Rollup merge of rust-lang#125779 - GuillaumeGomez:copy-code, r=rustdoc-team

[rustdoc] Add copy code feature

This PR adds a "copy code" to code blocks. Since this is a JS only feature, the HTML is generated with JS when the user hovers the code block to prevent generating DOM unless needed.

Two things to note:
 1. I voluntarily kept the current behaviour of the run button (only when hovering a code block with a mouse) so it doesn't do anything on mobile. I plan to send a follow-up where the buttons would "expandable" or something. Still need to think which approach would be the best.
 2. I used a picture and not text like the run button to remain consistent with the "copy path" button. I'd also prefer for the run button to use a picture (like what is used in mdbook) but again, that's something to be discussed later on.

The rendering looks like this:

![Screenshot from 2024-06-03 21-29-48](https://github.com/rust-lang/rust/assets/3050060/a0b18f9c-b3dd-4a65-89a7-5a7a303b5c2b)
![Screenshot from 2024-06-03 21-30-20](https://github.com/rust-lang/rust/assets/3050060/b3b084ff-2716-4160-820b-d4774681a961)

It can be tested [here](https://guillaume-gomez.fr/rustdoc/bar/struct.Bar.html) (without the run button) and [here](https://guillaume-gomez.fr/rustdoc/foo/struct.Bar.html) (with the run button).

Fixes rust-lang#86851.

r? ``@notriddle``

Author: GuillaumeGomez

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

@@ -16,6 +16,24 @@
 	--src-sidebar-width: 300px;
 	--desktop-sidebar-z-index: 100;
 	--sidebar-elems-left-padding: 24px;
+	/* clipboard <https://github.com/rust-lang/crates.io/commits/main/public/assets/copy.svg> */
+	--clipboard-image: url('data:image/svg+xml,<svg width="19" height="18" viewBox="0 0 24 25" \
+xmlns="http://www.w3.org/2000/svg" aria-label="Copy to clipboard">\
+<path d="M18 20h2v3c0 1-1 2-2 2H2c-.998 0-2-1-2-2V5c0-.911.755-1.667 1.667-1.667h5A3.323 3.323 0 \
+0110 0a3.323 3.323 0 013.333 3.333h5C19.245 3.333 20 4.09 20 5v8.333h-2V9H2v14h16v-3zM3 \
+7h14c0-.911-.793-1.667-1.75-1.667H13.5c-.957 0-1.75-.755-1.75-1.666C11.75 2.755 10.957 2 10 \
+2s-1.75.755-1.75 1.667c0 .911-.793 1.666-1.75 1.666H4.75C3.793 5.333 3 6.09 3 7z"/>\
+<path d="M4 19h6v2H4zM12 11H4v2h8zM4 17h4v-2H4zM15 15v-3l-4.5 4.5L15 21v-3l8.027-.032L23 15z"/>\
+</svg>');
+	--copy-path-height: 34px;
+	--copy-path-width: 33px;
+	/* Checkmark <https://www.svgrepo.com/svg/335033/checkmark> */
+	--checkmark-image: url('data:image/svg+xml,<svg viewBox="-1 -1 23 23" \
+xmlns="http://www.w3.org/2000/svg" fill="black" height="18px">\
+<g><path d="M9 19.414l-6.707-6.707 1.414-1.414L9 16.586 20.293 5.293l1.414 1.414"></path>\
+</g></svg>');
+	--button-left-margin: 4px;
+	--button-border-radius: 2px;
 }
 
 /* See FiraSans-LICENSE.txt for the Fira Sans license. */
@@ -723,6 +741,11 @@ ul.block, .block li {
 	position: relative;
 	margin-bottom: 10px;
 }
+
+.rustdoc .example-wrap > pre {
+	border-radius: 6px;
+}
+
 /* For the last child of a div, the margin will be taken care of
 	by the margin-top of the next item. */
 .rustdoc .example-wrap:last-child {
@@ -1427,25 +1450,55 @@ documentation. */
 	top: 20px;
 }
 
