PDFOffice_Windows_exe/PDF Office/ViewModels/HomePanel/PDFTools/PDFToolsContentViewModel.cs

using Prism.Commands;
using Prism.Mvvm;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Controls;

namespace PDF_Office.ViewModels.HomePanel.PDFTools
{
    public class PDFToolsContentViewModel : BindableBase
    {
        #region 属性
        /// <summary>
        /// 扩展/收缩
        /// </summary>
        private bool _isExpendTools = false;
        public bool IsExpendTools
        {
            get { return _isExpendTools; }
            set { SetProperty(ref _isExpendTools, value); }
        }

        #endregion

        #region Command and Event
        public DelegateCommand<object> OpenMenuCommand { get; set; }
        public DelegateCommand ExpendCommand { get; set; }

        public event EventHandler<bool> ExpendToolsHanlder;

        #endregion

        public PDFToolsContentViewModel()
        {
            InitCommand();
        }

        private void InitCommand()
        {
            OpenMenuCommand = new DelegateCommand<object>(OpenMenu);
            ExpendCommand = new DelegateCommand(Expend);
        }

        private void Expend()
        {
            IsExpendTools = !IsExpendTools;
            ExpendToolsHanlder?.Invoke(null, IsExpendTools);
        }

        private void OpenMenu(object obj)
        {
            var menu = App.Current.FindResource("ExpendToolsContextMenu") as ContextMenu;
            var btn = obj as Button;
            if (menu != null && btn != null)
            {
                if (menu.Items.Count == 1)
                {
                    var item = menu.Items[0] as MenuItem;
                    if (_isExpendTools)
                    {
                        item.Header = "收缩";
                    }
                    else
                    {
                        item.Header = "展开";
                    }

                    item.Command = ExpendCommand;
                    //btn.ContextMenu = menu;
                    menu.PlacementTarget = btn;
                    menu.IsOpen = true;
                }
            }
        }
    }
}