Work on linearGradient attributes gradientUnits and gradientTransform. Adapt number of segment steps depending on difference in gradient.

svn path=/trunk/libsvgtiny/; revision=3914

3 files changed, 249 insertions, 139 deletions

diff --git a/svgtiny.c b/svgtiny.c
index 09c6bdd..10635ac 100644
--- a/svgtiny.c
+++ b/svgtiny.c
@@ -879,83 +879,93 @@ void svgtiny_parse_font_attributes(const xmlNode *node,
 void svgtiny_parse_transform_attributes(xmlNode *node,
 		struct svgtiny_parse_state *state)
 {
-	char *transform, *s;
+	char *transform;
+
+	/* parse transform */
+	transform = (char *) xmlGetProp(node, (const xmlChar *) "transform");
+	if (transform) {
+		svgtiny_parse_transform(transform, &state->ctm.a, &state->ctm.b,
+				&state->ctm.c, &state->ctm.d,
+				&state->ctm.e, &state->ctm.f);
+		xmlFree(transform);
+	}
+}
+
+
+/**
+ * Parse a transform string.
+ */
+
+void svgtiny_parse_transform(char *s, float *ma, float *mb,
+		float *mc, float *md, float *me, float *mf)
+{
 	float a, b, c, d, e, f;
-	float ctm_a, ctm_b, ctm_c, ctm_d, ctm_e, ctm_f;
+	float za, zb, zc, zd, ze, zf;
 	float angle, x, y;
 	int n;
 
-	/* parse transform */
-	s = transform = (char *) xmlGetProp(node,
-			(const xmlChar *) "transform");
-	if (transform) {
-		for (unsigned int i = 0; transform[i]; i++)
-			if (transform[i] == ',')
-				transform[i] = ' ';
-
-		while (*s) {
-			a = d = 1;
-			b = c = 0;
-			e = f = 0;
-			if (sscanf(s, "matrix (%f %f %f %f %f %f) %n",
+	for (unsigned int i = 0; s[i]; i++)
+		if (s[i] == ',')
+			s[i] = ' ';
+
+	while (*s) {
+		a = d = 1;
+		b = c = 0;
+		e = f = 0;
+		if (sscanf(s, "matrix (%f %f %f %f %f %f) %n",
 					&a, &b, &c, &d, &e, &f, &n) == 6)
-				;
-			else if (sscanf(s, "translate (%f %f) %n",
+			;
+		else if (sscanf(s, "translate (%f %f) %n",
 					&e, &f, &n) == 2)
-				;
-			else if (sscanf(s, "translate (%f) %n",
+			;
+		else if (sscanf(s, "translate (%f) %n",
 					&e, &n) == 1)
-				;
-			else if (sscanf(s, "scale (%f %f) %n",
+			;
+		else if (sscanf(s, "scale (%f %f) %n",
 					&a, &d, &n) == 2)
-				;
-			else if (sscanf(s, "scale (%f) %n",
+			;
+		else if (sscanf(s, "scale (%f) %n",
 					&a, &n) == 1)
-				d = a;
-			else if (sscanf(s, "rotate (%f %f %f) %n",
+			d = a;
+		else if (sscanf(s, "rotate (%f %f %f) %n",
 					&angle, &x, &y, &n) == 3) {
-				angle = angle / 180 * M_PI;
-				a = cos(angle);
-				b = sin(angle);
-				c = -sin(angle);
-				d = cos(angle);
-				e = -x * cos(angle) + y * sin(angle) + x;
-				f = -x * sin(angle) - y * cos(angle) + y;
-	                } else if (sscanf(s, "rotate (%f) %n",
+			angle = angle / 180 * M_PI;
+			a = cos(angle);
+			b = sin(angle);
+			c = -sin(angle);
+			d = cos(angle);
+			e = -x * cos(angle) + y * sin(angle) + x;
+			f = -x * sin(angle) - y * cos(angle) + y;
+		} else if (sscanf(s, "rotate (%f) %n",
 					&angle, &n) == 1) {
-				angle = angle / 180 * M_PI;
-				a = cos(angle);
-				b = sin(angle);
-				c = -sin(angle);
-				d = cos(angle);
-	                } else if (sscanf(s, "skewX (%f) %n",
+			angle = angle / 180 * M_PI;
+			a = cos(angle);
+			b = sin(angle);
+			c = -sin(angle);
+			d = cos(angle);
+		} else if (sscanf(s, "skewX (%f) %n",
 					&angle, &n) == 1) {
-				angle = angle / 180 * M_PI;
-				c = tan(angle);
-	                } else if (sscanf(s, "skewY (%f) %n",
+			angle = angle / 180 * M_PI;
+			c = tan(angle);
+		} else if (sscanf(s, "skewY (%f) %n",
 					&angle, &n) == 1) {
-				angle = angle / 180 * M_PI;
-				b = tan(angle);
-	                } else
-				break;
-			ctm_a = state->ctm.a * a + state->ctm.c * b;
-			ctm_b = state->ctm.b * a + state->ctm.d * b;
-			ctm_c = state->ctm.a * c + state->ctm.c * d;
-			ctm_d = state->ctm.b * c + state->ctm.d * d;
-			ctm_e = state->ctm.a * e + state->ctm.c * f +
-					state->ctm.e;
-			ctm_f = state->ctm.b * e + state->ctm.d * f +
-					state->ctm.f;
-			state->ctm.a = ctm_a;
-			state->ctm.b = ctm_b;
-			state->ctm.c = ctm_c;
-			state->ctm.d = ctm_d;
-			state->ctm.e = ctm_e;
-			state->ctm.f = ctm_f;
-			s += n;
-		}
-
-		xmlFree(transform);
+			angle = angle / 180 * M_PI;
+			b = tan(angle);
+		} else
+			break;
+		za = *ma * a + *mc * b;
+		zb = *mb * a + *md * b;
+		zc = *ma * c + *mc * d;
+		zd = *mb * c + *md * d;
+		ze = *ma * e + *mc * f + *me;
+		zf = *mb * e + *md * f + *mf;
+		*ma = za;
+		*mb = zb;
+		*mc = zc;
+		*md = zd;
+		*me = ze;
+		*mf = zf;
+		s += n;
 	}
 }
 
