DataGridView 中的动画图像

Question

我编写了下面的帮助程序类，以便为 DataGridView 中的图像设置动画，但它不起作用（图像没有动画）。

在此之前，我在wen上找到了一些示例代码，但它们也不起作用。

我想了解它是如何工作的，而不是仅仅因为它有效就在我的应用中塞进一段代码。为什么我的代码没有达到预期的效果？

编辑

我发现了它不起作用的原因。源DataTable 本身不包含图像：它们通过其CellFormatting 处理程序方法分配给代码中其他地方的DataGridView 的单元格。由于这个事件也一直触发，所以总是传递一个新的图像对象，所以它总是显示图像的第 1 帧。当我创建一个存储有原生图像值的新列时，它们会根据需要进行动画处理。

现在的问题是：是否可以在DataGridView 的CellFormatting 事件处理方法中为分配给.FormattedValue 属性的图像设置动画？

Public Class DataGridViewImageAnimator

    Private WithEvents MyDataGridView As DataGridView

    Public Sub New(dataGridView As DataGridView)

        MyDataGridView = dataGridView

    End Sub

    Private MyAnimatedImages As New Dictionary(Of Point, Image)

    Private Sub ImageAnimator_FrameChanged(sender As Object, e As EventArgs)

        Dim imageCells = MyDataGridView.Rows.Cast(Of DataGridViewRow).SelectMany(
            Function(dgvr) dgvr.Cells.OfType(Of DataGridViewImageCell))

        For Each cell In imageCells

            Dim img = TryCast(cell.FormattedValue, Image)

            If img IsNot Nothing AndAlso MyAnimatedImages.ContainsValue(img) Then

                MyDataGridView.InvalidateCell(cell)

            End If
        Next

    End Sub

    Private Sub MyDataGridView_CellPainting(
            sender As Object,
            e As DataGridViewCellPaintingEventArgs
            ) Handles MyDataGridView.CellPainting

        If e.ColumnIndex >= 0 AndAlso e.RowIndex >= 0 Then

            Dim cell = MyDataGridView(e.ColumnIndex, e.RowIndex)

            Dim drawPoint = MyDataGridView.GetCellDisplayRectangle(e.ColumnIndex, e.RowIndex, True).Location

            Dim pt = New Point(e.ColumnIndex, e.RowIndex)

            Dim cellImg = TryCast(cell.FormattedValue, Image)

            If MyAnimatedImages.ContainsKey(pt) AndAlso Equals(MyAnimatedImages(pt), cellImg) Then
                'If image is already registered as animated, and is still in cell

                ImageAnimator.UpdateFrames()

                e.Graphics.DrawImage(cellImg, drawPoint)

            Else

                If MyAnimatedImages.ContainsKey(pt) Then
                    'If image registered as animated is no longer in cell

                    ImageAnimator.StopAnimate(MyAnimatedImages(pt), AddressOf ImageAnimator_FrameChanged)

                    MyAnimatedImages.Remove(pt)

                End If

                If cellImg IsNot Nothing AndAlso ImageAnimator.CanAnimate(cellImg) Then
                    'If cell contains an image not yet registered as animated

                    MyAnimatedImages(pt) = cellImg

                    ImageAnimator.Animate(MyAnimatedImages(pt), AddressOf ImageAnimator_FrameChanged)

                    ImageAnimator.UpdateFrames()

                    e.Graphics.DrawImage(cellImg, drawPoint)

                End If

            End If

        End If

    End Sub

End Class

Answer 1

带有自定义单元格的自定义列提供了一些优势。

所有设计逻辑都集中在一个地方，并且可以在设计时使用DataGridView设计器将其选为列模板。

性能相当好（用 200 个动画单元测试），我没有注意到任何闪烁。

可以像往常一样使用设计器设置、通过代码或手动调整行/列的大小来拉伸或缩放动画 Gif。

但是，我不能认为它是完整的，因为我找不到使用此自定义 Column 类方法或属性来启动所有动画的好方法。

编辑：
向DataGridView (DataGridView.Animate()) 添加了扩展方法。
这允许隐藏无效过程。
DataGridView数据绑定完成后，只需调用扩展方法即可：

