netsurf/image/svg.c

/*
 * This file is part of NetSurf, http://netsurf-browser.org/
 * Licensed under the GNU General Public License,
 *                http://www.opensource.org/licenses/gpl-license
 * Copyright 2007 James Bursa <bursa@users.sourceforge.net>
 */

/** \file
 * Content for image/svg (implementation).
 */

#include <assert.h>
#include <setjmp.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <libxml/parser.h>
#include <libxml/debugXML.h>
#include "utils/config.h"
#include "content/content.h"
#include "css/css.h"
#include "desktop/plotters.h"
#include "desktop/options.h"
#include "image/svg.h"
#include "utils/log.h"
#include "utils/messages.h"
#include "utils/utils.h"


struct svg_redraw_state {
	/* screen origin */
	int origin_x;
	int origin_y;

	float viewport_width;
	float viewport_height;

	/* current transformation matrix */
	struct {
		float a, b, c, d, e, f;
	} ctm;

	struct css_style style;

	/* paint attributes */
	colour fill;
	colour stroke;
	int stroke_width;
};


static bool svg_redraw_svg(xmlNode *svg, struct svg_redraw_state state);
static bool svg_redraw_path(xmlNode *path, struct svg_redraw_state state);
static bool svg_redraw_rect(xmlNode *rect, struct svg_redraw_state state);
static bool svg_redraw_circle(xmlNode *circle, struct svg_redraw_state state);
static bool svg_redraw_line(xmlNode *line, struct svg_redraw_state state);
static bool svg_redraw_text(xmlNode *text, struct svg_redraw_state state);
static void svg_parse_position_attributes(const xmlNode *node,
		const struct svg_redraw_state state,
		float *x, float *y, float *width, float *height);
static float svg_parse_length(const xmlChar *s, int viewport_size,
		const struct svg_redraw_state state);
static void svg_parse_paint_attributes(const xmlNode *node,
		struct svg_redraw_state *state);
static void svg_parse_color(const char *s, colour *c);
static void svg_parse_font_attributes(const xmlNode *node,
		struct svg_redraw_state *state);


/**
 * Create a CONTENT_SVG.
 */

bool svg_create(struct content *c, const char *params[])
{
	c->data.svg.doc = 0;
	c->data.svg.svg = 0;

	return true;
}


/**
 * Convert a CONTENT_SVG for display.
 */

bool svg_convert(struct content *c, int w, int h)
{
	xmlDoc *document;
	xmlNode *svg;
	union content_msg_data msg_data;

	/* parse XML to tree */
	document = xmlReadMemory(c->source_data, c->source_size,
			c->url, 0, XML_PARSE_NONET | XML_PARSE_COMPACT);
	if (!document) {
		LOG(("xmlReadMemory failed"));
		msg_data.error = messages_get("ParsingFail");
		content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
		return false;
	}
	c->data.svg.doc = document;

	/* xmlDebugDumpDocument(stderr, document); */

	/* find root <svg> element */
	for (svg = document->children;
			svg && svg->type != XML_ELEMENT_NODE;
			svg = svg->next)
		continue;
	if (!svg) {
		LOG(("no element in svg"));
		msg_data.error = "no element in svg";
		content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
		return false;
	}
	if (strcmp(svg->name, "svg") != 0) {
		LOG(("root element is not svg"));
		msg_data.error = "root element is not svg";
		content_broadcast(c, CONTENT_MSG_ERROR, msg_data);
		return false;
        }
	c->data.svg.svg = svg;

	/* get graphic dimensions */
	struct svg_redraw_state state;
	state.viewport_width = w;
	state.viewport_height = h;
	float x, y, width, height;
	svg_parse_position_attributes(svg, state, &x, &y, &width, &height);
	c->width = width;
	c->height = height;

	/*c->title = malloc(100);
	if (c->title)
		snprintf(c->title, 100, messages_get("svgTitle"),
				width, height, c->source_size);*/
	//c->size += ?;
	c->status = CONTENT_STATUS_DONE;
	return true;
}


