Implement Phase 2: Complete resizable panels with enhanced toggle functionality and memory persistence

docs/dev-plan.md

@@ -72,17 +72,33 @@ Astrolabe is a focused tool for managing, editing, and previewing Vega-Lite visu
 
 ---
 
-### **Phase 2: Resizable Panels**
+### **Phase 2: Resizable Panels** ✅ **COMPLETE**
 **Goal**: Make panels draggable to resize
 
-- [ ] Add resize handles/dividers between panels
-- [ ] Implement vanilla JS drag handlers for horizontal resizing
-- [ ] Store panel widths in localStorage (restore on load)
-- [ ] Implement toggle button logic to show/hide each panel
-- [ ] Handle edge cases (minimum widths, hiding panels)
+- [x] Add resize handles/dividers between panels
+- [x] Implement vanilla JS drag handlers for horizontal resizing
+- [x] Store panel widths in localStorage (restore on load)
+- [x] Implement toggle button logic to show/hide each panel
+- [x] Handle edge cases (minimum widths, hiding panels)
 
 **Deliverable**: Fully interactive layout with resizable and toggleable panels
 
+**Key Achievements**:
+- Added 4px retro-styled resize handles between panels with hover/drag feedback
+- Implemented smooth mouse-based dragging with real-time width updates
+- Added 200px minimum width constraints to prevent unusable panels
+- Created intelligent toggle system with proportional space redistribution
+- Implemented panel memory system that preserves preferred sizes across hide/show cycles
+- Added comprehensive localStorage persistence for panel sizes, visibility, and memory
+- Fixed CSS flex properties to allow dynamic width changes (flex: 0 1 auto)
+- Enhanced toggle buttons with proper state management and visual feedback
+
+**Advanced Features**:
+- **Smart Memory**: Panels remember their preferred sizes even when hidden
+- **Proportional Expansion**: Remaining visible panels expand proportionally when others are hidden
+- **Stable Proportions**: Toggle hide/show cycles maintain original size relationships
+- **Manual Resize Memory**: Dragging resize handles updates the memory for future toggle operations
+
 ---
 
 ### **Phase 3: Monaco Editor Integration** ✅ **COMPLETE**
@@ -285,4 +301,6 @@ Astrolabe is a focused tool for managing, editing, and previewing Vega-Lite visu
 ---
 
 **Current Phase**: Phase 5 - Data Model + LocalStorage
-**Status**: Ready to begin implementation
+**Status**: Ready to begin implementation
+
+**Note**: Phase 2 (Resizable Panels) was completed after Phase 4 to fill the gap

index.html

@@ -67,6 +67,9 @@
                 </div>
             </div>
 
+            <!-- Resize Handle 1 -->
+            <div class="resize-handle" id="resize-handle-1"></div>
+
             <!-- Editor Panel -->
             <div class="panel editor-panel" id="editor-panel">
                 <div class="panel-header">
@@ -77,6 +80,9 @@
                 </div>
             </div>
 
+            <!-- Resize Handle 2 -->
+            <div class="resize-handle" id="resize-handle-2"></div>
+
             <!-- Preview Panel -->
             <div class="panel preview-panel" id="preview-panel">
                 <div class="panel-header">
@@ -93,6 +99,19 @@
         let editor; // Global editor instance
         let renderTimeout; // For debouncing
 
+        // Panel resizing variables
+        let isResizing = false;
+        let currentHandle = null;
+        let startX = 0;
+        let startWidths = [];
+
+        // Panel memory for toggle functionality
+        let panelMemory = {
+            snippetWidth: '25%',
+            editorWidth: '50%',
+            previewWidth: '25%'
+        };
+
         // Sample Vega-Lite specification
         const sampleSpec = {
             "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
@@ -116,6 +135,262 @@
             }
         };
 
