删除toolkit:listpicker绑定的最后一个元素问题
删除toolkit:listpicker绑定的最后一个元素会抛出SelectedItem must always be set to a valid value这个异常。
目测是这段代码的问题:
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private static void OnSelectedItemChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
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{
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((ListPicker)o).OnSelectedItemChanged(e.OldValue, e.NewValue);
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}
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[SuppressMessage("Microsoft.Naming", "CA2204:Literals should be spelled correctly", MessageId = "SelectedItem", Justification = "Property name.")]
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private void OnSelectedItemChanged(object oldValue, object newValue)
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{
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if (newValue != null && (null == Items || Items.Count == 0))
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{
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if (null == Template)
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{
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// Can't set the value now; remember it for later
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_deferredSelectedItem = newValue;
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return;
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}
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else
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{
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throw new InvalidOperationException(Properties.Resources.InvalidSelectedItem);
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}
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}
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// Validate new value
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int newValueIndex = (null != newValue) ? Items.IndexOf(newValue) : -1;
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if ((-1 == newValueIndex) && (0 < Items.Count))
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{
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throw new InvalidOperationException(Properties.Resources.InvalidSelectedItem);
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}
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// Synchronize SelectedIndex property
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if (!_updatingSelection)
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{
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_updatingSelection = true;
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SelectedIndex = newValueIndex;
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_updatingSelection = false;
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}
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// Switch to Normal mode or size for current item
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if (ListPickerMode.Normal != ListPickerMode)
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{
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ListPickerMode = ListPickerMode.Normal;
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}
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else
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{
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SizeForAppropriateView(false);
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}
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// Fire SelectionChanged event
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var handler = SelectionChanged;
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if (null != handler)
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{
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IList removedItems = (null == oldValue) ? new object[0] : new object[] { oldValue };
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IList addedItems = (null == newValue) ? new object[0] : new object[] { newValue };
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handler(this, new SelectionChangedEventArgs(removedItems, addedItems));
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}
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}
有兴趣的动手改一改
作者:wingyiu
补充:移动开发 , IOS ,