WPF_Practice/PacticeSolution/MVVMCanvasRectangle/ViewModel/RectModelView.cs

using MVVMCanvasRectangle.Model;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MVVMCanvasRectangle.ViewModel
{
    internal class RectModelView : INotifyPropertyChanged
    {
        private int _count;
        public ObservableCollection<RectItem> RectItems { get; set; }

        public event PropertyChangedEventHandler? PropertyChanged;

        public int Count
        {
            get { return _count; }
            set
            {
                _count = value;
                this.RectItems.Clear();
                for (int i = 0; i < _count; i++)
                {
                    this.RectItems.Add(new RectItem { X = i * 40, Y = 10, Width = 30, Height = 30 });
                }
            }
        }

        public RectModelView()
        {
            _count = 0;
            this.RectItems = new ObservableCollection<RectItem>();
        }

        public void AddOne()
        {
            RectItem lastRect = this.RectItems.LastOrDefault();
            if (lastRect == null)
                this.RectItems.Add(new RectItem() { X = 0, Y = 10, Width = 30, Height = 30 });
            else
                this.RectItems.Add(new RectItem() { X = lastRect.X + 40, Y = 10, Width = 30, Height = 30 });
        }
    }
}