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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,85 +1,116 @@ | ||
| Public Class MyImage | ||
| Public Class MyImage | ||
| Inherits Image | ||
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| Private FileCacheExpiredTime As TimeSpan = New TimeSpan(7, 0, 0, 0) ' 一个星期的缓存有效期 | ||
| #Region "辅助属性注册" | ||
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| ''' <summary> | ||
| ''' 是否使用缓存 | ||
| ''' 网络图片的缓存有效期。 | ||
| ''' 在这个时间后，才会重新尝试下载图片。 | ||
| ''' </summary> | ||
| ''' <returns></returns> | ||
| Public Property UseCache As Boolean | ||
| Public FileCacheExpiredTime As New TimeSpan(7, 0, 0, 0) '7 天 | ||
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| ''' <summary> | ||
| ''' 是否允许将网络图片存储到本地用作缓存。 | ||
| ''' </summary> | ||
| Public Property EnableCache As Boolean | ||
| Get | ||
| Return GetValue(UseCacheProperty) | ||
| Return _EnableCache | ||
| End Get | ||
| Set(value As Boolean) | ||
| SetValue(UseCacheProperty, value) | ||
| _EnableCache = value | ||
| End Set | ||
| End Property | ||
| Public Shared ReadOnly UseCacheProperty As DependencyProperty = DependencyProperty.Register("UseCache", GetType(Boolean), GetType(MyImage), New PropertyMetadata(True)) | ||
| Private _EnableCache As Boolean = True | ||
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| '将 Source 属性映射到 XAML | ||
| Public Shared Shadows ReadOnly SourceProperty As DependencyProperty = DependencyProperty.Register( | ||
| "Source", GetType(String), GetType(MyImage), New PropertyMetadata(New PropertyChangedCallback( | ||
| Sub(sender, e) If sender IsNot Nothing Then CType(sender, MyImage).Source = e.NewValue.ToString()))) | ||
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| #End Region | ||
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| Private _SourceData As String = "" | ||
| Private _Source As String = "" | ||
| ''' <summary> | ||
| ''' 重写Image的Source属性 | ||
| ''' 与 Image 的 Source 类似。 | ||
| ''' 若输入以 http 开头的字符串，则会尝试下载图片然后显示，图片会保存为本地缓存。 | ||
| ''' 支持 WebP 格式的图片。 | ||
| ''' </summary> | ||
| Public Shadows Property Source As String | ||
| Public Shadows Property Source As String '覆写 Image 的 Source 属性 | ||
| Get | ||
| Return _SourceData | ||
| Return _Source | ||
| End Get | ||
| Set(value As String) | ||
| If String.IsNullOrEmpty(value) Then Exit Property | ||
| _SourceData = value | ||
| If value = "" Then value = Nothing | ||
| If _Source = value Then Exit Property | ||
| _Source = value | ||
| Dim TempPath As String = $"{PathTemp}MyImage\{GetHash(value)}.png" | ||
| Try | ||
| If Not value.StartsWithF("http") Then ' 本地资源直接使用 | ||
| MyBase.Source = New MyBitmap(_SourceData) | ||
| '空 | ||
| If value Is Nothing Then | ||
| MyBase.Source = Nothing | ||
| Exit Property | ||
| End If | ||
| Dim NeedDownload As Boolean = True '是否需要下载/本地是否有有效缓存 | ||
| Dim TempFilePath As String = PathTemp & "Cache\MyImage\" & GetHash(_SourceData) & ".png" | ||
| If UseCache AndAlso File.Exists(TempFilePath) AndAlso (DateTime.Now - File.GetCreationTime(TempFilePath)) < FileCacheExpiredTime Then NeedDownload = False ' 缓存文件存在且未过期，不需要重下 | ||
| If Not NeedDownload Then | ||
| MyBase.Source = New MyBitmap(TempFilePath) | ||
| '本地图片 | ||
| If Not value.StartsWithF("http") Then | ||
| MyBase.Source = New MyBitmap(value) | ||
| Exit Property | ||
| End If | ||
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| If File.Exists(TempFilePath) Then '先显示着旧图片，下载新图片 | ||
