WPF: ¿cómo puedo centrar todos los artículos en un WrapPanel?

Estoy usando un WrapPanel como el ItemsPanel de ItemsControl . En este momento, los elementos en el control se envuelven así:

 |1234567 | |890 | 

Me gustaría que se envuelvan así:

 | 1234567 | | 890 | 

Conceptualmente, el proceso de disposición debe alinear cada línea de elementos de modo que se centre dentro de los WrapPanel del WrapPanel .

¿Alguien puede explicar cómo es posible, por favor?

El WrapPanel no le permitirá alinear su contenido, solo a sí mismo. Aquí hay una técnica que le permite establecer HorizontalContentAlignment :

 using System; using System.Windows; using System.Windows.Controls; public class AlignableWrapPanel : Panel { public HorizontalAlignment HorizontalContentAlignment { get { return (HorizontalAlignment)GetValue(HorizontalContentAlignmentProperty); } set { SetValue(HorizontalContentAlignmentProperty, value); } } public static readonly DependencyProperty HorizontalContentAlignmentProperty = DependencyProperty.Register("HorizontalContentAlignment", typeof(HorizontalAlignment), typeof(AlignableWrapPanel), new FrameworkPropertyMetadata(HorizontalAlignment.Left, FrameworkPropertyMetadataOptions.AffectsArrange)); protected override Size MeasureOverride(Size constraint) { Size curLineSize = new Size(); Size panelSize = new Size(); UIElementCollection children = base.InternalChildren; for (int i = 0; i < children.Count; i++) { UIElement child = children[i] as UIElement; // Flow passes its own constraint to children child.Measure(constraint); Size sz = child.DesiredSize; if (curLineSize.Width + sz.Width > constraint.Width) //need to switch to another line { panelSize.Width = Math.Max(curLineSize.Width, panelSize.Width); panelSize.Height += curLineSize.Height; curLineSize = sz; if (sz.Width > constraint.Width) // if the element is wider then the constraint - give it a separate line { panelSize.Width = Math.Max(sz.Width, panelSize.Width); panelSize.Height += sz.Height; curLineSize = new Size(); } } else //continue to accumulate a line { curLineSize.Width += sz.Width; curLineSize.Height = Math.Max(sz.Height, curLineSize.Height); } } // the last line size, if any need to be added panelSize.Width = Math.Max(curLineSize.Width, panelSize.Width); panelSize.Height += curLineSize.Height; return panelSize; } protected override Size ArrangeOverride(Size arrangeBounds) { int firstInLine = 0; Size curLineSize = new Size(); double accumulatedHeight = 0; UIElementCollection children = this.InternalChildren; for (int i = 0; i < children.Count; i++) { Size sz = children[i].DesiredSize; if (curLineSize.Width + sz.Width > arrangeBounds.Width) //need to switch to another line { ArrangeLine(accumulatedHeight, curLineSize, arrangeBounds.Width, firstInLine, i); accumulatedHeight += curLineSize.Height; curLineSize = sz; if (sz.Width > arrangeBounds.Width) //the element is wider then the constraint - give it a separate line { ArrangeLine(accumulatedHeight, sz, arrangeBounds.Width, i, ++i); accumulatedHeight += sz.Height; curLineSize = new Size(); } firstInLine = i; } else //continue to accumulate a line { curLineSize.Width += sz.Width; curLineSize.Height = Math.Max(sz.Height, curLineSize.Height); } } if (firstInLine < children.Count) ArrangeLine(accumulatedHeight, curLineSize, arrangeBounds.Width, firstInLine, children.Count); return arrangeBounds; } private void ArrangeLine(double y, Size lineSize, double boundsWidth, int start, int end) { double x = 0; if (this.HorizontalContentAlignment == HorizontalAlignment.Center) { x = (boundsWidth - lineSize.Width) / 2; } else if (this.HorizontalContentAlignment == HorizontalAlignment.Right) { x = (boundsWidth - lineSize.Width); } UIElementCollection children = InternalChildren; for (int i = start; i < end; i++) { UIElement child = children[i]; child.Arrange(new Rect(x, y, child.DesiredSize.Width, lineSize.Height)); x += child.DesiredSize.Width; } } } 

Lamentablemente, el stock WrapPanel no hará lo que está pidiendo, ya que su intención es llenar todo el espacio disponible horizontalmente (o verticalmente) antes de envolverlo. Probablemente tendrá que diseñar su propio WrapPanel para manejar este caso. Puede comenzar con esta muestra que muestra cómo crear su propio WrapPanel .

