/// <summary>
/// Creates the container for an item.
/// </summary>
/// <param name="item">The item.</param>
/// <param name="itemTemplate">An optional item template.</param>
/// <returns>The created container control.</returns>
protected virtual IControl CreateContainer(object item, IDataTemplate itemTemplate)
{
if (item == null)
{
return(null);
}
else if (itemTemplate != null && itemTemplate.Match(item))
{
var result = itemTemplate.Build(item);
result.DataContext = item;
return(result);
}
else
{
return(Owner.MaterializeDataTemplate(item));
}
}
public static IDataTemplate?FindDataTemplate(
this IControl control,
object data,
IDataTemplate?primary = null)
{
if (primary?.Match(data) == true)
{
return(primary);
}
var currentTemplateHost = control as ILogical;
while (currentTemplateHost != null)
{
if (currentTemplateHost is IDataTemplateHost hostCandidate && hostCandidate.IsDataTemplatesInitialized)
{
foreach (IDataTemplate dt in hostCandidate.DataTemplates)
{
if (dt.Match(data))
{
return(dt);
}
}
}
currentTemplateHost = currentTemplateHost.LogicalParent;
}
var global = AvaloniaLocator.Current.GetService <IGlobalDataTemplates>();
if (global != null && global.IsDataTemplatesInitialized)
{
foreach (IDataTemplate dt in global.DataTemplates)
{
if (dt.Match(data))
{
return(dt);
}
}
}
return(null);
}
/// <summary>
/// Find a data template that matches a piece of data.
/// </summary>
/// <param name="control">The control searching for the data template.</param>
/// <param name="data">The data.</param>
/// <param name="primary">
/// An optional primary template that can will be tried before the DataTemplates in the
/// tree are searched.
/// </param>
/// <returns>The data template or null if no matching data template was found.</returns>
public static IDataTemplate FindDataTemplate(
this IControl control,
object data,
IDataTemplate primary = null)
{
if (primary?.Match(data) == true)
{
return(primary);
}
foreach (var i in control.GetSelfAndLogicalAncestors().OfType <IDataTemplateHost>())
{
if (i.IsDataTemplatesInitialized)
{
foreach (IDataTemplate dt in i.DataTemplates)
{
if (dt.Match(data))
{
return(dt);
}
}
}
}
IGlobalDataTemplates global = AvaloniaLocator.Current.GetService <IGlobalDataTemplates>();
if (global != null)
{
if (global.IsDataTemplatesInitialized)
{
foreach (IDataTemplate dt in global.DataTemplates)
{
if (dt.Match(data))
{
return(dt);
}
}
}
}
return(null);
}
/// <summary>
/// Creates the child control.
/// </summary>
/// <returns>The child control or null.</returns>
protected virtual IControl CreateChild()
{
var content = Content;
var oldChild = Child;
var newChild = content as IControl;
if (content != null && newChild == null)
{
// We have content and it isn't a control, so first try to recycle the existing
// child control to display the new data by querying if the template that created
// the child can recycle items and that it also matches the new data.
if (oldChild != null &&
_dataTemplate != null &&
_dataTemplate.SupportsRecycling &&
_dataTemplate.Match(content))
{
newChild = oldChild;
}
else
{
// We couldn't recycle an existing control so find a data template for the data
// and use it to create a control.
_dataTemplate = this.FindDataTemplate(content, ContentTemplate) ?? FuncDataTemplate.Default;
newChild = _dataTemplate.Build(content);
// Try to give the new control its own name scope.
var controlResult = newChild as Control;
if (controlResult != null)
{
NameScope.SetNameScope(controlResult, new NameScope());
}
}
}
else
{
_dataTemplate = null;
}
return(newChild);
}
/// <summary>
/// Updates the <see cref="Child"/> control based on the control's <see cref="Content"/>.
/// </summary>
/// <remarks>
/// Usually the <see cref="Child"/> control is created automatically when
/// <see cref="ApplyTemplate"/> is called; however for this to happen, the control needs to
/// be attached to a logical tree (if the control is not attached to the logical tree, it
/// is reasonable to expect that the DataTemplates needed for the child are not yet
/// available). This method forces the <see cref="Child"/> control's creation at any point,
/// and is particularly useful in unit tests.
/// </remarks>
public void UpdateChild()
{
var content = Content;
var oldChild = Child;
var newChild = content as IControl;
if (content != null && newChild == null)
{
// We have content and it isn't a control, so first try to recycle the existing
// child control to display the new data by querying if the template that created
// the child can recycle items and that it also matches the new data.
if (oldChild != null &&
_dataTemplate != null &&
_dataTemplate.SupportsRecycling &&
_dataTemplate.Match(content))
{
newChild = oldChild;
}
else
{
// We couldn't recycle an existing control so find a data template for the data
// and use it to create a control.
_dataTemplate = this.FindDataTemplate(content, ContentTemplate) ?? FuncDataTemplate.Default;
newChild = _dataTemplate.Build(content);
// Try to give the new control its own name scope.
var controlResult = newChild as Control;
if (controlResult != null)
{
NameScope.SetNameScope(controlResult, new NameScope());
}
}
}
else
{
_dataTemplate = null;
}
// Remove the old child if we're not recycling it.
if (oldChild != null && newChild != oldChild)
{
VisualChildren.Remove(oldChild);
}
// Set the DataContext if the data isn't a control.
if (!(content is IControl))
{
DataContext = content;
}
// Update the Child.
if (newChild == null)
{
Child = null;
}
else if (newChild != oldChild)
{
((ISetInheritanceParent)newChild).SetParent(this);
Child = newChild;
if (oldChild?.Parent == this)
{
LogicalChildren.Remove(oldChild);
}
if (newChild.Parent == null)
{
var templatedLogicalParent = TemplatedParent as ILogical;
if (templatedLogicalParent != null)
{
((ISetLogicalParent)newChild).SetParent(templatedLogicalParent);
}
else
{
LogicalChildren.Add(newChild);
}
}
VisualChildren.Add(newChild);
}
_createdChild = true;
}
/// <summary>
/// Creates the container for an item.
/// </summary>
/// <param name="item">The item.</param>
/// <param name="itemTemplate">An optional item template.</param>
/// <returns>The created container control.</returns>
protected virtual IControl CreateContainer(object item, IDataTemplate itemTemplate)
{
if (item == null)
{
return null;
}
else if (itemTemplate != null && itemTemplate.Match(item))
{
var result = itemTemplate.Build(item);
result.DataContext = item;
return result;
}
else
{
return Owner.MaterializeDataTemplate(item);
}
}