From 370c219cf58f122c84bb435b4004b43bdd209bc3 Mon Sep 17 00:00:00 2001
From: Michael Orlitzky <michael@orlitzky.com>
Date: Sat, 7 Jun 2025 11:39:59 -0400
Subject: [PATCH] src/svgtiny*.{c,h}: move the libcss unit context into the
 parser state

This will make it easier to use the same unit context for style
composition that we do for style computation.
---
 src/svgtiny.c          | 22 +++++++++++++++++++++-
 src/svgtiny_css.c      | 28 +++++++++-------------------
 src/svgtiny_internal.h |  5 +++++
 3 files changed, 35 insertions(+), 20 deletions(-)

diff --git a/src/svgtiny.c b/src/svgtiny.c
index 1cc003e..0f47df9 100644
--- a/src/svgtiny.c
+++ b/src/svgtiny.c
@@ -1404,6 +1404,11 @@ initialise_parse_state(struct svgtiny_parse_state *state,
 		return svgtiny_LIBCSS_ERROR;
 	}
 
+	/* ...and the unit context, whose other fields were
+	 * initialized along with the parser state itself */
+	state->unit_ctx.viewport_width  = FLTTOFIX(viewport_width);
+	state->unit_ctx.viewport_height = FLTTOFIX(viewport_height);
+
 	return svgtiny_OK;
 }
 
@@ -1606,7 +1611,22 @@ svgtiny_code svgtiny_parse(struct svgtiny_diagram *diagram,
 {
 	dom_document *document;
 	dom_element *svg;
-	struct svgtiny_parse_state state;
+	struct svgtiny_parse_state state = {
+		/* Initialize the unit context here because it has a
+		 * const member and doing it any other way subverts
+		 * the type system. The magic numbers below were taken
+		 * from the libcss example program without much
+		 * thought, because at the moment we don't support any
+		 * properties with units. */
+		.unit_ctx = {
+			.font_size_default = FLTTOFIX(16.0),
+			.font_size_minimum = FLTTOFIX(6.0),
+			.device_dpi        = FLTTOFIX(96.0),
+			.root_style        = NULL,
+			.pw                = NULL,
+			.measure           = NULL,
+		}
+	};
 	svgtiny_code code;
 
 	assert(diagram);
diff --git a/src/svgtiny_css.c b/src/svgtiny_css.c
index 3ac078a..d827688 100644
--- a/src/svgtiny_css.c
+++ b/src/svgtiny_css.c
@@ -73,6 +73,14 @@ static css_error get_libcss_node_data(void *pw, void *node,
 static struct css_select_handler svgtiny_select_handler;
 
 
+/* Every call to svgtiny_select_style() needs this, so let's only make
+ * one copy. */
+static const css_media media_all = {
+	.type = CSS_MEDIA_ALL,
+};
+
+
+
 /**
  * Convenient wrapper around css_select_style()
  *
@@ -86,27 +94,9 @@ css_error svgtiny_select_style(struct svgtiny_parse_state *state,
 				const css_stylesheet *inline_sheet,
 				css_select_results **result)
 {
-	const css_media media_all = {
-		.type = CSS_MEDIA_ALL,
-	};
-
-	/* These magic numbers below were taken from the libcss
-	 * example program without much thought, because at the moment
-	 * we don't support any properties with units. */
-	const css_unit_ctx unitctx = {
-		.viewport_width    = FLTTOFIX(state->viewport_width),
-		.viewport_height   = FLTTOFIX(state->viewport_height),
-		.font_size_default = FLTTOFIX(16.0),
-		.font_size_minimum = FLTTOFIX(6.0),
-		.device_dpi        = FLTTOFIX(96.0),
-		.root_style        = NULL,
-		.pw                = NULL,
-		.measure           = NULL,
-	};
-
 	return css_select_style(state->select_ctx,
 			node,
-			&unitctx,
+			&state->unit_ctx,
 			&media_all,
 			inline_sheet,
 			&svgtiny_select_handler,
diff --git a/src/svgtiny_internal.h b/src/svgtiny_internal.h
index 00595dd..89524ab 100644
--- a/src/svgtiny_internal.h
+++ b/src/svgtiny_internal.h
@@ -61,6 +61,11 @@ struct svgtiny_parse_state {
 	 * precede it. */
 	css_select_ctx *select_ctx;
 
+	/* A libcss unit context. This is used to compute and compose
+	 * styles, and is convenient to create once and pass along
+	 * with the rest of the state. */
+	css_unit_ctx unit_ctx;
+
 	/* Keep track of the parent element's computed style so that
 	 * we can compose its children's computed styles with it. */
 	css_computed_style *parent_style;
-- 
2.49.0