/**
 * Redraw a CONTENT_SVG.
 */

bool svg_redraw(struct content *c, int x, int y,
		int width, int height,
		int clip_x0, int clip_y0, int clip_x1, int clip_y1,
		float scale, unsigned long background_colour)
{
	assert(c->data.svg.svg);

	struct svg_redraw_state state;

	state.origin_x = x;
	state.origin_y = y;
	state.viewport_width = width;
	state.viewport_height = height;
	state.ctm.a = 1;
	state.ctm.b = 0;
	state.ctm.c = 0;
	state.ctm.d = 1;
	state.ctm.e = 0;
	state.ctm.f = 0;
	state.style = css_base_style;
	state.style.font_size.value.length.value = option_font_size * 0.1;
	state.fill = 0x000000;
	state.stroke = TRANSPARENT;
	state.stroke_width = 1;

	plot.clg(0xffffff);

	return svg_redraw_svg(c->data.svg.svg, state);
}


/**
 * Redraw a <svg> or <g> element node.
 */

bool svg_redraw_svg(xmlNode *svg, struct svg_redraw_state state)
{
	float x, y;

	svg_parse_position_attributes(svg, state,
			&x, &y,
			&state.viewport_width, &state.viewport_height);
	svg_parse_paint_attributes(svg, &state);
	svg_parse_font_attributes(svg, &state);

	/* parse viewBox */
	xmlAttr *view_box = xmlHasProp(svg, (const xmlChar *) "viewBox");
	if (view_box) {
		const char *s = (const char *) view_box->children->content;
		float min_x, min_y, width, height;
		if (sscanf(s, "%f,%f,%f,%f",
				&min_x, &min_y, &width, &height) == 4 ||
				sscanf(s, "%f %f %f %f",
				&min_x, &min_y, &width, &height) == 4) {
			state.ctm.a = state.viewport_width / width;
			state.ctm.d = state.viewport_height / height;
			state.ctm.e = -min_x;
			state.ctm.f = -min_y;
		}
	}

	for (xmlNode *child = svg->children; child; child = child->next) {
		bool ok = true;

		if (child->type == XML_ELEMENT_NODE) {
			if (strcmp(child->name, "svg") == 0)
				ok = svg_redraw_svg(child, state);
			else if (strcmp(child->name, "g") == 0)
				ok = svg_redraw_svg(child, state);
			else if (strcmp(child->name, "path") == 0)
				ok = svg_redraw_path(child, state);
			else if (strcmp(child->name, "rect") == 0)
				ok = svg_redraw_rect(child, state);
			else if (strcmp(child->name, "circle") == 0)
				ok = svg_redraw_circle(child, state);
			else if (strcmp(child->name, "line") == 0)
				ok = svg_redraw_line(child, state);
			else if (strcmp(child->name, "text") == 0)
				ok = svg_redraw_text(child, state);
		}

		if (!ok)
			return false;
	}

	return true;
}


/**
 * Redraw a <path> element node.
 */

bool svg_redraw_path(xmlNode *path, struct svg_redraw_state state)
{
	svg_parse_paint_attributes(path, &state);

	/* read d attribute */
	char *s = (char *) xmlGetProp(path, (const xmlChar *) "d");
	if (!s) {
		LOG(("path missing d attribute"));
		return false;
	}

	/* allocate space for path: it will never have more elements than d */
	float *p = malloc(sizeof p[0] * strlen(s));
	if (!p) {
		LOG(("out of memory"));
		return false;
	}

	/* parse d and build path */
	for (unsigned int i = 0; s[i]; i++)
		if (s[i] == ',')
			s[i] = ' ';
	unsigned int i = 0;
	float last_x = 0, last_y = 0;
	while (*s) {
		char command[2];
		int plot_command;
		float x, y, x1, y1, x2, y2;
		int n;

		LOG(("s \"%s\"", s));

		/* M, m, L, l (2 arguments) */
		if (sscanf(s, " %1[MmLl] %f %f %n", command, &x, &y, &n) == 3) {
			LOG(("moveto or lineto"));
			if (*command == 'M' || *command == 'm')
				plot_command = PLOTTER_PATH_MOVE;
			else
				plot_command = PLOTTER_PATH_LINE;
			do {
				p[i++] = plot_command;
				if ('a' <= *command) {
					x += last_x;
					y += last_y;
				}
				p[i++] = last_x = x;
				p[i++] = last_y = y;
				s += n;
				plot_command = PLOTTER_PATH_LINE;
			} while (sscanf(s, "%f %f %n", &x, &y, &n) == 2);

