From 0312d7177af048a89e0259f78bceda9123b517fc Mon Sep 17 00:00:00 2001
From: Michael Orlitzky <michael@orlitzky.com>
Date: Tue, 17 Oct 2023 20:09:42 -0400
Subject: [PATCH] src/svgtiny.c: parse styles in
 svgtiny_parse_paint_attributes()

Now that the scaffolding is in place, we do the work to parse our two
supported CSS paint attributes, fill-opacity and stroke-opacity. This
amounts to,

  * Calling svgtiny_select_style(), which is just a wrapper around
    css_select_style()
  * Passing the result to css_computed_foo_opacity() to get the
    computed styles
  * Populating fill_opacity and stroke_opacity in the parser state
    if the corresponding styles exist

There's also a temporary hack to avoid crashing on the root node that
later goes away when we implement parent/child style composition.
---
 src/svgtiny.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 53 insertions(+), 3 deletions(-)

diff --git a/src/svgtiny.c b/src/svgtiny.c
index a77e3b4..3ad6eec 100644
--- a/src/svgtiny.c
+++ b/src/svgtiny.c
@@ -2071,14 +2071,23 @@ void svgtiny_parse_paint_attributes(dom_element *node,
 {
 	dom_string *attr;
 	dom_exception exc;
+	css_error code;
+	uint8_t   fill_opacity_type;
+	css_fixed fill_opacity;
+	uint8_t   stroke_opacity_type;
+	css_fixed stroke_opacity;
 
 	/* We store the result of svgtiny_parse_style_inline() in
 	 * inline_sheet, and that function returns NULL on error; in
 	 * particular you do not need to css_stylesheet_destroy() the
-	 * result if it is NULL. We initialize inline_sheet to NULL to
-	 * retain the same semantics. */
+	 * result if it is NULL, and css_stylesheet_destroy() checks
+	 * for that case. */
 	css_stylesheet *inline_sheet = NULL;
 
+	/* Initialize this to NULL for the same reason: so that we can
+	 * safely destroy it later even if we never populated it. */
+	css_select_results *styles = NULL;
+
 	exc = dom_element_get_attribute(node, state->interned_fill, &attr);
 	if (exc == DOM_NO_ERR && attr != NULL) {
 		svgtiny_parse_color(attr, &state->fill, &state->fill_grad, state);
@@ -2141,8 +2150,49 @@ void svgtiny_parse_paint_attributes(dom_element *node,
 		dom_string_unref(attr);
 	}
 
-	if (inline_sheet != NULL) {
+	struct dom_element *parent;
+	dom_element_parent_node(node, &parent);
+	if (parent == NULL) {
+		/* This is the root <svg> node, skip it.
+		 *
+		 * While initialising its selection state, libcss sets its
+		 * node_data->bloom pointer using css__get_parent_bloom().
+		 * But if there is no parent, that function returns,
+		 *
+		 *   static css_bloom empty_bloom[CSS_BLOOM_SIZE];
+		 *
+		 * A problem later arises because when libcss FINALISES its
+		 * selection state, it frees node_data->bloom! That obviously
+		 * won't work then node has no parent, i.e. if it's the root
+		 * <svg> element.
+		 */
 		css_stylesheet_destroy(inline_sheet);
+		return;
+	}
+	else {
+		/* We only needed to know if it was NULL */
+		dom_node_unref(parent);
+	}
+
+	code = svgtiny_select_style(state, node, inline_sheet, &styles);
+	css_stylesheet_destroy(inline_sheet);
+	if (code != CSS_OK) {
+		return;
+	}
+
+	fill_opacity_type = css_computed_fill_opacity(
+				styles->styles[CSS_PSEUDO_ELEMENT_NONE],
+				&fill_opacity);
+	stroke_opacity_type = css_computed_stroke_opacity(
+				styles->styles[CSS_PSEUDO_ELEMENT_NONE],
+				&stroke_opacity);
+	css_select_results_destroy(styles);
+
+	if (fill_opacity_type == CSS_FILL_OPACITY_SET) {
+		state->fill_opacity = FIXTOFLT(fill_opacity);
+	}
+	if (stroke_opacity_type == CSS_STROKE_OPACITY_SET) {
+		state->stroke_opacity = FIXTOFLT(stroke_opacity);
 	}
 }
 
-- 
2.44.2