DataGridView1.DataSource = [DataSource]
DataGridView1.Animate()

包含扩展方法的模块：

Imports System.Runtime.CompilerServices

Module DGVExtesions

    <Extension()>
    Public Sub Animate(ByVal AnimatedGrid As DataGridView)
        Try
            For Each row As DataGridViewRow In AnimatedGrid.Rows
                For Each cell As DataGridViewCell In row.Cells.OfType(Of AnimatedDGVColumn.AnimatedCell)()
                    AnimatedGrid.InvalidateCell(cell)
                Next
            Next
        Catch ex As Exception
            Trace.WriteLine("Exception: {0}", ex.Message)
        End Try

    End Sub

End Module

当然，这还不够好。需要进行更多研究。

这是自定义动画列类：

Imports System.ComponentModel
Imports System.Windows.Forms

Public Class AnimatedDGVColumn
    Inherits System.Windows.Forms.DataGridViewColumn

    Private custCellTemplate As AnimatedCell

    Public Sub New()
        Me.custCellTemplate = New AnimatedCell
        Me.custCellTemplate.ImageLayout = DataGridViewImageCellLayout.Zoom
        MyBase.CellTemplate = custCellTemplate
        Me.AutoSizeMode = DataGridViewAutoSizeColumnMode.None
        Me.DefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleCenter
    End Sub

    <Description("The ImageLayout in the Cells for this Column"), Category("Appearance")> _
    <EditorBrowsable(EditorBrowsableState.Always), Browsable(True)>
    Public Property ImageLayout As DataGridViewImageCellLayout
        Get
            Return Me.custCellTemplate.ImageLayout
        End Get
        Set(ByVal value As DataGridViewImageCellLayout)
            Me.custCellTemplate.ImageLayout = value
        End Set
    End Property

    Public Overloads Property CellTemplate As AnimatedCell
        Get
            Return Me.custCellTemplate
        End Get
        Set(value As AnimatedCell)
            Me.custCellTemplate = value
            MyBase.CellTemplate = value
        End Set
    End Property

    Public Class AnimatedCell
        Inherits System.Windows.Forms.DataGridViewImageCell

        Private Animation As Image
        Private IsAnimating As Boolean

        Public Sub New()
            Me.Animation = Nothing
            Me.IsAnimating = False
        End Sub

        Public Overloads Property ImageLayout() As DataGridViewImageCellLayout
            Get
                Return MyBase.ImageLayout
            End Get
            Set(ByVal value As DataGridViewImageCellLayout)
                MyBase.ImageLayout = value
            End Set
        End Property

        Protected Overrides Sub Paint(graphics As Graphics, clipBounds As Rectangle, cellBounds As Rectangle, rowIndex As Integer, elementState As DataGridViewElementStates, value As Object, formattedValue As Object, errorText As String, cellStyle As DataGridViewCellStyle, advancedBorderStyle As DataGridViewAdvancedBorderStyle, paintParts As DataGridViewPaintParts)
            If (IsDBNull(value)) OrElse (value Is Nothing) Then Return
            If Me.Animation Is Nothing Then
                Me.Animation = CType(formattedValue, Image)
            End If
            Animate()
            ImageAnimator.UpdateFrames()

            MyBase.Paint(graphics, clipBounds, cellBounds, rowIndex, elementState, Nothing, Me.Animation, errorText, cellStyle, advancedBorderStyle, paintParts)
        End Sub

        Private Sub Animate()
            If Me.IsAnimating = True Then Return
            If (Me.Animation IsNot Nothing) AndAlso ImageAnimator.CanAnimate(Me.Animation) = True Then
                ImageAnimator.Animate(Me.Animation, AddressOf Me.RotateFrame)
                Me.IsAnimating = True
            End If
        End Sub

        Private Sub RotateFrame(o As Object, e As EventArgs)
            If Me.RowIndex > -1 Then
                Me.DataGridView.InvalidateCell(Me)
            End If
        End Sub

        Public Overrides Function Clone() As Object
            Dim result As AnimatedCell = New AnimatedCell With {
                        .IsAnimating = False,
                        .Animation = Nothing,
                        .ImageLayout = Me.ImageLayout
                        }
            Return result
        End Function

    End Class

End Class