internal bool CanExecute(INode node, CanvasControl hostingControl)
{
var commandParameter = CommandParameter;
if (commandParameter == UseNodeParameter)
{
commandParameter = node;
}
else if (commandParameter == UseNodeTagParameter)
{
commandParameter = node.Tag;
}
var commandTarget = CommandTarget;
if (commandTarget == UseCanvasControlTarget)
{
commandTarget = hostingControl;
}
if (CanExecuteHandler != null)
{
var args = new CanExecuteCommandEventArgs(Command, commandParameter, commandTarget);
CanExecuteHandler(commandTarget, args);
if (args.Handled)
{
return(args.CanExecute);
}
}
return(Command.CanExecute(commandParameter, commandTarget));
}
/// <summary>
/// Helper method for the <see cref="ShowContentsCommand"/> binding.
/// </summary>
private void OnCanShowContentsExecuted(object sender, CanExecuteCommandEventArgs e)
{
if (graphControl == null)
{
e.Handled = false;
return;
}
// see if we can execute the command...
IFoldingView graph = graphControl.Graph.Lookup <IFoldingView>();
if (graph != null)
{
INode node = FindNode(graph, e.Parameter);
if (node != null)
{
// yes, we found a node - notify the binding.
e.CanExecute = true;
e.Handled = true;
}
}
else
{
e.Handled = false;
}
}
private void ToggleItemSelectionCanExecute(object sender, CanExecuteCommandEventArgs e)
{
// if we have an item, the command can be executed
var modelItem = (e.Parameter as IModelItem) ?? graphControl.CurrentItem;
e.CanExecute = modelItem != null;
e.Handled = true;
}
/// <summary>
/// Helper method that determines whether the <see cref="HideChildrenCommand"/> can be executed.
/// </summary>
private void CanExecuteHideChildren(object sender, CanExecuteCommandEventArgs e)
{
var node = (e.Parameter ?? graphControl.CurrentItem) as INode;
if (node != null && !doingLayout && filteredGraphWrapper != null)
{
e.CanExecute = filteredGraphWrapper.OutDegree(node) > 0;
}
else
{
e.CanExecute = false;
}
e.Handled = true;
}
/// <summary>
/// Helper method that determines whether the <see cref="DecreaseSequenceCommand"/> can be executed.
/// </summary>
private void CanExecuteDecreaseSequence(object sender, CanExecuteCommandEventArgs e)
{
var node = e.Parameter as INode;
if (node != null)
{
var data = (SequenceConstraintsInfo)node.Tag;
e.CanExecute = data.CanDecreaseValue();
}
else
{
e.CanExecute = false;
}
e.Handled = true;
}
/// <summary>
/// Helper method that determines whether the <see cref="ToggleConstraintsStateCommand"/> can be executed.
/// </summary>
/// <remarks>
/// Always returns true.
/// </remarks>
private void CanExecuteToggleConstraintsState(object sender, CanExecuteCommandEventArgs e)
{
e.CanExecute = true;
e.Handled = true;
}
private void NextPage_CanExecute(object sender, CanExecuteCommandEventArgs e)
{
e.CanExecute = IsPageNumberValid(pageNumber + 1);
e.Handled = true;
}
private void DisableCommand(object sender, CanExecuteCommandEventArgs e)
{
e.CanExecute = false;
e.Handled = true;
}
/// <summary>
/// Helper method that determines whether the <see cref="ShowParentCommand"/> can be executed.
/// </summary>
private void CanExecuteShowAll(object sender, CanExecuteCommandEventArgs e)
{
e.CanExecute = filteredGraphWrapper != null && hiddenNodesSet.Count != 0 && !doingLayout;
e.Handled = true;
}