-a.test-arrow {
+.example-wrap > a.test-arrow, .example-wrap .button-holder {
 	visibility: hidden;
 	position: absolute;
-	padding: 5px 10px 5px 10px;
-	border-radius: 5px;
-	font-size: 1.375rem;
-	top: 5px;
-	right: 5px;
+	top: 4px;
+	right: 4px;
 	z-index: 1;
+}
+a.test-arrow {
+	padding: 5px 7px;
+	border-radius: var(--button-border-radius);
+	font-size: 1rem;
 	color: var(--test-arrow-color);
 	background-color: var(--test-arrow-background-color);
 }
 a.test-arrow:hover {
 	color: var(--test-arrow-hover-color);
 	background-color: var(--test-arrow-hover-background-color);
 }
-.example-wrap:hover .test-arrow {
+.example-wrap .button-holder {
+	display: flex;
+}
+.example-wrap:hover > .test-arrow {
+	padding: 2px 7px;
+}
+.example-wrap:hover > .test-arrow, .example-wrap:hover > .button-holder {
 	visibility: visible;
 }
+.example-wrap .button-holder .copy-button {
+	color: var(--copy-path-button-color);
+	background: var(--main-background-color);
+	height: var(--copy-path-height);
+	width: var(--copy-path-width);
+	margin-left: var(--button-left-margin);
+	padding: 2px 0 0 4px;
+	border: 0;
+	cursor: pointer;
+	border-radius: var(--button-border-radius);
+}
+.example-wrap .button-holder .copy-button::before {
+	filter: var(--copy-path-img-filter);
+	content: var(--clipboard-image);
+}
+.example-wrap .button-holder .copy-button:hover::before {
+	filter: var(--copy-path-img-hover-filter);
+}
+.example-wrap .button-holder .copy-button.clicked::before {
+	content: var(--checkmark-image);
+	padding-right: 5px;
+}
 
 .code-attribute {
 	font-weight: 300;
@@ -1610,7 +1663,7 @@ a.tooltip:hover::after {
 }
 
 #settings-menu, #help-button {
-	margin-left: 4px;
+	margin-left: var(--button-left-margin);
 	display: flex;
 }
 #sidebar-button {
@@ -1641,7 +1694,7 @@ a.tooltip:hover::after {
 	justify-content: center;
 	background-color: var(--button-background-color);
 	border: 1px solid var(--border-color);
-	border-radius: 2px;
+	border-radius: var(--button-border-radius);
 	color: var(--settings-button-color);
 	/* Rare exception to specifying font sizes in rem. Since this is acting
 	   as an icon, it's okay to specify their sizes in pixels. */
@@ -1693,8 +1746,8 @@ a.tooltip:hover::after {
 #copy-path {
 	color: var(--copy-path-button-color);
 	background: var(--main-background-color);
-	height: 34px;
-	width: 33px;
+	height: var(--copy-path-height);
+	width: var(--copy-path-width);
 	margin-left: 10px;
 	padding: 0;
 	padding-left: 2px;
@@ -1703,27 +1756,13 @@ a.tooltip:hover::after {
 }
 #copy-path::before {
 	filter: var(--copy-path-img-filter);
-	/* clipboard <https://github.com/rust-lang/crates.io/commits/main/public/assets/copy.svg> */
-	content: url('data:image/svg+xml,<svg width="19" height="18" viewBox="0 0 24 25" \
-xmlns="http://www.w3.org/2000/svg" aria-label="Copy to clipboard">\
-<path d="M18 20h2v3c0 1-1 2-2 2H2c-.998 0-2-1-2-2V5c0-.911.755-1.667 1.667-1.667h5A3.323 3.323 0 \
-0110 0a3.323 3.323 0 013.333 3.333h5C19.245 3.333 20 4.09 20 5v8.333h-2V9H2v14h16v-3zM3 \
-7h14c0-.911-.793-1.667-1.75-1.667H13.5c-.957 0-1.75-.755-1.75-1.666C11.75 2.755 10.957 2 10 \
-2s-1.75.755-1.75 1.667c0 .911-.793 1.666-1.75 1.666H4.75C3.793 5.333 3 6.09 3 7z"/>\
-<path d="M4 19h6v2H4zM12 11H4v2h8zM4 17h4v-2H4zM15 15v-3l-4.5 4.5L15 21v-3l8.027-.032L23 15z"/>\
-</svg>');
-	width: 19px;
-	height: 18px;
+	content: var(--clipboard-image);
 }
 #copy-path:hover::before {
 	filter: var(--copy-path-img-hover-filter);
 }
 #copy-path.clicked::before {
-	/* Checkmark <https://www.svgrepo.com/svg/335033/checkmark> */
-	content: url('data:image/svg+xml,<svg viewBox="-1 -1 23 23" xmlns="http://www.w3.org/2000/svg" \
-		fill="black" height="18px">\
-		<g><path d="M9 19.414l-6.707-6.707 1.414-1.414L9 16.586 20.293 5.293l1.414 1.414"></path>\
-		</g></svg>');
+	content: var(--checkmark-image);
 }
 
