バウンティを開始すると、過去数か月間は見つけられなかった解決策が突然見つかるようです。
私は自分のソリューションを追加することに答えています。これは現在機能していますが、確実に改善できます。
私が提案しているのは、次の 2 つの異なる情報源に基づいています。
XAML から始めましょう。
<ItemsControl ItemsSource="{Binding Items}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Border BorderBrush="{StaticResource PhoneForegroundBrush}">
<utils:TemplateSelector Content="{Binding}"/>
<toolkit:GestureService.GestureListener>
<toolkit:GestureListener
DragStarted="GestureListener_OnDragStarted"
DragDelta="GestureListener_OnDragDelta"
DragCompleted="GestureListener_OnDragCompleted"/>
</toolkit:GestureService.GestureListener>
</Border>
</DataTemplate>
</ItemsControl.ItemTemplate>
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas x:Name="WidgetsCanvas" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
( Windows Phone Toolkittoolkitから取得)
次に、3 つのドラッグ ハンドラの実装を見てみましょう。
private int _zindex; //Used to keep the moved element on the top, not working for now
private FrameworkElement _movedObject; //The element that we're moving. Used to avoid moving multiple items if they overlap
private void GestureListener_OnDragStarted(object sender, DragStartedGestureEventArgs e)
{
if (_movedObject != null) return; // We're already moving something!
// Initialize the drag
var fe = sender as FrameworkElement; // The element that we want to move
(fe as Border).BorderThickness = new Thickness(5); // A simple effect to mark the element on the screen
_movedObject = fe; // We set the current object to the one which is moving
Canvas.SetZIndex(fe, _zindex++); // This should take the moved object on the top but it's not working
}
private void GestureListener_OnDragDelta(object sender, DragDeltaGestureEventArgs e)
{
var fe = sender as FrameworkElement;
if (!fe.Equals(_movedObject)) return; // We change the object's position only if this is the one who started the event
var offset = DragManager.GetOffset(fe); // We get the current position
var canvas = DragManager.FindChild<Canvas>(Application.Current.RootVisual, "ItemsCanvas"); // We need the container of our object to force it to stay inside the container
//The new position is given by the old one plus the change reported by the event
var horizontalOffset = offset.HorizontalValue + e.HorizontalChange;
var verticalOffset = offset.VerticalValue + e.VerticalChange;
// We need to check if the new position is outside our container's bounds
if (horizontalOffset < 0) horizontalOffset = 0;
else if (horizontalOffset > (canvas.ActualWidth - fe.ActualWidth)) horizontalOffset = canvas.ActualWidth - fe.ActualWidth;
if (verticalOffset < 0) verticalOffset = 0;
else if (verticalOffset > (canvas.ActualHeight - fe.ActualHeight)) verticalOffset = canvas.ActualHeight - fe.ActualHeight;
// Once we've got everything set, we can move our component
DragManager.SetOffset(fe, horizontalOffset, verticalOffset);
}
private void GestureListener_OnDragCompleted(object sender, DragCompletedGestureEventArgs e)
{
var fe = sender as FrameworkElement;
(fe as Border).BorderThickness = new Thickness(0); // We undo our effect
_movedObject = null; // The movement is done so we can reset our current object and wait for a new one to come
}
ハンドラーは、私が呼び出したクラスで動作しますDragManager。そのコードは非常に単純です:
public static class DragManager
{
public static void SetOffset(FrameworkElement fe, double horizontalOffset, double verticalOffset)
{
var trans = new TranslateTransform
{
X = horizontalOffset,
Y = verticalOffset
};
// I don't know what may change, in terms of performance, between applying the transform or just changing the margins. I'm using the margins because the transform may be needed for some other purpose
//fe.RenderTransform = trans;
fe.Margin = new Thickness(horizontalOffset, verticalOffset, 0, 0); // We just change our object's margins to reflect its new position
// We store the current position in the objects Tag (maybe there's a better solution but I'm quite new to C#/xaml)
fe.Tag = new Offset
{
VerticalValue = verticalOffset,
HorizontalValue = horizontalOffset,
Transform = trans
};
}
public static Offset GetOffset(FrameworkElement fe)
{
if (fe.Tag == null) fe.Tag = new Offset();
return (Offset)fe.Tag;
}
public struct Offset
{
public double HorizontalValue { get; set; }
public double VerticalValue { get; set; }
public TranslateTransform Transform { get; set; }
}
public static T FindChild<T>(DependencyObject parent, string childName) where T : DependencyObject
{
// Confirm parent and childName are valid.
if (parent == null)
{
return null;
}
T foundChild = null;
var childrenCount = VisualTreeHelper.GetChildrenCount(parent);
for (var i = 0; i < childrenCount; i++)
{
var child = VisualTreeHelper.GetChild(parent, i);
// If the child is not of the request child type child
var childType = child as T;
if (childType == null)
{
// recursively drill down the tree
foundChild = FindChild<T>(child, childName);
// If the child is found, break so we do not overwrite the found child.
if (foundChild != null)
{
break;
}
}
else if (!String.IsNullOrEmpty(childName))
{
var frameworkElement = child as FrameworkElement;
// If the child's name is set for search
if (frameworkElement != null && frameworkElement.Name == childName)
{
// if the child's name is of the request name
foundChild = (T)child;
break;
}
// Need this in case the element we want is nested
// in another element of the same type
foundChild = FindChild<T>(child, childName);
}
else
{
// child element found.
foundChild = (T)child;
break;
}
}
return foundChild;
}
}
すでに述べたように、このコードは現在機能しています。
誰かがそれを改善するための提案を持っている場合は、ここに書いてください。そうすれば、この種のことを行うためのより良い方法を確認/テストできます!