利用子类化技术为DBGrid增加鼠标滚动

作者：yifei(尹加俊)
信箱：yifei1900@163.com
为DBGrid增加鼠标滚动功能的演示，核心代码如下：
//---------------------------------------------------------------------------
#include <vcl.h>
#pragma hdrstop

#include "MainFormUnit.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TMainForm *MainForm;
//---------------------------------------------------------------------------
FARPROC OldProc = NULL; //用于保存旧的DBGrid控件的WindowProc
//---------------------------------------------------------------------------
/**
* 声明新的DBGrid的WindowProc
*/
LRESULT CALLBACK DBGridProc(HWND hWnd,UINT uMsg,WPARAM wParam,LPARAM lParam)
// 本文转自 C Builder 研究 - http://www.ccrun.com/article.asp?i=630&d=1h3y54
{
//处理感兴趣的Window消息
if(uMsg == WM_MOUSEWHEEL) {
if((short)HIWORD(wParam) > 0) {
::PostMessage(hWnd,WM_VSCROLL,SB_LINEUP,0);
} else {
::PostMessage(hWnd,WM_VSCROLL,SB_LINEDOWN,0);
}
}

//调用原DBGrid的WindowProc
return (::CallWindowProc(OldProc,hWnd,uMsg,wParam,lParam));
}
//---------------------------------------------------------------------------
__fastcall TMainForm::TMainForm(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::FormShow(TObject *Sender)
{
this->ADOCn->ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source="
ExtractFilePath(Application->ExeName) "Data.mdb;Persist Security Info=True";
this->ADOCn->Connected = true;
this->DataSet->Open();

//配置新的窗体函数
OldProc = (FARPROC)::SetWindowLong(this->DBGrid->Handle,GWL_WNDPROC,(long)DBGridProc);
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::FormClose(TObject *Sender, TCloseAction &Action)
{
//还原窗体函数
::SetWindowLong(this->DBGrid->Handle,GWL_WNDPROC,(long)OldProc);

this->ADOCn->Connected = false;
}
//---------------------------------------------------------------------------
今天偶然看到了2ccc站点上有给DBGrid增加滚动功能的代码，想想这个功能还真的很实用(但是他们的演示代码真的不怎么样，没有一点实用性)，又搜索了一下网络发现只有Delphi和VB的例子，于是我就把写了一份BCB的代码，没有用网络上那些演示代码的方法，采用了一种比较实用的方法。
点击下载演示代码