How to Draw Bitmap from a bmp File?

support — Fri, 05 Jan 2007 07:06:52 +0000

How to load a bitmap from bmp file and draw it in DC?

There are two main steps:

Load the bitmap from the file to a memory DC.
Paint the content of the memory DC to the one which display the bitmap.

In MFC, there is no API to load a bitmap directly from a file, but you can use a Win32 API: LoadImage.
Here is the delaration of LoadImage.

HANDLE LoadImage(
HINSTANCE hinst, //handle to instance, if load from file, it should be NULL
LPCTSTR lpszName, //image resource name or the image file path
UINT uType, //image type
//1. IMAGE_BITMAP
//2. IMAGE_CURSOR
//3. IMAGE_ICON
int cxDesired, //desired width
int cyDesired, //desired height
UINT fuLoad //load options
);

After this, the following steps are similar with loading a bitmap from resource. Here is a short example.

CClientDC dc(this);
CDC *mdc=new CDC;
mdc->CreateCompatibleDC(&dc);

CBitmap bitmap;
//CBitmap is devived from CGdiObject
//It has a handle:m_hObject, which can obtained with LoadImage
bitmap.m_hObject=(HBITMAP)::LoadImage(
NULL,
“b1.bmp”,
IMAGE_BITMAP,
500,
400,
LR_LOADFROMFILE);

mdc->SelectObject(bitmap);
CRect rect;
GetClientRect(&rect);
//BitBlt()
dc.BitBlt(0,0,rect.right,rect.bottom,mdc,0,0,SRCCOPY);

//release mdc
delete mdc;

Tags: Bitmap, Cpp, How-to, Win32/MFC

Simple code to create an EMF or Bitmap file from existed draw code

hamo — Sun, 17 Dec 2006 02:04:30 +0000

We often need to create an Enhanced Meta File(EMF) or Bitmap(bmp) from an existed DC draw code. It’s not very difficult but it’s boring to code again and again.
The following is a simple solution, what you need to do is only to implement an IPicDrawer and call DrawEnhMeta or DrawBitmap function.

struct IPicDrawer
{
virtual void GetSize(CSize&) = 0; // It’s the smallest size for EMF
virtual BOOL Draw(CDC*) = 0;
};

BOOL DrawEnhMeta(LPCTSTR lpszFileName, IPicDrawer *pIDrawer)
{
// Draw EMF file, the limitation of DC function refer to MSDN
HDC hDC = ::CreateEnhMetaFile(NULL, lpszFileName, NULL,
_T(“FQ EMF Func\0No Title\0″));
CDC *pDC = CDC::FromHandle(hDC);
if(pDC)
{
CSize sz;
pIDrawer->GetSize(sz);
pDC->FillRect(CRect(0,0,sz.cx,sz.cy), &CBrush(RGB(255,255,255)));
if(pIDrawer->Draw(pDC))
{
HENHMETAFILE hEmf = ::CloseEnhMetaFile(hDC);
if(hEmf)
{
::DeleteEnhMetaFile(hEmf);
return TRUE;
}
else
::DeleteFile(lpszFileName);
}
}
return FALSE;
}

BOOL DrawBitmap(LPCTSTR lpszFileName, IPicDrawer *pIDrawer)
{
// Draw 24 bit true color bitmap file
HANDLE hFile = ::CreateFile(lpszFileName, GENERIC_READ | GENERIC_WRITE,
0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
BOOL bRet = FALSE;
if(hFile)
{
CSize sz;
pIDrawer->GetSize(sz);
BITMAPINFO BmpInfo = {0, }; //
BmpInfo.bmiHeader.biWidth = sz.cx;
BmpInfo.bmiHeader.biHeight = sz.cy;
BmpInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
BmpInfo.bmiHeader.biPlanes = 1;
BmpInfo.bmiHeader.biBitCount = 24; // 24bit
BmpInfo.bmiHeader.biCompression = BI_RGB;
BmpInfo.bmiHeader.biSizeImage = BmpInfo.bmiHeader.biBitCount / 8 *
BmpInfo.bmiHeader.biWidth * BmpInfo.bmiHeader.biHeight;

BITMAPFILEHEADER bmpFileHeader = {0, }; //
bmpFileHeader.bfType = *(WORD*)_T(“BM”);
bmpFileHeader.bfOffBits =
sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);
bmpFileHeader.bfOffBits +=
sizeof(DWORD) – (bmpFileHeader.bfOffBits % sizeof(DWORD));
bmpFileHeader.bfSize = bmpFileHeader.bfOffBits + BmpInfo.bmiHeader.biSizeImage;
//write file header and image information
DWORD dwNum = 0;
bRet = ::WriteFile(hFile, &bmpFileHeader, sizeof(BITMAPFILEHEADER),
&dwNum, NULL);
bRet = bRet && ::WriteFile(hFile, &(BmpInfo.bmiHeader), sizeof(BITMAPINFOHEADER),
&dwNum, NULL);
if(bRet)
{
bRet = FALSE;
//create file mapping
HANDLE hMap = ::CreateFileMapping(hFile, NULL, PAGE_READWRITE,
0, bmpFileHeader.bfSize, NULL);
if(hMap)
{
// create bitmap object
void *pBits = NULL;
HBITMAP hBMP = ::CreateDIBSection(NULL, &BmpInfo, DIB_RGB_COLORS,
&pBits, hMap, bmpFileHeader.bfOffBits);
if(hBMP)
{
// draw the specified figure to file
CDC memTmpDC;
memTmpDC.CreateCompatibleDC(NULL);
if(memTmpDC.GetSafeHdc())
{
CBitmap *pbmp;
pbmp = CBitmap::FromHandle(hBMP);
if(pbmp)
{
memTmpDC.SelectObject(pbmp);
memTmpDC.FillRect(CRect(0,0,sz.cx,sz.cy), &CBrush(RGB(255,255,255)));
bRet = pIDrawer->Draw(&memTmpDC);
}
}
::DeleteObject(hBMP);
}
::CloseHandle(hMap);
}
}
::CloseHandle(hFile);
}
if(!bRet)
::DeleteFile(lpszFileName);
return bRet;
}

Tags: Bitmap, emf, Win32/MFC

Code Library » Bitmap

How to Draw Bitmap from a bmp File?

Simple code to create an EMF or Bitmap file from existed draw code