' Silverlight Speed Tutorial VB source-code

' Written by John Bower, Deep Space Objects

' =========================================

Partial Public Class Page

    Inherits Canvas

    Dim imgSprite As New Image      ' Create new Image

    Dim txtFPS As New TextBlock   ' Create new TextBlock

    Dim cParent As Canvas        ' Create cParent

    Dim sbLoop As New Storyboard

    Dim intX, intY As Integer

    Dim movingLeft, movingUp As Boolean

    Dim FrameRate, LastTime As Integer

    ' Page_Loaded - Called when the canvas is loaded

    ' ================================================

    Public Sub Page_Loaded(ByVal o As Object, ByVal e As EventArgs)

        ' Required to initialize variables

        InitializeComponent()

        ' set rootCanvas to the canvas that called this function

        cParent = FindName("parentCanvas")

        ' Create Image

        attachImage()

        ' Create FPS TextBlock

        attachFPSText()

        ' Create Storyboard

        attachStoryboard()

    End Sub

    ' Image attachment - Adds an Image object ot the canvas

    ' =====================================================

    Private Sub attachImage()

        ' Set up the new Image object

        imgSprite.Source = New Uri("images/car.jpg", UriKind.Relative)

        ' Add the Image to the Parent Canvas

        cParent.Children.Add(imgSprite)

    End Sub

    ' FPS attachment - Adds FPS textblock to the canvas

    ' =================================================

    Private Sub attachFPSText()

        ' add textblock to canvas

        cParent.Children.Add(txtFPS)

    End Sub

    ' Storyboard attachment - Adds the storyboard to the Canvas

    ' =========================================================

    Private Sub attachStoryboard()

        ' set up the new Storyboard

        sbLoop.SetValue(Storyboard.NameProperty, "loop")

        ' Add the Storyboard to the Canvas

        cParent.Resources.Add(sbLoop)

        AddHandler sbLoop.Completed, AddressOf loop_Completed

        ' Start playing the Storyboard loop

        sbLoop.Begin()

    End Sub

    ' Loop function - Handles storyboard.completed event

    ' ==================================================

    Private Sub loop_Completed(ByVal sender As Object, ByVal e As EventArgs)

        ' Update frame rate

        updateFPS()

        ' Y-Axis logic

        If movingUp Then

            intY -= 1 ' update Y

            If intY < 0 Then ' bounce

                movingUp = Not movingUp

            End If

        Else

            intY += 1 ' update Y

            If intY > (cParent.Height - imgSprite.Height) Then ' bounce

                movingUp = Not movingUp

            End If

        End If

        ' X-Axis logic

        If movingLeft Then

            intX -= 2 ' update X

            If intX < 0 Then ' bounce

                movingLeft = Not movingLeft

            End If

        Else

            intX += 2 ' update X

            If intX > (cParent.Width - imgSprite.Width) Then ' bounce

                movingLeft = Not movingLeft

            End If

        End If

        ' Update the Image object's position

        imgSprite.SetValue(Canvas.LeftProperty, intX)

        imgSprite.SetValue(Canvas.TopProperty, intY)

        ' Restart the Storyboard

        sbLoop.Begin()

    End Sub

    ' Frames per second - Updates FPS variables

    ' =========================================

    Private Sub updateFPS()

        If LastTime > Date.Now.Millisecond Then

            txtFPS.Text = "FPS: " & FrameRate

            FrameRate = 0

            LastTime = Date.Now.Millisecond

        Else

            LastTime = Date.Now.Millisecond

            FrameRate += 1

        End If

    End Sub

End Class