 @keyframes rotating {

src/librustdoc/html/static/js/main.js

@@ -1771,9 +1771,37 @@ href="https://doc.rust-lang.org/${channel}/rustdoc/read-documentation/search.htm
 }());
 
 // This section handles the copy button that appears next to the path breadcrumbs
+// and the copy buttons on the code examples.
 (function() {
-    let reset_button_timeout = null;
+    // Common functions to copy buttons.
+    function copyContentToClipboard(content) {
+        const el = document.createElement("textarea");
+        el.value = content;
+        el.setAttribute("readonly", "");
+        // To not make it appear on the screen.
+        el.style.position = "absolute";
+        el.style.left = "-9999px";
 
+        document.body.appendChild(el);
+        el.select();
+        document.execCommand("copy");
+        document.body.removeChild(el);
+    }
+
+    function copyButtonAnimation(button) {
+        button.classList.add("clicked");
+
+        if (button.reset_button_timeout !== undefined) {
+            window.clearTimeout(button.reset_button_timeout);
+        }
+
+        button.reset_button_timeout = window.setTimeout(() => {
+            button.reset_button_timeout = undefined;
+            button.classList.remove("clicked");
+        }, 1000);
+    }
+
+    // Copy button that appears next to the path breadcrumbs.
     const but = document.getElementById("copy-path");
     if (!but) {
         return;
@@ -1788,29 +1816,49 @@ href="https://doc.rust-lang.org/${channel}/rustdoc/read-documentation/search.htm
             }
         });
 
-        const el = document.createElement("textarea");
-        el.value = path.join("::");
-        el.setAttribute("readonly", "");
-        // To not make it appear on the screen.
-        el.style.position = "absolute";
-        el.style.left = "-9999px";
-
-        document.body.appendChild(el);
-        el.select();
-        document.execCommand("copy");
-        document.body.removeChild(el);
-
-        but.classList.add("clicked");
+        copyContentToClipboard(path.join("::"));
+        copyButtonAnimation(but);
+    };
 
-        if (reset_button_timeout !== null) {
-            window.clearTimeout(reset_button_timeout);
+    // Copy buttons on code examples.
+    function copyCode(codeElem) {
+        if (!codeElem) {
+            // Should never happen, but the world is a dark and dangerous place.
+            return;
         }
+        copyContentToClipboard(codeElem.textContent);
+    }
 
