90 susbscription dispose when undock the viewer parent container

[boexler]

Fix subscription disposal when undocking the viewer parent container

Overview

This PR addresses Issue #90 by implementing proper subscription lifecycle management for NLogViewer controls used in docking systems.

Problem

When NLogViewer controls are used in docking systems, moving controls between different parent windows causes subscription leaks and improper disposal. The root cause is that when undocking occurs, the Unloaded event is triggered, which automatically disposes the subscription, leaving the control unable to receive log events.

Solution

1. Added Manual Subscription Control Methods

• StartListen(): Starts listening for log events by subscribing to the cache target
• StopListen(): Stops listening for log events by disposing the subscription

2. Enhanced Parent Window Management

• Improved parent window reference tracking
• Added proper disposal handling when parent window closes
• Enhanced FindChildByUid method with cycle detection and improved tree traversal

3. Comprehensive Documentation

• Added detailed documentation for the new methods
• Explained the root cause and proper usage patterns
• Provided practical examples for docking scenarios
• Referenced Issue Susbscription dispose when undock the viewer parent container. #90 with context

Key Features

• Automatic Management: Control automatically calls StartListen() when loaded and StopListen() when properly disposed
• Safe to Call Multiple Times: Methods handle edge cases like design-time mode and missing parent windows
• Docking System Support: Properly handles subscription lifecycle in complex UI scenarios
• Memory Leak Prevention: Ensures subscriptions are properly disposed to prevent memory leaks

Usage Example

private void OnDockChanged(object sender, DockChangedEventArgs e)
{
    // Control is being undocked - MUST call StartListen() because 
    // the Unloaded event was triggered and disposed the subscription
    nLogViewer.StartListen();
}

Technical Details

• Subscribes to CacheTarget's observable stream with 100ms buffering for performance
• Manages parent window references for proper disposal
• Prevents duplicate subscriptions
• Handles design-time mode gracefully

Files Changed

• src/NLogViewer/NLogViewer.xaml.cs - Added StartListen/StopListen methods and enhanced disposal logic
• src/NLogViewer/Extensions/DependencyObjectExtensions.cs - Improved FindChildByUid method
• README.md - Added comprehensive documentation

Testing

• Verified proper subscription management in docking scenarios
• Confirmed no memory leaks when moving controls between windows
• Tested automatic disposal when parent window closes
• Validated safe multiple calls to StartListen/StopListen methods

Breaking Changes

None - this is a backward-compatible enhancement.

Related Issues

• Fixes Issue #90

Commits

• 79fcfbb - Add StartListen/StopListen methods to fix docking system issue
• 173dac7 - Refactor FindChildByUid method with cycle detection and improved tree traversal
• d4e1c72 - Add documentation for parent window subscription disposal
• bbd85ad - Add documentation for StartListen/StopListen methods and Issue Susbscription dispose when undock the viewer parent container. #90