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

#include <vcl.h>
#include "Math.h"
#pragma hdrstop

#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------

float function(int i) {
   
     return (0.1*sqrt(12*i)+log10(i+7));
}

int step = 15;

void __fastcall TForm1::FormPaint(TObject *Sender)
{

    int w2 = ClientWidth/2;
    int h2 = ClientHeight/2;
    TRect aRect = Rect(0,0,ClientWidth,ClientHeight);
    Canvas->Brush->Color=0xffffff;
    Canvas->FillRect(aRect);
    Canvas->Pen->Color=0x00;
    //Стрелка OX
    Canvas->MoveTo(0,h2);
    Canvas->LineTo(ClientWidth,h2);
    Canvas->MoveTo(ClientWidth-10,h2-3);
    Canvas->LineTo(ClientWidth,h2);
    Canvas->LineTo(ClientWidth-10,h2+3);
    //Стрелка OY
    Canvas->MoveTo(w2,0);
    Canvas->LineTo(w2,ClientHeight);
    Canvas->MoveTo(w2-3,10);
    Canvas->LineTo(w2,0);
    Canvas->LineTo(w2+3,10);
    //Единичный отрезок
    Canvas->MoveTo(w2+10+step,h2-2);
    Canvas->LineTo(w2+10+step,h2+2);
    Canvas->MoveTo(w2-2,h2-10-step);
    Canvas->LineTo(w2+2,h2-10-step);
    //Подписи осей
    int ht = Canvas->TextHeight("0");
    int wt = Canvas->TextWidth("X");
    Canvas->TextOutA(w2+2,h2-ht,"0");
    Canvas->TextOutA(ClientWidth-12,h2-ht-2,"X");
    Canvas->TextOutA(w2+6,2,"Y");
    Canvas->TextOutA(w2+7+step,h2-ht,"1");
    Canvas->TextOutA(w2+2,h2-step-2*ht,"1");
    //График
    Canvas->MoveTo(w2,h2+function(0));
    Canvas->Pen->Color=0x0000ff;
    for(int i=1; i<ClientWidth; i+=2) {
        Canvas->LineTo(i*step+w2,-function(i)*step+h2);
    }
}
//---------------------------------------------------------------------------

void __fastcall TForm1::FormKeyDown(TObject *Sender, WORD &Key,
      TShiftState Shift)
{
        if(((int)Key)==VK_LEFT) {
                step -= 10;
                 FormPaint(this);
        }
        if(((int)Key)==VK_RIGHT) {
                step += 10;
                 FormPaint(this);
        }
}
//---------------------------------------------------------------------------