-        function reset_button() {
-            reset_button_timeout = null;
-            but.classList.remove("clicked");
+    function addCopyButton(event) {
+        let elem = event.target;
+        while (!hasClass(elem, "example-wrap")) {
+            elem = elem.parentElement;
+            if (elem.tagName === "body" || hasClass(elem, "docblock")) {
+                return;
+            }
+        }
+        // Since the button will be added, no need to keep this listener around.
+        elem.removeEventListener("mouseover", addCopyButton);
+
+        const parent = document.createElement("div");
+        parent.className = "button-holder";
+        const runButton = elem.querySelector(".test-arrow");
+        if (runButton !== null) {
+            // If there is a run button, we move it into the same div.
+            parent.appendChild(runButton);
         }
+        elem.appendChild(parent);
+        const copyButton = document.createElement("button");
+        copyButton.className = "copy-button";
+        copyButton.title = "Copy code to clipboard";
+        copyButton.addEventListener("click", () => {
+            copyCode(elem.querySelector("pre > code"));
+            copyButtonAnimation(copyButton);
+        });
+        parent.appendChild(copyButton);
+    }
 
-        reset_button_timeout = window.setTimeout(reset_button, 1000);
-    };
+    onEachLazy(document.querySelectorAll(".docblock .example-wrap"), elem => {
+        elem.addEventListener("mouseover", addCopyButton);
+    });
 }());

tests/rustdoc-gui/copy-code.goml

@@ -0,0 +1,54 @@
+// Checks that the "copy code" button is not triggering JS error and its display
+// isn't broken.
+go-to: "file://" + |DOC_PATH| + "/test_docs/fn.foo.html"
+
+define-function: (
+    "check-copy-button",
+    [],
+    block {
+        // First we ensure that there are no "copy code" currently existing.
+        assert-count: (".example-wrap .copy-button", 0)
+        move-cursor-to: ".example-wrap"
+        assert-count: (".example-wrap .copy-button", 1)
+        // We now ensure it's only displayed when the example is hovered.
+        assert-css: (".example-wrap .copy-button", { "visibility": "visible" })
+        move-cursor-to: ".search-input"
+        assert-css: (".example-wrap .copy-button", { "visibility": "hidden" })
+        // Checking that the copy button has the same size as the "copy path" button.
+        compare-elements-size: (
+            "#copy-path",
+            ".example-wrap:nth-of-type(1) .copy-button",
+            ["height", "width"],
+        )
+    },
+)
+
+call-function: ("check-copy-button", {})
+// Checking that the run button and the copy button have the same height.
+compare-elements-size: (
+    ".example-wrap:nth-of-type(1) .test-arrow",
+    ".example-wrap:nth-of-type(1) .copy-button",
+    ["height"],
+)
+// ... and the same y position.
+compare-elements-position: (
+    ".example-wrap:nth-of-type(1) .test-arrow",
+    ".example-wrap:nth-of-type(1) .copy-button",
+    ["y"],
+)
+store-size: (".example-wrap:nth-of-type(1) .copy-button", {
+    "height": copy_height,
+    "width": copy_width,
+})
+assert: |copy_height| > 0 && |copy_width| > 0
+
+// Checking same things for the copy button when there is no run button.
+go-to: "file://" + |DOC_PATH| + "/lib2/sub_mod/struct.Foo.html"
+call-function: ("check-copy-button", {})
+// Ensure there is no run button.
+assert-count: (".example-wrap .test-arrow", 0)
+// Check it's the same size without a run button.
+assert-size: (".example-wrap:nth-of-type(1) .copy-button", {
+    "height": |copy_height|,
+    "width": |copy_width|,
+})

tests/rustdoc-gui/run-on-hover.goml

@@ -17,16 +17,16 @@ define-function: (
             "visibility": "visible",
             "color": |color|,
             "background-color": |background|,
-            "font-size": "22px",
-            "border-radius": "5px",
+            "font-size": "16px",
+            "border-radius": "2px",
         })
         move-cursor-to: ".test-arrow"
         assert-css: (".test-arrow:hover", {
             "visibility": "visible",
             "color": |hover_color|,
             "background-color": |hover_background|,
-            "font-size": "22px",
-            "border-radius": "5px",
+            "font-size": "16px",
+            "border-radius": "2px",
         })
     },
 )