+        // Panel toggle and expansion functions
+        function updatePanelMemory() {
+            const snippetPanel = document.getElementById('snippet-panel');
+            const editorPanel = document.getElementById('editor-panel');
+            const previewPanel = document.getElementById('preview-panel');
+
+            // Only update memory for visible panels
+            if (snippetPanel.style.display !== 'none') {
+                panelMemory.snippetWidth = snippetPanel.style.width || '25%';
+            }
+            if (editorPanel.style.display !== 'none') {
+                panelMemory.editorWidth = editorPanel.style.width || '50%';
+            }
+            if (previewPanel.style.display !== 'none') {
+                panelMemory.previewWidth = previewPanel.style.width || '25%';
+            }
+        }
+
+        function redistributePanelWidths() {
+            console.log('🔄 Redistributing panel widths...');
+
+            const snippetPanel = document.getElementById('snippet-panel');
+            const editorPanel = document.getElementById('editor-panel');
+            const previewPanel = document.getElementById('preview-panel');
+
+            const panels = [
+                { element: snippetPanel, id: 'snippet', memoryKey: 'snippetWidth' },
+                { element: editorPanel, id: 'editor', memoryKey: 'editorWidth' },
+                { element: previewPanel, id: 'preview', memoryKey: 'previewWidth' }
+            ];
+
+            const visiblePanels = panels.filter(panel => panel.element.style.display !== 'none');
+            console.log('👁️ Visible panels:', visiblePanels.map(p => p.id));
+
+            if (visiblePanels.length === 0) return;
+
+            // Get total desired width from memory
+            let totalMemoryWidth = 0;
+            console.log('📊 Memory widths:');
+            visiblePanels.forEach(panel => {
+                const width = parseFloat(panelMemory[panel.memoryKey]);
+                console.log(`  ${panel.id}: ${panelMemory[panel.memoryKey]} → ${width}`);
+                totalMemoryWidth += width;
+            });
+            console.log('📊 Total memory width:', totalMemoryWidth);
+
+            // Redistribute proportionally to fill 100%
+            console.log('🧮 Calculating new widths:');
+            visiblePanels.forEach(panel => {
+                const memoryWidth = parseFloat(panelMemory[panel.memoryKey]);
+                const newWidth = (memoryWidth / totalMemoryWidth) * 100;
+                console.log(`  ${panel.id}: ${memoryWidth}/${totalMemoryWidth} * 100 = ${newWidth}%`);
+                panel.element.style.width = `${newWidth}%`;
+            });
+        }
+
+        function togglePanel(panelId) {
+            console.log('🔘 Toggle clicked for:', panelId);
+
+            // Fix ID mapping - buttons use plural, panels use singular
+            const panelIdMap = {
+                'snippets': 'snippet-panel',
+                'editor': 'editor-panel',
+                'preview': 'preview-panel'
+            };
+
+            const actualPanelId = panelIdMap[panelId];
+            const panel = document.getElementById(actualPanelId);
+            const button = document.getElementById('toggle-' + panelId);
+
+            console.log('🔍 Looking for panel:', actualPanelId, 'Found:', !!panel);
+            console.log('🔍 Looking for button:', 'toggle-' + panelId, 'Found:', !!button);
+
+            if (!panel || !button) {
+                console.error('❌ Panel or button not found!');
+                return;
+            }
+
+            console.log('📏 BEFORE toggle - Panel widths:');
+            logCurrentWidths();
+
+            if (panel.style.display === 'none') {
+                console.log('👁️ SHOWING panel:', panelId);
+                // Show panel
+                panel.style.display = 'flex';
+                button.classList.add('active');
+
+                // Restore from memory and redistribute
+                redistributePanelWidths();
+            } else {
+                console.log('🙈 HIDING panel:', panelId);
+                // Hide panel - DON'T update memory, just hide
+                panel.style.display = 'none';
+                button.classList.remove('active');
+
+                // Redistribute remaining panels
+                redistributePanelWidths();
+            }
+
+            console.log('📏 AFTER toggle - Panel widths:');
+            logCurrentWidths();
+            console.log('💾 Panel memory:', panelMemory);
+
+            saveLayoutToStorage();
+        }
+
+        function logCurrentWidths() {
+            const snippetPanel = document.getElementById('snippet-panel');
+            const editorPanel = document.getElementById('editor-panel');
+            const previewPanel = document.getElementById('preview-panel');
+
+            console.log('  Snippets:', {
+                width: snippetPanel.style.width || 'default',
+                display: snippetPanel.style.display || 'default',
+                visible: snippetPanel.style.display !== 'none'
+            });
+            console.log('  Editor:', {
+                width: editorPanel.style.width || 'default',
+                display: editorPanel.style.display || 'default',
+                visible: editorPanel.style.display !== 'none'
+            });
+            console.log('  Preview:', {
+                width: previewPanel.style.width || 'default',
+                display: previewPanel.style.display || 'default',
+                visible: previewPanel.style.display !== 'none'
+            });
+        }
+
+        // Panel resizing functions
+        function saveLayoutToStorage() {
+            const snippetPanel = document.getElementById('snippet-panel');
+            const editorPanel = document.getElementById('editor-panel');
+            const previewPanel = document.getElementById('preview-panel');
+
