PDFOffice_Windows_exe/PDF Office/ViewModels/PageEdit/PageEditContentViewModel.cs

using Prism.Mvvm;
using Prism.Regions;
using Prism.Services.Dialogs;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Media;
using ComPDFKitViewer.PdfViewer;
using PDF_Office.Model;
using System.Collections.ObjectModel;
using PDF_Office.Model.PageEdit;
using Prism.Commands;
using System.Windows;
using System.Windows.Media.Imaging;
using System.Windows.Controls.Primitives;
using System.Diagnostics;
using System.Windows.Controls;
using PDF_Office.Tools;
using System.Windows.Threading;
using Prism.Events;
using PDF_Office.EventAggregators;

namespace PDF_Office.ViewModels.PageEdit
{
    public class PageEditContentViewModel : BindableBase, INavigationAware
    {

        private CPDFViewer PDFViewer;

        private ViewContentViewModel viewContentViewModel;

        private IDialogService dialogs;

        private IEventAggregator eventor;

        /// <summary>
        /// 是否正在初始化所有列表项，正在初始化时，不刷新图片
        /// </summary>
        private bool isInitaling = false;

        private ScrollEventType scrollType = ScrollEventType.EndScroll;

        /// <summary>
        /// 辅助判断滚轮是否暂停滚动的计时器(暂时没有更好的方法来判断滚轮是否停止滚动)
        /// 只要滚动就重新计时、通过计时开始0.3秒后没有刷新计时来粗略判断用户是否有暂停滚动
        /// </summary>
        private DispatcherTimer timer = new DispatcherTimer();

        private string unicode = null;

        #region 属性
        private Visibility isvisible;

        public Visibility IsVisible
        {
            get { return isvisible; }
            set
            {
                SetProperty(ref isvisible, value);
            }
        }


        private int selecedIndex;
        /// <summary>
        /// 选中项的索引
        /// </summary>
        public int SelectedIndex
        {
            get { return selecedIndex; }
            set
            {
                SetProperty(ref selecedIndex, value);
            }
        }


        #endregion

        #region 命令

        #endregion

        /// <summary>
        /// 项数据集合
        /// </summary>
        public ObservableCollection<PageEditItem> PageEditItems { get; set; }

        public PageEditContentViewModel(IDialogService dialogService, IEventAggregator eventAggregator)
        {
            dialogs = dialogService;
            eventor = eventAggregator;
            unicode = App.mainWindowViewModel.SelectedItem.Unicode;
            PageEditItems = new ObservableCollection<PageEditItem>();
            eventAggregator.GetEvent<PageEditRefreshEvent>().Subscribe(OnPageEditRefreshEvent, e=>e.Unicode== unicode);

        }


        #region 事件
        private void OnPageEditRefreshEvent(PageEditRefreshEventArgs e)
        {
            //UI发送事件过来通知刷新图片时
            //调整逻辑,前后预加载5页
            RefreshItemImage(e.PageRange.Item1-5,e.PageRange.Item2+5);
        }

        #endregion

        /// <summary>
        /// 从PDFView获取所有Items集合
        /// </summary>
        private void GetSourceItems()
        {
            PageEditItems.Clear();
            isInitaling = true;
            for (int i = 0; i < PDFViewer.Document.PageCount; i++)
            {
                PageEditItem item = new PageEditItem();
                item.PageNumber = i + 1;
                var pagesize = PDFViewer.Document.GetPageSize(i);

                item.PageSize = $"{pagesize.Width}mm*{pagesize.Height} mm";
                PageEditItems.Add(item);
            }
            isInitaling = false;
        }

        /// <summary>
        /// 刷新书签列表
        /// </summary>
        public void RefreshBookMarkList()
        {
            if (PDFViewer != null)
            {
                var booklist = PDFViewer.Document.GetBookmarkList();
                if (booklist == null)
                { 
                    return; 
                }
                //获取所有书签的Index集合
                List<int> marks = new List<int>();
                for (int i = 0; i < booklist.Count; i++)
                {
                    marks.Add(booklist[i].PageIndex);
                }

                //不能只遍历marks集合，考虑书签集合元素删除的情况
                for (int k = 0; k < PageEditItems.Count; k++)
                {
                    if (marks.Contains(k))
                        PageEditItems[k].HaveBookMark = true;
                    else
                        PageEditItems[k].HaveBookMark = false;
                }
            }
        }

        /// <summary>
        /// 刷新指定范围的图片
        /// </summary>
        /// <param name="startIndex"></param>
        /// <param name="endIndex"></param>
        private async void RefreshItemImage(int startIndex,int endIndex)
        {
            for (int i = startIndex; i <=endIndex;i++)
            {
                if (i <= PDFViewer.Document.PageCount - 1&&i>=0)
                {
                    //宽高为样式中图片控件宽高
                    await PDFViewer.GetThumbnail(i, 208, 294);
                }
            }
        }


        #region Navigate
        public bool IsNavigationTarget(NavigationContext navigationContext)
        {
            return true;
        }

        public void OnNavigatedFrom(NavigationContext navigationContext)
        {
           

        }

        /// <summary>
        /// 从其他页面导航过来的时候会触发
        /// 考虑只有在页面编辑的时候会进行页面的删减,可以尝试逻辑优化:仅第一次进入页面编辑时重新刷新页面
        /// </summary>
        /// <param name="navigationContext"></param>
        public void OnNavigatedTo(NavigationContext navigationContext)
        {
            navigationContext.Parameters.TryGetValue<ViewContentViewModel>(ParameterNames.ViewContentViewModel, out viewContentViewModel);
            navigationContext.Parameters.TryGetValue<CPDFViewer>(ParameterNames.PDFViewer, out PDFViewer);
            if (PDFViewer != null)
            {
                PDFViewer.OnThumbnailGenerated += PDFViewer_OnThumbnailGenerated;

                GetSourceItems();

                RefreshBookMarkList();
            }
        }
        #endregion

        /// <summary>
        /// 从底层库获取对应页面的图片
        /// </summary>
        /// <param name="pageIndex"></param>
        /// <param name="thumb"></param>
        /// <param name="w"></param>
        /// <param name="h"></param>
        private void PDFViewer_OnThumbnailGenerated(int pageIndex, byte[] thumb, int w, int h)
        {
            try
            {
                if (PageEditItems.Count >= pageIndex + 1&&!PageEditItems[pageIndex].IsGetImage)
                {
                    PixelFormat fmt = PixelFormats.Bgra32;
                    BitmapSource bps = BitmapSource.Create(w, h, 96.0, 96.0, fmt, null, thumb, (w * fmt.BitsPerPixel + 7) / 8);
                    PageEditItems[pageIndex].Image = bps;
                    PageEditItems[pageIndex].IsGetImage = true;
                }
            }
            catch
            {
              
            }
        }
    }
}