feat(layouts): add resizable side panels with localStorage persistence

assets/js/resizable-panels.js

@@ -0,0 +1,259 @@
+/**
+ * Resizable Panels Feature
+ * Allows users to adjust the width of side panels (left sidebar and right TOC)
+ * Preferences are saved to localStorage and restored on page load
+ * Includes reset functionality to restore default widths
+ */
+
+(function() {
+  'use strict';
+
+  const STORAGE_KEY = 'layer5-docs-panel-widths';
+  const DEFAULT_WIDTHS = {
+    sidebar: 2,      // col-xl-2 = ~16.66%
+    toc: 2,          // col-xl-2 = ~16.66%
+    main: 8          // col-xl-8 = ~66.66%
+  };
+
+  // CSS class shortcuts for Bootstrap grid columns
+  const COL_CLASSES = {
+    'col-1': 8.33,
+    'col-2': 16.66,
+    'col-3': 25,
+    'col-4': 33.33,
+    'col-5': 41.66,
+    'col-6': 50,
+    'col-7': 58.33,
+    'col-8': 66.66,
+    'col-9': 75,
+    'col-10': 83.33,
+    'col-11': 91.66,
+    'col-12': 100
+  };
+
+  class ResizablePanels {
+    constructor() {
+      this.sidebar = document.querySelector('.td-sidebar');
+      this.toc = document.querySelector('.td-sidebar-toc');
+      this.main = document.querySelector('main[role="main"]');
+      this.row = document.querySelector('.row.flex-xl-nowrap');
+
+      if (!this.row || !this.sidebar || !this.main) {
+        console.warn('Resizable panels: Required elements not found');
+        return;
+      }
+
+      this.isResizing = false;
+      this.currentResizeTarget = null;
+      this.startX = 0;
+      this.startWidth = 0;
+
+      this.init();
+    }
+
+    init() {
+      // Load saved widths from localStorage
+      this.loadSavedWidths();
+
+      // Create resize handles
+      this.createResizeHandles();
+
+      // Add event listeners
+      this.addEventListeners();
+
+      // Add reset button
+      this.addResetButton();
+    }
+
+    loadSavedWidths() {
+      try {
+        const saved = localStorage.getItem(STORAGE_KEY);
+        if (saved) {
+          const widths = JSON.parse(saved);
+          this.applyWidths(widths);
+        }
+      } catch (error) {
+        console.error('Error loading saved panel widths:', error);
+      }
+    }
+
+    createResizeHandles() {
+      // Create resize handle between sidebar and main content
+      const sidebarHandle = document.createElement('div');
+      sidebarHandle.className = 'resizable-panel-handle resizable-panel-handle--right';
+      sidebarHandle.setAttribute('data-resize-target', 'sidebar');
+      sidebarHandle.setAttribute('title', 'Drag to resize sidebar');
+      this.sidebar.appendChild(sidebarHandle);
+
+      // Create resize handle for TOC (if it exists)
+      if (this.toc) {
+        const tocHandle = document.createElement('div');
+        tocHandle.className = 'resizable-panel-handle resizable-panel-handle--left';
+        tocHandle.setAttribute('data-resize-target', 'toc');
+        tocHandle.setAttribute('title', 'Drag to resize table of contents');
+        this.toc.appendChild(tocHandle);
+      }
+    }
+
+    addEventListeners() {
+      document.addEventListener('mousedown', (e) => this.onMouseDown(e));
+      document.addEventListener('mousemove', (e) => this.onMouseMove(e));
+      document.addEventListener('mouseup', (e) => this.onMouseUp(e));
+    }
+
+    onMouseDown(e) {
+      if (!e.target.classList.contains('resizable-panel-handle')) {
+        return;
+      }
+
+      this.isResizing = true;
+      this.currentResizeTarget = e.target.getAttribute('data-resize-target');
+      this.startX = e.clientX;
+
+      // Store current widths for delta calculation
+      this.startWidths = this.getCurrentWidths();
+
+      // Add active state
+      e.target.classList.add('resizable-panel-handle--active');
+      document.body.style.userSelect = 'none';
+      document.body.style.cursor = 'col-resize';
+    }
+
+    onMouseMove(e) {
+      if (!this.isResizing) return;
+
+      const delta = e.clientX - this.startX;
+      const adjustment = delta / window.innerWidth; // Convert pixels to percentage-like ratio
+
+      let newWidths = { ...this.startWidths };
+
+      if (this.currentResizeTarget === 'sidebar') {
+        // Resizing left sidebar
+        const sidebarPercent = (this.startWidths.sidebar * 100) / 12; // Convert col units to percentage
+        const mainPercent = (this.startWidths.main * 100) / 12;
+
+        const newSidebarPercent = sidebarPercent + (adjustment * 100);
