效果图

素材

代码

 Dim B0, B1, B3 As Bitmap
    Private B As Bitmap = Nothing
    Private Sub Loading_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        B0 = My.Resources.P0.Clone
        B1 = My.Resources.P1.Clone
        B3 = My.Resources.P3.Clone
        Me.Show()
    End Sub

    Private Sub Play()
        For I As Single = 0.1 To 1.5 Step 0.02
            If Me.Disposing Then Exit Sub
            MakeBg(I)
            Threading.Thread.Sleep(10)
            Application.DoEvents()
        Next
        MakeBg(1.5)
        Threading.Thread.Sleep(2000)
        For I As Single = 255 To 0 Step -1
            If Me.Disposing Then Exit Sub
            DSAPI.控件.Form窗体.透明窗体样式显示图像(Me, B, I)
            Application.DoEvents()
        Next
    End Sub
    Private Sub MakeBg(Db As Single)
        Try
            If B IsNot Nothing Then B.Dispose()
            B = Nothing
            If Db < 1.5 Then
                B = B0.Clone
                Using G As Graphics = Graphics.FromImage(B)
                    G.Clip = New Region(New Rectangle(0, 0, 625, 656))
                    Dim _B1 As Bitmap = New Bitmap(625, 656)
                    Using G2 As Graphics = Graphics.FromImage(_B1)
                        G2.Clip = New Region(New RectangleF(0, 0, 625, 656))
                        Dim W, H As Integer
                        Dim _B As Bitmap = MakeImg(Db)
                        W = (625 - _B.Width) / 2
                        H = (656 - _B.Height) / 2
                        G2.DrawImage(_B, New Rectangle(W, H, _B.Width, _B.Height), New Rectangle(0, 0, _B.Width, _B.Height), GraphicsUnit.Pixel)
                        _B.Dispose()
                    End Using
                    Dim _B3 As Bitmap = B1.Clone
                    DSAPI.图形图像.应用透明度遮罩(_B3, _B1)
                    _B1.Dispose()
                    G.DrawImage(_B3, New Rectangle(0, 0, 625, 656), New Rectangle(0, 0, 625, 656), GraphicsUnit.Pixel)
                End Using
            Else
                B = B1.Clone
            End If
            DSAPI.控件.Form窗体.透明窗体样式显示图像(Me, B, 255)
        Catch
        End Try
    End Sub

    Private Sub Loading_Shown(sender As Object, e As EventArgs) Handles Me.Shown
        For I As Single = 0 To 255
            DSAPI.控件.Form窗体.透明窗体样式显示图像(Me, B0, I)
            Application.DoEvents()
            If Me.Opacity = 0 Then Me.Opacity = 1
        Next
        Play()
        Me.Close()
    End Sub

    Private Function MakeImg(Db As Single) As Bitmap
        Try
            Dim W, H As Integer
            W = 410 * Db
            H = 431 * Db
            Dim BB As New Bitmap(W, H)
            Using G As Graphics = Graphics.FromImage(BB)
                G.Clip = New Region(New Rectangle(0, 0, W, H))
                G.DrawImage(B3, New Rectangle(0, 0, W, H), New Rectangle(0, 0, 410, 431), GraphicsUnit.Pixel)
            End Using
            Return BB
        Catch
            Return Nothing
        End Try
    End Function

　　原理：

1 缩放黑影大小，并绘制到和花图一样的图片上

2 使用黑影图作为花图的透明度遮罩，有黑影的地方不透明，其他地方透明

3 将花图绘制到灰白的花上