gh-138122: Tachyon heatmap: Make toggle switches keyboard accessible (#142601)

Author: StanFromIreland

Lib/profiling/sampling/_heatmap_assets/heatmap.css

@@ -682,6 +682,10 @@
   opacity: 0.85;
 }
 
+.toggle-switch:focus-visible {
+  border-radius: 4px;
+}
+
 .toggle-switch .toggle-label {
   font-size: 11px;
   font-weight: 500;

Lib/profiling/sampling/_heatmap_assets/heatmap.js

@@ -733,14 +733,18 @@ function toggleAllBytecode() {
     }
 }
 
-// Keyboard shortcut: 'b' toggles all bytecode panels
+// Keyboard shortcut: 'b' toggles all bytecode panels, Enter/Space activates toggle switches
 document.addEventListener('keydown', function(e) {
     if (e.target.tagName === 'INPUT' || e.target.tagName === 'TEXTAREA') {
         return;
     }
     if (e.key === 'b' && !e.ctrlKey && !e.altKey && !e.metaKey) {
         toggleAllBytecode();
     }
+    if ((e.key === 'Enter' || e.key === ' ') && e.target.classList.contains('toggle-switch')) {
+        e.preventDefault();
+        e.target.click();
+    }
 });
 
 // Handle hash changes

Lib/profiling/sampling/_heatmap_assets/heatmap_pyfile_template.html

@@ -70,17 +70,17 @@
                 </div>
                 <div class="legend-separator" aria-hidden="true"></div>
                 <div class="legend-controls">
-                    <div class="toggle-switch" id="toggle-color-mode" title="Toggle between self time and total time coloring">
+                    <div class="toggle-switch" id="toggle-color-mode" title="Toggle between self time and total time coloring" tabindex="0">
                         <span class="toggle-label active" data-text="Self Time">Self Time</span>
                         <div class="toggle-track"></div>
                         <span class="toggle-label" data-text="Total Time">Total Time</span>
                     </div>
-                    <div class="toggle-switch" id="toggle-cold" title="Toggle visibility of lines with zero samples">
+                    <div class="toggle-switch" id="toggle-cold" title="Toggle visibility of lines with zero samples" tabindex="0">
                         <span class="toggle-label active" data-text="Show All">Show All</span>
                         <div class="toggle-track"></div>
                         <span class="toggle-label" data-text="Hot Only">Hot Only</span>
                     </div>
-                    <div class="toggle-switch" id="toggle-spec-view" title="Color lines by specialization level (requires bytecode data)">
+                    <div class="toggle-switch" id="toggle-spec-view" title="Color lines by specialization level (requires bytecode data)" tabindex="0">
                         <span class="toggle-label active" data-text="Heat">Heat</span>
                         <div class="toggle-track"></div>
                         <span class="toggle-label" data-text="Specialization">Specialization</span>

Lib/profiling/sampling/_shared_assets/base.css

@@ -387,6 +387,7 @@ body {
 button:focus-visible,
 select:focus-visible,
 input:focus-visible,
+.toggle-switch:focus-visible,
 a.toolbar-btn:focus-visible {
   outline: 2px solid var(--python-gold);
   outline-offset: 2px;