Rustdoc accessibility: use an icon for the [-]/[+] controls

src/librustdoc/html/render/write_shared.rs

@@ -175,9 +175,45 @@ pub(super) fn write_shared(
         cx.write_shared(SharedResource::InvocationSpecific { basename: p }, content, &options.emit)
     };
 
+    fn add_background_image_to_css(
+        cx: &Context<'_>,
+        css: &mut String,
+        rule: &str,
+        file: &'static str,
+    ) {
+        css.push_str(&format!(
+            "{} {{ background-image: url({}); }}",
+            rule,
+            SharedResource::ToolchainSpecific { basename: file }
+                .path(cx)
+                .file_name()
+                .unwrap()
+                .to_str()
+                .unwrap()
+        ))
+    }
+
+    // Add all the static files. These may already exist, but we just
+    // overwrite them anyway to make sure that they're fresh and up-to-date.
+    let mut rustdoc_css = static_files::RUSTDOC_CSS.to_owned();
+    add_background_image_to_css(
+        cx,
+        &mut rustdoc_css,
+        "details.undocumented[open] > summary::before, \
+         details.rustdoc-toggle[open] > summary::before, \
+         details.rustdoc-toggle[open] > summary.hideme::before",
+        "toggle-minus.svg",
+    );
+    add_background_image_to_css(
+        cx,
+        &mut rustdoc_css,
+        "details.undocumented > summary::before, details.rustdoc-toggle > summary::before",
+        "toggle-plus.svg",
+    );
+    write_minify("rustdoc.css", &rustdoc_css)?;
+
     // Add all the static files. These may already exist, but we just
     // overwrite them anyway to make sure that they're fresh and up-to-date.
-    write_minify("rustdoc.css", static_files::RUSTDOC_CSS)?;
     write_minify("settings.css", static_files::SETTINGS_CSS)?;
     write_minify("noscript.css", static_files::NOSCRIPT_CSS)?;
 
@@ -217,6 +253,8 @@ pub(super) fn write_shared(
     write_toolchain("wheel.svg", static_files::WHEEL_SVG)?;
     write_toolchain("clipboard.svg", static_files::CLIPBOARD_SVG)?;
     write_toolchain("down-arrow.svg", static_files::DOWN_ARROW_SVG)?;
+    write_toolchain("toggle-minus.svg", static_files::TOGGLE_MINUS_PNG)?;
+    write_toolchain("toggle-plus.svg", static_files::TOGGLE_PLUS_PNG)?;
 
     let mut themes: Vec<&String> = themes.iter().collect();
     themes.sort();

src/librustdoc/html/static/css/rustdoc.css

@@ -1508,11 +1508,35 @@ details.rustdoc-toggle > summary.hideme > span {
 }
 
 details.rustdoc-toggle > summary::before {
-	content: "[+]";
-	font-weight: 300;
-	font-size: 0.8em;
-	letter-spacing: 1px;
+	content: "";
 	cursor: pointer;
+	width: 17px;
+	height: max(17px, 1.1em);
+	background-repeat: no-repeat;
+	background-position: top left;
+	display: inline-block;
+	vertical-align: middle;
+	opacity: .5;
+}
+
+/* Screen readers see the text version at the end the line.
+	Visual readers see the icon at the start of the line, but small and transparent. */
+details.rustdoc-toggle > summary::after {
+	content: "Expand";
+	overflow: hidden;
+	width: 0;
+	height: 0;
+	position: absolute;
+}
+
+details.rustdoc-toggle > summary.hideme::after {
+	/* "hideme" toggles already have a description when they're contracted */
+	content: "";
+}
+
+details.rustdoc-toggle > summary:focus::before,
+details.rustdoc-toggle > summary:hover::before {
+	opacity: 1;
 }
 
 details.rustdoc-toggle.top-doc > summary,
@@ -1560,20 +1584,44 @@ details.rustdoc-toggle[open] > summary.hideme > span {
 	display: none;
 }
 
-details.rustdoc-toggle[open] > summary::before {
-	content: "[−]";
-	display: inline;
+details.rustdoc-toggle[open] > summary::before,
+details.rustdoc-toggle[open] > summary.hideme::before {
+	width: 17px;
+	height: max(17px, 1.1em);
+	background-repeat: no-repeat;
+	background-position: top left;
+	display: inline-block;
+	content: "";
+}
+
+details.rustdoc-toggle[open] > summary::after,
+details.rustdoc-toggle[open] > summary.hideme::after {
+	content: "Collapse";
 }
 
 details.undocumented > summary::before {
-	content: "[+] Show hidden undocumented items";
+	padding-left: 17px;
+	height: max(17px, 1.1em);
+	background-repeat: no-repeat;
+	background-position: top left;
+	content: "Show hidden undocumented items";
 	cursor: pointer;
 	font-size: 16px;
 	font-weight: 300;
+	opacity: .5;
+}
+
+details.undocumented > summary:focus::before,
+details.undocumented > summary:hover::before {
+	opacity: 1;
 }
 
 details.undocumented[open] > summary::before {
-	content: "[−] Hide undocumented items";
+	padding-left: 17px;
+	height: max(17px, 1.1em);
+	background-repeat: no-repeat
+	background-position: top left;
+	content: "Hide undocumented items";
 }
 
 /* Media Queries */

src/librustdoc/html/static/css/themes/ayu.css

@@ -229,6 +229,11 @@ details.undocumented > summary::before {
 	color: #999;
 }
 
+details.rustdoc-toggle > summary::before,
+details.undocumented > summary::before {
+	filter: invert(100%);
+}
+
 #crate-search {
 	color: #c5c5c5;
 	background-color: #141920;

src/librustdoc/html/static/css/themes/dark.css

@@ -194,6 +194,11 @@ details.undocumented > summary::before {
 	color: #999;
 }
 
+details.rustdoc-toggle > summary::before,
+details.undocumented > summary::before {
+	filter: invert(100%);
+}
+
 #crate-search {
 	color: #111;
 	background-color: #f0f0f0;

src/librustdoc/html/static_files.rs

@@ -47,6 +47,12 @@ crate static CLIPBOARD_SVG: &[u8] = include_bytes!("static/images/clipboard.svg"
 /// The file contents of `down-arrow.svg`, the icon used for the crate choice combobox.
 crate static DOWN_ARROW_SVG: &[u8] = include_bytes!("static/images/down-arrow.svg");
 
+/// The file contents of `toggle-minus.svg`, the icon used for opened toggles.
+crate static TOGGLE_MINUS_PNG: &[u8] = include_bytes!("static/images/toggle-minus.svg");
+
+/// The file contents of `toggle-plus.svg`, the icon used for closed toggles.
+crate static TOGGLE_PLUS_PNG: &[u8] = include_bytes!("static/images/toggle-plus.svg");
+
 /// The contents of `COPYRIGHT.txt`, the license listing for files distributed with documentation
 /// output.
 crate static COPYRIGHT: &[u8] = include_bytes!("static/COPYRIGHT.txt");