Оформить существующий функционал в отдельный класс и использовать

//---------------------------------------------------------------------------
 
#include <vcl.h>
#pragma hdrstop
 
#include "Unit1.h"
#include "Unit2.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
// êîíñòàíòû êóðñîðîâ
const int crFill  = 1;
const int crPlus  = 2;
const int crDraw  = 3;
const int crErase = 4;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------
 
void __fastcall TForm1::FormCreate(TObject *Sender)
{
// ðåãèñòðàöèÿ êóðñîðîâ
Screen->Cursors[crFill] = LoadCursor(HInstance, "FILL");
Screen->Cursors[crPlus] = LoadCursor(HInstance, "PLUS");
Screen->Cursors[crDraw] = LoadCursor(HInstance, "DRAW");
Screen->Cursors[crErase] = LoadCursor(HInstance, "ERASE");
 
// çàäàíèå ñâîéñòâ êèñòè îñíîâíîãî è âñïîìîãàòåëüíîãî öâåòîâ
 Image1->Canvas->Brush->Color = clBlack;
 Image2->Canvas->Brush->Color = clWhite;
// çàïîëíåíèå îêîí îñíîâíîãî è âñïîìîãàòåëüíîãî öâåòîâ
 Image1->Canvas->FillRect(Rect(0,0,Image1->Width,Image1->Height));
 Image2->Canvas->FillRect(Rect(0,0,Image2->Width,Image2->Height));
// çàäàíèå øèðèíû ýëåìåíòà ïàëèòðû öâåòîâ
 int HW = Image4->Width / 10;
// çàêðàñêà ýëåìåíòîâ ïàëèòðû öâåòîâ
 for(int i = 1; i <=10; i++)
  {
   switch (i)
   {
    case 1:Image4->Canvas->Brush->Color = clBlack;
           break;
    case 2:Image4->Canvas->Brush->Color = clAqua;
           break;
    case 3:Image4->Canvas->Brush->Color = clBlue;
           break;
    case 4:Image4->Canvas->Brush->Color = clFuchsia;
           break;
    case 5:Image4->Canvas->Brush->Color = clGreen;
           break;
    case 6:Image4->Canvas->Brush->Color = clLime;
           break;
    case 7:Image4->Canvas->Brush->Color = clMaroon;
           break;
    case 8:Image4->Canvas->Brush->Color = clRed;
           break;
    case 9:Image4->Canvas->Brush->Color = clYellow;
           break;
    case 10:Image4->Canvas->Brush->Color = clWhite;
   }
   Image4->Canvas->Rectangle((i-1)*HW,0,i*HW,Image4->Height);
  }
// ðèñîâàíèå êðåñòà íà õîëñòå - òîëüêî äëÿ òåñòèðîâàíèÿ
  Image3->Canvas->MoveTo(0,0);
  BitMap->Assign(Image3->Picture);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::UndoClick(TObject *Sender)
{
Image3->Picture->Assign(BitMap);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::SBBrushClick(TObject *Sender)
