170 lines
4.2 KiB
C#
170 lines
4.2 KiB
C#
using OrderSupportTicket.Models.Api;
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using OrderSupportTicket.Services;
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using System;
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using System.Globalization;
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using System.Threading.Tasks;
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using System.Windows;
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using System.Windows.Media;
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using WPFCommon.Models;
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namespace OrderSupportTicket.ViewModels;
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/// <summary>
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/// 留言气泡中的公开图片附件。
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/// </summary>
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public sealed class ChatAttachmentViewModel : BindableBaseEx
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{
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private bool _isLoading;
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private bool _isLoadFailed;
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private ImageSource _image;
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public ChatAttachmentViewModel(TicketAttachmentDto dto)
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{
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if (dto == null)
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throw new ArgumentNullException(nameof(dto));
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Id = dto.Id;
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OriginalName = dto.OriginalName;
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ContentType = dto.ContentType;
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ByteSize = dto.ByteSize;
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ReadUrl = dto.ReadUrl;
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}
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/// <summary>
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/// 附件唯一 ID。
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/// </summary>
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public string Id { get; }
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/// <summary>
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/// 原始文件名。
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/// </summary>
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public string OriginalName { get; }
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/// <summary>
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/// 图片 MIME 类型。
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/// </summary>
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public string ContentType { get; }
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/// <summary>
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/// 图片字节数。
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/// </summary>
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public long ByteSize { get; }
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/// <summary>
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/// 服务端生成的短时读取地址。
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/// </summary>
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public string ReadUrl { get; }
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/// <summary>
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/// 已下载并解码的图片；加载完成前为空。
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/// </summary>
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public ImageSource Image
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{
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get => _image;
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private set
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{
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if (SetValue(ref _image, value))
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RaisePropertyChanged(nameof(HasImage));
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}
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}
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/// <summary>
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/// 是否已成功显示图片。
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/// </summary>
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public bool HasImage => Image != null;
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/// <summary>
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/// 图片是否已经确认加载失败。加载完成前保持为 false。
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/// </summary>
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public bool IsLoadFailed
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{
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get => _isLoadFailed;
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private set
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{
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if (SetValue(ref _isLoadFailed, value))
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RaisePropertyChanged(nameof(ToolTipText));
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}
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}
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/// <summary>
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/// 附件名称、大小与加载状态提示。
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/// </summary>
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public string ToolTipText
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{
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get
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{
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var name = string.IsNullOrWhiteSpace(OriginalName) ? "图片" : OriginalName;
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var size = FormatSize(ByteSize);
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if (string.IsNullOrWhiteSpace(ReadUrl))
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return name + "（" + size + "，暂不可用）";
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if (_isLoading)
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return name + "（" + size + "，加载中…）";
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if (IsLoadFailed)
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return name + "（" + size + "，加载失败）";
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return name + "（" + size + "）";
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}
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}
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/// <summary>
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/// 下载并解码短时读取地址。失败时保留占位提示，不阻断文字留言展示。
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/// </summary>
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public async Task LoadAsync()
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{
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if (Image != null || _isLoading)
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return;
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if (string.IsNullOrWhiteSpace(ReadUrl))
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{
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IsLoadFailed = true;
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return;
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}
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IsLoadFailed = false;
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_isLoading = true;
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RaisePropertyChanged(nameof(ToolTipText));
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try
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{
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var image = await ProductImageLoader.LoadAsync(ReadUrl);
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if (image == null)
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IsLoadFailed = true;
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else
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await SetImageAsync(image);
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}
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catch
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{
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IsLoadFailed = true;
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}
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finally
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{
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_isLoading = false;
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RaisePropertyChanged(nameof(ToolTipText));
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}
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}
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private async Task SetImageAsync(ImageSource image)
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{
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if (image == null)
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return;
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var dispatcher = Application.Current?.Dispatcher;
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if (dispatcher == null || dispatcher.CheckAccess())
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{
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Image = image;
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IsLoadFailed = false;
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return;
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}
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await dispatcher.InvokeAsync(() =>
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{
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Image = image;
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IsLoadFailed = false;
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});
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}
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private static string FormatSize(long byteSize)
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{
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if (byteSize >= 1024 * 1024)
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return (byteSize / 1024d / 1024d).ToString("0.0", CultureInfo.CurrentCulture) + " MB";
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if (byteSize >= 1024)
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return (byteSize / 1024d).ToString("0.0", CultureInfo.CurrentCulture) + " KB";
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return byteSize.ToString(CultureInfo.CurrentCulture) + " B";
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}
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}
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