// NumEdit.cpp : 实现文件
//

#include "stdafx.h"
#include "NumEdit.h"


// CNumEdit

IMPLEMENT_DYNAMIC(CNumEdit, CEdit)

CNumEdit::CNumEdit()
{
	m_bNegative = FALSE;
	m_bPoint = FALSE;
	m_bZero = FALSE;
}

CNumEdit::~CNumEdit()
{
}

BEGIN_MESSAGE_MAP(CNumEdit, CEdit)
	ON_WM_CHAR()
END_MESSAGE_MAP()


// CNumEdit 消息处理程序
void CNumEdit::OnChar(UINT nChar, UINT nRepCnt, UINT nFlags)
{
	// 获取插入符在客户区的坐标值;
	POINT caret;
	::GetCaretPos(&caret);	
	// 根据插入符位置获取最近的字符索引（插入符的前一个字符位置）;
	caret.x = LOWORD(CharFromPos(caret));

	CString strEdit;
	GetWindowText(strEdit);
	if ( strEdit.IsEmpty() )
	{// 如果文本框空,一键还原;
		m_bPoint = FALSE;
		m_bZero = FALSE;
		m_bNegative = FALSE;
	}

	if ( strEdit.Find(_T(".")) == -1 )
		m_bPoint = FALSE;

	if ( strEdit.Find(_T("-")) == -1 )
		m_bNegative = FALSE;

	// 退格键处理;
	if (nChar == VK_BACK && strEdit.GetLength()) //退格键;
	{
		// 是否删除了小数点;
		if ( caret.x && strEdit[caret.x-1] == _T('.') )
			m_bPoint = FALSE;

		// 是否删除了负号;
		if ( caret.x && strEdit[caret.x-1] == _T('-') )
			m_bNegative = FALSE;

		if ( m_bNegative )
		{
			if ( m_bPoint )
			{
				if ( m_bZero && caret.x == 2 )
				{
					m_bZero = FALSE;
				}
			}
			else
			{
				if ( m_bZero && caret.x == 2 && ( strEdit.GetLength() < 2 || strEdit[2] != _T('0')) )
				{
					m_bZero = FALSE;
				}
			}
		}
		else
		{
			if ( m_bPoint )
			{
				if ( m_bZero && caret.x == 1  )
				{
					m_bZero = FALSE;
				}
			}
			else
			{
				if ( m_bZero && caret.x == 1 && ( strEdit.GetLength() < 1 || strEdit[1] != _T('0')) )
				{
					m_bZero = FALSE;
				}
			}
		}

		CEdit::OnChar(nChar, nRepCnt, nFlags);
	}

	// 数字键处理;
	if (isdigit(nChar)) 
	{
		// 判断是否已有负号,若字符在负号前,退出;
		if ( m_bNegative && caret.x == 0 )
			return;

		if ( m_bNegative )
		{
			// 负号前不能有任何字符,或者再输入负号;
			if ( caret.x == 0 || nChar == _T('-'))
				return;

			if ( m_bZero )
			{
				// 前置零前后都不能再有零;
				if ( (caret.x == 1 || caret.x == 2 ) && nChar == _T('0') )
					return;
			}
			else
			{
				// 负号的前置0只能在负号后面;
				if (caret.x == 1 && nChar == _T('0'))
				{
					m_bZero = TRUE;
				}
			}
		}
		else 
		{
			if ( m_bZero )
			{
				// 已有前置0,不能再设置前置0;
				if ( (caret.x == 0 || caret.x == 1) && nChar == _T('0'))
					return;
			}
			else
			{
				if (caret.x == 0 && nChar == _T('0'))
				{
					m_bZero = TRUE;
				}
			}
		}

		CEdit::OnChar(nChar, nRepCnt, nFlags);
	}
	else if (nChar == '-' && !m_bNegative)
	{// 负号只能在第一位;
		if (0 != caret.x)
			return;

		m_bNegative = TRUE;
		CEdit::OnChar(nChar, nRepCnt, nFlags);
	}
	else if (nChar == '.' && !m_bPoint)
	{//小数点可以在第一位，但不能在负号后面;
		if ( m_bNegative && caret.x == 1)
		{// 小数点不能在负号后面,即第二个字符索引;
			return;
		}
		m_bPoint = TRUE;
		CEdit::OnChar(nChar, nRepCnt, nFlags);
	}
}

BOOL CNumEdit::PreTranslateMessage(MSG* pMsg)
{
	// TODO: 在此添加专用代码和/或调用基类
	if ( pMsg->message == WM_KEYDOWN )
	{
		if ( pMsg->wParam == VK_DELETE )
		{
			POINT caret;
			::GetCaretPos(&caret);	
			// 根据插入符位置获取最近的字符索引（插入符的前一个字符位置）;
			LONG nPos  = LOWORD(CharFromPos(caret));
			printf("NumEdit,%d,%d\t 插入符最近的字符位置：%d\n", caret.x, caret.y, nPos);

			CString strEdit;
			GetWindowText(strEdit);

			if (strEdit.GetLength())
			{
				// 是否删除了小数点或负号;
				if ( strEdit.GetAt(nPos) == _T('.') )
					m_bPoint = FALSE;

				if ( strEdit.GetAt(nPos) == _T('-') )
					m_bNegative = FALSE;

				if ( m_bNegative )
				{
					if ( m_bPoint )
					{
						if ( m_bZero && caret.x == 2 )
						{
							m_bZero = FALSE;
						}
					}
					else
					{
						if ( m_bZero && caret.x == 2 && ( strEdit.GetLength() < 2 || strEdit[2] != _T('0')) )
						{
							m_bZero = FALSE;
						}
					}
				}
				else
				{
					if ( m_bPoint )
					{
						if ( m_bZero && caret.x == 1  )
						{
							m_bZero = FALSE;
						}
					}
					else
					{
						if ( m_bZero && caret.x == 1 && ( strEdit.GetLength() < 1 || strEdit[1] != _T('0')) )
						{
							m_bZero = FALSE;
						}
					}
				}
			}
		}
	}

	return CEdit::PreTranslateMessage(pMsg);
}