{
if (((TSpeedButton *)Sender)->Down)
  BitMap->Assign(Image3->Picture);
 RBegin = false;
 RDrag = false;
 REnd = false;
if((Sender == SBLine))
  Image3->Cursor = crDraw;
else if(Sender == SBBrush)
  Image3->Cursor = crFill;
/*else if(Sender == SBErase)
  Image3->Cursor = crErase; */
else if(Sender == SBColor)
Image3->Cursor = crDefault;
else Image3->Cursor = crPlus;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Image3MouseDown(TObject *Sender,
      TMouseButton Button, TShiftState Shift, int X, int Y)
{
if((Sender == Image4) || SBColor->Down)
// ðåæèì óñòàíîâêè îñíîâíîãî è âñïîìîãàòåëüíîãî öâåòîâ
 {
  if(Button == mbLeft)
  {
// óñòàíîâêà îñíîâíîãî öâåòà
    Image1->Canvas->Brush->Color = ((TImage *)Sender)->Canvas->Pixels[X][Y];
    Image1->Canvas->FillRect(Rect(0,0,Image1->Width,Image1->Height));
  }
  else
  {
// óñòàíîâêà âñïîìîãàòåëüíîãî öâåòà
    Image2->Canvas->Brush->Color = ((TImage *)Sender)->Canvas->Pixels[X][Y];
    Image2->Canvas->FillRect(Rect(0,0,Image2->Width,Image2->Height));
  }
 }
else
{
  X0 = X;
  Y0 = Y;
 // if (SBPen->Down)
 // {
// ðåæèì êàðàíäàøà
    Image3->Canvas->MoveTo(X,Y);
    Image3->Canvas->Pen->Color = Image1->Canvas->Brush->Color;
  }
   if (SBLine->Down)
// ðåæèì ëèíèè
  {
   X1 = X;
   Y1 = Y;
   Image3->Canvas->Pen->Mode = pmNotXor;
   Image3->Canvas->Pen->Color = Image1->Canvas->Brush->Color;
  }
  else if (SBBrush->Down)
// ðåæèì çàêðàñêè óêàçàííîé îáëàñòè õîëñòà
  {
   if (Button==mbLeft)
    Image3->Canvas->Brush->Color = Image1->Canvas->Brush->Color;
   else Image3->Canvas->Brush->Color = Image2->Canvas->Brush->Color;
   Image3->Canvas->FloodFill(X,Y,Image3->Canvas->Pixels[X][Y],fsSurface);
  }
  else if (SBRect->Down)
  {
// ðåæèì ðàáîòû ñ ðàìêîé
    if (REnd)
// ñòèðàíèå ïðåæíåé ðàìêè
    {
    Image3->Canvas->DrawFocusRect(R);
    if ((X < R.Right) && (X > R.Left) && (Y > R.Top) && (Y < R.Bottom))
// ðåæèì íà÷àëà ïåðåòàñêèâàíèÿ ôðàãìåíòà
    {
// óñòàíîâêà ôëàãîâ
      RDrag = true;
      REnd = false;
// çàïîìèíàíèå íà÷àëüíîãî ïîëîæåíèÿ ïåðåòàñêèâàåìîãî ôðàãìåíòà
      R0 = R;
// çàïîìèíàíèå èçîáðàæåíèÿ
      BitMap->Assign(Image3->Picture);
// óñòàíîâêà öâåòà êèñòè
      Image3->Canvas->Brush->Color = Image2->Canvas->Brush->Color;
 
