/// <summary>
/// Called when the SharedSizeScope for a given grid has changed.
/// Unregisters the grid from it's current scope and finds a new one (if any)
/// </summary>
/// <remarks>
/// This method, while not efficient, correctly handles nested scopes, with any order of scope changes.
/// </remarks>
internal void SharedScopeChanged()
{
_sharedSizeHost?.UnegisterGrid(this);
_sharedSizeHost = null;
var scope = this.GetVisualAncestors().OfType <Control>()
.FirstOrDefault(c => c.GetValue(IsSharedSizeScopeProperty));
if (scope != null)
{
_sharedSizeHost = scope.GetValue(s_sharedSizeScopeHostProperty);
_sharedSizeHost.RegisterGrid(this);
}
InvalidateMeasure();
}
/// <summary>
/// Callback when a grid is attached to the visual tree. Finds the innermost SharedSizeScope and registers the grid
/// in it.
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">The event arguments.</param>
private void Grid_AttachedToVisualTree(object sender, VisualTreeAttachmentEventArgs e)
{
var scope =
new Control[] { this }.Concat(this.GetVisualAncestors().OfType <Control>())
.FirstOrDefault(c => c.GetValue(IsSharedSizeScopeProperty));
if (_sharedSizeHost != null)
{
throw new AvaloniaInternalException("Shared size scope already present when attaching to visual tree!");
}
if (scope != null)
{
_sharedSizeHost = scope.GetValue(s_sharedSizeScopeHostProperty);
_sharedSizeHost.RegisterGrid(this);
}
}
/// <summary>
/// Callback when a grid is detached from the visual tree. Unregisters the grid from its SharedSizeScope if any.
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">The event arguments.</param>
private void Grid_DetachedFromVisualTree(object sender, VisualTreeAttachmentEventArgs e)
{
_sharedSizeHost?.UnegisterGrid(this);
_sharedSizeHost = null;
}
