web: refactor svg drawing and related code

5 files changed, 166 insertions, 109 deletions

diff --git a/web/static/sw.js b/web/static/sw.js
index 263c288..acb2c20 100644
--- a/web/static/sw.js
+++ b/web/static/sw.js
@@ -1,5 +1,5 @@
 const CACHE_PREFIX = 'dartboat-'
-const CACHE_VERSION = '26';
+const CACHE_VERSION = '27';
 const CACHE_NAME = `${CACHE_PREFIX}${CACHE_VERSION}`;
 
 const CACHE_FILES = [
diff --git a/web/web_dom.c b/web/web_dom.c
index 54a6c8d..2467fb6 100644
--- a/web/web_dom.c
+++ b/web/web_dom.c
@@ -1,5 +1,6 @@
 #include "web_dom.h"
 
+#include <stdarg.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -56,7 +57,9 @@ void dom_elem_free(struct dom_elem *e)
 	free(e);
 }
 
-void dom_elem_add_attr(struct dom_elem *e, char *name, char *val)
+// this function takes ownership of the passed val string, freeing it when the
+// dom_elem is freed.
+static void dom_elem_add_attrp(struct dom_elem *e, char *name, char *val)
 {
 	if (e->n_attrs == e->size_attrs) {
 		e->size_attrs += e->size_attrs ? e->size_attrs : 1;
@@ -67,14 +70,31 @@ void dom_elem_add_attr(struct dom_elem *e, char *name, char *val)
 	}
 
 	e->attr_names[e->n_attrs] = strdup(name);
-	e->attr_vals[e->n_attrs++] = strdup(val);
+	e->attr_vals[e->n_attrs++] = val;
+}
+
+void dom_elem_add_attr(struct dom_elem *e, char *name, char *val)
+{
+	dom_elem_add_attrp(e, name, strdup(val));
 }
 
 void dom_elem_add_attrd(struct dom_elem *e, char *name, double val)
 {
-	char str[512];
-	sprintf(str, "%f", val);
-	dom_elem_add_attr(e, name, str);
+	char *str;
+	asprintf(&str, "%f", val);
+	dom_elem_add_attrp(e, name, str);
+}
+
+void dom_elem_add_attrf(struct dom_elem *e, char *name, char *fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+
+	char *str;
+	vasprintf(&str, fmt, args);
+	dom_elem_add_attrp(e, name, str);
+
+	va_end(args);
 }
 
 void dom_elem_add_child(struct dom_elem *e, struct dom_elem *child)
diff --git a/web/web_dom.h b/web/web_dom.h
index 45afd15..7806916 100644
--- a/web/web_dom.h
+++ b/web/web_dom.h
@@ -16,6 +16,7 @@ struct dom_elem *dom_text_init(char *content);
 void dom_elem_free(struct dom_elem *e);
 void dom_elem_add_attr(struct dom_elem *e, char *name, char *val);
 void dom_elem_add_attrd(struct dom_elem *e, char *name, double val);
+void dom_elem_add_attrf(struct dom_elem *e, char *name, char *fmt, ...);
 void dom_elem_add_child(struct dom_elem *e, struct dom_elem *child);
 
 void dom_append_elemv(char *sel, int elemc, struct dom_elem **elemv);
diff --git a/web/web_svg.c b/web/web_svg.c
index 1d0b9aa..125f8a4 100644
--- a/web/web_svg.c
+++ b/web/web_svg.c
@@ -3,80 +3,104 @@
 #include "web_opts.h"
 
 #include "board.h"
-#include "comp.h"
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 
-#include <emscripten/emscripten.h>
-
 #define C_BLACK "#272b2c"
 #define C_WHITE "#fbe3ba"
 #define C_RED "#f6302f"
 #define C_GREEN "#22912d"
 #define C_WIRE "#909ca0"
 #define C_WIRE_INNER "#d8e6ec"
+#define C_NUMBER_RING "#ddd"
+#define C_NUMBER "#fff"
+#define C_POINT "#33f"
+#define C_POINT_OUTLINE "#ff0"
+
+#define POINT_RADIUS 6
 
