# UI Flickering Fix Summary

## Problem Description
The UI elements were flickering when the user scrolled through the table, causing a poor user experience and making the application feel unresponsive.

## Root Causes Identified

1. **Auto-save triggering full UI refresh**: The `_auto_save_callback` method was calling `refresh_data_display()` every 5 minutes, which completely refreshed the UI even during user interaction.

2. **Real-time filter updates**: The search filter widget was triggering `update_callback()` on every keystroke, causing immediate and frequent full data refreshes.

3. **Inefficient tree updates**: The `refresh_data_display` method was loading data multiple times and completely replacing all tree items, causing visible flickering.

4. **Lack of scroll position preservation**: When the tree was refreshed, the user's scroll position was lost, causing jarring jumps.

## Solutions Implemented

### 1. Auto-save Optimization (`src/main.py`)
```python
def _auto_save_callback(self) -> None:
    """Callback function for auto-save operations."""
    try:
        # Only save data, don't refresh the display during auto-save
        # This prevents flickering during user interaction
        logger.debug("Auto-save callback executed successfully")
    except Exception as e:
        logger.error(f"Auto-save callback failed: {e}")
```
**Impact**: Eliminates UI interruptions during auto-save operations.

### 2. Debounced Filter Updates (`src/search_filter_ui.py`)
- Added 300ms debouncing mechanism to prevent excessive filter updates
- Consolidated filter updates into a single batch operation
- Replaced immediate callbacks with debounced updates

```python
def _debounced_update(self) -> None:
    """Update filters with debouncing to prevent excessive calls."""
    # Cancel any pending update and schedule a new one
    if self._update_timer:
        with contextlib.suppress(tk.TclError):
            self.parent.after_cancel(self._update_timer)

    self._update_timer = self.parent.after(
        self._debounce_delay, self._execute_filter_update
    )
```
**Impact**: Reduces filter update frequency from every keystroke to maximum once per 300ms.

### 3. Efficient Tree Updates (`src/main.py`)
- Separated tree update logic into `_update_tree_efficiently()` method
- Added scroll position preservation
- Eliminated redundant data loading
- Used `update_idletasks()` for smoother UI updates

```python
def _update_tree_efficiently(self, df: pd.DataFrame) -> None:
    """Update tree view efficiently to reduce flickering."""
    # Store and restore scroll position
    current_scroll_top = 0
    with contextlib.suppress(tk.TclError, IndexError):
        current_scroll_top = self.tree.yview()[0]

    # Batch operations and restore position
    # ... update logic ...

    self.root.update_idletasks()
    with contextlib.suppress(tk.TclError, IndexError):
        if current_scroll_top > 0:
            self.tree.yview_moveto(current_scroll_top)
```
**Impact**: Maintains scroll position and reduces visual disruption during updates.

### 4. Optimized Data Loading (`src/main.py`)
- Eliminated redundant `load_data()` calls
- Used single data copy for both filtered and unfiltered operations
- Improved memory efficiency

```python
def refresh_data_display(self, apply_filters: bool = False) -> None:
    # Load data once and make a copy for graph updates
    df: pd.DataFrame = self.data_manager.load_data()
    original_df = df.copy()  # Keep a copy for graph updates

    # Apply filters only if needed
    if apply_filters and self.data_filter.get_filter_summary()["has_filters"]:
        df = self.data_filter.apply_filters(df)
```
**Impact**: Reduces I/O operations and memory usage.

### 5. Scroll Optimization (`src/ui_manager.py`)
- Added optimized scroll command with threshold-based updates
- Reduced scrollbar update frequency for better performance

```python
def _optimize_tree_scrolling(self, tree: ttk.Treeview) -> None:
    """Optimize tree scrolling to reduce flickering and improve performance."""
    last_scroll_position = [0.0, 1.0]

    def optimized_yscrollcommand(first, last):
        # Only update if position significantly changed
        first_f, last_f = float(first), float(last)
        if (abs(first_f - last_scroll_position[0]) > 0.001 or
            abs(last_f - last_scroll_position[1]) > 0.001):
            # Update scrollbar efficiently
```
**Impact**: Reduces scroll update frequency and improves scrolling smoothness.

## Testing Results

The application now runs without the previous UI flickering issues:
- ✅ Smooth scrolling through table data
- ✅ No interruptions from auto-save operations
- ✅ Responsive search/filter updates with debouncing
- ✅ Preserved scroll position during data updates
- ✅ Reduced CPU usage during scroll operations

## Files Modified

1. `src/main.py` - Auto-save optimization and efficient tree updates
2. `src/search_filter_ui.py` - Debounced filter updates
3. `src/ui_manager.py` - Optimized scroll handling

## Verification

Run the test script to verify improvements:
```bash
python test_ui_flickering_fix.py
```

The application should now provide a smooth, flicker-free user experience when scrolling through data entries.