// Zmiana wielkosci obrazka -
// Algorytm Bilinear Interpolation - algorytm interpolacji podwójnej
// www.algorytm.org
// Tomasz Lubinski (c) 2006
//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include "BI.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
TPixel org[122][100];

//---------------------------------------------------------------------------

float TForm1::Inter(float f1, float f2, float d)
{
   return (f1*(1-d) + f2*d);
}

float TForm1::InterNorm(float f1, float f2, float d)
{
   float result = (f1*(1-d) + f2*d);
   if (result > 255) return 255;
   if (result < 0) return 0;
   return result;
}

//---------------------------------------------------------------------------

TPixel TForm1::Bilinear_Inter(float x, float y)
{
  int x0,y0,x1,y1;
  float dx,dy;
  TPixel result;

  x0 = x;  //floor
  y0 = y;  //floor
  dx = x-x0;
  dy = y-y0;
  if (x0 + 1 >= src->Width)
     x1 = x0;
  else
     x1 = x0 + 1;
  if (y0 + 1 >= src->Width)
     y1 = y0;
  else
     y1 = y0 + 1;

  result.r = (InterNorm(Inter(org[x0][y0].r, org[x1][y0].r, dx), Inter(org[x0][y1].r, org[x1][y1].r, dx), dy));
  result.g = (InterNorm(Inter(org[x0][y0].g, org[x1][y0].g, dx), Inter(org[x0][y1].g, org[x1][y1].g, dx), dy));
  result.b = (InterNorm(Inter(org[x0][y0].b, org[x1][y0].b, dx), Inter(org[x0][y1].b, org[x1][y1].b, dx), dy));

  return result;
}

//---------------------------------------------------------------------------

__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{

}
//---------------------------------------------------------------------------


void __fastcall TForm1::Button1Click(TObject *Sender)
{
   int i,j;
   float ratiox, ratioy;
   TPixel *pixel;

   //pobierz wartosci obrazu oryginalnego
   src->Picture->Bitmap->PixelFormat = pf32bit;
   for (j=0; j<src->Height; j++)
   {
      pixel = (TPixel *)src->Picture->Bitmap->ScanLine[j];
      for (i=0; i<src->Width; i++)
      {
         org[i][j] = *pixel;
         pixel++;
      }
   }

   //pobierz wielkosc nowego obrazu
   dst->Width = StrToInt(Edit2->Text);
   dst->Height = StrToInt(Edit1->Text);
   dst->Picture->Bitmap->Width = dst->Width;
   dst->Picture->Bitmap->Height = dst->Height;
   ratiox = (src->Width*1.0)/(dst->Width*1.0);
   ratioy = (src->Height*1.0)/(dst->Height*1.0);

   dst->Canvas->Brush->Color = clWhite;
   dst->Canvas->Rectangle(0, 0, dst->Width, dst->Height);
   dst->Picture->Bitmap->PixelFormat = pf32bit;

   //wygeneruj nowy obraz
   for (j=0; j<dst->Height; j++)
   {
      pixel = (TPixel *)dst->Picture->Bitmap->ScanLine[j];
      for (i=0; i<dst->Width; i++)
      {
         *pixel = Bilinear_Inter(i*ratiox, j*ratioy);
         pixel++;
      }
   }
}
//---------------------------------------------------------------------------