-static inline struct dom_elem *svg_elem_init(char *name, int size_attrs)
+static struct dom_elem *svg_elem_init(char *name, int size_attrs)
 {
 	return dom_elem_init("http://www.w3.org/2000/svg", name, size_attrs);
 }
 
+static struct dom_elem *gen_circle(double r, char *col)
+{
+	struct dom_elem *e = svg_elem_init("circle", 2);
+	dom_elem_add_attrd(e, "r", r);
+	dom_elem_add_attr(e, "fill", col);
+
+	return e;
+}
+
 // draws a ring if angles are equal
 static struct dom_elem *gen_arc(double a1, double a2, double r1, double r2,
 	char *col)
 {
-	struct ccoords cc1 = pol_to_cart(
-		(struct pcoords){ .a = (a1 == a2 ? 1 : a2), .r = r1 });
-	struct ccoords cc2 = pol_to_cart(
-		(struct pcoords){ .a = (a1 == a2 ? 0 : a1), .r = r1 });
-	struct ccoords cc3 = pol_to_cart(
-		(struct pcoords){ .a = (a1 == a2 ? 0 : a1), .r = r2 });
-	struct ccoords cc4 = pol_to_cart(
-		(struct pcoords){ .a = (a1 == a2 ? 1 : a2), .r = r2 });
+	bool ring = (a1 == a2);
+	if (ring) {
+		// these values are not significant. the ring is drawn as two
+		// consecutive arcs, so the path goes from one angle to the
+		// other and back to the first.
+		a1 = 0;
+		a2 = 1;
+	}
+
+	struct ccoords cc1 = pol_to_cart((struct pcoords){ .a = a2, .r = r1 });
+	struct ccoords cc2 = pol_to_cart((struct pcoords){ .a = a1, .r = r1 });
+	struct ccoords cc3 = pol_to_cart((struct pcoords){ .a = a1, .r = r2 });
+	struct ccoords cc4 = pol_to_cart((struct pcoords){ .a = a2, .r = r2 });
 
 	struct dom_elem *e = svg_elem_init("path", 2);
 	dom_elem_add_attr(e, "fill", col);
 
+	// (arc)
+	// M - move to inner start
+	// A - draw arc to inner end
+	// L - draw line to outer end
+	// A - draw arc to outer start
+	// Z - draw line to inner start
+	//
+	// (ring)
+	// M - move to inner 1
+	// A - draw arc to inner 2
+	// A - draw arc to inner 1
+	// Z - draw zero-length line to close path
+	// M - move to outer 2
+	// A - draw arc to outer 1
+	// A - draw arc to outer 2
+	// Z - draw zero-length line to close path
+	//
+	// for default `nonzero' fill-rule to work for rings, the inner and
+	// outer arcs must go in opposite directions
 	char buf[512];
-	int buflen = 0;
-	buflen += sprintf(buf + buflen, "M%f %f", cc1.x, cc1.y);
-	buflen += sprintf(buf + buflen, "A%f %f 0 0 0 %f %f",
-		r1, r1, cc2.x, cc2.y);
-	if (a1 == a2)
-		buflen += sprintf(buf + buflen, "A%f %f 0 1 0 %f %f",
+	int len = 0;
+	len += sprintf(buf + len, "M%f %fA%f %f 0 0 0 %f %fL",
+		cc1.x, cc1.y, r1, r1, cc2.x, cc2.y);
+	if (ring)
+		len += -1 + sprintf(buf + len - 1, "A%f %f 0 1 0 %f %fZM",
 			r1, r1, cc1.x, cc1.y);
-	buflen += sprintf(buf + buflen, "L%f %f", cc3.x, cc3.y);
-	buflen += sprintf(buf + buflen, "A%f %f 0 0 1 %f %f",
-		r2, r2, cc4.x, cc4.y);
-	if (a1 == a2)
-		buflen += sprintf(buf + buflen, "A%f %f 0 1 1 %f %f",
+	len += sprintf(buf + len, "%f %fA%f %f 0 0 1 %f %fZ",
+		cc3.x, cc3.y, r2, r2, cc4.x, cc4.y);
+	if (ring)
+		sprintf(buf + len - 1, "A%f %f 0 1 1 %f %fZ",
 			r2, r2, cc3.x, cc3.y);
-	buf[buflen++] = 'Z';
-	buf[buflen++] = 0;
 	dom_elem_add_attr(e, "d", buf);
 
