private static object CoerceSelectedValue(DependencyObject d, object baseValue)
{
NativeComboBox cb = (NativeComboBox)d;
if (cb._selectionChangeIsOnIndex || cb._selectionChangeIsOnItem)
{
// If we're in the middle of a selection change (SelectedIndex
// or SelectedItem), accept the value.
return(baseValue);
}
else
{
// Otherwise, this is a user-initiated change to SelectedValue.
// Find the corresponding item.
int index;
object item = cb.FindItemWithValue(baseValue, out index);
// if the search fails, coerce the value to null. Unless there
// are no items at all, in which case wait for the items to appear
// and search again.
if (item == DependencyProperty.UnsetValue && cb.Items.Count > 0)
{
baseValue = null;
}
// Store the new selected item so we don't have to look for it again
// in OnSelectedValueChanged.
cb._selectionInfo = new SelectionInfo(item == DependencyProperty.UnsetValue ? null : item, index);
}
return(baseValue);
}
private static void OnDisplayMemberPathChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
NativeComboBox cb = (NativeComboBox)d;
// Refresh the combobox
cb.Refresh();
}
private static void OnSelectedValueChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
NativeComboBox cb = (NativeComboBox)d;
// we only want to change the other ones if the change comes from
// SelectedItem (otherwise it's already done by the one that was
// originally changed (SelectedIndex or SelectedValue)
if (!cb._selectionChangeIsOnItem && !cb._selectionChangeIsOnIndex)
{
cb._selectionChangeIsOnValue = true;
try
{
cb.SetCurrentValue(NativeComboBox.SelectedIndexProperty, cb._selectionInfo.Index);
// Note: always update the value of SelectedItem last when
// synchronizing selection properties, so that all the properties
// are up to date when the selection changed event is fired.
cb.SetCurrentValue(NativeComboBox.SelectedItemProperty, cb._selectionInfo.Item);
}
finally
{
cb._selectionChangeIsOnValue = false;
cb._selectionInfo = null;
}
}
}
private static void OnItemsSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
NativeComboBox cb = (NativeComboBox)d;
IEnumerable newValue = (IEnumerable)e.NewValue;
if (e.NewValue != null)
{
// ItemsSource is non-null. Go to ItemsSource mode
cb.Items.SetItemsSource(newValue);
}
else
{
// ItemsSource is explicitly null. Return to normal mode.
cb.Items.ClearItemsSource();
}
cb.SetCurrentValue(NativeComboBox.SelectedIndexProperty, -1);
}
private static object CoerceSelectedItem(DependencyObject d, object baseValue)
{
NativeComboBox cb = (NativeComboBox)d;
if (baseValue == null || cb.SkipCoerceSelectedItemCheck)
{
return(baseValue);
}
int selectedIndex = cb.SelectedIndex;
if ((selectedIndex > -1 && selectedIndex < cb.Items.Count && cb.Items[selectedIndex] == baseValue) ||
cb.Items.Contains(baseValue))
{
return(baseValue);
}
return(DependencyProperty.UnsetValue); // reset baseValue to old value.
}
private static object CoerceSelectedIndex(DependencyObject d, object baseValue)
{
NativeComboBox cb = (NativeComboBox)d;
int index = (int)baseValue;
if (index < 0)
{
return(-1);
}
else if (index >= cb.Items.Count)
{
return(cb.Items.Count - 1);
}
else
{
return(index);
}
}
private static void OnSelectedValuePathChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
NativeComboBox cb = (NativeComboBox)d;
cb._selectionChangeIsOnItem = true;
cb._selectionChangeIsOnIndex = true;
try
{
object item = null;
if (cb.SelectedItem != null)
{
item = PropertyPathHelper.AccessValueByApplyingPropertyPathIfAny(cb.SelectedItem, (string)e.NewValue);
}
cb.SetCurrentValue(NativeComboBox.SelectedValueProperty, item);
}
finally
{
cb._selectionChangeIsOnItem = false;
cb._selectionChangeIsOnIndex = false;
}
}
private static void OnSelectedItemChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
NativeComboBox cb = (NativeComboBox)d;
object newValue = e.NewValue;
// we only want to change the other ones if the change comes from
// SelectedItem (otherwise it's already done by the one that was
// originally changed (SelectedIndex or SelectedValue)
if (!cb._selectionChangeIsOnValue && !cb._selectionChangeIsOnIndex)
{
cb._selectionChangeIsOnItem = true;
try
{
if (newValue == null)
{
// we use SetCurrentValue to preserve any potential bindings.
cb.SetCurrentValue(NativeComboBox.SelectedValueProperty, null);
cb.SetCurrentValue(NativeComboBox.SelectedIndexProperty, -1);
}
else
{
// we use SetCurrentValue to preserve any potential bindings.
cb.SetCurrentValue(NativeComboBox.SelectedValueProperty, PropertyPathHelper.AccessValueByApplyingPropertyPathIfAny(newValue, cb.SelectedValuePath));
cb.SetCurrentValue(NativeComboBox.SelectedIndexProperty, cb.Items.IndexOf(newValue));
}
}
finally
{
cb._selectionChangeIsOnItem = false;
}
}
// Raise the selection changed event
cb.OnSelectionChanged(e.OldValue, e.NewValue);
}
private static void OnSelectedIndexChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
NativeComboBox cb = (NativeComboBox)d;
int newValue = (int)e.NewValue;
if (!cb._changingSelectionInHtml)
{
cb._changingSelectionProgrammatically = true;
try
{
cb.SetSelectedIndexInNativeHtmlDom(newValue);
}
finally
{
cb._changingSelectionProgrammatically = false;
}
}
// we only want to change the other ones if the change comes from
// SelectedIndex (otherwise it's already done by the one that was
// originally changed (SelectedItem or SelectedValue)
if (!cb._selectionChangeIsOnValue && !cb._selectionChangeIsOnItem)
{
cb._selectionChangeIsOnIndex = true;
try
{
if (newValue == -1)
{
// Note : we use SetCurrentValue to preserve any potential bindings.
cb.SetCurrentValue(NativeComboBox.SelectedValueProperty, null);
// Skip the call to Items.IndexOf()
cb.SkipCoerceSelectedItemCheck = true;
try
{
// Note: always update the value of SelectedItem last when
// synchronizing selection properties, so that all the properties
// are up to date when the selection changed event is fired.
cb.SetCurrentValue(NativeComboBox.SelectedItemProperty, null);
}
finally
{
cb.SkipCoerceSelectedItemCheck = false;
}
}
else
{
object item = cb.Items[newValue];
// Note : we use SetCurrentValue to preserve any potential bindings.
cb.SetCurrentValue(NativeComboBox.SelectedValueProperty, PropertyPathHelper.AccessValueByApplyingPropertyPathIfAny(item, cb.SelectedValuePath));
// Skip the call to Items.IndexOf()
cb.SkipCoerceSelectedItemCheck = true;
try
{
// Note: always update the value of SelectedItem last when
// synchronizing selection properties, so that all the properties
// are up to date when the selection changed event is fired.
cb.SetCurrentValue(NativeComboBox.SelectedItemProperty, item);
}
finally
{
cb.SkipCoerceSelectedItemCheck = false;
}
}
}
finally
{
cb._selectionChangeIsOnIndex = false;
}
}
}
