GroveEngine/docs/UI_MODULE_PHASE7_COMPLETE.md

UIModule Phase 7 - Complete Documentation

Date: 2025-11-28 Status: ✅ COMPLETE

Overview

Phase 7 implements advanced UI features that make UIModule production-ready:

• Phase 7.1: UIScrollPanel - Scrollable containers with mouse wheel support
• Phase 7.2: Tooltips - Hover tooltips with smart positioning

Phase 7.1: UIScrollPanel

Features Implemented

Core Scrolling

• ✅ Vertical and horizontal scrolling (configurable)
• ✅ Automatic content size calculation
• ✅ Scroll offset clamping to valid range
• ✅ Content clipping (visibility culling)

Mouse Interaction

• ✅ Mouse wheel scrolling - Smooth scroll with wheel
• ✅ Drag-to-scroll - Click and drag content to scroll
• ✅ Scrollbar dragging - Drag the scrollbar thumb

Scrollbar Rendering

• ✅ Visual scrollbar with track and thumb
• ✅ Proportional thumb size (based on content/viewport ratio)
• ✅ Hover color support
• ✅ Configurable width, colors, and styling

Performance

• ✅ Visibility culling - Only renders visible children
• ✅ Efficient scroll offset application
• ✅ No allocations during scroll

Files Created

modules/UIModule/Widgets/
├── UIScrollPanel.h          # ScrollPanel widget header
└── UIScrollPanel.cpp        # Implementation (190 lines)

JSON Configuration

{
  "type": "scrollpanel",
  "id": "scroll_main",
  "width": 760,
  "height": 500,
  "scrollVertical": true,
  "scrollHorizontal": false,
  "showScrollbar": true,
  "dragToScroll": true,
  "style": {
    "bgColor": "0x2a2a2aFF",
    "borderColor": "0x444444FF",
    "borderWidth": 2.0,
    "scrollbarColor": "0x666666FF",
    "scrollbarWidth": 12.0
  },
  "layout": {
    "type": "vertical",
    "spacing": 5,
    "padding": 10
  },
  "children": [
    { "type": "label", "text": "Item 1" },
    { "type": "label", "text": "Item 2" },
    ...
  ]
}

Properties

Property	Type	Default	Description
scrollVertical	bool	true	Enable vertical scrolling
scrollHorizontal	bool	false	Enable horizontal scrolling
showScrollbar	bool	true	Show visual scrollbar
dragToScroll	bool	true	Enable drag-to-scroll
style.bgColor	color	0x2a2a2aFF	Background color
style.borderColor	color	0x444444FF	Border color
style.borderWidth	float	1.0	Border width
style.scrollbarColor	color	0x666666FF	Scrollbar thumb color
style.scrollbarWidth	float	8.0	Scrollbar width

Integration

UIContext - Added mouse wheel support:

float mouseWheelDelta = 0.0f;  // Wheel delta this frame

UIModule - Mouse wheel event handling:

// Subscribe to wheel events
m_io->subscribe("input:mouse:wheel");

// Process wheel events
if (msg.topic == "input:mouse:wheel") {
    m_context->mouseWheelDelta = msg.data->getDouble("delta", 0.0);
}

// Route to scrollpanel
if (m_context->mouseWheelDelta != 0.0f && hoveredWidget) {
    UIWidget* widget = hoveredWidget;
    while (widget) {
        if (widget->getType() == "scrollpanel") {
            scrollPanel->handleMouseWheel(m_context->mouseWheelDelta);
            break;
        }
        widget = widget->parent;
    }
}

SDL Input Forwarding:

if (event.type == SDL_MOUSEWHEEL) {
    auto mouseWheel = std::make_unique<JsonDataNode>("mouse_wheel");
    mouseWheel->setDouble("delta", static_cast<double>(event.wheel.y));
    uiIO->publish("input:mouse:wheel", std::move(mouseWheel));
}

Usage Example

// JSON defines a scrollpanel with 35+ items
// See assets/ui/test_scroll.json for full example

// Test demonstrates:
// 1. Mouse wheel scrolling (up/down)
// 2. Scrollbar dragging
// 3. Content drag scrolling
// 4. Mixed widget types (labels, buttons, sliders, checkboxes)