diff --git a/svgtiny_gradient.c b/svgtiny_gradient.c
index c88c804..31dba1e 100644
--- a/svgtiny_gradient.c
+++ b/svgtiny_gradient.c
@@ -7,6 +7,7 @@
 
 #define _GNU_SOURCE  /* for strndup */
 #include <assert.h>
+#include <math.h>
 #include <string.h>
 #include "svgtiny.h"
 #include "svgtiny_internal.h"
@@ -18,6 +19,7 @@ static svgtiny_code svgtiny_parse_linear_gradient(xmlNode *linear,
 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);
+static void svgtiny_invert_matrix(float *m, float *inv);
 
 
 /**
@@ -33,6 +35,13 @@ void svgtiny_find_gradient(const char *id, struct svgtiny_parse_state *state)
 	state->gradient_y1 = "0%";
 	state->gradient_x2 = "100%";
 	state->gradient_y2 = "0%";
+	state->gradient_user_space_on_use = false;
+	state->gradient_transform.a = 1;
+	state->gradient_transform.b = 0;
+	state->gradient_transform.c = 0;
+	state->gradient_transform.d = 1;
+	state->gradient_transform.e = 0;
+	state->gradient_transform.f = 0;
 
 	xmlNode *gradient = svgtiny_find_element_by_id(
 			(xmlNode *) state->document, id);
@@ -74,6 +83,25 @@ svgtiny_code svgtiny_parse_linear_gradient(xmlNode *linear,
 			state->gradient_x2 = content;
 		else if (strcmp(name, "y2") == 0)
 			state->gradient_y2 = content;
+		else if (strcmp(name, "gradientUnits") == 0)
+			state->gradient_user_space_on_use =
+					strcmp(content, "userSpaceOnUse") == 0;
+		else if (strcmp(name, "gradientTransform") == 0) {
+			float a = 1, b = 0, c = 0, d = 1, e = 0, f = 0;
+			char *s = strdup(content);
+			if (!s)
+				return svgtiny_OUT_OF_MEMORY;
+			svgtiny_parse_transform(s, &a, &b, &c, &d, &e, &f);
+			free(s);
+			fprintf(stderr, "transform %g %g %g %g %g %g\n",
+					a, b, c, d, e, f);
+			state->gradient_transform.a = a;
+			state->gradient_transform.b = b;
+			state->gradient_transform.c = c;
+			state->gradient_transform.d = d;
+			state->gradient_transform.e = e;
+			state->gradient_transform.f = f;
+		}
         }
 