La respuesta simple es que no se puede alinear al centro el contenido de un WrapPanel. Puede centrar y alinear el panel, pero la última línea se alineará a la izquierda dentro del panel.

Alterar sugerencias:

Use la cuadrícula con filas y columnas. Si no agrega elementos a la colección dinámicamente, esto podría funcionar muy bien.

Crea tu propia versión del WrapPanel que funcione de la manera que lo necesites. Este documento de MSDN describe cómo funcionan los paneles e incluye una sección sobre cómo crear paneles personalizados. También tiene un enlace a un panel personalizado de muestra.

Versión con VerticalContentAlignment (para paneles verticales):

 public class AlignableWrapPanel : Panel { public AlignableWrapPanel() { _orientation = Orientation.Horizontal; } private static bool IsWidthHeightValid(object value) { var v = (double)value; return (double.IsNaN(v)) || (v >= 0.0d && !double.IsPositiveInfinity(v)); } public static readonly DependencyProperty ItemWidthProperty = DependencyProperty.Register("ItemWidth", typeof(double), typeof(AlignableWrapPanel), new FrameworkPropertyMetadata(double.NaN, FrameworkPropertyMetadataOptions.AffectsMeasure), IsWidthHeightValid); [TypeConverter(typeof(LengthConverter))] public double ItemWidth { get { return (double)GetValue(ItemWidthProperty); } set { SetValue(ItemWidthProperty, value); } } public static readonly DependencyProperty ItemHeightProperty = DependencyProperty.Register("ItemHeight", typeof(double), typeof(AlignableWrapPanel), new FrameworkPropertyMetadata(double.NaN, FrameworkPropertyMetadataOptions.AffectsMeasure), IsWidthHeightValid); [TypeConverter(typeof(LengthConverter))] public double ItemHeight { get { return (double)GetValue(ItemHeightProperty); } set { SetValue(ItemHeightProperty, value); } } public static readonly DependencyProperty OrientationProperty = StackPanel.OrientationProperty.AddOwner(typeof(AlignableWrapPanel), new FrameworkPropertyMetadata(Orientation.Horizontal, FrameworkPropertyMetadataOptions.AffectsMeasure, OnOrientationChanged)); public Orientation Orientation { get { return _orientation; } set { SetValue(OrientationProperty, value); } } private static void OnOrientationChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { var p = (AlignableWrapPanel)d; p._orientation = (Orientation)e.NewValue; } private Orientation _orientation; private struct UvSize { internal UvSize(Orientation orientation, double width, double height) { U = V = 0d; _orientation = orientation; Width = width; Height = height; } internal UvSize(Orientation orientation) { U = V = 0d; _orientation = orientation; } internal double U; internal double V; private readonly Orientation _orientation; internal double Width { get { return (_orientation == Orientation.Horizontal ? U : V); } private set { if (_orientation == Orientation.Horizontal) U = value; else V = value; } } internal double Height { get { return (_orientation == Orientation.Horizontal ? V : U); } private set { if (_orientation == Orientation.Horizontal) V = value; else U = value; } } } protected override Size MeasureOverride(Size constraint) { var curLineSize = new UvSize(Orientation); var panelSize = new UvSize(Orientation); var uvConstraint = new UvSize(Orientation, constraint.Width, constraint.Height); var itemWidth = ItemWidth; var itemHeight = ItemHeight; var itemWidthSet = !double.IsNaN(itemWidth); var itemHeightSet = !double.IsNaN(itemHeight); var childConstraint = new Size( (itemWidthSet ? itemWidth : constraint.Width), (itemHeightSet ? itemHeight : constraint.Height)); var children = InternalChildren; for (int i = 0, count = children.Count; i < count; i++) { var child = children[i]; if (child == null) continue; //Flow passes its own constrint to children child.Measure(childConstraint); //this is the size of the child in UV space var sz = new UvSize( Orientation, (itemWidthSet ? itemWidth : child.DesiredSize.Width), (itemHeightSet ? itemHeight : child.DesiredSize.Height)); if (curLineSize.U + sz.U > uvConstraint.U) { //need to switch to another line panelSize.U = Math.Max(curLineSize.U, panelSize.U); panelSize.V += curLineSize.V; curLineSize = sz; if (!