Phase 7.2: Tooltips

Features Implemented

Core Tooltip System

• ✅ Hover delay (default 500ms)
• ✅ Tooltip text from widget tooltip property
• ✅ Automatic show/hide based on hover
• ✅ Reset on widget change

Smart Positioning

• ✅ Default: cursor offset (10px right, 10px down)
• ✅ Edge avoidance: Flips to opposite side if near screen edge
• ✅ Clamps to screen bounds
• ✅ Dynamic position update with cursor

Rendering

• ✅ Semi-transparent background
• ✅ Border rendering
• ✅ Text rendering with padding
• ✅ Renders on top of all UI elements

Styling

• ✅ Configurable colors (bg, text, border)
• ✅ Configurable padding, font size
• ✅ Configurable delays and offsets

Files Created

modules/UIModule/Core/
├── UITooltip.h              # TooltipManager header
└── UITooltip.cpp            # Implementation (120 lines)

Widget Property

All widgets now support the tooltip property:

// UIWidget.h
class UIWidget {
    std::string tooltip;  // Tooltip text (empty = no tooltip)
    ...
};

JSON Configuration

{
  "type": "button",
  "id": "btn_save",
  "text": "Save",
  "tooltip": "Save your current work to disk",
  "onClick": "file:save"
}

Tooltip Configuration

class UITooltipManager {
public:
    // Timing
    float hoverDelay = 0.5f;      // Seconds before showing

    // Positioning
    float offsetX = 10.0f;        // Offset from cursor
    float offsetY = 10.0f;

    // Styling
    uint32_t bgColor = 0x2a2a2aEE;      // Semi-transparent
    uint32_t textColor = 0xFFFFFFFF;
    uint32_t borderColor = 0x666666FF;
    float borderWidth = 1.0f;
    float fontSize = 14.0f;
    float padding = 8.0f;
    float maxWidth = 300.0f;
};

Integration

UITree - Parse tooltip from JSON:

void UITree::parseCommonProperties(UIWidget* widget, const IDataNode& node) {
    widget->tooltip = node.getString("tooltip", "");
    ...
}

UIModule - Tooltip manager lifecycle:

// Initialize
m_tooltipManager = std::make_unique<UITooltipManager>();

// Update (after widget update)
if (m_tooltipManager) {
    m_tooltipManager->update(hoveredWidget, *m_context, deltaTime);
}

// Render (after all UI rendering)
if (m_tooltipManager && m_tooltipManager->isVisible()) {
    m_tooltipManager->render(*m_renderer,
        m_context->screenWidth, m_context->screenHeight);
}

Usage Example

{
  "type": "slider",
  "id": "volume",
  "tooltip": "Drag to adjust volume (0-100)",
  "min": 0.0,
  "max": 100.0,
  "value": 75.0
}

Result: Hovering over the slider for 500ms shows a tooltip with "Drag to adjust volume (0-100)".

Build & Test

Build UIModule

cd /path/to/GroveEngine
cmake -DGROVE_BUILD_UI_MODULE=ON -DGROVE_BUILD_BGFX_RENDERER=ON -B build-bgfx
cmake --build build-bgfx --target UIModule -j4

Build Tests

# Build both Phase 7 tests
cmake --build build-bgfx --target test_28_ui_scroll test_29_ui_advanced -j4

Run Tests

Test 28: ScrollPanel

cd build-bgfx/tests
./test_28_ui_scroll

Expected:

• Window with scrollpanel containing 35+ items
• Mouse wheel scrolls content up/down
• Scrollbar visible on right side
• Drag scrollbar to navigate
• Drag content to scroll
• Various widget types (labels, buttons, sliders, checkboxes)

Test 29: Tooltips

cd build-bgfx/tests
./test_29_ui_advanced

Expected:

• Multiple widgets with tooltips
• Hover over widget → wait 500ms → tooltip appears
• Tooltip follows cursor with offset
• Tooltips avoid screen edges
• Move cursor away → tooltip disappears
• Different tooltips for different widgets

Test Files

tests/visual/
├── test_28_ui_scroll.cpp        # ScrollPanel test (340 lines)
└── test_29_ui_advanced.cpp      # Tooltips test (335 lines)

assets/ui/
├── test_scroll.json             # ScrollPanel layout (35 items)
└── test_tooltips.json           # Tooltips layout (various widgets)

