/*********************************************************
* This program calculates the Fourier coefficients of a  *
* periodic analytic function F(x) by using the procedure *
* AnalyticFourierHn of file fourier.cpp and draws the    *
* reconstructed signal from Fourier coefficients.        *     
* ------------------------------------------------------ *
* SAMPLE RUN:                                            *
*                                                        *
* F(x) = 0 from -pi to 0 and sin(x) from 0 to pi         *
* (one period).                                          *
*                                                        *
* Lowest  harmonic: 0                                    *
* Highest harmonic: 25                                   *
*                                                        *
* A graph is displayed (reconstructed curve F(x) with    *
* 25 harmonics).                                         *
*                                                        *
*         C++ version in API style by J-P Moreau, Paris. *
*                       (www.jpmoreau.fr)                *
**********************************************************
Used files: 
  ganafour.mak,
  basis_r.cpp, fourier.cpp, graph2d.cpp, vmblock.cpp
  basis.h,                  graph2d.h,   vmblock.h
--------------------------------------------------------*/
#include <stdio.h>
#include <math.h>
#include <basis.h>     // ABS, REAL etc.   

#include <windows.h>

HDC  hdc;
RECT rect;
HPEN hpen, hpenOld;

//Functions used here of graph2D.cpp
void CourbeXY(int,int,float *,double,double);
void Legendes (int,char *,char *,char *,int,int,char *,int,int,char *);

//Function of fourier.cpp
void AnalyticFourierHn(REAL,REAL,int,REAL *,REAL *);

//"home made" graphic commands for hdc environment used by above functions
void DrawPixel(int ix,int iy) {
  //sorry, no other available command found
  Rectangle(hdc,rect.left+ix,rect.top+iy,
	            rect.left+ix+2,rect.top+iy+1);
}

void Swap(int *i1,int *i2) {
  int it;
  it=*i1; *i1=*i2; *i2=it;
}

void DrawLine(int ix1,int iy1,int ix2,int iy2) {
  int i,il,ix,iy;
  double dx,dy;
  if (ix2<ix1) {
	Swap(&ix1,&ix2); Swap(&iy1,&iy2);
  }
  il=(int) sqrt((ix2-ix1)*(ix2-ix1)+(iy2-iy1)*(iy2-iy1));
  dx=(double) (ix2-ix1)/il; 
  dy=(double) (iy2-iy1)/il;
  ix=ix1; iy=iy1;
  for (i=1;i<il+1; i++) {
	DrawPixel(ix,iy);
	ix=(int) (ix1+i*dx); 
	iy=(int) (iy1+i*dy);
  }
}

void OutText(int ix,int iy,char *s) {
  RECT rct;
  rct.left=ix; rct.right=ix+10*strlen(s);
  rct.top=iy-5; rct.bottom=iy+15;
  DrawText(hdc, s, -1, &rct,
                DT_SINGLELINE | DT_CENTER | DT_VCENTER);
}

//calculate the Fourier coefficients of F(x) and
//draw reconstructed curve from Fourier coefficients
void Exec_anal_four()  {

  int h1,h2,i,j,mpoints;
  REAL x1,x2, a,b;
  REAL Ai[26], Bi[26];
  REAL dx,x, om,T;
  float Y[256];

  extern MaxX, MaxY;  //drawing zone in pixels

  x1=-PI; x2=PI;      //x begin, x end of period
  h1=0; h2=25;        //lower, highest harmonic
  //calculate 26 Fourier coefficients
  for (i=h1; i<=h2; i++) {
    AnalyticFourierHn(x1,x2,i,&a,&b);
    Ai[i]=a; Bi[i]=b;
  }
  //reconstruct signal F(x) from Fourier coefficients
  mpoints=256; dx=(x2-x1)/(mpoints-1); T=ABS(x2-x1);
  x=x1-dx;
  for (i=1; i<=mpoints; i++) {
    x += dx; Y[i]=0;
    for (j=h1; j<=h2; j++) {
      if (j==0)
        Y[i] += (float) Ai[0];
      else {
        om=2*PI*j/T;
        Y[i] += (float) (Ai[j]*cos(om*x)+Bi[j]*sin(om*x));
      }
    }
  }
  //draw reconstructed signal F(x)
  MaxX=(rect.right-rect.left);
  MaxY=(rect.bottom-rect.top);
  CourbeXY(mpoints,10,Y,x1,x2);
  Legendes(10,"  Reconstructed Signal F(x)  ","X","Y",MaxX-220,50,"Curve: 256 points",
	                                                  MaxX-250,80,"26 Fourier coefficients");
}

//Handle window Paint and Destroy messages
long FAR PASCAL /*_export*/ WndProc(HWND hwnd,
    UINT message, UINT wParam, LONG lParam) 
{
   
    PAINTSTRUCT ps;

    switch (message) {
        case WM_PAINT:
	    hdc = BeginPaint(hwnd, &ps);
	    GetClientRect(hwnd, &rect);
            hpen = CreatePen(PS_SOLID, 1, RGB(0, 0, 255));
            hpenOld = SelectObject(hdc,hpen);

            Exec_anal_four();
               
            SelectObject(hdc,hpenOld);
            DeleteObject(hpen);
            EndPaint(hwnd, &ps);
            return 0;
        case WM_DESTROY:
            PostQuitMessage(0);
            return 0;
    }
    return DefWindowProc(hwnd, message, wParam, lParam);
}

// main program
int PASCAL WinMain(HANDLE hInstance, HANDLE hPrevInstance,
    LPSTR lpszCmdParam, int nCmdShow)
{
    static char szAppName[] = "Ganafour";
    HWND        hwnd;
    MSG         msg;
    WNDCLASS    wndclass;

    if (!hPrevInstance) {
        wndclass.style         = CS_HREDRAW | CS_VREDRAW;
        wndclass.lpfnWndProc   = WndProc;
        wndclass.cbClsExtra    = 0;
        wndclass.cbWndExtra    = 0;
        wndclass.hInstance     = hInstance;
        wndclass.hIcon         = LoadIcon(NULL, IDI_APPLICATION);
        wndclass.hCursor       = LoadCursor(NULL, IDC_ARROW);
        wndclass.hbrBackground = GetStockObject(WHITE_BRUSH);
        wndclass.lpszMenuName  = NULL;
        wndclass.lpszClassName = szAppName;

        RegisterClass(&wndclass);
    }

    hwnd = CreateWindow(szAppName,  // window class name
        " Fourier coefficients (analytic function)",    // window caption
        WS_OVERLAPPEDWINDOW,        // window style                       
        CW_USEDEFAULT,              // initial x position
        CW_USEDEFAULT,              // initial y position
        CW_USEDEFAULT,              // initial x size
        CW_USEDEFAULT,              // initial y size
        NULL,                       // parent window handle
        NULL,                       // window menu handle
        hInstance,                  // program instance handle
        NULL);                      // creation parameters

   ShowWindow(hwnd, nCmdShow);
   UpdateWindow(hwnd);

   while (GetMessage(&msg, NULL, 0, 0)) {
       TranslateMessage(&msg);
       DispatchMessage(&msg);
   }
   return msg.wParam;
}

//end of file ganafour.cpp