		/* Z, z (no arguments) */
		} else if (sscanf(s, " %1[Zz] %n", command, &n) == 1) {
			LOG(("closepath"));
			p[i++] = PLOTTER_PATH_CLOSE;
			s += n;

		/* H, h (1 argument) */
		} else if (sscanf(s, " %1[Hh] %f %n", command, &x, &n) == 2) {
			LOG(("horizontal lineto"));
			do {
				p[i++] = PLOTTER_PATH_LINE;
				if (*command == 'h')
					x += last_x;
				p[i++] = last_x = x;
				p[i++] = last_y;
				s += n;
			} while (sscanf(s, "%f %n", &x, &n) == 1);

		/* V, v (1 argument) */
		} else if (sscanf(s, " %1[Vv] %f %n", command, &y, &n) == 2) {
			LOG(("vertical lineto"));
			do {
				p[i++] = PLOTTER_PATH_LINE;
				if (*command == 'v')
					y += last_y;
				p[i++] = last_x;
				p[i++] = last_y = y;
				s += n;
			} while (sscanf(s, "%f %n", &x, &n) == 1);

		/* C, c (6 arguments) */
		} else if (sscanf(s, " %1[Cc] %f %f %f %f %f %f %n", command,
				&x1, &y1, &x2, &y2, &x, &y, &n) == 7) {
			LOG(("curveto"));
			do {
				p[i++] = PLOTTER_PATH_BEZIER;
				if (*command == 'c') {
					x1 += last_x;
					y1 += last_y;
					x2 += last_x;
					y2 += last_y;
					x += last_x;
					y += last_y;
				}
				p[i++] = x1;
				p[i++] = y1;
				p[i++] = x2;
				p[i++] = y2;
				p[i++] = last_x = x;
				p[i++] = last_y = y;
				s += n;
			} while (sscanf(s, "%f %f %f %f %f %f %n",
					&x1, &y1, &x2, &y2, &x, &y, &n) == 7);

		} else {
			LOG(("parse failed"));
			break;
		}
	}

	LOG(("path:"));
	for (unsigned int j = 0; j != i; j++) {
		LOG(("    %f", p[j]));
	}

	bool ok = plot.path(p, i, state.fill, state.stroke_width, state.stroke,
			&state.ctm.a);

	free(p);

	return true;
}


/**
 * Redraw a <rect> element node.
 */

bool svg_redraw_rect(xmlNode *rect, struct svg_redraw_state state)
{
	float x, y, width, height;

	svg_parse_position_attributes(rect, state,
			&x, &y, &width, &height);
	svg_parse_paint_attributes(rect, &state);

	int p[8] = { x, y,
		x + width, y,
		x + width, y + height,
		x,         y + height };
	for (unsigned int i = 0; i != 8; i += 2) {
		p[i] = state.origin_x + state.ctm.a * p[i] +
				state.ctm.c * p[i+1] + state.ctm.e;
		p[i+1] = state.origin_y + state.ctm.b * p[i] +
				state.ctm.d * p[i+1] + state.ctm.f;
	}

	if (state.fill != TRANSPARENT)
		if (!plot.polygon(p, 4, state.fill))
			return false;

	if (state.stroke != TRANSPARENT) {
		for (unsigned int i = 0; i != 8; i += 2) {
			if (!plot.line(p[i], p[i+1], p[(i+2)%8], p[(i+3)%8],
					state.stroke_width, state.stroke,
					false, false))
				return false;
		}
	}

	return true;
}


/**
 * Redraw a <circle> element node.
 */

bool svg_redraw_circle(xmlNode *circle, struct svg_redraw_state state)
{
	float x = 0, y = 0, r = 0;

	for (xmlAttr *attr = circle->properties; attr; attr = attr->next) {
		if (strcmp(attr->name, "cx") == 0)
			x = svg_parse_length(attr->children->content,
					state.viewport_width, state);
		else if (strcmp(attr->name, "cy") == 0)
			y = svg_parse_length(attr->children->content,
					state.viewport_height, state);
		else if (strcmp(attr->name, "r") == 0)
			r = svg_parse_length(attr->children->content,
					state.viewport_width, state);
        }
	svg_parse_paint_attributes(circle, &state);

