101 lines
4.2 KiB
C#
101 lines
4.2 KiB
C#
using System.Windows;
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using System.Windows.Controls;
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namespace PettingZoo.UI
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{
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// Source: http://daniel-albuschat.blogspot.nl/2011/07/gridlayout-for-wpf-escape-margin-hell.html
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// The GridLayout is a special Panel that can be used exactly like the Grid Panel, except that it
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// defines a new property ChildMargin. ChildMargin's left, top, right and bottom margins will be applied
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// to all children in a way that the children will have a vertical space of ChildMargin.Top+ChildMargin.Bottom
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// and a horizontal space of ChildMargin.Left+ChildMargin.Right between them.
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// However, there is no margin for the borders of the internal widget, so that the GridLayout itself can be
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// aligned to another element without a margin.
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// It's best to have a look at TestWindow, which effectively tests all possible alignments of children.
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public class GridLayout : Grid
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{
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public static readonly DependencyProperty ChildMarginProperty = DependencyProperty.Register(
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"ChildMargin",
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typeof (Thickness),
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typeof (GridLayout),
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new FrameworkPropertyMetadata(new Thickness(5))
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{
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AffectsArrange = true,
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AffectsMeasure = true
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});
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// The child margin defines a margin that will be automatically applied to all children of this Grid.
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// However, the children at the edges will have the respective margins remove. E.g. the leftmost children will have
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// a Margin.Left of 0 and the children in the first row will have a Margin.Top of 0.
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// The margins that are not set to 0 are set to half the ChildMargin's value, since it's neighbour will also apply it,
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// effectively doubling it.
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public Thickness ChildMargin
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{
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get => (Thickness) GetValue(ChildMarginProperty);
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set
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{
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SetValue(ChildMarginProperty, value);
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UpdateChildMargins();
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}
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}
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// UpdateChildMargin first finds out what's the rightmost column and bottom row and then applies
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// the correct margins to all children.
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public void UpdateChildMargins()
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{
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var maxColumn = 0;
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var maxRow = 0;
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foreach (UIElement element in InternalChildren)
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{
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var row = GetRow(element);
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var column = GetColumn(element);
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if (row > maxRow)
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maxRow = row;
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if (column > maxColumn)
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maxColumn = column;
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}
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foreach (UIElement element in InternalChildren)
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{
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if (element is not FrameworkElement fe)
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continue;
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var row = GetRow(fe);
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var column = GetColumn(fe);
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var factorLeft = 0.5;
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var factorTop = 0.5;
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var factorRight = 0.5;
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var factorBottom = 0.5;
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// Top row - no top margin
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if (row == 0)
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factorTop = 0;
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// Bottom row - no bottom margin
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if (row == maxRow)
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factorBottom = 0;
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// Leftmost column = no left margin
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if (column == 0)
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factorLeft = 0;
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// Rightmost column - no right margin
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if (column == maxColumn)
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factorRight = 0;
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fe.Margin = new Thickness(ChildMargin.Left*factorLeft,
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ChildMargin.Top*factorTop,
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ChildMargin.Right*factorRight,
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ChildMargin.Bottom*factorBottom);
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}
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}
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// We change all children's margins in MeasureOverride, since this is called right before
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// the layouting takes place. I was first skeptical to do this here, because I thought changing
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// the margin will trigger a LayoutUpdate, which in turn would lead to an endless recursion,
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// but apparantly WPF takes care of this.
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protected override Size MeasureOverride(Size availableSize)
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{
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UpdateChildMargins();
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return base.MeasureOverride(availableSize);
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}
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}
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} |