+        const newMainPercent = mainPercent - (adjustment * 100);
+
+        // Constrain widths: min 1 col, max 5 cols for sidebar; min 4 cols for main
+        if (newSidebarPercent >= 8.33 && newSidebarPercent <= 41.66 && newMainPercent >= 33.33) {
+          newWidths.sidebar = Math.round((newSidebarPercent / 100) * 12);
+          newWidths.main = Math.round((newMainPercent / 100) * 12);
+        }
+      } else if (this.currentResizeTarget === 'toc') {
+        // Resizing right TOC panel
+        const tocPercent = (this.startWidths.toc * 100) / 12;
+        const mainPercent = (this.startWidths.main * 100) / 12;
+
+        const newTocPercent = tocPercent - (adjustment * 100);
+        const newMainPercent = mainPercent + (adjustment * 100);
+
+        // Constrain widths: min 1 col, max 5 cols for toc; min 4 cols for main
+        if (newTocPercent >= 8.33 && newTocPercent <= 41.66 && newMainPercent >= 33.33) {
+          newWidths.toc = Math.round((newTocPercent / 100) * 12);
+          newWidths.main = Math.round((newMainPercent / 100) * 12);
+        }
+      }
+
+      this.applyWidths(newWidths);
+    }
+
+    onMouseUp(e) {
+      if (!this.isResizing) return;
+
+      this.isResizing = false;
+      const handle = document.querySelector('.resizable-panel-handle--active');
+      if (handle) {
+        handle.classList.remove('resizable-panel-handle--active');
+      }
+
+      document.body.style.userSelect = '';
+      document.body.style.cursor = '';
+
+      // Save widths to localStorage
+      this.savePanelWidths();
+    }
+
+    applyWidths(widths) {
+      const { sidebar, toc, main } = widths;
+
+      // Update sidebar
+      this.removeBootstrapColClasses(this.sidebar);
+      this.sidebar.classList.add(`col-xl-${sidebar}`);
+
+      // Update main
+      this.removeBootstrapColClasses(this.main);
+      this.main.classList.add(`col-xl-${main}`);
+
+      // Update TOC if it exists
+      if (this.toc) {
+        this.removeBootstrapColClasses(this.toc);
+        this.toc.classList.add(`col-xl-${toc}`);
+      }
+    }
+
+    getCurrentWidths() {
+      const getColNumber = (element) => {
+        const classes = element.className.split(' ');
+        const colClass = classes.find(c => c.match(/col-xl-\d+/));
+        return colClass ? parseInt(colClass.split('-')[2]) : null;
+      };
+
+      return {
+        sidebar: getColNumber(this.sidebar) || DEFAULT_WIDTHS.sidebar,
+        toc: this.toc ? (getColNumber(this.toc) || DEFAULT_WIDTHS.toc) : DEFAULT_WIDTHS.toc,
+        main: getColNumber(this.main) || DEFAULT_WIDTHS.main
+      };
+    }
+
+    removeBootstrapColClasses(element) {
+      const classes = element.className.split(' ').filter(c => !c.match(/col-xl-\d+/));
+      element.className = classes.join(' ').trim();
+    }
+
+    savePanelWidths() {
+      try {
+        const widths = this.getCurrentWidths();
+        localStorage.setItem(STORAGE_KEY, JSON.stringify(widths));
+      } catch (error) {
+        console.error('Error saving panel widths:', error);
+      }
+    }
+
+    addResetButton() {
+      // Find the feature-info-container or page-header to add reset button
+      const pageHeader = document.querySelector('.page-header');
+      if (!pageHeader) return;
+
+      const resetButton = document.createElement('button');
+      resetButton.id = 'reset-panel-widths';
+      resetButton.className = 'btn btn-sm btn-outline-secondary ms-2';
+      resetButton.innerHTML = '<i class="bi bi-arrow-clockwise"></i> Reset Layout';
+      resetButton.setAttribute('title', 'Reset panel widths to default');
+
+      resetButton.addEventListener('click', () => this.resetPanelWidths());
+
+      // Find a good place to insert the button
+      const featureContainer = pageHeader.querySelector('.feature-info-container');
+      if (featureContainer) {
+        featureContainer.insertAdjacentElement('beforeend', resetButton);
+      } else {
+        pageHeader.insertAdjacentElement('beforeend', resetButton);
+      }
+    }
+
+    resetPanelWidths() {
+      this.applyWidths(DEFAULT_WIDTHS);
+      this.savePanelWidths();
+    }
+  }
+
+  // Initialize when DOM is ready
+  if (document.readyState === 'loading') {
+    document.addEventListener('DOMContentLoaded', () => {
+      new ResizablePanels();
+    });
+  } else {
+    new ResizablePanels();
+  }
+})();