	int px = state.origin_x + state.ctm.a * x +
			state.ctm.c * y + state.ctm.e;
	int py = state.origin_y + state.ctm.b * x +
			state.ctm.d * y + state.ctm.f;
	int pr = r * state.ctm.a;

	if (state.fill != TRANSPARENT)
		if (!plot.disc(px, py, pr, state.fill, true))
			return false;

	if (state.stroke != TRANSPARENT)
		if (!plot.disc(px, py, pr, state.stroke, false))
			return false;

	return true;
}


/**
 * Redraw a <line> element node.
 */

bool svg_redraw_line(xmlNode *line, struct svg_redraw_state state)
{
	float x1 = 0, y1 = 0, x2 = 0, y2 = 0;

	for (xmlAttr *attr = line->properties; attr; attr = attr->next) {
		if (strcmp(attr->name, "x1") == 0)
			x1 = svg_parse_length(attr->children->content,
					state.viewport_width, state);
		else if (strcmp(attr->name, "y1") == 0)
			y1 = svg_parse_length(attr->children->content,
					state.viewport_height, state);
		else if (strcmp(attr->name, "x2") == 0)
			x2 = svg_parse_length(attr->children->content,
					state.viewport_width, state);
		else if (strcmp(attr->name, "y2") == 0)
			y2 = svg_parse_length(attr->children->content,
					state.viewport_height, state);
        }
	svg_parse_paint_attributes(line, &state);

	int px1 = state.origin_x + state.ctm.a * x1 +
			state.ctm.c * y1 + state.ctm.e;
	int py1 = state.origin_y + state.ctm.b * x1 +
			state.ctm.d * y1 + state.ctm.f;
	int px2 = state.origin_x + state.ctm.a * x2 +
			state.ctm.c * y2 + state.ctm.e;
	int py2 = state.origin_y + state.ctm.b * x2 +
			state.ctm.d * y2 + state.ctm.f;

	return plot.line(px1, py1, px2, py2, state.stroke_width, state.stroke,
			false, false);
}


/**
 * Redraw a <text> or <tspan> element node.
 */

bool svg_redraw_text(xmlNode *text, struct svg_redraw_state state)
{
	float x, y, width, height;

	svg_parse_position_attributes(text, state,
			&x, &y, &width, &height);
	svg_parse_font_attributes(text, &state);
	int px = state.origin_x + state.ctm.a * x +
			state.ctm.c * y + state.ctm.e;
	int py = state.origin_y + state.ctm.b * x +
			state.ctm.d * y + state.ctm.f;
	state.ctm.e = px - state.origin_x;
	state.ctm.f = py - state.origin_y;

	struct css_style style = state.style;
	style.font_size.value.length.value *= state.ctm.a;

	for (xmlNode *child = text->children; child; child = child->next) {
		bool ok = true;

		if (child->type == XML_TEXT_NODE) {
			ok = plot.text(px, py,
					&css_base_style,
					child->content, strlen(child->content),
					0xffffff, 0x000000);
		} else if (child->type == XML_ELEMENT_NODE &&
				strcmp(child->name, "tspan") == 0) {
			ok = svg_redraw_text(child, state);
		}

		if (!ok)
			return false;
	}

	return true;
}


/**
 * Parse x, y, width, and height attributes, if present.
 */

void svg_parse_position_attributes(const xmlNode *node,
		const struct svg_redraw_state state,
		float *x, float *y, float *width, float *height)
{
	*x = 0;
	*y = 0;
	*width = state.viewport_width;
	*height = state.viewport_height;

	for (xmlAttr *attr = node->properties; attr; attr = attr->next) {
		if (strcmp(attr->name, "x") == 0)
			*x = svg_parse_length(attr->children->content,
					state.viewport_width, state);
		else if (strcmp(attr->name, "y") == 0)
			*y = svg_parse_length(attr->children->content,
					state.viewport_height, state);
		else if (strcmp(attr->name, "width") == 0)
			*width = svg_parse_length(attr->children->content,
					state.viewport_width, state);
		else if (strcmp(attr->name, "height") == 0)
			*height = svg_parse_length(attr->children->content,
					state.viewport_height, state);
	}
}