+            // DON'T update memory here - it's already updated during manual resize
+
+            const layout = {
+                snippetWidth: snippetPanel.style.width || '25%',
+                editorWidth: editorPanel.style.width || '50%',
+                previewWidth: previewPanel.style.width || '25%',
+                snippetVisible: snippetPanel.style.display !== 'none',
+                editorVisible: editorPanel.style.display !== 'none',
+                previewVisible: previewPanel.style.display !== 'none',
+                memory: panelMemory
+            };
+
+            localStorage.setItem('astrolabe-layout', JSON.stringify(layout));
+        }
+
+        function loadLayoutFromStorage() {
+            try {
+                const saved = localStorage.getItem('astrolabe-layout');
+                if (saved) {
+                    const layout = JSON.parse(saved);
+
+                    // Restore memory if available
+                    if (layout.memory) {
+                        panelMemory = layout.memory;
+                    }
+
+                    // Restore panel visibility
+                    const snippetPanel = document.getElementById('snippet-panel');
+                    const editorPanel = document.getElementById('editor-panel');
+                    const previewPanel = document.getElementById('preview-panel');
+
+                    snippetPanel.style.display = layout.snippetVisible !== false ? 'flex' : 'none';
+                    editorPanel.style.display = layout.editorVisible !== false ? 'flex' : 'none';
+                    previewPanel.style.display = layout.previewVisible !== false ? 'flex' : 'none';
+
+                    // Update toggle button states
+                    document.getElementById('toggle-snippets').classList.toggle('active', layout.snippetVisible !== false);
+                    document.getElementById('toggle-editor').classList.toggle('active', layout.editorVisible !== false);
+                    document.getElementById('toggle-preview').classList.toggle('active', layout.previewVisible !== false);
+
+                    // Restore widths and redistribute
+                    snippetPanel.style.width = layout.snippetWidth;
+                    editorPanel.style.width = layout.editorWidth;
+                    previewPanel.style.width = layout.previewWidth;
+
+                    redistributePanelWidths();
+                }
+            } catch (error) {
+                // Ignore errors, use default layout
+            }
+        }
+
+        function initializeResize() {
+            const handles = document.querySelectorAll('.resize-handle');
+            const panels = [
+                document.getElementById('snippet-panel'),
+                document.getElementById('editor-panel'),
+                document.getElementById('preview-panel')
+            ];
+
+            handles.forEach((handle, index) => {
+                handle.addEventListener('mousedown', (e) => {
+                    isResizing = true;
+                    currentHandle = index;
+                    startX = e.clientX;
+                    startWidths = panels.map(panel => panel.getBoundingClientRect().width);
+
+                    handle.classList.add('dragging');
+                    document.body.style.cursor = 'col-resize';
+                    document.body.style.userSelect = 'none';
+
+                    e.preventDefault();
+                });
+            });
+
+            document.addEventListener('mousemove', (e) => {
+                if (!isResizing) return;
+
+                const deltaX = e.clientX - startX;
+                const containerWidth = document.querySelector('.main-panels').getBoundingClientRect().width;
+
+                if (currentHandle === 0) {
+                    // Resizing between snippet and editor panels
+                    const minWidth = 200;
+                    const newSnippetWidth = Math.max(minWidth, startWidths[0] + deltaX);
+                    const newEditorWidth = Math.max(minWidth, startWidths[1] - deltaX);
+
+                    if (newSnippetWidth >= minWidth && newEditorWidth >= minWidth) {
+                        panels[0].style.width = `${(newSnippetWidth / containerWidth) * 100}%`;
+                        panels[1].style.width = `${(newEditorWidth / containerWidth) * 100}%`;
+                    }
+                } else if (currentHandle === 1) {
+                    // Resizing between editor and preview panels
+                    const minWidth = 200;
+                    const newEditorWidth = Math.max(minWidth, startWidths[1] + deltaX);
+                    const newPreviewWidth = Math.max(minWidth, startWidths[2] - deltaX);
+
+                    if (newEditorWidth >= minWidth && newPreviewWidth >= minWidth) {
+                        panels[1].style.width = `${(newEditorWidth / containerWidth) * 100}%`;
+                        panels[2].style.width = `${(newPreviewWidth / containerWidth) * 100}%`;
+                    }
+                }
+            });
+
+            document.addEventListener('mouseup', () => {
+                if (isResizing) {
+                    isResizing = false;
+                    currentHandle = null;
+
+                    document.querySelectorAll('.resize-handle').forEach(h => h.classList.remove('dragging'));
+                    document.body.style.cursor = '';
+                    document.body.style.userSelect = '';
+
+                    // Update memory ONLY after manual resize
+                    updatePanelMemory();
+                    console.log('🎯 Manual resize completed - Updated memory:', panelMemory);
+
+                    saveLayoutToStorage();
+                }
+            });
+        }
+
         // Render function that takes spec from editor
         async function renderVisualization() {
             const previewContainer = document.getElementById('vega-preview');
@@ -185,6 +460,12 @@
         }
 
