C++针对bmp格式解析实例
本文实例讲述了C++针对bmp格式解析的方法，分享给大家供大家参考。具体方法如下：
写这代码时，容易出现如下错误：
1.忘了on_wm_paint() 一直在界面上画不出来
2.正确写法
BYTE*pBits=(BYTE*)lpBase+pbitmapFileHeader->bfOffBits;
写成了
BYTE*pBits= pbitmapFileHeader->bfOffBits;
这里主要是用了前面一篇中的CWnd框架。
.cpp源文件如下：
#include"ReadBMP.h"
#include"resource.h"
#include<afxdlgs.h>
CMyApptheApp;
BOOLCMyApp::InitInstance()
{
m_pMainWnd=newCMainWindow;
m_pMainWnd->ShowWindow(m_nCmdShow);
returnTRUE;//必须返回TRUE,否则不会进入消息循环，界面会直接退出
}
//CMainWindow
BEGIN_MESSAGE_MAP(CMainWindow,CWnd)
ON_WM_CREATE()
ON_WM_PAINT()
ON_COMMAND(IDC_OPEN,OnOpen)
END_MESSAGE_MAP()
//构造函数
CMainWindow::CMainWindow()
{
LPCTSTRlpszClassName=::AfxRegisterWndClass(CS_HREDRAW|CS_VREDRAW,::LoadCursorA(NULL,IDC_ARROW),(HBRUSH)(COLOR_3DFACE+1),theApp.LoadIcon(IDI_MAIN));
CreateEx(WS_EX_CLIENTEDGE,lpszClassName,"xxx",WS_OVERLAPPEDWINDOW,CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,NULL,NULL);
}
//析构函数
CMainWindow::~CMainWindow()
{
}
//消息映射函数
intCMainWindow::OnCreate(LPCREATESTRUCTlpCreateStruct)
{
//OutputDebugString("oncreate");
CClientDCdc(this);
m_hMemDC=::CreateCompatibleDC(dc);
m_nWidth=0;
m_nHeight=0;
//设置菜单
HMENUhMenu=::LoadMenuA(theApp.m_hInstance,(LPCSTR)IDR_MENU);
::SetMenu(m_hWnd,hMenu);
return0;
}
voidCMainWindow::OnNcDestroy()
{
deletethis;
}
voidCMainWindow::OnDestroy()
{
}
voidCMainWindow::OnPaint()
{
CPaintDCdc(this);
::BitBlt(dc,0,0,m_nWidth,m_nHeight,m_hMemDC,0,0,SRCCOPY);
}
voidCMainWindow::OnOpen()
{
CFileDialogdlg(TRUE);
if(IDOK!=dlg.DoModal())
{
return;
}
HANDLE hFile=::CreateFile(dlg.GetPathName(),GENERIC_READ,FILE_SHARE_READ,NULL,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,NULL);
if(INVALID_HANDLE_VALUE==hFile)
{
return;
}
HANDLE hFileMap=::CreateFileMapping(hFile,NULL,PAGE_READONLY,0,0,NULL);
if(NULL==hFileMap)
{
return;
}
LPVOIDlpBase=::MapViewOfFile(hFileMap,FILE_MAP_READ,0,0,0);
if(NULL==lpBase)
{
return;
}
//从头结构中取三个信息：1.bfOffBits位图数据在文件中的起始位置，2.m_nWidth图像的宽，3.m_nHeight图像的高
BITMAPFILEHEADER*pbitmapFileHeader;
BITMAPINFO*pbitmapInfo;
pbitmapFileHeader=(BITMAPFILEHEADER*)lpBase;
if(pbitmapFileHeader->bfType!=MAKEWORD('B','M'))
{
MessageBox("notbmp");
::UnmapViewOfFile(lpBase);
::CloseHandle(hFileMap);
::CloseHandle(hFile);
}
//DWORDbfOffBits=pbitmapFileHeader->bfOffBits;
BYTE*pBits=(BYTE*)lpBase+pbitmapFileHeader->bfOffBits;
pbitmapInfo=(BITMAPINFO*)((BYTE*)lpBase+sizeof(BITMAPFILEHEADER));
m_nWidth=pbitmapInfo->bmiHeader.biWidth;
m_nHeight=pbitmapInfo->bmiHeader.biHeight;
//显示BMP文件到内存设备
//得客户区DC
CClientDCdc(this);
//创建与客户区DC兼容的位图
HBITMAPhBitmap=::CreateCompatibleBitmap(dc,m_nWidth,m_nHeight);
if(hBitmap==0)
{
return;
}
//位图选入内存DC
::SelectObject(m_hMemDC,hBitmap);
//图像数据放到建立的DC中
::SetDIBitsToDevice(m_hMemDC,0,0,m_nWidth,m_nHeight,0,0,0,m_nHeight,pBits,pbitmapInfo,DIB_RGB_COLORS);
::InvalidateRect(m_hWnd,NULL,TRUE);
::DeleteObject(hBitmap);
::UnmapViewOfFile(lpBase);
::CloseHandle(hFileMap);
::CloseHandle(hFile);
}
.h头文件如下：
#include<afxwin.h>
classCMyApp:publicCWinApp
{
public:
virtualBOOLInitInstance();
};
//CMainWindow
classCMainWindow:publicCWnd
{
public:
CMainWindow();
~CMainWindow();
protected:
HDCm_hMemDC;//与客户区兼容的内存DC句柄
UINTm_nWidth;//BMP的宽度
UINTm_nHeight;//BMP的高度
//消息映射
afx_msgvoidOnNcDestroy();
afx_msgintOnCreate(LPCREATESTRUCTlpCreateStruct);
afx_msgvoidOnDestroy();
afx_msgvoidOnOpen();
afx_msgvoidOnPaint();
DECLARE_MESSAGE_MAP()
};
希望本文所述对大家的C++程序设计有所帮助。