 	unsigned int i = 0;
@@ -170,14 +198,29 @@ svgtiny_code svgtiny_add_path_linear_gradient(float *p, unsigned int n,
 			state->gradient_x2, state->gradient_y2);
 	float gradient_x0, gradient_y0, gradient_x1, gradient_y1,
 	      gradient_dx, gradient_dy;
-	gradient_x0 = object_x0 + svgtiny_parse_length(state->gradient_x1,
-			object_x1 - object_x0, *state);
-	gradient_y0 = object_y0 + svgtiny_parse_length(state->gradient_y1,
-			object_y1 - object_y0, *state);
-	gradient_x1 = object_x0 + svgtiny_parse_length(state->gradient_x2,
-			object_x1 - object_x0, *state);
-	gradient_y1 = object_y0 + svgtiny_parse_length(state->gradient_y2,
-			object_y1 - object_y0, *state);
+	if (!state->gradient_user_space_on_use) {
+		gradient_x0 = object_x0 +
+				svgtiny_parse_length(state->gradient_x1,
+					object_x1 - object_x0, *state);
+		gradient_y0 = object_y0 +
+				svgtiny_parse_length(state->gradient_y1,
+					object_y1 - object_y0, *state);
+		gradient_x1 = object_x0 +
+				svgtiny_parse_length(state->gradient_x2,
+					object_x1 - object_x0, *state);
+		gradient_y1 = object_y0 +
+				svgtiny_parse_length(state->gradient_y2,
+					object_y1 - object_y0, *state);
+	} else {
+		gradient_x0 = svgtiny_parse_length(state->gradient_x1,
+				state->viewport_width, *state);
+		gradient_y0 = svgtiny_parse_length(state->gradient_y1,
+				state->viewport_height, *state);
+		gradient_x1 = svgtiny_parse_length(state->gradient_x2,
+				state->viewport_width, *state);
+		gradient_y1 = svgtiny_parse_length(state->gradient_y2,
+				state->viewport_height, *state);
+	}
 	gradient_dx = gradient_x1 - gradient_x0;
 	gradient_dy = gradient_y1 - gradient_y0;
 	#ifdef GRADIENT_DEBUG
@@ -227,9 +270,19 @@ svgtiny_code svgtiny_add_path_linear_gradient(float *p, unsigned int n,
 		state->diagram->shape_count++;
 	}*/
 
+	/* invert gradient transform for applying to vertices */
+	float trans[6];
+	svgtiny_invert_matrix(&state->gradient_transform.a, trans);
+	fprintf(stderr, "inverse transform %g %g %g %g %g %g\n",
+			trans[0], trans[1], trans[2], trans[3],
+			trans[4], trans[5]);
+
 	/* compute points on the path for triangle vertices */
+	/* r, r0, r1 are distance along gradient vector */
 	unsigned int steps = 10;
-	float x0, y0, x1, y1;
+	float x0, y0, x0_trans, y0_trans, r0; /* segment start point */
+	float x1, y1, x1_trans, y1_trans, r1; /* segment end point */
+	float c0x, c0y, c1x, c1y; /* segment control points (beziers only) */
 	float gradient_norm_squared = gradient_dx * gradient_dx +
 	                              gradient_dy * gradient_dy;
 	struct grad_point {
@@ -242,84 +295,107 @@ svgtiny_code svgtiny_add_path_linear_gradient(float *p, unsigned int n,
 	float min_r = 1000;
 	unsigned int min_pt = 0;
 	for (unsigned int j = 0; j != n; ) {
-		switch ((int) p[j]) {
-		case svgtiny_PATH_MOVE:
+		int segment_type = (int) p[j];
+
+		if (segment_type == 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;
+			continue;
+		}
+
+		assert(segment_type == svgtiny_PATH_CLOSE ||
+				segment_type == svgtiny_PATH_LINE ||
+				segment_type == svgtiny_PATH_BEZIER);
+
+		/* start point (x0, y0) */
+		x0_trans = trans[0]*x0 + trans[2]*y0 + trans[4];
+		y0_trans = trans[1]*x0 + trans[3]*y0 + trans[5];
+		r0 = ((x0_trans - gradient_x0) * gradient_dx +
+				(y0_trans - gradient_y0) * gradient_dy) /
+				gradient_norm_squared;
+		pts[pts_count].x = x0;
+		pts[pts_count].y = y0;
+		pts[pts_count].r = r0;
+		if (r0 < min_r) {
+			min_r = r0;
+			min_pt = pts_count;
+		}
+		pts_count++;
+
+		/* end point (x1, y1) */
+		if (segment_type == svgtiny_PATH_LINE) {
+			x1 = p[j + 1];
+			y1 = p[j + 2];
+			j += 3;
+		} else if (segment_type == svgtiny_PATH_CLOSE) {
+			x1 = p[1];
+			y1 = p[2];
+			j++;
+		} else /* svgtiny_PATH_BEZIER */ {
+			c0x = p[j + 1];
+			c0y = p[j + 2];
+			c1x = p[j + 3];
+			c1y = p[j + 4];
+			x1 = p[j + 5];
+			y1 = p[j + 6];
+			j += 7;
+		}
+		x1_trans = trans[0]*x1 + trans[2]*y1 + trans[4];
+		y1_trans = trans[1]*x1 + trans[3]*y1 + trans[5];
+		r1 = ((x1_trans - gradient_x0) * gradient_dx +
+				(y1_trans - gradient_y0) * gradient_dy) /
+				gradient_norm_squared;
+
+		/* determine steps from change in r */
+		steps = ceilf(fabsf(r1 - r0) / 0.05);
+		if (steps == 0)
+			steps = 1;
+		fprintf(stderr, "r0 %g, r1 %g, steps %i\n",
+				r0, r1, steps);
+
+		/* loop through intermediate points */
+		for (unsigned int z = 1; z != steps; z++) {
+			float t, x, y, x_trans, y_trans, r;
+			t = (float) z / (float) steps;
+			if (segment_type == svgtiny_PATH_BEZIER) {
 				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];
+					3 * t * (1-t) * (1-t) * c0x +
+					3 * t * t * (1-t) * c1x +
+					t * t * t * x1;
 				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) /
+					3 * t * (1-t) * (1-t) * c0y +
+					3 * t * t * (1-t) * c1y +
+					t * t * t * y1;
+			} else {
+				x = (1-t) * x0 + t * x1;
+				y = (1-t) * y0 + t * y1;
+			}
+			x_trans = trans[0]*x + trans[2]*y + trans[4];
+			y_trans = trans[1]*x + trans[3]*y + trans[5];
+			r = ((x_trans - gradient_x0) * gradient_dx +
+					(y_trans - 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, "(%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;
 			}
-			fprintf(stderr, "\n");
-			x0 = p[j + 5];
-			y0 = p[j + 6];
-			j += 7;
-			break;
-		default:
-			assert(0);
+			pts_count++;
 		}
+		fprintf(stderr, "\n");
+
+		/* next segment start point is this segment end point */
+		x0 = x1;
+		y0 = y1;
 	}
 	fprintf(stderr, "pts_count %i, min_pt %i, min_r %.3f\n",
 			pts_count, min_pt, min_r);
 