(sz.U > uvConstraint.U)) continue; //the element is wider then the constrint - give it a separate line panelSize.U = Math.Max(sz.U, panelSize.U); panelSize.V += sz.V; curLineSize = new UvSize(Orientation); } else { //continue to accumulate a line curLineSize.U += sz.U; curLineSize.V = Math.Max(sz.V, curLineSize.V); } } //the last line size, if any should be added panelSize.U = Math.Max(curLineSize.U, panelSize.U); panelSize.V += curLineSize.V; //go from UV space to W/H space return new Size(panelSize.Width, panelSize.Height); } protected override Size ArrangeOverride(Size finalSize) { var firstInLine = 0; var itemWidth = ItemWidth; var itemHeight = ItemHeight; double accumulatedV = 0; var itemU = (Orientation == Orientation.Horizontal ? itemWidth : itemHeight); var curLineSize = new UvSize(Orientation); var uvFinalSize = new UvSize(Orientation, finalSize.Width, finalSize.Height); var itemWidthSet = !double.IsNaN(itemWidth); var itemHeightSet = !double.IsNaN(itemHeight); var useItemU = (Orientation == Orientation.Horizontal ? itemWidthSet : itemHeightSet); var children = InternalChildren; for (int i = 0, count = children.Count; i < count; i++) { var child = children[i]; if (child == null) continue; var sz = new UvSize( Orientation, (itemWidthSet ? itemWidth : child.DesiredSize.Width), (itemHeightSet ? itemHeight : child.DesiredSize.Height)); if (curLineSize.U + sz.U > uvFinalSize.U) { //need to switch to another line ArrangeLine(finalSize, accumulatedV, curLineSize, firstInLine, i, useItemU, itemU); accumulatedV += curLineSize.V; curLineSize = sz; if (sz.U > uvFinalSize.U) { //the element is wider then the constraint - give it a separate line //switch to next line which only contain one element ArrangeLine(finalSize, accumulatedV, sz, i, ++i, useItemU, itemU); accumulatedV += sz.V; curLineSize = new UvSize(Orientation); } firstInLine = i; } else { //continue to accumulate a line curLineSize.U += sz.U; curLineSize.V = Math.Max(sz.V, curLineSize.V); } } //arrange the last line, if any if (firstInLine < children.Count) { ArrangeLine(finalSize, accumulatedV, curLineSize, firstInLine, children.Count, useItemU, itemU); } return finalSize; } private void ArrangeLine(Size finalSize, double v, UvSize line, int start, int end, bool useItemU, double itemU) { double u; var isHorizontal = Orientation == Orientation.Horizontal; if (_orientation == Orientation.Vertical) { switch (VerticalContentAlignment) { case VerticalAlignment.Center: u = (finalSize.Height - line.U) / 2; break; case VerticalAlignment.Bottom: u = finalSize.Height - line.U; break; default: u = 0; break; } } else { switch (HorizontalContentAlignment) { case HorizontalAlignment.Center: u = (finalSize.Width - line.U) / 2; break; case HorizontalAlignment.Right: u = finalSize.Width - line.U; break; default: u = 0; break; } } var children = InternalChildren; for (var i = start; i < end; i++) { var child = children[i]; if (child == null) continue; var childSize = new UvSize(Orientation, child.DesiredSize.Width, child.DesiredSize.Height); var layoutSlotU = (useItemU ? itemU : childSize.U); child.Arrange(new Rect( isHorizontal ? u : v, isHorizontal ? v : u, isHorizontal ? layoutSlotU : line.V, isHorizontal ? line.V : layoutSlotU)); u += layoutSlotU; } } public static readonly DependencyProperty HorizontalContentAlignmentProperty = DependencyProperty.Register(nameof(HorizontalContentAlignment), typeof(HorizontalAlignment), typeof(AlignableWrapPanel), new FrameworkPropertyMetadata(HorizontalAlignment.Left, FrameworkPropertyMetadataOptions.AffectsArrange)); public HorizontalAlignment HorizontalContentAlignment { get { return (HorizontalAlignment)GetValue(HorizontalContentAlignmentProperty); } set { SetValue(HorizontalContentAlignmentProperty, value); } } public static readonly DependencyProperty VerticalContentAlignmentProperty = DependencyProperty.Register(nameof(VerticalContentAlignment), typeof(VerticalAlignment), typeof(AlignableWrapPanel), new FrameworkPropertyMetadata(VerticalAlignment.Top, FrameworkPropertyMetadataOptions.AffectsArrange)); public VerticalAlignment VerticalContentAlignment { get { return (VerticalAlignment)GetValue(VerticalContentAlignmentProperty); } set { SetValue(VerticalContentAlignmentProperty, value); } } } 