 	return e;
 }
 
-static struct dom_elem *gen_segment(double a, double r1, double r2, char *col)
-{
-	return gen_arc(a - SECTOR_WIDTH/2, a + SECTOR_WIDTH/2, r1, r2, col);
-}
-
 static struct dom_elem *gen_ring(double r, double w, char *col)
 {
-	return gen_arc(0, 0, r - w/2, r + w/2, col);
+	return gen_arc(0, 0, r - (w / 2), r + (w / 2), col);
 }
 
-static struct dom_elem *gen_circle(double r, char *col)
+static struct dom_elem *gen_segment(double a, double r1, double r2, char *col)
 {
-	struct dom_elem *e = svg_elem_init("circle", 2);
-	dom_elem_add_attr(e, "fill", col);
-	dom_elem_add_attrd(e, "r", r);
-
-	return e;
+	return gen_arc(a - (SECTOR_WIDTH / 2), a + (SECTOR_WIDTH / 2), r1, r2,
+		col);
 }
 
 static struct dom_elem *gen_line(double a, double r1, double r2, double w,
@@ -86,67 +110,95 @@ static struct dom_elem *gen_line(double a, double r1, double r2, double w,
 	struct ccoords cc2 = pol_to_cart((struct pcoords){ .a = a, .r = r2 });
 
 	struct dom_elem *e = svg_elem_init("line", 6);
-	dom_elem_add_attr(e, "stroke", col);
 	dom_elem_add_attrd(e, "x1", cc1.x);
 	dom_elem_add_attrd(e, "y1", cc1.y);
 	dom_elem_add_attrd(e, "x2", cc2.x);
 	dom_elem_add_attrd(e, "y2", cc2.y);
+	dom_elem_add_attr(e, "stroke", col);
 	dom_elem_add_attrd(e, "stroke-width", w);
 
 	return e;
 }
 
-static int draw_spider(int elemc, struct dom_elem **elemv)
+static int gen_segments(struct dom_elem **elemv)
 {
-	for (int i = 5; i > 1; --i) {
+	int elemc = 0;
+
+	for (int i = R_DOUBLE; i > R_25; --i) {
+		for (int j = 0; j < NUM_SECTORS; ++j) {
+			double a = 90 - (j * SECTOR_WIDTH);
+			if (a < 0)
+				a += 360;
+			elemv[elemc++] = gen_segment(a, OUTER_DISTS[i - 1],
+				OUTER_DISTS[i],
+				i % 2 ? (j % 2 ? C_GREEN : C_RED) :
+					(j % 2 ? C_WHITE : C_BLACK));
+		}
+	}
+
+	elemv[elemc++] = gen_circle(OUTER_DISTS[R_25], C_GREEN);
+	elemv[elemc++] = gen_circle(OUTER_DISTS[R_BULL], C_RED);
+
+	return elemc;
+}
+
+static int gen_wires(struct dom_elem **elemv)
+{
+	int elemc = 0;
+
+	for (int i = R_DOUBLE; i > R_25; --i) {
 		elemv[elemc++] = gen_ring(OUTER_DISTS[i], WIRE_WIDTH, C_WIRE);
-		elemv[elemc++] = gen_ring(OUTER_DISTS[i], WIRE_WIDTH/2,
+		elemv[elemc++] = gen_ring(OUTER_DISTS[i], WIRE_WIDTH / 2,
 			C_WIRE_INNER);
 	}
 
