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| /// <summary>
/// A layout that create lines / rows.
/// </summary>
/// <seealso cref="Xamarin.Forms.Layout{Xamarin.Forms.View}" />
/// <autogeneratedoc />
public class InlineWrapLayout : Layout<View>
{
private readonly Dictionary<Size, LayoutData> layoutDataCache = new Dictionary<Size, LayoutData>();
public static readonly BindableProperty ColumnSpacingProperty = BindableProperty.Create(
"ColumnSpacing",
typeof(double),
typeof(InlineWrapLayout),
5.0,
propertyChanged: (bindable, oldvalue, newvalue) =>
{
((InlineWrapLayout)bindable).InvalidateLayout();
});
public static readonly BindableProperty RowSpacingProperty = BindableProperty.Create(
"RowSpacing",
typeof(double),
typeof(InlineWrapLayout),
5.0,
propertyChanged: (bindable, oldvalue, newvalue) =>
{
((InlineWrapLayout)bindable).InvalidateLayout();
});
/// <summary>
/// Gets or sets the column spacing.
/// </summary>
/// <value>
/// The column spacing.
/// </value>
/// <autogeneratedoc />
public double ColumnSpacing
{
set { SetValue(ColumnSpacingProperty, value); }
get { return (double)GetValue(ColumnSpacingProperty); }
}
/// <summary>
/// Gets or sets the row spacing.
/// </summary>
/// <value>
/// The row spacing.
/// </value>
/// <autogeneratedoc />
public double RowSpacing
{
set { SetValue(RowSpacingProperty, value); }
get { return (double)GetValue(RowSpacingProperty); }
}
protected override SizeRequest OnMeasure(double widthConstraint, double heightConstraint)
{
var layoutData = GetLayoutData(widthConstraint, heightConstraint);
if (layoutData.VisibleChildCount == 0)
{
return new SizeRequest();
}
return new SizeRequest(layoutData.Size);
}
/// <summary>
/// Positions and sizes the children of a Layout.
/// </summary>
/// <param name="x">A value representing the x coordinate of the child region bounding box.</param>
/// <param name="y">A value representing the y coordinate of the child region bounding box.</param>
/// <param name="width">A value representing the width of the child region bounding box.</param>
/// <param name="height">A value representing the height of the child region bounding box.</param>
/// <remarks>
/// Implementors wishing to change the default behavior of a Layout should override this method. It is suggested to still call the base method and modify its calculated results.
/// </remarks>
/// <autogeneratedoc />
protected override void LayoutChildren(double x, double y, double width, double height)
{
var layoutData = GetLayoutData(width, height);
if (layoutData.VisibleChildCount == 0)
{
return;
}
double xChild = x;
double yChild = y;
int row = 0;
int column = 0;
foreach (var child in Children)
{
if (!child.IsVisible)
{
continue;
}
LayoutChildIntoBoundingRegion(child, new Rectangle(new Point(xChild, yChild), layoutData.ChildrenSizesRows[row][column]));
if (column >= layoutData.ChildrenSizesRows[row].Count - 1)
{
xChild = x;
yChild += RowSpacing + layoutData.ChildrenSizesRows[row].Max(s => s.Height);
row++;
column = 0;
}
else
{
xChild += ColumnSpacing + layoutData.ChildrenSizesRows[row][column].Width;
column++;
}
}
}
private LayoutData GetLayoutData(double width, double height)
{
var size = new Size(width, height);
// Check if cached information is available.
if (layoutDataCache.ContainsKey(size))
{
return layoutDataCache[size];
}
int visibleChildCount = 0;
var currentChildrenSizesRow = new List<Size>();
var childrenSizesRows = new List<List<Size>> { currentChildrenSizesRow };
// Enumerate through all the children.
foreach (View child in Children)
{
// Skip invisible children.
if (!child.IsVisible)
continue;
// Count the visible children.
visibleChildCount++;
// Get the child's requested size.
var childSizeRequest = child.Measure(Double.PositiveInfinity, Double.PositiveInfinity);
if (childSizeRequest.Minimum.Width > width)
throw new Exception($"L'element {child.GetType()} est trop large {childSizeRequest.Request.Width} vs {width} demandés");
// la vue ne tient pas -> passer à la suivante (on utilise la taille minimum)
if (currentChildrenSizesRow.Sum(s => s.Width + ColumnSpacing) + childSizeRequest.Request.Width > width && currentChildrenSizesRow.Count > 0)
{
currentChildrenSizesRow = new List<Size>();
childrenSizesRows.Add(currentChildrenSizesRow);
};
if (childSizeRequest.Request.Width <= width)
currentChildrenSizesRow.Add(childSizeRequest.Request);
else
currentChildrenSizesRow.Add(new Size(width, childSizeRequest.Request.Height));
}
double totalWidth = 0;
double totalHeight = 0;
if (visibleChildCount != 0)
{
// Calculate the number of rows and columns.
if (Double.IsPositiveInfinity(width))
{
childrenSizesRows = new List<List<Size>>
{
new List<Size>(childrenSizesRows.SelectMany(r => r))
};
}
totalWidth = Math.Max(0, childrenSizesRows.Max(r => r.Sum(s => s.Width + ColumnSpacing) - ColumnSpacing));
totalHeight = Math.Max(0, childrenSizesRows.Sum(r => r.Count > 0 ? r.Max(s => s.Height) + RowSpacing : 0) - RowSpacing);
}
var totalSize = new Size(totalWidth, totalHeight);
var layoutData = new LayoutData(visibleChildCount, childrenSizesRows, totalSize);
layoutDataCache.Add(size, layoutData);
return layoutData;
}
/// <summary>
/// Invalidates the current layout.
/// </summary>
/// <remarks>
/// Calling this method will invalidate the measure and triggers a new layout cycle.
/// </remarks>
/// <autogeneratedoc />
protected override void InvalidateLayout()
{
base.InvalidateLayout();
// Discard all layout information for children added or removed.
layoutDataCache.Clear();
}
/// <summary>
/// Invoked whenever a child of the layout has emitted <see cref="E:Xamarin.Forms.VisualElement.MeaureInvalidated" />. Implement this method to add class handling for this event.
/// </summary>
/// <autogeneratedoc />
protected override void OnChildMeasureInvalidated()
{
base.OnChildMeasureInvalidated();
// Discard all layout information for child size changed.
layoutDataCache.Clear();
}
private struct LayoutData
{
public int VisibleChildCount { get; private set; }
public Size Size { get; private set; }
public List<List<Size>> ChildrenSizesRows { get; private set; }
public LayoutData(int visibleChildCount, List<List<Size>> childrenSizesRows, Size size) : this()
{
ChildrenSizesRows = childrenSizesRows;
VisibleChildCount = visibleChildCount;
Size = size;
}
public Size CellSize { get; private set; }
public int Rows { get; private set; }
public int Columns { get; private set; }
public LayoutData(int visibleChildCount, Size cellSize, int rows, int columns) : this()
{
VisibleChildCount = visibleChildCount;
CellSize = cellSize;
Rows = rows;
Columns = columns;
}
}
} |
[XAMARIN] View générée dynamiquement en Xaml ou MVVM
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