获取文件的缩略图Thumbnail和通过 AQS - Advanced Query Syntax 搜索本地文件

演示如何获取文件的缩略图

FileSystem/ThumbnailAccess.xaml

<Page

    x:Class="XamlDemo.FileSystem.ThumbnailAccess"

    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

    xmlns:local="using:XamlDemo.FileSystem"

    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

    mc:Ignorable="d">

    <Grid Background="Transparent">

       <ScrollViewer Margin="120 0 0 0">

            <StackPanel>

                <Button Name="btnGetThumbnail" Content="获取文件的缩略图" Click="btnGetThumbnail_Click_1" />

                <Image Name="img" Stretch="None" HorizontalAlignment="Left" Margin="0 10 0 0" />

                <TextBlock Name="lblMsg" FontSize="14.667" Margin="0 10 0 0" />

            </StackPanel>

        </ScrollViewer>

    </Grid>

</Page>

FileSystem/ThumbnailAccess.xaml.cs

/*

 * 演示如何获取文件的缩略图

 *

 * 获取指定文件或文件夹的缩略图，返回 StorageItemThumbnail 类型的数据

 * StorageFile.GetThumbnailAsync(ThumbnailMode mode, uint requestedSize, ThumbnailOptions options)

 * StorageFolder.GetThumbnailAsync(ThumbnailMode mode, uint requestedSize, ThumbnailOptions options)

 *     ThumbnailMode mode - 用于描述缩略图的目的，以使系统确定缩略图图像的调整方式（PicturesView, VideosView, MusicView, DocumentsView, ListView, SingleItem）

 *         关于 ThumbnailMode 的详细介绍参见：http://msdn.microsoft.com/en-us/library/windows/apps/hh465350.aspx

 *     uint requestedSize - 期望尺寸的最长边长的大小

 *     ThumbnailOptions options - 检索和调整缩略图的行为（None, ReturnOnlyIfCached, ResizeThumbnail, UseCurrentScale）

 */

using System;

using Windows.Storage;

using Windows.Storage.FileProperties;

using Windows.Storage.Pickers;

using Windows.UI.Xaml;

using Windows.UI.Xaml.Controls;

using Windows.UI.Xaml.Media.Imaging;

namespace XamlDemo.FileSystem

{

    public sealed partial class ThumbnailAccess : Page

    {

        public ThumbnailAccess()

        {

            this.InitializeComponent();

        }

        private async void btnGetThumbnail_Click_1(object sender, RoutedEventArgs e)

        {

            if (XamlDemo.Common.Helper.EnsureUnsnapped())

            {

                FileOpenPicker openPicker = new FileOpenPicker();

                openPicker.FileTypeFilter.Add("*");

                StorageFile file = await openPicker.PickSingleFileAsync();

                if (file != null)

                {

                    ThumbnailMode thumbnailMode = ThumbnailMode.PicturesView;

                    ThumbnailOptions thumbnailOptions = ThumbnailOptions.UseCurrentScale;

                    uint requestedSize = 200;

                    using (StorageItemThumbnail thumbnail = await file.GetThumbnailAsync(thumbnailMode, requestedSize, thumbnailOptions))

                    {

                        if (thumbnail != null)

                        {

                            BitmapImage bitmapImage = new BitmapImage();

                            bitmapImage.SetSource(thumbnail);

                            img.Source = bitmapImage;

                            lblMsg.Text = "file name: " + file.Name;

                            lblMsg.Text += Environment.NewLine;

                            lblMsg.Text += "requested size: " + requestedSize;

                            lblMsg.Text += Environment.NewLine;

                            lblMsg.Text += "returned size: " + thumbnail.OriginalWidth + "*" + thumbnail.OriginalHeight;

                        }

                    }

                }

            }

        }

    }

}

4、演示如何通过 AQS - Advanced Query Syntax 搜索本地文件

FileSystem/AQS.xaml.cs

 
 

/*

 * 演示如何通过 AQS - Advanced Query Syntax 搜索本地文件

 */

using System;

using System.Collections.Generic;

using Windows.Storage;

using Windows.Storage.BulkAccess;

using Windows.Storage.FileProperties;

using Windows.Storage.Search;

using Windows.UI.Xaml.Controls;

using Windows.UI.Xaml.Navigation;

namespace XamlDemo.FileSystem

{

    public sealed partial class AQS : Page

    {

        public AQS()

        {

            this.InitializeComponent();

        }

        protected async override void OnNavigatedTo(NavigationEventArgs e)

        {

            // 准备在“音乐库”中进行搜索（需要在 Package.appxmanifest 的“功能”中选中“音乐库”）

            StorageFolder musicFolder = KnownFolders.MusicLibrary;

            // 准备搜索所有类型的文件

            List<string> fileTypeFilter = new List<string>();

            fileTypeFilter.Add("*");

            // 搜索的查询参数

            QueryOptions queryOptions = new QueryOptions(CommonFileQuery.OrderByDate, fileTypeFilter);

            // 指定 AQS 字符串，参见 http://msdn.microsoft.com/zh-cn/library/windows/apps/aa965711.aspx

            queryOptions.UserSearchFilter = "五月天";

            // 根据指定的参数创建一个查询

            StorageFileQueryResult fileQuery = musicFolder.CreateFileQueryWithOptions(queryOptions);

            lblMsg.Text = "在音乐库中搜索“五月天”，结果如下：";

            lblMsg.Text += Environment.NewLine;

            // 开始搜索，并返回检索到的文件列表

            IReadOnlyList<StorageFile> files = await fileQuery.GetFilesAsync();

            if (files.Count == 0)

            {

                lblMsg.Text += "什么都没搜到";

            }

            else

            {

                foreach (StorageFile file in files)

                {

                    lblMsg.Text += file.Name;

                    lblMsg.Text += Environment.NewLine;

                }

            }

            // 关于 QueryOptions 的一些用法，更详细的 QueryOptions 的说明请参见 msdn

            queryOptions = new QueryOptions();

            queryOptions.FolderDepth = FolderDepth.Deep;

            queryOptions.IndexerOption = IndexerOption.UseIndexerWhenAvailable;

            queryOptions.SortOrder.Clear();

            var sortEntry = new SortEntry();

            sortEntry.PropertyName = "System.FileName";

            sortEntry.AscendingOrder = true;

            queryOptions.SortOrder.Add(sortEntry);

            fileQuery = KnownFolders.PicturesLibrary.CreateFileQueryWithOptions(queryOptions);

        }

    }

}

 
 

获取文件的缩略图Thumbnail和通过 AQS - Advanced Query Syntax 搜索本地文件的相关教程结束。