 	for (int i = 0; i < NUM_SECTORS; ++i) {
-		double a = 90 - i*SECTOR_WIDTH - SECTOR_WIDTH/2;
-		if (a < 0) a += 360;
-
-		elemv[elemc++] = gen_line(a, OUTER_DISTS[1],
-			OUTER_DISTS[5] + 10, WIRE_WIDTH, C_WIRE);
-		elemv[elemc++] = gen_line(a, OUTER_DISTS[1],
-			OUTER_DISTS[5] + 10, WIRE_WIDTH/2, C_WIRE_INNER);
+		double a = 90 - (i * SECTOR_WIDTH) - (SECTOR_WIDTH / 2);
+		if (a < 0)
+			a += 360;
+		elemv[elemc++] = gen_line(a, OUTER_DISTS[R_25],
+			OUTER_DISTS[R_DOUBLE] + 10, WIRE_WIDTH, C_WIRE);
+		elemv[elemc++] = gen_line(a, OUTER_DISTS[R_25],
+			OUTER_DISTS[R_DOUBLE] + 10, WIRE_WIDTH / 2,
+			C_WIRE_INNER);
 	}
 
-	for (int i = 1; i >= 0; --i) {
+	for (int i = R_25; i >= R_BULL; --i) {
 		elemv[elemc++] = gen_ring(OUTER_DISTS[i], WIRE_WIDTH, C_WIRE);
-		elemv[elemc++] = gen_ring(OUTER_DISTS[i], WIRE_WIDTH/2,
+		elemv[elemc++] = gen_ring(OUTER_DISTS[i], WIRE_WIDTH / 2,
 			C_WIRE_INNER);
 	}
 
 	return elemc;
 }
 
-static int draw_numbers(int elemc, struct dom_elem **elemv)
+static int gen_numbers(struct dom_elem **elemv)
 {
-	elemv[elemc++] = gen_ring(DIAMETER/2 - WIRE_WIDTH*4, WIRE_WIDTH,
-		"#ddd");
+	int elemc = 0;
+
+	elemv[elemc++] = gen_ring((DIAMETER / 2) - (WIRE_WIDTH * 4),
+		WIRE_WIDTH, C_NUMBER_RING);
+
+	int r = (DIAMETER / 2) - (33 / 2);
+	for (int i = 0; i < NUM_SECTORS; ++i) {
+		struct dom_elem *e = svg_elem_init("text", 5);
+		elemv[elemc++] = e;
 
-	int r = DIAMETER/2 - 33/2;
-	for (int i = 0; i < 20; ++i) {
-		struct dom_elem *e = elemv[elemc++] = svg_elem_init("text", 5);
 		dom_elem_add_attr(e, "font-size", "33");
-		dom_elem_add_attr(e, "fill", "#fff");
 		dom_elem_add_attr(e, "text-anchor", "middle");
 		dom_elem_add_attr(e, "dominant-baseline", "central");
+		dom_elem_add_attr(e, "fill", C_NUMBER);
 
-		char buf[512];
-		double a = 90 - i*SECTOR_WIDTH;
-		if (a < 0) a += 360;
+		double a = 90 - (i * SECTOR_WIDTH);
+		if (a < 0)
+			a += 360;
 		struct ccoords cc = pol_to_cart(
 			(struct pcoords){ .a = a, .r = r });
-		sprintf(buf, "scale(1 -1) translate(%f %f) rotate(%f)",
-			cc.x, -cc.y, a <= 180 ? 90 -a : 270 -a);
-		dom_elem_add_attr(e, "transform", buf);
+		dom_elem_add_attrf(e, "transform",
+			"scale(1 -1) translate(%f %f) rotate(%f)",
+			cc.x, -cc.y, a <= 180 ? 90 - a : 270 - a);
 
-		e->content = malloc(3);
-		sprintf(e->content, "%d", SECTORS[i]);
+		asprintf(&e->content, "%d", SECTORS[i]);
 	}
 
 	return elemc;
@@ -157,24 +209,10 @@ static void draw_board()
 	struct dom_elem **elemv = malloc(200 * sizeof(*elemv));
 	int elemc = 0;
 
