最近有個需求是當程式在做複雜的運算時，需要告知使用者程式仍然運作，而若用彈出單一Loading對話框的方式又不太適用，因此會想跟網頁一樣能在控制項上外加載入動畫。
在找不到更好的解法前，這邊我先考慮用擴充方法來實作這樣的需求功能。主要是利用擴充方法啟動控制項的載入畫面，啟動多執行緒去更新載入動畫。程式碼如下： #Region “Imports” Imports System.Runtime.CompilerServices Imports System.Collections.Specialized Imports System.Windows.Forms Imports System.Drawing Imports System.Threading Imports System.Drawing.Imaging
#End Region
Public Module ControlLoadingExtension
#Region “Class” Class LoadingInfo Private _loaddingBmp As Image Private _loaddingBmpActiveFrameIdx As Integer Private _loaddingBmpDimension As FrameDimension Private _loaddingBmpFrameCount As Integer Private _displayLocation As Point
Property LoaddingBmp As Image Get Return _loaddingBmp End Get Set(ByVal value As Image) If _loaddingBmp IsNot value Then _loaddingBmp = value LoaddingBmpDimension = New FrameDimension(value.FrameDimensionsList(0)) LoaddingBmpFrameCount = value.GetFrameCount(LoaddingBmpDimension) LoaddingBmpActiveFrameIdx = 0 End If End Set End Property
Property LoaddingBmpActiveFrameIdx As Integer Get Return _loaddingBmpActiveFrameIdx End Get Set(ByVal value As Integer) _loaddingBmpActiveFrameIdx = value LoaddingBmp.SelectActiveFrame(LoaddingBmpDimension, value) End Set End Property
Property LoaddingBmpDimension As FrameDimension Get Return _loaddingBmpDimension End Get Private Set(ByVal value As FrameDimension) _loaddingBmpDimension = value End Set End Property
Property LoaddingBmpFrameCount As Integer Get Return _loaddingBmpFrameCount End Get Private Set(ByVal value As Integer) _loaddingBmpFrameCount = value End Set End Property
Property DisplayLocation As Point Get Return _displayLocation End Get Set(ByVal value As Point) _displayLocation = value End Set End Property End Class #End Region
#Region “Var” Private _loadingStatePool As HybridDictionary Private _updateThread As Thread #End Region
#Region “Private Property” Private ReadOnly Property m_LoadingStatePool() As HybridDictionary Get If _loadingStatePool Is Nothing Then _loadingStatePool = New HybridDictionary End If Return _loadingStatePool End Get End Property
Private Property m_UpdateThread As Thread Get If _updateThread Is Nothing Then _updateThread = New Thread(AddressOf ThreadingUpdatePhoto) With {.IsBackground = True} End If Return _updateThread End Get Set(ByVal value As Thread) _updateThread = value End Set End Property #End Region
#Region “Private Method” Private Sub InvalidLoaddingBmp(ByVal ctrl As Control) Dim info As LoadingInfo = DirectCast(m_LoadingStatePool(ctrl), LoadingInfo) ctrl.Invalidate(New Rectangle(info.DisplayLocation, info.LoaddingBmp.Size)) End Sub
Private Sub BindingControlEvent(ByVal ctrl As Control) UnBindingControlEvent(ctrl) AddHandler ctrl.Paint, AddressOf Control_Paint AddHandler ctrl.HandleDestroyed, AddressOf Control_HandleDestroyed AddHandler ctrl.Resize, AddressOf Control_Resize End Sub
Private Sub UnBindingControlEvent(ByVal ctrl As Control) RemoveHandler ctrl.Paint, AddressOf Control_Paint RemoveHandler ctrl.HandleDestroyed, AddressOf Control_HandleDestroyed RemoveHandler ctrl.Resize, AddressOf Control_Resize End Sub
Private Function GetDisplayLocation(ByVal ctrl As Control) As Point Dim info As LoadingInfo = DirectCast(m_LoadingStatePool(ctrl), LoadingInfo) Dim bmp As Bitmap = info.LoaddingBmp Return New Point(ctrl.Width \ 2 - bmp.Width \ 2, ctrl.Height \ 2 - bmp.Height \ 2) End Function
Private Sub AdjustDisplayLocation(ByVal ctrl As Control) Dim info As LoadingInfo = DirectCast(m_LoadingStatePool(ctrl), LoadingInfo) Dim bmp As Bitmap = info.LoaddingBmp info.DisplayLocation = GetDisplayLocation(ctrl) End Sub
Private Sub PaintGraphic(ByVal g As Graphics, ByVal ctrl As Control) Dim info As LoadingInfo = DirectCast(m_LoadingStatePool(ctrl), LoadingInfo) Dim bmp As Bitmap = info.LoaddingBmp info.LoaddingBmpActiveFrameIdx = (info.LoaddingBmpActiveFrameIdx + 1) Mod info.LoaddingBmpFrameCount g.DrawImage(bmp, info.DisplayLocation) End Sub
Private Sub ThreadingUpdatePhoto() While True For idx As Integer = m_LoadingStatePool.Count - 1 To 0 Step -1 InvalidLoaddingBmp(DirectCast(m_LoadingStatePool.Keys(idx), Control)) Next Thread.Sleep(100) End While End Sub #End Region
#Region “Public Method” _ Function IsLoadingState(ByVal ctrl As Control) As Boolean Return m_LoadingStatePool.Contains(ctrl) End Function
_ Sub ActiveLoadingState(ByVal ctrl As Control, ByVal loaddingBmp As Image) If loaddingBmp Is Nothing Then Throw New ArgumentNullException(“loaddingBmp”) End If DeActiveLoadingState(ctrl) m_LoadingStatePool.Add(ctrl, New LoadingInfo() With {.LoaddingBmp = loaddingBmp}) AdjustDisplayLocation(ctrl) BindingControlEvent(ctrl) If m_LoadingStatePool.Count = 1 Then m_UpdateThread.Start() End If End Sub
_ Sub DeActiveLoadingState(ByVal ctrl As Control) If IsLoadingState(ctrl) Then UnBindingControlEvent(ctrl) m_LoadingStatePool.Remove(ctrl) ctrl.Invalidate() End If If m_LoadingStatePool.Count = 0 Then Try m_UpdateThread.Abort() Catch ex As Exception Finally m_UpdateThread = Nothing End Try End If End Sub #End Region
#Region “Event Process” Private Sub Control_Paint(ByVal sender As Object, ByVal e As PaintEventArgs) PaintGraphic(e.Graphics, DirectCast(sender, Control)) End Sub
Private Sub Control_HandleDestroyed(ByVal sender As Object, ByVal e As EventArgs) DeActiveLoadingState(DirectCast(sender, Control)) End Sub
Private Sub Control_Resize(ByVal sender As Object, ByVal e As EventArgs) AdjustDisplayLocation(DirectCast(sender, Control)) End Sub #End Region End Module
範例介面如下：
範例程式碼如下：
Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click For Each c As Control In Me.Controls c.ActiveLoadingState(My.Resources.ajax_loader__1_) Next End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click For Each c As Control In Me.Controls c.DeActiveLoadingState() Next End Sub End Class
運行結果如下：