feat: UseCache 选项和异步加载图片

Plain Craft Launcher 2/Controls/MyImage.vb

@@ -1,9 +1,24 @@
-Public Class MyImage
+Imports System.Threading.Tasks
+
+Public Class MyImage
     Inherits Image
 
     '事件
 
     Private _SourceData As String = ""
+    Private _UseCache As Boolean = False
+    Private _DownloadTask As Task
+
+    Private FileCacheExpiredTime As TimeSpan = New TimeSpan(7, 0, 0, 0) ' 一个星期的缓存有效期
+
+    Public Property UseCache As Boolean
+        Get
+            Return _UseCache
+        End Get
+        Set(value As Boolean)
+            _UseCache = value
+        End Set
+    End Property
 
     ''' <summary>
     ''' 重写Image的Source属性
@@ -15,7 +30,32 @@
         Set(value As String)
             If String.IsNullOrEmpty(value) Then Exit Property
             _SourceData = value
-            MyBase.Source = New MyBitmap(_SourceData)
+            If Not value.StartsWithF("http") Then ' 本地资源直接使用
+                MyBase.Source = New MyBitmap(_SourceData)
+                Exit Property
+            End If
+            If _DownloadTask IsNot Nothing AndAlso Not _DownloadTask.IsCompleted Then ' 之前下载任务还在，直接砍了
+                _DownloadTask.Dispose()
+            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 And File.Exists(TempFilePath) And (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)
+                Exit Property
+            End If
+            ' 异步下载图片
+            Dim TaskID = 0
+            _DownloadTask = New Task(Sub()
+                                         NetDownload(_SourceData, TempFilePath, True)
+                                     End Sub)
+            TaskID = _DownloadTask.Id
+            _DownloadTask.Start()
+            _DownloadTask.ContinueWith(Sub(t)
+                                           If t.IsCompleted AndAlso t.Id = TaskID Then ' 任务没有被干掉
+                                               MyBase.Source = New MyBitmap(TempFilePath)
+                                           End If
+                                       End Sub, TaskScheduler.FromCurrentSynchronizationContext())
         End Set
     End Property
     Public Shared Shadows ReadOnly SourceProperty As DependencyProperty = DependencyProperty.Register("Source", GetType(String), GetType(MyImage), New PropertyMetadata(New PropertyChangedCallback(