langs a-z

Task/Image-noise/Visual-Basic-.NET/image-noise.visual

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+Imports System.Drawing.Imaging
+
+Public Class frmSnowExercise
+
+  Dim bRunning As Boolean = True
+
+  Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
+
+    ' Tell windows we want to handle all the painting and that we want it to double buffer
+    ' the form's rectangle (Double Buffering removes/reduces flickering).
+    SetStyle(ControlStyles.AllPaintingInWmPaint Or ControlStyles.UserPaint Or ControlStyles.OptimizedDoubleBuffer, True)
+    UpdateStyles()
+
+    ' Prevent the user from resizing the window. Our draw code is not
+    ' setup to recalculate on the fly.
+    FormBorderStyle = Windows.Forms.FormBorderStyle.FixedSingle
+    MaximizeBox = False
+
+    ' The window size and the client rectangle aren't the same.
+    ' To get the proper dimensions for our exercise we need to
+    ' figure out the difference and add it to our 320x240
+    ' requirement.
+    Width = 320 + Size.Width - ClientSize.Width
+    Height = 240 + Size.Height - ClientSize.Height
+
+    ' Pop the window, bring it to the front and give windows time to
+    ' reflect the changes.
+    Show()
+    Activate()
+    Application.DoEvents()
+
+    ' Hit the loop and keep going until we receive a close request.
+    RenderLoop()
+
+    ' We're done. Exit the application.
+    Close()
+
+  End Sub
+
+  Private Sub Form1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles Me.KeyPress
+    ' Close the application when the user hits escape.
+    If e.KeyChar = ChrW(Keys.Escape) Then bRunning = False
+  End Sub
+
+  Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
+    ' We'll cancel the form close request if we're still running so we don't get an error during runtime and set the close request flag.
+    e.Cancel = bRunning
+    bRunning = False
+  End Sub
+
+  Private Sub RenderLoop()
+
+    Const cfPadding As Single = 5.0F
+
+    Dim b As New Bitmap(ClientSize.Width, ClientSize.Width, PixelFormat.Format32bppArgb)
+    Dim g As Graphics = Graphics.FromImage(b)
+    Dim r As New Random(Now.Millisecond)
+    Dim oBMPData As BitmapData = Nothing
+    Dim oPixels() As Integer = Nothing
+    Dim oBlackWhite() As Integer = {Color.White.ToArgb, Color.Black.ToArgb}
+    Dim oStopwatch As New Stopwatch
+    Dim fElapsed As Single = 0.0F
+    Dim iLoops As Integer = 0
+    Dim sFPS As String = "0.0 FPS"
+    Dim oFPSSize As SizeF = g.MeasureString(sFPS, Font)
+    Dim oFPSBG As RectangleF = New RectangleF(ClientSize.Width - cfPadding - oFPSSize.Width, cfPadding, oFPSSize.Width, oFPSSize.Height)
+
+    ' Get ourselves a nice, clean, black canvas to work with.
+    g.Clear(Color.Black)
+
+    ' Prep our bitmap for a read.
+    oBMPData = b.LockBits(New Rectangle(0, 0, b.Width, b.Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb)
+
+    ' Allocate sufficient space for the pixel data and
+    ' flash copy it to our array.
+    ' We want an integer to hold the color for each pixel in the canvas.
+    Array.Resize(oPixels, b.Width * b.Height)
+    Runtime.InteropServices.Marshal.Copy(oBMPData.Scan0, oPixels, 0, oPixels.Length)
+    b.UnlockBits(oBMPData)
+
+    ' Start looping.
+    Do
+      ' Find our frame time and add it to the total amount of time
+      ' elapsed since our last FPS update (once per second).
+      fElapsed += oStopwatch.ElapsedMilliseconds / 1000.0F
+      oStopwatch.Reset()
+      oStopwatch.Start()
+
+      ' Adjust the number of loops since the last whole second has elapsed.
+      iLoops += 1
+
+      If fElapsed >= 1.0F Then
+        ' Since we've now had a whole second elapse
+        ' figure the Frames Per Second,
+        ' measure our string,
+        ' setup our backing rectangle for the FPS string (so it's clearly visible over the snow)
+        ' reset our loop counter
+        ' and our elapsed counter.
+        sFPS = (iLoops / fElapsed).ToString("0.0") & " FPS"
+        oFPSSize = g.MeasureString(sFPS, Font)
+        oFPSBG = New RectangleF(ClientSize.Width - cfPadding - oFPSSize.Width, cfPadding, oFPSSize.Width, oFPSSize.Height)
+        fElapsed -= 1.0F ' We don't set this to 0 incase our frame time has gone a bit over 1 second since last update.
+        iLoops = 0
+      End If
+
+      ' Generate our snow.
+      For i As Integer = 0 To oPixels.GetUpperBound(0)
+        oPixels(i) = oBlackWhite(r.Next(oBlackWhite.Length))
+      Next
+
+      ' Prep the bitmap for an update.
+      oBMPData = b.LockBits(New Rectangle(0, 0, b.Width, b.Height), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb)
+      ' Flash copy the new data into our bitmap.
+      Runtime.InteropServices.Marshal.Copy(oPixels, 0, oBMPData.Scan0, oPixels.Length)
+      b.UnlockBits(oBMPData)
+
+      ' Draw the backing for our FPS display.
+      g.FillRectangle(Brushes.Black, oFPSBG)
+      ' Draw our FPS.
+      g.DrawString(sFPS, Font, Brushes.Yellow, oFPSBG.Left, oFPSBG.Top)
+
+      ' Update the form's background and draw.
+      BackgroundImage = b
+      Invalidate(ClientRectangle)
+
+      ' Let windows handle some queued events.
+      Application.DoEvents()
+    Loop While bRunning
+
+  End Sub
+End Class