t].r, a, pts[a].r, b, pts[b].r, + mean_r); + while (current_stop != stop_count && current_stop_r < mean_r) { + current_stop++; + if (current_stop == stop_count) + break; + red0 = red1; + green0 = green1; + blue0 = blue1; + red1 = svgtiny_RED(state-> + gradient_stop[current_stop].color); + green1 = svgtiny_GREEN(state-> + gradient_stop[current_stop].color); + blue1 = svgtiny_BLUE(state-> + gradient_stop[current_stop].color); + last_stop_r = current_stop_r; + current_stop_r = state-> + gradient_stop[current_stop].offset; + } + float *p = malloc(10 * sizeof p[0]); + if (!p) + return svgtiny_OUT_OF_MEMORY; + p[0] = svgtiny_PATH_MOVE; + p[1] = pts[t].x; + p[2] = pts[t].y; + p[3] = svgtiny_PATH_LINE; + p[4] = pts[a].x; + p[5] = pts[a].y; + p[6] = svgtiny_PATH_LINE; + p[7] = pts[b].x; + p[8] = pts[b].y; + p[9] = svgtiny_PATH_CLOSE; + svgtiny_transform_path(p, 10, state); + struct svgtiny_shape *shape = svgtiny_add_shape(state); + if (!shape) { + free(p); + return svgtiny_OUT_OF_MEMORY; + } + shape->path = p; + shape->path_length = 10; + /*shape->fill = svgtiny_TRANSPARENT;*/ + if (current_stop == 0) + shape->fill = state->gradient_stop[0].color; + else if (current_stop == stop_count) + shape->fill = state-> + gradient_stop[stop_count - 1].color; + else { + float stop_r = (mean_r - last_stop_r) / + (current_stop_r - last_stop_r); + shape->fill = svgtiny_RGB( + (int) ((1 - stop_r) * red0 + stop_r * red1), + (int) ((1 - stop_r) * green0 + stop_r * green1), + (int) ((1 - stop_r) * blue0 + stop_r * blue1)); + } + shape->stroke = svgtiny_TRANSPARENT; + #ifdef GRADIENT_DEBUG + shape->stroke = svgtiny_RGB(0, 0, 0xff); + #endif + state->diagram->shape_count++; + if (pts[a].r < pts[b].r) { + t = a; + a = (a + 1) % pts_count; + } else { + t = b; + b = b == 0 ? pts_count - 1 : b - 1; + } + } + + /* render gradient vector for debugging */ + #ifdef GRADIENT_DEBUG + { + float *p = malloc(7 * sizeof p[0]); + if (!p) + return svgtiny_OUT_OF_MEMORY; + p[0] = svgtiny_PATH_MOVE; + p[1] = gradient_x0; + p[2] = gradient_y0; + p[3] = svgtiny_PATH_LINE; + p[4] = gradient_x1; + p[5] = gradient_y1; + p[6] = svgtiny_PATH_CLOSE; + svgtiny_transform_path(p, 7, state); + struct svgtiny_shape *shape = svgtiny_add_shape(state); + if (!shape) { + free(p); + return svgtiny_OUT_OF_MEMORY; + } + shape->path = p; + shape->path_length = 7; + shape->fill = svgtiny_TRANSPARENT; + shape->stroke = svgtiny_RGB(0xff, 0, 0); + state->diagram->shape_count++; + } + #endif + + /* render triangle vertices with r values for debugging */ + #ifdef GRADIENT_DEBUG + for (unsigned int i = 0; i != pts_count; i++) { + struct svgtiny_shape *shape = svgtiny_add_shape(state); + if (!shape) + return svgtiny_OUT_OF_MEMORY; + char *text = malloc(20); + if (!text) + return svgtiny_OUT_OF_MEMORY; + sprintf(text, "%i=%.3f", i, pts[i].r); + shape->text = text; + shape->text_x = state->ctm.a * pts[i].x + + state->ctm.c * pts[i].y + state->ctm.e; + shape->text_y = state->ctm.b * pts[i].x + + state->ctm.d * pts[i].y + state->ctm.f; + shape->fill = svgtiny_RGB(0, 0, 0); + state->diagram->shape_count++; + } + #endif + + /* plot actual path outline */ + if (state->stroke != svgtiny_TRANSPARENT) { + svgtiny_transform_path(p, n, state); + + struct svgtiny_shape *shape = svgtiny_add_shape(state); + if (!shape) { + free(p); + return svgtiny_OUT_OF_MEMORY; + } + shape->path = p; + shape->path_length = n; + shape->fill = svgtiny_TRANSPARENT; + state->diagram->shape_count++; + } + + return svgtiny_OK; +} + + +/** + * Get the bounding box of path. + */ + +void svgtiny_path_bbox(float *p, unsigned int n, + float *x0, float *y0, float *x1, float *y1) +{ + *x0 = *x1 = p[1]; + *y0 = *y1 = p[2]; + + for (unsigned int j = 0; j != n; ) { + unsigned int points = 0; + switch ((int) p[j]) { + case svgtiny_PATH_MOVE: + case svgtiny_PATH_LINE: + points = 1; + break; + case svgtiny_PATH_CLOSE: + points = 0; + break; + case svgtiny_PATH_BEZIER: + points = 3; + break; + default: + assert(0); + } + j++; + for (unsigned int k = 0; k != points; k++) { + float x = p[j], y = p[j + 1]; + if (x < *x0) + *x0 = x; + else if (*x1 < x) + *x1 = x; + if (y < *y0) + *y0 = y; + else if (*y1 < y) + *y1 = y; + j += 2; + } + } +} + + +/** + * Find an element in the document by id. + */ + +xmlNode *svgtiny_find_element_by_id(xmlNode *node, const char *id) +{ + xmlNode *child; + xmlNode *found; + + for (child = node->children; child; child = child->next) { + if (child->type != XML_ELEMENT_NODE) + continue; + xmlAttr *attr = xmlHasProp(child, (const xmlChar *) "id"); + if (attr && strcmp(id, (const char *) attr->children->content) + == 0) + return child; + found = svgtiny_find_element_by_id(child, id); + if (found) + return found; + } + + return 0; +} + -- cgit v1.2.3