| Rename(TempFilePath, TempFilePath & ".old") | ||
| MyBase.Source = New MyBitmap(TempFilePath & ".old") | ||
| '从缓存加载网络图片 | ||
| If EnableCache AndAlso File.Exists(TempPath) Then | ||
| MyBase.Source = New MyBitmap(TempPath) | ||
| If (Date.Now - File.GetCreationTime(TempPath)) < FileCacheExpiredTime Then | ||
| Exit Property '无需刷新缓存 | ||
| Else | ||
| File.Delete(TempPath) '需要刷新缓存 | ||
| End If | ||
| Else | ||
| MyBase.Source = Nothing '清空显示 | ||
| End If | ||
| ' 开一个线程下载在线图片 | ||
| RunInNewThread(Sub() PicLoader(_SourceData, TempFilePath), "MyImage PicLoader " & GetUuid() & "#", ThreadPriority.BelowNormal) | ||
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| '下载网络图片 | ||
| RunInNewThread( | ||
| Sub() | ||
| Dim Url As String = value '重新捕获变量，以检测在下载过程中 Source 被修改的情况 | ||
| Dim Retried As Boolean = False | ||
| RetryStart: | ||
| Dim TempDownloadingPath As String = TempPath & RandomInteger(0, 10000000) | ||
| Try | ||
| Log("[MyImage] 正在下载图片：" & Url) | ||
| NetDownload(Url, TempDownloadingPath, True) | ||
| If Url <> Source Then | ||
| '若 Source 在下载时被修改，则不显示 | ||
| File.Delete(TempDownloadingPath) | ||
| ElseIf EnableCache Then | ||
| '保存缓存并显示 | ||
| Rename(TempDownloadingPath, TempPath) | ||
| RunInUi(Sub() MyBase.Source = New MyBitmap(TempPath)) | ||
| Else | ||
| '直接显示 | ||
| RunInUiWait(Sub() MyBase.Source = New MyBitmap(TempDownloadingPath)) | ||
| File.Delete(TempDownloadingPath) | ||
| End If | ||
| Catch ex As Exception | ||
| Try | ||
| File.Delete(TempDownloadingPath) | ||
| Catch | ||
| End Try | ||
| If Not Retried Then | ||
| Log(ex, $"下载图片可重试地失败（{Url}）", LogLevel.Developer) | ||
| Retried = True | ||
| Thread.Sleep(1000) | ||
| GoTo RetryStart | ||
| Else | ||
| Log(ex, $"下载图片失败（{Url}）", LogLevel.Hint) | ||
| End If | ||
| End Try | ||
| End Sub, "MyImage PicLoader " & GetUuid() & "#", ThreadPriority.BelowNormal) | ||
| Catch ex As Exception | ||
| Log(ex, "加载图片失败") | ||
| Log(ex, $"加载图片失败（{value}）", LogLevel.Hint) | ||
| Try | ||
| File.Delete(TempPath) '删除缓存，以免缓存出现问题导致一直加载失败 | ||
| Catch | ||
| End Try | ||
| End Try | ||
| End Set | ||
| End Property | ||
| Public Shared Shadows ReadOnly SourceProperty As DependencyProperty = DependencyProperty.Register("Source", GetType(String), GetType(MyImage), New PropertyMetadata(New PropertyChangedCallback( | ||
| Sub(sender As DependencyObject, e As DependencyPropertyChangedEventArgs) | ||
| If Not IsNothing(sender) Then | ||
| If String.IsNullOrEmpty(e.NewValue.ToString()) Then Exit Sub | ||
| CType(sender, MyImage).Source = e.NewValue.ToString() | ||
| End If | ||
| End Sub))) | ||
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| Private Sub PicLoader(FileUrl As String, TempFilePath As String) | ||
| Dim Retried As Boolean = False | ||
| RetryStart: | ||
| Try | ||
| Dim UnCompleteFile As String = TempFilePath & ".dl" '加一个下载中的后缀，防止中途关闭程序下载中断但是没下完，从而导致第二次显示的是损坏的图片…… | ||
| NetDownload(FileUrl, UnCompleteFile) | ||
| Rename(UnCompleteFile, TempFilePath) | ||
| RunInUi(Sub() | ||
| MyBase.Source = New MyBitmap(TempFilePath) | ||
| End Sub) | ||
| File.Delete(TempFilePath & ".old") | ||
| Catch ex As Exception | ||
| If Not Retried Then | ||
| Retried = True | ||
| GoTo RetryStart | ||
| Else | ||
| Log(ex, $"[MyImage] 下载图片失败") | ||
| End If | ||
| End Try | ||
| End Sub | ||
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| End Class |