60 lines
1.9 KiB
C#
60 lines
1.9 KiB
C#
using System;
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using System.Collections.Concurrent;
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using System.Collections.Generic;
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using System.Globalization;
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using System.IO;
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using System.Linq;
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using System.Net;
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using System.Text;
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using System.Threading.Tasks;
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using System.Windows.Data;
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using System.Windows.Media.Imaging;
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using Work;
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namespace _29WxOrderWpf.Converters
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{
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public class ImageUrlToBitmapImageConverter : IValueConverter
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{
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/// <summary> 缓存上限，防止大量缩略图重复下载导致内存膨胀 </summary>
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private const int MaxCacheCount = 200;
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private readonly ConcurrentDictionary<string, BitmapImage> _imageCache = new ConcurrentDictionary<string, BitmapImage>();
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public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
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{
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if (value is string url && Uri.IsWellFormedUriString(url, UriKind.Absolute))
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{
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if (_imageCache.TryGetValue(url, out BitmapImage cached))
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{
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return cached;
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}
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try
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{
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// 直接加载绑定如果遇到有问题的网络图片会直接崩溃。
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BitmapImage bitMap = AllBase.ImageBuild.LoadBitmipImageFromUrl(url);
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if (bitMap != null)
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{
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if (_imageCache.Count >= MaxCacheCount)
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{
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_imageCache.Clear();
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}
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_imageCache[url] = bitMap;
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}
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return bitMap;
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}
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catch
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{
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}
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}
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return null;
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}
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public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
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{
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throw new NotImplementedException(); // 不需要反向转换，所以不实现。
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}
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}
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}
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