-	elemv[elemc++] = gen_circle(DIAMETER/2, C_BLACK);
-
-	for (int i = 5; i > 1; --i) {
-		for (int j = 0; j < NUM_SECTORS; ++j) {
-			double a = 90 - j*SECTOR_WIDTH;
-			if (a < 0) a += 360;
-			elemv[elemc++] = gen_segment(a, OUTER_DISTS[i-1],
-				OUTER_DISTS[i],
-				i % 2 ? (j % 2 ? C_GREEN : C_RED) :
-					(j % 2 ? C_WHITE : C_BLACK));
-		}
-	}
-
-	elemv[elemc++] = gen_circle(OUTER_DISTS[1], C_GREEN);
-	elemv[elemc++] = gen_circle(OUTER_DISTS[0], C_RED);
-
-	elemc = draw_spider(elemc, elemv);
-	elemc = draw_numbers(elemc, elemv);
+	elemv[elemc++] = gen_circle(DIAMETER / 2, C_BLACK);
+	elemc += gen_segments(elemv + elemc);
+	elemc += gen_wires(elemv + elemc);
+	elemc += gen_numbers(elemv + elemc);
 
 	dom_append_elemv("#dartboard .base", elemc, elemv);
 
@@ -185,22 +223,21 @@ static void draw_board()
 
 static void create_board()
 {
-	char buf[512];
-
 	struct dom_elem *e = svg_elem_init("svg", 2);
 	dom_elem_add_attr(e, "id", "dartboard");
-	sprintf(buf, "0 0 %f %f", DIAMETER, DIAMETER);
-	dom_elem_add_attr(e, "viewBox", buf);
+	dom_elem_add_attrf(e, "viewBox", "0 0 %f %f", DIAMETER, DIAMETER);
 	dom_append_elemv("#dartboard-container", 1, &e);
+	free(e);
 
 	struct dom_elem **elemv = malloc(2 * sizeof(*elemv));
 	int elemc = 0;
 
-	sprintf(buf, "translate(%f %f) scale(1 -1)", DIAMETER/2, DIAMETER/2);
 	for (int i = 0; i < 2; ++i) {
 		struct dom_elem *e = svg_elem_init("g", 2);
 		dom_elem_add_attr(e, "class", i ? "overlay" : "base");
-		dom_elem_add_attr(e, "transform", buf);
+		dom_elem_add_attrf(e, "transform",
+			"translate(%f %f) scale(1 -1)",
+			DIAMETER / 2, DIAMETER / 2);
 		elemv[elemc++] = e;
 	}
 
@@ -211,19 +248,23 @@ static void create_board()
 	free(elemv);
 }
 
+void svg_init()
+{
+	create_board();
+	draw_board();
+}
+
 void svg_draw_point(double x, double y)
 {
-	struct dom_elem *e = gen_circle(6, "#33f");
-	dom_elem_add_attr(e, "stroke", "#ff0");
-	dom_elem_add_attr(e, "stroke-width", "2");
+	struct dom_elem *e = gen_circle(POINT_RADIUS, C_POINT);
 	dom_elem_add_attrd(e, "cx", x);
 	dom_elem_add_attrd(e, "cy", y);
+	dom_elem_add_attr(e, "stroke", C_POINT_OUTLINE);
+	dom_elem_add_attr(e, "stroke-width", "2");
 
-	if (delay_ms >= SVG_THROW_ANIM_MS) {
-		char buf[64];
-		sprintf(buf, "animation: throw-anim %dms;", SVG_THROW_ANIM_MS);
-		dom_elem_add_attr(e, "style", buf);
-	}
+	if (delay_ms >= SVG_THROW_ANIM_MS)
+		dom_elem_add_attrf(e, "style", "animation: throw-anim %dms;",
+			SVG_THROW_ANIM_MS);
 
 	dom_append_elemv("#dartboard .overlay", 1, &e);
 	dom_elem_free(e);
@@ -233,9 +274,3 @@ void svg_clear_points()
 {
 	dom_set_content("#dartboard .overlay", NULL);
 }
-
-void svg_init()
-{
-	create_board();
-	draw_board();
-}
diff --git a/web/web_svg.h b/web/web_svg.h
index 9110200..33fd023 100644
--- a/web/web_svg.h
+++ b/web/web_svg.h
@@ -4,6 +4,7 @@
 #define SVG_THROW_ANIM_MS 250
 
 void svg_init();
+
 void svg_draw_point(double x, double y);
 void svg_clear_points();