Работа с потоками - C++

//---------------------------------------------------------------------------
 
#include <vcl.h>
#pragma hdrstop
#include <process.h>
#include "Unit1.h"
#include <conio.h>
#include <stdio.h>
#include <time.h>
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
 
 void drawLine(int x1, int y1, int x2, int y2)
{
    int deltaX = abs(x2 - x1);
    int deltaY = abs(y2 - y1);
    int signX = x1 < x2 ? 1 : -1;
    int signY = y1 < y2 ? 1 : -1;
    int error = deltaX - deltaY;
    void setPixel(
    int x1,
    int y1)  ;
    for (;;)
    {
        setPixel(x1, y1);
 
        if(x1 == x2 && y1 == y2)
            break;
 
        int error2 = error * 2;
 
        if(error2 > -deltaY)
        {
            error -= deltaY;
            x1 += signX;
        }
 
        if(error2 < deltaX)
        {
            error += deltaX;
            y1 += signY;
        }
    }
}
 
   void line(int x1, int y1, int x2, int y2)
{       void setPixel(
    int x1,
    int y1)  ;
double k = ((double)(y2 - y1)) / (x2 - x1);
double y = y1;
for (int x = x1; x <= x2; x++, y += k)
setPixel(x, (int)y);
}
 int a[ 5 ];
 
  void Thread( void* pParams )
  { int x1 = 2 + rand() %7;
    int x2 = 2 + rand() %7;
    int y1 = 2 + rand() %7;
    int y2 = 2 + rand() %7;
   line(x1, y1, x2, y2);
  }
 
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
    : TForm(Owner)
{
 
//Image1->Canvas->LineTo(rand()%Image1->Height,rand()%Image1->Width);
 
//Image2->Canvas->LineTo(rand()%Image1->Height,rand()%Image1->Width);
}
//------------------------------------