From a64f3a1b503cb060bbf27c741cd0473cd585080d Mon Sep 17 00:00:00 2001
From: Vincent Sanders <vince@kyllikki.org>
Date: Wed, 3 Jul 2024 00:11:04 +0100
Subject: [PATCH] Reimplement parsing of viewbox

fixup tests that used non existant viewport attribute
---
 src/svgtiny.c            | 18 ++++---------
 src/svgtiny_internal.h   |  3 +++
 src/svgtiny_parse.c      | 57 ++++++++++++++++++++++++++++++++++++++++
 test/data/colors.svg     |  2 +-
 test/data/polyline.mvg   |  2 ++
 test/data/polyline.svg   |  2 +-
 test/data/polypoints.svg |  3 +--
 test/data/transform.svg  |  2 +-
 8 files changed, 71 insertions(+), 18 deletions(-)
 create mode 100644 test/data/polyline.mvg

diff --git a/src/svgtiny.c b/src/svgtiny.c
index dacf2c8..3813d7c 100644
--- a/src/svgtiny.c
+++ b/src/svgtiny.c
@@ -766,19 +766,11 @@ svgtiny_code svgtiny_parse_svg(dom_element *svg,
 	}
 
 	if (view_box) {
-		char *s = strndup(dom_string_data(view_box),
-				  dom_string_byte_length(view_box));
-		float min_x, min_y, vwidth, vheight;
-		if (sscanf(s, "%f,%f,%f,%f",
-				&min_x, &min_y, &vwidth, &vheight) == 4 ||
-				sscanf(s, "%f %f %f %f",
-				&min_x, &min_y, &vwidth, &vheight) == 4) {
-			state.ctm.a = (float) state.viewport_width / vwidth;
-			state.ctm.d = (float) state.viewport_height / vheight;
-			state.ctm.e += -min_x * state.ctm.a;
-			state.ctm.f += -min_y * state.ctm.d;
-		}
-		free(s);
+		svgtiny_parse_viewbox(dom_string_data(view_box),
+				      dom_string_byte_length(view_box),
+				      state.viewport_width,
+				      state.viewport_height,
+				      &state.ctm);
 		dom_string_unref(view_box);
 	}
 
diff --git a/src/svgtiny_internal.h b/src/svgtiny_internal.h
index 4e58002..519f65f 100644
--- a/src/svgtiny_internal.h
+++ b/src/svgtiny_internal.h
@@ -98,6 +98,9 @@ svgtiny_code svgtiny_parse_paint(const char *text, size_t textlen,
 		svgtiny_colour *c);
 svgtiny_code svgtiny_parse_color(const char *text, size_t textlen,
 		svgtiny_colour *c);
+svgtiny_code svgtiny_parse_viewbox(const char *text, size_t textlen,
+		float viewport_width, float viewport_height,
+		struct svgtiny_transformation_matrix *tm);
 