/**
 * Parse a length as a number of pixels.
 */

float svg_parse_length(const xmlChar *s, int viewport_size,
		const struct svg_redraw_state state)
{
	int num_length = strspn(s, "0123456789+-.");
	const xmlChar *unit = s + num_length;
	float n = atof((const char *) s);
	float font_size = css_len2px(&state.style.font_size.value.length, 0);

	if (unit[0] == 0) {
		return n;
	} else if (unit[0] == '%') {
		return n / 100.0 * viewport_size;
	} else if (unit[0] == 'e' && unit[1] == 'm') {
		return n * font_size;
	} else if (unit[0] == 'e' && unit[1] == 'x') {
		return n / 2.0 * font_size;
	} else if (unit[0] == 'p' && unit[1] == 'x') {
		return n;
	} else if (unit[0] == 'p' && unit[1] == 't') {
		return n * 1.25;
	} else if (unit[0] == 'p' && unit[1] == 'c') {
		return n * 15.0;
	} else if (unit[0] == 'm' && unit[1] == 'm') {
		return n * 3.543307;
	} else if (unit[0] == 'c' && unit[1] == 'm') {
		return n * 35.43307;
	} else if (unit[0] == 'i' && unit[1] == 'n') {
		return n * 90;
	}

	return 0;
}


/**
 * Parse paint attributes, if present.
 */

void svg_parse_paint_attributes(const xmlNode *node,
		struct svg_redraw_state *state)
{
	for (const xmlAttr *attr = node->properties; attr; attr = attr->next) {
		if (strcmp(attr->name, "fill") == 0)
			svg_parse_color((const char *) attr->children->content,
					&state->fill);
		else if (strcmp(attr->name, "stroke") == 0)
			svg_parse_color((const char *) attr->children->content,
					&state->stroke);
		else if (strcmp(attr->name, "stroke-width") == 0)
			state->stroke_width = svg_parse_length(
					attr->children->content,
					state->viewport_width, *state);
	}
}


/**
 * Parse a colour.
 */

void svg_parse_color(const char *s, colour *c)
{
	unsigned int r, g, b;
	float rf, gf, bf;
	size_t len = strlen(s);

	if (len == 4 && s[0] == '#') {
		if (sscanf(s + 1, "%1x%1x%1x", &r, &g, &b) == 3)
			*c = (b << 20) | (b << 16) |
			     (g << 12) | (g << 8) |
			     (r << 4) | r;
	} else if (len == 7 && s[0] == '#') {
		if (sscanf(s + 1, "%2x%2x%2x", &r, &g, &b) == 3)
			*c = (b << 16) | (g << 8) | r;
	} else if (10 <= len && s[0] == 'r' && s[1] == 'g' && s[2] == 'b' &&
			s[3] == '(' && s[len - 1] == ')') {
		if (sscanf(s + 4, "%i,%i,%i", &r, &g, &b) == 3)
			*c = (b << 16) | (g << 8) | r;
		else if (sscanf(s + 4, "%f%%,%f%%,%f%%", &rf, &gf, &bf) == 3) {
			b = bf * 255 / 100;
			g = gf * 255 / 100;
			r = rf * 255 / 100;
			*c = (b << 16) | (g << 8) | r;
		}
	} else {
		*c = named_colour(s);
	}
}


/**
 * Parse font attributes, if present.
 */

void svg_parse_font_attributes(const xmlNode *node,
		struct svg_redraw_state *state)
{
	for (const xmlAttr *attr = node->properties; attr; attr = attr->next) {
		if (strcmp(attr->name, "font-size") == 0) {
			/*if (css_parse_length(
					(const char *) attr->children->content,
					&state->style.font_size.value.length,
					true, true)) {
				state->style.font_size.size =
						CSS_FONT_SIZE_LENGTH;
			}*/
		}
        }
}


/**
 * Destroy a CONTENT_SVG and free all resources it owns.
 */

void svg_destroy(struct content *c)
{
	if (c->data.svg.doc)
		xmlFreeDoc(c->data.svg.doc);
}