CMakeLists.txt Changes

# tests/CMakeLists.txt

# Test 28: UIModule ScrollPanel Test (Phase 7.1)
add_executable(test_28_ui_scroll
    visual/test_28_ui_scroll.cpp
)
target_link_libraries(test_28_ui_scroll PRIVATE
    GroveEngine::impl SDL2 pthread dl X11
)

# Test 29: UIModule Advanced Features Test (Phase 7.2)
add_executable(test_29_ui_advanced
    visual/test_29_ui_advanced.cpp
)
target_link_libraries(test_29_ui_advanced PRIVATE
    GroveEngine::impl SDL2 pthread dl X11
)

# modules/UIModule/CMakeLists.txt

add_library(UIModule SHARED
    ...
    Core/UITooltip.cpp
    ...
    Widgets/UIScrollPanel.cpp
    ...
)

Architecture Quality

Follows All UIModule Patterns ✅

• ✅ Inherits from UIWidget (ScrollPanel)
• ✅ Communication via IIO pub/sub
• ✅ JSON configuration
• ✅ Hot-reload ready
• ✅ Style system integration
• ✅ Factory registration

Code Quality ✅

• ✅ Clean separation of concerns
• ✅ Clear method names
• ✅ Documented public API
• ✅ Follows existing patterns

Performance ✅

• ✅ No allocations during scroll
• ✅ Visibility culling for scrollpanel
• ✅ Efficient tooltip updates
• ✅ Minimal overhead

Known Limitations

ScrollPanel

• ⚠️ No proper scissor clipping (uses bounding box culling)
  • Widgets partially visible at edges may still render
  • Real solution: Add scissor test to UIRenderer/BgfxRenderer
• ⚠️ Scrollbar always vertical (no horizontal scrollbar rendering yet)
• ⚠️ No kinetic scrolling (momentum)
• ⚠️ No touch/multitouch support

Tooltips

• ⚠️ Text measurement approximate (CHAR_WIDTH = 8.0f)
  • Real solution: Add measureText() to UIRenderer
• ⚠️ No multi-line tooltips
• ⚠️ No rich text formatting
• ⚠️ Fixed hover delay (not configurable per-widget)

Future Enhancements (Not Implemented)

Phase 7.3+: Optional Features

• ❌ Animations - Fade in/out, slide, scale
• ❌ Data Binding - Auto-sync widget ↔ IDataNode
• ❌ Drag & Drop - Draggable widgets with drop zones
• ❌ Hot-Reload Layouts - Runtime JSON reload
• ❌ Multi-line TextInput - Textarea widget
• ❌ Tree View - Hierarchical list widget
• ❌ Tab Container - Tabbed panels

These features were deprioritized as Phase 7.1 (ScrollPanel) and Phase 7.2 (Tooltips) are the most critical for production use.

Conclusion

Phase 7 is COMPLETE ✅

UIModule now has:

• ✅ 8+ widget types (Panel, Label, Button, Image, Slider, Checkbox, ProgressBar, TextInput, ScrollPanel)
• ✅ Flexible layout system (vertical, horizontal, stack, absolute)
• ✅ Theme/Style system with color palettes
• ✅ Complete event system (click, hover, focus, value_changed, text_submit, etc.)
• ✅ Scrollable containers with mouse wheel support
• ✅ Tooltips with smart positioning
• ✅ Hot-reload support
• ✅ Comprehensive tests (Phases 1-7 all tested)

UIModule is now production-ready! 🚀

Summary Table

Feature	Status	Files	Lines	Tests
UIScrollPanel	✅ Complete	2	190	test_28
Tooltips	✅ Complete	2	120	test_29
Mouse Wheel	✅ Complete	3	~50	Both
JSON Parsing	✅ Complete	1	~30	Both
Documentation	✅ Complete	1	This file	-

Total Phase 7: ~400 lines of code, fully tested and documented.

---

Previous Phases:

• ✅ Phase 1: Core Foundation
• ✅ Phase 2: Layout System
• ✅ Phase 3: Interaction & Events
• ✅ Phase 4: More Widgets
• ✅ Phase 5: Styling & Themes
• ✅ Phase 6: Text Input
• ✅ Phase 7: Advanced Features ← YOU ARE HERE

Next Steps: UIModule is feature-complete. Future work should focus on:

1. Performance profiling
2. Real-world usage in games/apps
3. Bug fixes from production use
4. Optional: Phase 7.3+ features if needed