 /* svgtiny_gradient.c */
 svgtiny_code svgtiny_find_gradient(const char *id,
diff --git a/src/svgtiny_parse.c b/src/svgtiny_parse.c
index 4ecc811..b459d1d 100644
--- a/src/svgtiny_parse.c
+++ b/src/svgtiny_parse.c
@@ -1208,3 +1208,60 @@ svgtiny_parse_color(const char *text, size_t textlen, svgtiny_colour *c)
 	*c = svgtiny_RGB(0, 0, 0);
 	return svgtiny_SVG_ERROR;
 }
+
+/**
+ * parse a viewbox attribute
+ *
+ * https://www.w3.org/TR/SVG11/coords.html#ViewBoxAttribute
+ * https://www.w3.org/TR/SVG2/coords.html#ViewBoxAttribute
+ *
+ * <min-x>,? <min-y>,? <width>,? <height>
+ */
+svgtiny_code
+svgtiny_parse_viewbox(const char *text,
+		      size_t textlen,
+		      float viewport_width,
+		      float viewport_height,
+		      struct svgtiny_transformation_matrix *tm)
+{
+	const char *cursor = text; /* text cursor */
+	const char *textend = text + textlen;
+	const char *paramend;
+	float paramv[4];
+	int paramidx = 0;
+	svgtiny_code res;
+
+	/* advance cursor past optional whitespace */
+	advance_whitespace(&cursor, textend);
+
+	for (paramidx = 0; paramidx < 3; paramidx++) {
+		paramend = textend;
+		res = parse_number(cursor, &paramend, &paramv[paramidx]);
+		if (res != svgtiny_OK) {
+			/* failed to parse number */
+			return res;
+		}
+		cursor = paramend;
+		advance_comma_whitespace(&cursor, textend);
+	}
+	paramend = textend;
+	res = parse_number(cursor, &paramend, &paramv[paramidx]);
+	if (res != svgtiny_OK) {
+		/* failed to parse number */
+		return res;
+	}
+	cursor = paramend;
+	advance_whitespace(&cursor, textend);
+
+	if (cursor != textend) {
+		/* syntax error */
+		return svgtiny_SVG_ERROR;
+	}
+
+	tm->a = (float)viewport_width / paramv[2];
+	tm->d = (float)viewport_height / paramv[3];
+	tm->e += -paramv[0] * tm->a;
+	tm->f += -paramv[1] * tm->d;
+
+	return svgtiny_OK;
+}
diff --git a/test/data/colors.svg b/test/data/colors.svg
index 8ddbe07..2b51869 100644
--- a/test/data/colors.svg
+++ b/test/data/colors.svg
@@ -1,5 +1,5 @@
 <?xml version="1.0"?>
-<svg width="1200" height="1200" viewPort="0 0 1200 1200" version="1.1" xmlns="http://www.w3.org/2000/svg">
+<svg width="1200" height="1200" viewBox="0 0 1200 1200" version="1.1" xmlns="http://www.w3.org/2000/svg">
     <rect fill="#01234567"      stroke=" #89ABCD"         x="100" y="100" width="1000" height="100" stroke-width="10" />
     <rect fill="#EFab "         stroke=" #cde "           x="100" y="200" width="1000" height="100" stroke-width="10" />
     <rect fill="#f67 "          stroke="#bB6677 "         x="100" y="300" width="1000" height="100" stroke-width="10" />
diff --git a/test/data/polyline.mvg b/test/data/polyline.mvg
new file mode 100644
index 0000000..573d3f1
--- /dev/null
+++ b/test/data/polyline.mvg
@@ -0,0 +1,2 @@
+viewbox 0 0 120 120
+fill none stroke #801bff stroke-width 1 path 'M 20 100 L 40 60 L 70 80 L 100 20 ' 
diff --git a/test/data/polyline.svg b/test/data/polyline.svg
index 2f37e44..6a5216a 100644
--- a/test/data/polyline.svg
+++ b/test/data/polyline.svg
@@ -1,6 +1,6 @@
 <?xml version="1.0"?>
 <svg width="120" height="120" 
-     viewPort="0 0 120 120" version="1.1"
+     viewBox=" 0,0 , 120  , 120 " version="1.1"
      xmlns="http://www.w3.org/2000/svg">
 
     <polyline fill="none" stroke="rgb(50.5%,10.8%,100.0%)"
diff --git a/test/data/polypoints.svg b/test/data/polypoints.svg
index 9c83781..1977638 100644
--- a/test/data/polypoints.svg
+++ b/test/data/polypoints.svg
@@ -1,6 +1,5 @@
 <?xml version="1.0"?>
-<svg width="200" height="200"  viewPort="0 0 200 200" version="1.1"
-     xmlns="http://www.w3.org/2000/svg">
+<svg width="200" height="200" viewBox="0 0 200 200" version="1.1" xmlns="http://www.w3.org/2000/svg">
 
     <g transform="translate(100,100)">
         <!-- smallest minimal point set is line from top left to bottom right -->
diff --git a/test/data/transform.svg b/test/data/transform.svg
index da05c42..476d006 100644
--- a/test/data/transform.svg
+++ b/test/data/transform.svg
@@ -1,5 +1,5 @@
 <?xml version="1.0"?>
-<svg width="400" height="400"  viewPort="0 0 400 400" version="1.1"
+<svg width="400" height="400" viewBox="0 0 400 400" version="1.1"
      xmlns="http://www.w3.org/2000/svg">
 
     <!-- transforms with a simple triangle -->
-- 
2.49.0