         document.addEventListener('DOMContentLoaded', function () {
+            // Load saved layout
+            loadLayoutFromStorage();
+
+            // Initialize resize functionality
+            initializeResize();
+
             // Initialize Monaco Editor
             require.config({ paths: { vs: 'https://cdnjs.cloudflare.com/ajax/libs/monaco-editor/0.47.0/min/vs' } });
             require(['vs/editor/editor.main'], async function () {
@@ -235,26 +516,12 @@
                 renderVisualization();
             });
 
-            // Basic toggle functionality
+            // Enhanced toggle functionality with memory and expansion
             const toggleButtons = document.querySelectorAll('.toggle-btn');
-            const panels = {
-                'toggle-snippets': document.getElementById('snippet-panel'),
-                'toggle-editor': document.getElementById('editor-panel'),
-                'toggle-preview': document.getElementById('preview-panel')
-            };
-
             toggleButtons.forEach(button => {
                 button.addEventListener('click', function () {
-                    const panelId = this.id;
-                    const panel = panels[panelId];
-
-                    if (panel.style.display === 'none') {
-                        panel.style.display = 'flex';
-                        this.classList.add('active');
-                    } else {
-                        panel.style.display = 'none';
-                        this.classList.remove('active');
-                    }
+                    const panelId = this.id.replace('toggle-', ''); // Remove 'toggle-' prefix
+                    togglePanel(panelId);
                 });
             });
 

src/styles.css

@@ -89,6 +89,24 @@ body {
     border-right: none;
 }
 
+.resize-handle {
+    width: 4px;
+    background: #808080;
+    cursor: col-resize;
+    flex-shrink: 0;
+    position: relative;
+    border-left: 1px solid #a0a0a0;
+    border-right: 1px solid #606060;
+}
+
+.resize-handle:hover {
+    background: #606060;
+}
+
+.resize-handle.dragging {
+    background: #316ac5;
+}
+
 .panel-header {
     padding: 8px 12px;
     background: #c0c0c0;
@@ -108,15 +126,18 @@ body {
 
 /* Panel sizing */
 .snippet-panel {
-    flex: 0 0 20%;
+    width: 25%;
+    flex: 0 1 auto;
 }
 
 .editor-panel {
-    flex: 0 0 30%;
+    width: 50%;
+    flex: 0 1 auto;
 }
 
 .preview-panel {
-    flex: 0 0 50%;
+    width: 25%;
+    flex: 0 1 auto;
 }
 
 /* Toggle buttons */