Aquí está la versión de Silverlight

Gracias especiales a @DTig ,

 using System.Windows.Controls; using System.Windows; using Telerik.Windows; using System; using System.Linq; public class AlignableWrapPanel : Panel { public HorizontalAlignment HorizontalContentAlignment { get { return (HorizontalAlignment)GetValue(HorizontalContentAlignmentProperty); } set { SetValue(HorizontalContentAlignmentProperty, value); } } public static readonly DependencyProperty HorizontalContentAlignmentProperty = DependencyProperty.Register("HorizontalContentAlignment", typeof(HorizontalAlignment), typeof(AlignableWrapPanel), new FrameworkPropertyMetadata(HorizontalAlignment.Left, FrameworkPropertyMetadataOptions.AffectsArrange)); protected override Size MeasureOverride(Size constraint) { Size curLineSize = new Size(); Size panelSize = new Size(); UIElementCollection children = base.Children; for (int i = 0; i < children.Count; i++) { UIElement child = children[i] as UIElement; // Flow passes its own constraint to children child.Measure(constraint); Size sz = child.DesiredSize; if (curLineSize.Width + sz.Width > constraint.Width) //need to switch to another line { panelSize.Width = Math.Max(curLineSize.Width, panelSize.Width); panelSize.Height += curLineSize.Height; curLineSize = sz; if (sz.Width > constraint.Width) // if the element is wider then the constraint - give it a separate line { panelSize.Width = Math.Max(sz.Width, panelSize.Width); panelSize.Height += sz.Height; curLineSize = new Size(); } } else //continue to accumulate a line { curLineSize.Width += sz.Width; curLineSize.Height = Math.Max(sz.Height, curLineSize.Height); } } // the last line size, if any need to be added panelSize.Width = Math.Max(curLineSize.Width, panelSize.Width); panelSize.Height += curLineSize.Height; return panelSize; } protected override Size ArrangeOverride(Size arrangeBounds) { int firstInLine = 0; Size curLineSize = new Size(); double accumulatedHeight = 0; UIElementCollection children = this.Children; for (int i = 0; i < children.Count; i++) { Size sz = children[i].DesiredSize; if (curLineSize.Width + sz.Width > arrangeBounds.Width) //need to switch to another line { ArrangeLine(accumulatedHeight, curLineSize, arrangeBounds.Width, firstInLine, i); accumulatedHeight += curLineSize.Height; curLineSize = sz; if (sz.Width > arrangeBounds.Width) //the element is wider then the constraint - give it a separate line { ArrangeLine(accumulatedHeight, sz, arrangeBounds.Width, i, ++i); accumulatedHeight += sz.Height; curLineSize = new Size(); } firstInLine = i; } else //continue to accumulate a line { curLineSize.Width += sz.Width; curLineSize.Height = Math.Max(sz.Height, curLineSize.Height); } } if (firstInLine < children.Count) ArrangeLine(accumulatedHeight, curLineSize, arrangeBounds.Width, firstInLine, children.Count); return arrangeBounds; } private void ArrangeLine(double y, Size lineSize, double boundsWidth, int start, int end) { double x = 0; if (this.HorizontalContentAlignment == HorizontalAlignment.Center) { x = (boundsWidth - lineSize.Width) / 2; } else if (this.HorizontalContentAlignment == HorizontalAlignment.Right) { x = (boundsWidth - lineSize.Width); } UIElementCollection children = Children; for (int i = start; i < end; i++) { UIElement child = children[i]; var rect = new System.Windows.Rect(x, y, child.DesiredSize.Width, lineSize.Height); child.Arrange(rect); x += child.DesiredSize.Width; } } } 

