Improve calculation of scraped example minimized height

Author: willcrichton

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

@@ -1931,18 +1931,24 @@ in storage.js
 }
 
 .scraped-example:not(.expanded) .code-wrapper {
-	max-height: 120px;
+	/* scrape-examples.js has a constant DEFAULT_MAX_LINES (call it N) for the number
+	 * of lines shown in the un-expanded example code viewer. This pre needs to have
+	 * a max-height equal to line-height * N. The line-height is currently 1.5em,
+	 * and we include additional 10px for padding. */
+	 max-height: calc(1.5em * 5 + 10px);
 }
 
 .scraped-example:not(.expanded) .code-wrapper pre {
 	overflow-y: hidden;
-	max-height: 120px;
 	padding-bottom: 0;
+	/* See above comment, should be the same max-height. */
+	max-height: calc(1.5em * 5 + 10px);
 }
 
 .more-scraped-examples .scraped-example:not(.expanded) .code-wrapper,
 .more-scraped-examples .scraped-example:not(.expanded) .code-wrapper pre {
-	max-height: 240px;
+	/* See above comment, except this height is based on HIDDEN_MAX_LINES. */
+	max-height: calc(1.5em * 10 + 10px);
 }
 
 .scraped-example .code-wrapper .next,

src/librustdoc/html/static/js/scrape-examples.js

@@ -6,6 +6,8 @@
     // Number of lines shown when code viewer is not expanded.
     // DEFAULT is the first example shown by default, while HIDDEN is
     // the examples hidden beneath the "More examples" toggle.
+    //
+    // NOTE: these values MUST be synchronized with certain rules in rustdoc.css!
     const DEFAULT_MAX_LINES = 5;
     const HIDDEN_MAX_LINES = 10;
 
@@ -24,8 +26,10 @@
         } else {
             const wrapper = elt.querySelector(".code-wrapper");
             const halfHeight = wrapper.offsetHeight / 2;
-            const offsetMid = (lines.children[loc[0]].offsetTop
-                             + lines.children[loc[1]].offsetTop) / 2;
+            const offsetTop = lines.children[loc[0]].offsetTop;
+            const lastLine = lines.children[loc[1]];
+            const offsetBot = lastLine.offsetTop + lastLine.offsetHeight;
+            const offsetMid = (offsetTop + offsetBot) / 2;
             scrollOffset = offsetMid - halfHeight;
         }