mchSamples-MAUI/ch03_DataBinding/ex_BindingToA2dArray_v2/MyLayouts/MatrixLayoutManager.cs

using Microsoft.Maui.Layouts;

namespace ex_BindingToA2dArray_v2.MyLayouts;

public class MatrixLayoutManager : ILayoutManager
{
    MatrixLayout? MatrixLayout {get; set;}
    double LayoutWidth {get; set;}
    double LayoutHeight {get; set;}
    double MaxCellWidth {get; set;}
    double MaxCellHeight {get; set;}

    public MatrixLayoutManager(MatrixLayout matrixLayout)
    {
        MatrixLayout = matrixLayout;
    }

    public Size Measure(double widthConstraint, double heightConstraint)
    {
        if(MatrixLayout == null) 
            return new Size(widthConstraint, heightConstraint);

        int nbRows = MatrixLayout.NbRows;
        int nbColumns = MatrixLayout.NbColumns;

        var padding = MatrixLayout.Padding;
        var horizontalSpacing = MatrixLayout.HorizontalSpacing;
        var verticalSpacing = MatrixLayout.VerticalSpacing;

        MaxCellWidth = (widthConstraint - padding.HorizontalThickness - (nbColumns - 1)* horizontalSpacing)/nbColumns;
        MaxCellHeight = (heightConstraint - padding.VerticalThickness - (nbRows - 1)* verticalSpacing)/nbRows;

        double minDim = Math.Min(MaxCellWidth, MaxCellHeight);
        MaxCellWidth = minDim;
        MaxCellHeight = minDim;

        LayoutWidth = MaxCellWidth*nbColumns + (nbColumns-1)* horizontalSpacing + padding.HorizontalThickness;
        LayoutHeight = MaxCellHeight*nbRows + (nbRows-1)* verticalSpacing + padding.VerticalThickness;
        return new Size(LayoutWidth, LayoutHeight);
    }

    public Size ArrangeChildren(Rect bounds)
    {
        if(MatrixLayout == null) 
            return new Size(LayoutWidth, LayoutHeight);

        var padding = MatrixLayout.Padding;
        var horizontalSpacing = MatrixLayout.HorizontalSpacing;
        var verticalSpacing = MatrixLayout.VerticalSpacing;
        int nbColumns = MatrixLayout.NbColumns;
        double top = padding.Top + bounds.Top;
        double left = padding.Left + bounds.Left;

        for (int cellId = 0; cellId < MatrixLayout.Count; cellId++)
        {
            var cell = MatrixLayout[cellId];
            int numRow = cellId / nbColumns;
            int numColumn = cellId - numRow * nbColumns;

            double leftSide = left + numColumn * (MaxCellWidth + horizontalSpacing);
            double topSide = top + numRow * (MaxCellHeight + verticalSpacing);

            var destination = new Rect(leftSide, topSide, MaxCellWidth, MaxCellHeight);
            cell.Arrange(destination);
        }

        return new Size(LayoutWidth, LayoutHeight);
    }
}