//---------------------------------------------------------------------------
#include 
#pragma hdrstop    #include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
  // 取得統計直方圖的範圍
  TRect ARect = TRect(Edit1->Text.ToInt(),
                      Edit2->Text.ToInt(),
                      Edit3->Text.ToInt(),
                      Edit4->Text.ToInt());      // 以ARect為範圍統計直方圖
  Byte *ptr;
  long GrayCount[256] = {0}, MaxGrayCount = 0;
  for(int row = ARect.top; row < ARect.Bottom; row++)
  {
    ptr = (Byte *)Image1->Picture->Bitmap->ScanLine[row];
    for(int col = ARect.left; col < ARect.right; col++)
    {
      // 以8bit灰階圖為例
      GrayCount[ptr[col]]++;
      if(GrayCount[ptr[col]] > MaxGrayCount) MaxGrayCount = GrayCount[ptr[col]];
    }
  }      // 初始直方圖畫面
  Image2->Canvas->Brush->Color = clWhite;
  Image2->Canvas->FillRect(TRect(0, 0, Image1->Width, Image1->Height));      // 畫出直方圖
  for(int index = 0; index < 256; index++)
  {
    Image2->Canvas->MoveTo(index, Image2->Height);
    Image2->Canvas->LineTo(index, Image2->Height * (1.0 - (double)GrayCount[index] / (double)MaxGrayCount));
  }      // 標出ARect統計直方圖的範圍
  Image1->Canvas->Brush->Color = clWhite;
  Image1->Canvas->FrameRect(ARect);
}
//---------------------------------------------------------------------------