C + + for BMP format parsing instance _c language

This article describes the C + + for BMP format analysis method, share for everyone to reference. The specific methods are as follows:

When you write this code, you can easily get the following error:
1. Forget On_wm_paint () has been in the interface is not drawing out
2. Correct wording

Copy Code code as follows:

byte* pbits = (byte*) lpbase + pbitmapfileheader->bfoffbits;

Written a

Copy Code code as follows:

byte* pbits = pbitmapfileheader->bfoffbits;

This is mainly used in the previous article in the CWnd Framework.

The. CPP source files are as follows:

Copy Code code as follows:

#include "ReadBMP.h"
#include "resource.h"
#include <afxdlgs.h >

CMyApp Theapp;
BOOL cmyapp::initinstance ()
{
m_pMainWnd = new CMainWindow;
M_pmainwnd->showwindow (m_nCmdShow);
return TRUE; Must return true, otherwise the message loop will not enter and the interface exits directly
}

CMainWindow
Begin_message_map (CMainWindow, CWnd)
On_wm_create ()
On_wm_paint ()
On_command (Idc_open, OnOpen)
End_message_map ()
Constructors
Cmainwindow::cmainwindow ()
{
LPCTSTR lpszClassName =:: 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);
}
destructor
Cmainwindow::~cmainwindow ()
{

}
Message mapping functions
int cmainwindow::oncreate (lpcreatestruct lpcreatestruct)
{
OutputDebugString ("OnCreate");
CCLIENTDC DC (this);
M_HMEMDC =:: CreateCompatibleDC (DC);
m_nwidth = 0;
m_nheight = 0;
Set Menu
Hmenu hmenu =:: Loadmenua (Theapp.m_hinstance, (LPCSTR) idr_menu);
:: SetMenu (M_hwnd, hmenu);
return 0;
}

void Cmainwindow::onncdestroy ()
{
Delete this;
}
void Cmainwindow::ondestroy ()
{

}
void Cmainwindow::onpaint ()
{
CPAINTDC DC (this);
:: BitBlt (DC, 0, 0, m_nwidth, m_nheight, M_HMEMDC, 0, 0, srccopy);
}
void Cmainwindow::onopen ()
{
CFileDialog Dlg (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
}
LPVOID lpbase =:: MapViewOfFile (Hfilemap, file_map_read, 0, 0, 0);
if (NULL = = lpbase)
{
Return
}
Three information from scratch structure: 1.bfOffBits bitmap data in the file starting position, 2.m_nwidth image width, 3.m_nheight image high
bitmapfileheader* Pbitmapfileheader;
bitmapinfo* Pbitmapinfo;
Pbitmapfileheader = (bitmapfileheader*) lpbase;
if (Pbitmapfileheader->bftype!= makeword (' B ', ' M '))
{
MessageBox ("not BMP");
:: UnmapViewOfFile (Lpbase);
:: CloseHandle (Hfilemap);
:: CloseHandle (hfile);
}
DWORD bfoffbits = pbitmapfileheader->bfoffbits;
byte* pbits = (byte*) lpbase + pbitmapfileheader->bfoffbits;
Pbitmapinfo = (bitmapinfo*) ((byte*) lpbase + sizeof (bitmapfileheader));
M_nwidth = pbitmapinfo->bmiheader.biwidth;
M_nheight = pbitmapinfo->bmiheader.biheight;
Displaying BMP files to memory devices
Client Area DC
CCLIENTDC DC (this);
Create a bitmap compatible with the client area DC
Hbitmap hbitmap =:: CreateCompatibleBitmap (DC, M_nwidth, m_nheight);
if (hbitmap = 0)
{
Return
}
Bitmap selected into memory DC
:: SelectObject (M_HMEMDC, HBITMAP);

The image data is placed in the established DC
:: SetDIBitsToDevice (M_HMEMDC, 0, 0, m_nwidth, m_nheight, 0, 0, 0, m_nheight, pbits, Pbitmapinfo, dib_rgb_colors);

:: InvalidateRect (M_hwnd, NULL, TRUE);
::D eleteobject (HBITMAP);

:: UnmapViewOfFile (Lpbase);
:: CloseHandle (Hfilemap);
:: CloseHandle (hfile);

}

. h header documents are as follows:

Copy Code code as follows:

#include <afxwin.h>

Class Cmyapp:public CWINAPP
{
Public
Virtual BOOL InitInstance ();
};

CMainWindow
Class Cmainwindow:public CWnd
{
Public
CMainWindow ();
~cmainwindow ();

Protected
HDC M_HMEMDC; Memory DC handle compatible with client area
UINT M_nwidth; The width of BMP
UINT M_nheight; The height of BMP

Message map
afx_msg void OnNcDestroy ();
afx_msg int OnCreate (lpcreatestruct lpcreatestruct);
afx_msg void OnDestroy ();
afx_msg void OnOpen ();
afx_msg void OnPaint ();
Declare_message_map ()
};

I hope this article will help you with the C + + program design.