+	/* render triangles */
 	unsigned int stop_count = state->linear_gradient_stop_count;
 	assert(2 <= stop_count);
 	unsigned int current_stop = 0;
@@ -448,6 +524,7 @@ svgtiny_code svgtiny_add_path_linear_gradient(float *p, unsigned int n,
 		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);
+		shape->stroke = svgtiny_TRANSPARENT;
 		state->diagram->shape_count++;
 	}
 	#endif
@@ -515,6 +592,21 @@ void svgtiny_path_bbox(float *p, unsigned int n,
 
 
 /**
+ * Invert a transformation matrix.
+ */
+void svgtiny_invert_matrix(float *m, float *inv)
+{
+	float determinant = m[0]*m[3] - m[1]*m[2];
+	inv[0] = m[3] / determinant;
+	inv[1] = -m[1] / determinant;
+	inv[2] = -m[2] / determinant;
+	inv[3] = m[0] / determinant;
+	inv[4] = (m[2]*m[5] - m[3]*m[4]) / determinant;
+	inv[5] = (m[1]*m[4] - m[0]*m[5]) / determinant;
+}
+
+
+/**
  * Find an element in the document by id.
  */
 
diff --git a/svgtiny_internal.h b/svgtiny_internal.h
index 84ecf5c..a729f25 100644
--- a/svgtiny_internal.h
+++ b/svgtiny_internal.h
@@ -8,6 +8,8 @@
 #ifndef SVGTINY_INTERNAL_H
 #define SVGTINY_INTERNAL_H
 
+#include <stdbool.h>
+
 struct svgtiny_gradient_stop {
 	float offset;
 	svgtiny_colour color;
@@ -39,6 +41,10 @@ struct svgtiny_parse_state {
 	unsigned int linear_gradient_stop_count;
 	const char *gradient_x1, *gradient_y1, *gradient_x2, *gradient_y2;
 	struct svgtiny_gradient_stop gradient_stop[svgtiny_MAX_STOPS];
+	bool gradient_user_space_on_use;
+	struct {
+		float a, b, c, d, e, f;
+	} gradient_transform;
 };
 
 
@@ -47,6 +53,8 @@ float svgtiny_parse_length(const char *s, int viewport_size,
 		const struct svgtiny_parse_state state);
 void svgtiny_parse_color(const char *s, svgtiny_colour *c,
 		struct svgtiny_parse_state *state);
+void svgtiny_parse_transform(char *s, float *ma, float *mb,
+		float *mc, float *md, float *me, float *mf);
 struct svgtiny_shape *svgtiny_add_shape(struct svgtiny_parse_state *state);
 void svgtiny_transform_path(float *p, unsigned int n,
 		struct svgtiny_parse_state *state);