Necesitaba un WrapPanel que pudiera ampliar su contenido, por lo que, basado en https://stackoverflow.com/a/7747002/121122 y algo de manipulación, se me ocurrió esto:

 public class AlignableWrapPanel : Panel { public HorizontalAlignment HorizontalContentAlignment { get => (HorizontalAlignment)GetValue(HorizontalContentAlignmentProperty); set => SetValue(HorizontalContentAlignmentProperty, value); } public static readonly DependencyProperty HorizontalContentAlignmentProperty = DependencyProperty.Register( nameof(HorizontalContentAlignment), typeof(HorizontalAlignment), typeof(AlignableWrapPanel), new FrameworkPropertyMetadata(HorizontalAlignment.Left, FrameworkPropertyMetadataOptions.AffectsArrange)); protected override Size MeasureOverride(Size constraint) { var curLineSize = new Size(); var panelSize = new Size(); var children = InternalChildren; for (var i = 0; i < children.Count; i++) { var child = children[i]; // flow passes its own constraint to children child.Measure(constraint); var sz = child.DesiredSize; if (curLineSize.Width + sz.Width > constraint.Width) // need to switch to another line { panelSize.Width = Math.Max(curLineSize.Width, panelSize.Width); panelSize.Height += curLineSize.Height; curLineSize = sz; if (sz.Width > constraint.Width) // if the element is wider then the constraint - give it a separate line { panelSize.Width = Math.Max(sz.Width, panelSize.Width); panelSize.Height += sz.Height; curLineSize = new Size(); } } else // continue to add to the line { curLineSize.Width += sz.Width; curLineSize.Height = Math.Max(sz.Height, curLineSize.Height); } } // the last line size, if any need to be added panelSize.Width = Math.Max(curLineSize.Width, panelSize.Width); panelSize.Height += curLineSize.Height; return panelSize; } protected override Size ArrangeOverride(Size arrangeBounds) { var firstInLine = 0; var curLineSize = new Size(); var accumulatedHeight = 0D; var children = InternalChildren; for (var i = 0; i < children.Count; i++) { var desiredSize = children[i].DesiredSize; if (curLineSize.Width + desiredSize.Width > arrangeBounds.Width) // need to switch to another line { ArrangeLine(accumulatedHeight, curLineSize, arrangeBounds.Width, firstInLine, i); accumulatedHeight += curLineSize.Height; curLineSize = desiredSize; if( desiredSize.Width > arrangeBounds.Width || children[i] is FrameworkElement element && element.HorizontalAlignment == HorizontalAlignment.Stretch) { // the element is wider then the constraint or it stretches - give it a separate line ArrangeLine(accumulatedHeight, desiredSize, arrangeBounds.Width, i, ++i); accumulatedHeight += desiredSize.Height; curLineSize = new Size(); } firstInLine = i; } else // continue to add to the line { curLineSize.Width += desiredSize.Width; curLineSize.Height = Math.Max(desiredSize.Height, curLineSize.Height); } } if (firstInLine < children.Count) { ArrangeLine(accumulatedHeight, curLineSize, arrangeBounds.Width, firstInLine, children.Count); } return arrangeBounds; } private void ArrangeLine(double y, Size lineSize, double boundsWidth, int start, int end) { var children = InternalChildren; var x = 0D; if (HorizontalContentAlignment == HorizontalAlignment.Center) { x = (boundsWidth - lineSize.Width) / 2; } else if (HorizontalContentAlignment == HorizontalAlignment.Right) { x = boundsWidth - lineSize.Width; } var stretchChildren = new List(); for (var i = start; i < end; i++) { var child = children[i]; if (child is FrameworkElement element && element.HorizontalAlignment == HorizontalAlignment.Stretch) { stretchChildren.Add(child); } } var spaceAvailableForStretchChildren = boundsWidth - lineSize.Width; var spaceAvailablePerStretchChild = 0D; if (stretchChildren.Any()) { x = 0; // all available space will be filled so start at 0 spaceAvailablePerStretchChild = spaceAvailableForStretchChildren / stretchChildren.Count; spaceAvailablePerStretchChild = spaceAvailablePerStretchChild >= 0 ? spaceAvailablePerStretchChild : 0; } for (var i = start; i < end; i++) { var child = children[i]; double itemWidth; if(stretchChildren.Contains(child)) { itemWidth = child.DesiredSize.Width + spaceAvailablePerStretchChild; } else { itemWidth = child.DesiredSize.Width; } child.Arrange(new Rect(x, y, itemWidth, lineSize.Height)); x += itemWidth; } } }