Rollup merge of #128339 - GuillaumeGomez:click-code-example, r=notriddle

[rustdoc] Make the buttons remain when code example is clicked

Follow-up of https://github.com/rust-lang/rust/pull/125779.

One current issue we have with "run" button and the newly added copy code button is that if you're on mobile devices, you can't use them. I took a look at how `mdbook` is handling it and when you click on a code example, they show the buttons. I think it's a really good idea as if you want to copy the code on your mobile device, you will click on it, showing the buttons.

Feature can be tested [here](https://rustdoc.crud.net/imperio/click-code-example/foo/struct.Bar.html).

r? `@notriddle`

2 files changed, 37 insertions, 3 deletions

diff --git a/src/librustdoc/html/static/css/rustdoc.css b/src/librustdoc/html/static/css/rustdoc.css
index cafe5fe4c87..f4e231327a8 100644
--- a/src/librustdoc/html/static/css/rustdoc.css
+++ b/src/librustdoc/html/static/css/rustdoc.css
@@ -1477,7 +1477,20 @@ a.test-arrow:hover {
 .example-wrap:hover > .test-arrow {
 	padding: 2px 7px;
 }
-.example-wrap:hover > .test-arrow, .example-wrap:hover > .button-holder {
+/*
+On iPad, the ":hover" state sticks around, making things work not greatly. Do work around
+it, we move it into this media query. More information can be found at:
+https://css-tricks.com/solving-sticky-hover-states-with-media-hover-hover/
+
+However, using `@media (hover: hover)` makes this rule never to be applied in GUI tests, so
+instead, we check that it's not a "finger" cursor.
+*/
+@media not (pointer: coarse) {
+	.example-wrap:hover > .test-arrow, .example-wrap:hover > .button-holder {
+		visibility: visible;
+	}
+}
+.example-wrap .button-holder.keep-visible {
 	visibility: visible;
 }
 .example-wrap .button-holder .copy-button {
diff --git a/src/librustdoc/html/static/js/main.js b/src/librustdoc/html/static/js/main.js
index 40d65ae7910..e0ea234f9e7 100644
--- a/src/librustdoc/html/static/js/main.js
+++ b/src/librustdoc/html/static/js/main.js
@@ -1829,14 +1829,22 @@ href="https://doc.rust-lang.org/${channel}/rustdoc/read-documentation/search.htm
         copyContentToClipboard(codeElem.textContent);
     }
 
-    function addCopyButton(event) {
+    function getExampleWrap(event) {
         let elem = event.target;
         while (!hasClass(elem, "example-wrap")) {
             elem = elem.parentElement;
             if (elem.tagName === "body" || hasClass(elem, "docblock")) {
-                return;
+                return null;
             }
         }
+        return elem;
+    }
+
+    function addCopyButton(event) {
+        const elem = getExampleWrap(event);
+        if (elem === null) {
+            return;
+        }
         // Since the button will be added, no need to keep this listener around.
         elem.removeEventListener("mouseover", addCopyButton);
 
@@ -1858,7 +1866,20 @@ href="https://doc.rust-lang.org/${channel}/rustdoc/read-documentation/search.htm
         parent.appendChild(copyButton);
     }
 
+    function showHideCodeExampleButtons(event) {
+        const elem = getExampleWrap(event);
+        if (elem === null) {
+            return;
+        }
+        const buttons = elem.querySelector(".button-holder");
+        if (buttons === null) {
+            return;
+        }
+        buttons.classList.toggle("keep-visible");
+    }
+
     onEachLazy(document.querySelectorAll(".docblock .example-wrap"), elem => {
         elem.addEventListener("mouseover", addCopyButton);
+        elem.addEventListener("click", showHideCodeExampleButtons);
     });
 }());