    }
    }
    else
// ðåæèì íà÷àëà ðèñîâàíèÿ ðàìêè ôðàãìåíòà
    {
      RBegin = true;
      REnd = false;
      R.Top = X;
      R.Bottom = X;
      R.Left = Y;
      R.Right = Y;
      Image3->Canvas->DrawFocusRect(R);
     }
   }
 }
 
//---------------------------------------------------------------------------
void __fastcall TForm1::FormDestroy(TObject *Sender)
{
BitMap->Free();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::MOpenClick(TObject *Sender)
{
 if (OpenPictureDialog1->Execute())
 {
  Image3->Picture->LoadFromFile(OpenPictureDialog1->FileName);
  BitMap->Assign(Image3->Picture);
 }
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Image3MouseMove(TObject *Sender, TShiftState Shift,
      int X, int Y)
{
if (! Shift.Contains(ssLeft))  return;
// ðåæèì ëèíèè
if (SBLine->Down)
{
// ñòèðàíèå ïðåæíåé ëèíèè
  Image3->Canvas->MoveTo(X0,Y0);
  Image3->Canvas->LineTo(X1,Y1);
// ðèñîâàíèå íîâîé ëèíèè
  Image3->Canvas->MoveTo(X0,Y0);
  Image3->Canvas->LineTo(X,Y);
// çàïîìèíàíèå íîâûõ êîîðäèíàò êîíöà ëèíèè
  X1 = X;
  Y1 = Y;
}
 else if ((SBRect->Down && (RBegin || RDrag))
          )
 {
  if (RBegin)
   {
// Ðåæèì ðèñîâàíèÿ ðàìêè ôðàãìåíòà
    Image3->Canvas->DrawFocusRect(R);
    if (X0 < X) { R.Left = X0; R.Right = X; }
    else { R.Left = X; R.Right = X0; }
    if (Y0 < Y) { R.Top = Y0; R.Bottom = Y; }
    else { R.Top = Y; R.Bottom = Y0; }
    Image3->Canvas->DrawFocusRect(R);
   }
  else if (SBRect->Down)
  {
// Ðåæèì ïåðåòàñêèâàíèÿ ôðàãìåíòà
// âîññòàíîâëåíèå èçîáðàæåíèÿ ïîä ïåðåòàñêèâàåìûì ôðàãìåíòîì
   Image3->Canvas->CopyRect(R,BitMap->Canvas,R);
// åñëè íå íàæàòà êëàâèøà Ctrl - ñòèðàíèå èçîáðàæåíèÿ â R0
   if (! Shift.Contains(ssCtrl))
    Image3->Canvas->FillRect(R0);
// ôîðìèðîâàíèå íîâîãî ïîëîæåíèÿ ôðàãìåíòà
   R.Left = R.Left + X - X0;
   R.Right = R.Right + X - X0;
   R.Top = R.Top + Y - Y0;
   R.Bottom = R.Bottom + Y - Y0;
// çàïîìèíàíèå ïîëîæåíèÿ êóðñîðà ìûøè
   X0 = X;
   Y0 = Y;
// ðèñîâàíèå ôðàãìåíòà â íîâîì ïîëîæåíèè
   Image3->Canvas->CopyRect(R,BitMap->Canvas,R0);
// ðèñîâàíèå ðàìêè
   Image3->Canvas->DrawFocusRect(R);
  }
 }
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Image3MouseUp(TObject *Sender, TMouseButton Button,
      TShiftState Shift, int X, int Y)
{
if (SBLine->Down)              // íàðèñîâàòü ëèíèþ
{
 Image3->Canvas->MoveTo(X0,Y0);
 Image3->Canvas->LineTo(X1,Y1);
 Image3->Canvas->Pen->Mode = pmCopy;
 Image3->Canvas->MoveTo(X0,Y0);
 Image3->Canvas->LineTo(X,Y);
}
else if (SBRect->Down)
{
 if (RDrag) Image3->Canvas->DrawFocusRect(R);
 if (RBegin && ! REnd)
  {
   REnd = true;
  }
}
 
 RBegin = false;
 RDrag = false;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::MSaveClick(TObject *Sender)
{
if (SavePictureDialog1->Execute())
  {
    BitMap->Assign(Image3->Picture);
    BitMap->SaveToFile(SavePictureDialog1->FileName);
  }
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Close1Click(TObject *Sender)
{
Form1->Close();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::N1Click(TObject *Sender)
{
Form2->ShowModal();        
}
//---------------------------------------------------------------------------
 
 
void __fastcall TForm1::Image3Click(TObject *Sender)
{
        DoubleBuffered=true;
}

#include "line.h"
#pragma hdrstop
//---------------------------------------------------------------------------
void line::create(TImage* img, int coordX,int coordY,int X,int Y,TColor Color, int size)
{
 
if (coordX - X > 0)
        img->Left = X;
else
        img->Left = coordX;
if (coordY - Y > 0)
        img->Top = Y;
else
        img->Top = coordY;
img->Width = abs(coordX - X);
img->Height = abs(coordY - Y);
img->Transparent = true;
img->Canvas->Pen->Color = Color;
img->Canvas->Pen->Width = size;
img->Canvas->MoveTo(0,0);
img->Canvas->LineTo(abs(coordX - X),abs(coordY - Y));