Task: Image noise

C: #include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <SDL/SDL.h>
 
unsigned int frames = 0;
unsigned int t_acc = 0;
 
void print_fps ()
{
  static Uint32 last_t = 0;
  Uint32 t = SDL_GetTicks();
  Uint32 dt = t - last_t;
  t_acc += dt;
  if (t_acc > 1000)
  {
    unsigned int el_time = t_acc / 1000;
    printf("- fps: %g\n",
            (float) frames / (float) el_time);
    t_acc = 0;
    frames = 0;
  }
  last_t = t;
}
 
void blit_noise(SDL_Surface *surf)
{
  unsigned int i;
  long dim = surf->w * surf->h;
  while (1)
  {
    SDL_LockSurface(surf);
    for (i=0; i < dim; ++i) {
      ((unsigned char *)surf->pixels)[i] = ((rand() & 1) ? 255 : 0);
    }
    SDL_UnlockSurface(surf);
    SDL_Flip(surf);
    ++frames;
    print_fps();
  }
}
 
int main(void)
{
  SDL_Surface *surf = NULL;
  srand((unsigned int)time(NULL));
  SDL_Init(SDL_INIT_TIMER | SDL_INIT_VIDEO);
  surf = SDL_SetVideoMode(320, 240, 8, SDL_DOUBLEBUF | SDL_HWSURFACE);
  blit_noise(surf);
}








VB: 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

        
        
        
        SetStyle(ControlStyles.AllPaintingInWmPaint Or ControlStyles.UserPaint _
            Or ControlStyles.OptimizedDoubleBuffer, True)
        UpdateStyles()

        
        
        FormBorderStyle = Windows.Forms.FormBorderStyle.FixedSingle
        MaximizeBox = False

        
        
        
        
        Width = 320 + Size.Width - ClientSize.Width
        Height = 240 + Size.Height - ClientSize.Height

        
        
        Show()
        Activate()
        Application.DoEvents()

        
        RenderLoop()

        
        Close()

    End Sub

    Private Sub Form1_KeyPress(ByVal sender As Object, ByVal e As _
            System.Windows.Forms.KeyPressEventArgs) Handles Me.KeyPress
        
        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
        
        
        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)

        
        g.Clear(Color.Black)

        
        oBMPData = b.LockBits(New Rectangle(0, 0, b.Width, b.Height),
                          ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb)

        
        
        
        Array.Resize(oPixels, b.Width * b.Height)
        Runtime.InteropServices.Marshal.Copy(oBMPData.Scan0,
                                             oPixels, 0, oPixels.Length)
        b.UnlockBits(oBMPData)
        
        Do
            
            
            fElapsed += oStopwatch.ElapsedMilliseconds / 1000.0F
            oStopwatch.Reset() : oStopwatch.Start()
            
            iLoops += 1
            If fElapsed >= 1.0F Then
                
                
                
                
                
                
                
                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
                iLoops = 0
            End If

            
            For i As Integer = 0 To oPixels.GetUpperBound(0)
                oPixels(i) = oBlackWhite(r.Next(oBlackWhite.Length))
            Next

            
            oBMPData = b.LockBits(New Rectangle(0, 0, b.Width, b.Height),
                       ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb)
            
            Runtime.InteropServices.Marshal.Copy(oPixels, 0, oBMPData.Scan0,
                                                 oPixels.Length)
            b.UnlockBits(oBMPData)

            
            g.FillRectangle(Brushes.Black, oFPSBG)
            
            g.DrawString(sFPS, Font, Brushes.Yellow, oFPSBG.Left, oFPSBG.Top)

            
            BackgroundImage = b
            Invalidate(ClientRectangle)

            
            Application.DoEvents()
        Loop While bRunning

    End Sub
End Class