UWP 保存音乐或视频缩略图图片到本地
开发项目时，有时需要将本地媒体文件的缩略图保存到本地，下面是源码。
需要打开Package.appxmanifest 功能 图片库 访问权限。
<Page
x:Class="SaveBitmap.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:SaveBitmap"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Grid>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Image x:Name="image"/>
<Button x:Name="filePicker_bt" Grid.Row="1" Content="FelePicker" Tapped="filePicker_bt_Tapped" HorizontalAlignment="Left"/>
<Button x:Name="savePicture_bt" Grid.Row="1" Content="SavePicture" Tapped="savePicture_bt_Tapped" HorizontalAlignment="Right"/>
</Grid>
</Page>
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using System.Threading.Tasks;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.Graphics.Display;
using Windows.Graphics.Imaging;
using Windows.Storage;
using Windows.Storage.FileProperties;
using Windows.Storage.Pickers;
using Windows.UI.Popups;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Media.Imaging;
using Windows.UI.Xaml.Navigation;
// https://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x804 上介绍了“空白页”项模板
namespace SaveBitmap
{
/// <summary>
/// 可用于自身或导航至 Frame 内部的空白页。
/// </summary>
public sealed partial class MainPage : Page
{
public MainPage()
{
this.InitializeComponent();
}
private StorageFile save_file;
private async void filePicker_bt_Tapped(object sender, TappedRoutedEventArgs e)
{
FileOpenPicker file_picker = new FileOpenPicker();
file_picker.FileTypeFilter.Add(".mp4");
file_picker.FileTypeFilter.Add(".mp3");
save_file = await file_picker.PickSingleFileAsync();
try//防止专辑图片为空
{
using (var thumbnail = await save_file.GetThumbnailAsync(ThumbnailMode.MusicView, 200))//获取媒体专辑image
{
var video_cover = new BitmapImage();
video_cover.SetSource(thumbnail);
image.Source = video_cover;
}
}
catch
{
}
}
private async void savePicture_bt_Tapped(object sender, TappedRoutedEventArgs e)
{
try
{
await SaveImage(save_file, image);
bool result = await Windows.System.Launcher.LaunchFolderAsync(saved_folder);
}
catch (Exception error)
{
var message = new MessageDialog(error.ToString());
await message.ShowAsync();
}
}
private StorageFolder saved_folder;
private async Task<StorageFile> SaveImage(StorageFile file,Image image)
{
string desiredName = file.DisplayName + ".jpg";
saved_folder = await KnownFolders.PicturesLibrary.CreateFolderAsync("Saved Picture", CreationCollisionOption.OpenIfExists);
var saveFile = await saved_folder.CreateFileAsync(desiredName, CreationCollisionOption.GenerateUniqueName);
try
{
RenderTargetBitmap bitmap = new RenderTargetBitmap();
await bitmap.RenderAsync(image);
var pixelBuffer = await bitmap.GetPixelsAsync();
using (var fileStream = await saveFile.OpenAsync(FileAccessMode.ReadWrite))
{
var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, fileStream);
encoder.SetPixelData(BitmapPixelFormat.Bgra8,
BitmapAlphaMode.Ignore,
(uint)bitmap.PixelWidth,
(uint)bitmap.PixelHeight,
DisplayInformation.GetForCurrentView().LogicalDpi,
DisplayInformation.GetForCurrentView().LogicalDpi,
pixelBuffer.ToArray());
await encoder.FlushAsync();
}
}
catch
{
}
return saveFile;
}
}
}
运行截图
