在MFC中,如何读取外部的位图文件,让它显示在图片控件(Picture Control...
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发布时间：2022-05-07 09:46
共5个回答
热心网友
时间：2022-04-23 08:14
1.在你的对话框添一个按钮和一个图片控件(Picture Control).
2.添加一个类,我这里上传不了,只能将.h和.cpp复制过来,你再将拷贝到txt里,改一下扩展名就可以了。
这是Picture.h
#if !defined(AFX_PICTURE_H__COPYFREE_BY_YOVAV_GAD__SOURCES_AT_SUPERMAIN_DOT_COM__INCLUDED_)
#define AFX_PICTURE_H__COPYFREE_BY_YOVAV_GAD__SOURCES_AT_SUPERMAIN_DOT_COM__INCLUDED_
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
class CPicture
{
public:
void FreePictureData();
BOOL Load(CString sFilePathName);
BOOL Load(UINT ResourceName, LPCSTR ResourceType);
BOOL LoadPictureData(BYTE* pBuffer, int nSize);
BOOL SaveAsBitmap(CString sFilePathName);
BOOL Show(CDC* pDC, CPoint LeftTop, CPoint WidthHeight, int MagnifyX, int MagnifyY);
BOOL Show(CDC* pDC, CRect DrawRect);
BOOL ShowBitmapResource(CDC* pDC, const int BMPResource, CPoint LeftTop);
BOOL UpdateSizeOnDC(CDC* pDC);
CPicture();
virtual ~CPicture();
IPicture* m_IPicture; // Same As LPPICTURE (typedef IPicture __RPC_FAR *LPPICTURE)
LONG m_Height; // Height (In Pixels Ignor What Current Device Context Uses)
LONG m_Weight; // Size Of The Image Object In Bytes (File OR Resource)
LONG m_Width; // Width (In Pixels Ignor What Current Device Context Uses)
};
#endif
这是Picture.cpp
#include "stdafx.h"
#include "Picture.h"
#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
#define HIMETRIC_INCH 2540
#define ERROR_TITLE "CPicture Error" // Error Title (Related To This Class)...
//-----------------------------------------------------------------------------
// Does: Constructor - Create a New CPicture Object To Hold Picture Data
// ~~~~
//
//-----------------------------------------------------------------------------
CPicture::CPicture()
//=============================================================================
{
m_IPicture = NULL;
m_Height = 0;
m_Weight = 0;
m_Width = 0;
}
//-----------------------------------------------------------------------------
// Does: Destructor - Free Data And Information From The CPicture Object
// ~~~~
//
//-----------------------------------------------------------------------------
CPicture::~CPicture()
//=============================================================================
{
if(m_IPicture != NULL) FreePictureData(); // Important - Avoid Leaks...
}
//-----------------------------------------------------------------------------
// Does: Free The Allocated Memory That Holdes The IPicture Interface Data
// ~~~~ And Clear Picture Information
//
// Note: This Might Also Be Useful If U Only Need To Show The Picture Once
// ~~~~~ Or If U Copy The Picture To The Device Context, So It Can Still
// Remain On Screen - But IPicture Data Is Not Needed No More
//
//-----------------------------------------------------------------------------
void CPicture::FreePictureData()
//=============================================================================
{
if(m_IPicture != NULL)
{
m_IPicture->Release();
m_IPicture = NULL;
m_Height = 0;
m_Weight = 0;
m_Width = 0;
}
}
//-----------------------------------------------------------------------------
// Does: Open a Resource And Load It Into IPicture (Interface)
// ~~~~ (.BMP .DIB .EMF .GIF .ICO .JPG .WMF)
//
// Note: When Adding a Bitmap Resource It Would Automatically Show On "Bitmap"
// ~~~~ This NOT Good Coz We Need To Load It From a Custom Resource "BMP"
// To Add a Custom Rresource: Import Resource -> Open As -> Custom
// (Both .BMP And .DIB Should Be Found Under "BMP")
//
// InPut: ResourceName - As a UINT Defined (Example: IDR_PICTURE_RESOURCE)
// ~~~~~ ResourceType - Type Name (Example: "JPG")
//
// OutPut: TRUE If Succeeded...
// ~~~~~~
//-----------------------------------------------------------------------------
BOOL CPicture::Load(UINT ResourceName, LPCSTR ResourceType)
//=============================================================================
{
BOOL bResult = FALSE;
HGLOBAL hGlobal = NULL;
HRSRC hSource = NULL;
LPVOID lpVoid = NULL;
int nSize = 0;
if(m_IPicture != NULL) FreePictureData(); // Important - Avoid Leaks...
hSource = FindResource(AfxGetResourceHandle(), MAKEINTRESOURCE(ResourceName), ResourceType);
if(hSource == NULL)
{
HWND hWnd = AfxGetApp()->GetMainWnd()->m_hWnd;
MessageBoxEx(hWnd, "FindResource() Failed\t", ERROR_TITLE, MB_OK | MB_ICONSTOP, LANG_ENGLISH);
return(FALSE);
}
hGlobal = LoadResource(AfxGetResourceHandle(), hSource);
if(hGlobal == NULL)
{
HWND hWnd = AfxGetApp()->GetMainWnd()->m_hWnd;
MessageBoxEx(hWnd, "LoadResource() Failed\t", ERROR_TITLE, MB_OK | MB_ICONSTOP, LANG_ENGLISH);
return(FALSE);
}
lpVoid = LockResource(hGlobal);
if(lpVoid == NULL)
{
HWND hWnd = AfxGetApp()->GetMainWnd()->m_hWnd;
MessageBoxEx(hWnd, "LockResource() Failed\t", ERROR_TITLE, MB_OK | MB_ICONSTOP, LANG_ENGLISH);
return(FALSE);
}
nSize = (UINT)SizeofResource(AfxGetResourceHandle(), hSource);
if(LoadPictureData((BYTE*)hGlobal, nSize)) bResult = TRUE;
UnlockResource(hGlobal); // 16Bit Windows Needs This
FreeResource(hGlobal); // 16Bit Windows Needs This (32Bit - Automatic Release)
m_Weight = nSize; // Update Picture Size Info...
if(m_IPicture != NULL) // Do Not Try To Read From Memory That Is Not Exist...
{
m_IPicture->get_Height(&m_Height);
m_IPicture->get_Width(&m_Width);
// Calculate Its Size On a "Standard" (96 DPI) Device Context
m_Height = MulDiv(m_Height, 96, HIMETRIC_INCH);
m_Width = MulDiv(m_Width, 96, HIMETRIC_INCH);
}
else // Picture Data Is Not a Known Picture Type
{
m_Height = 0;
m_Width = 0;
bResult = FALSE;
}
return(bResult);
}
//-----------------------------------------------------------------------------
// Does: Open a File And Load It Into IPicture (Interface)
// ~~~~ (.BMP .DIB .EMF .GIF .ICO .JPG .WMF)
//
// InPut: sFilePathName - Path And FileName Target To Save
// ~~~~~
//
// OutPut: TRUE If Succeeded...
// ~~~~~~
//-----------------------------------------------------------------------------
BOOL CPicture::Load(CString sFilePathName)
//=============================================================================
{
BOOL bResult = FALSE;
CFile PictureFile;
CFileException e;
int nSize = 0;
if(m_IPicture != NULL) FreePictureData(); // Important - Avoid Leaks...
if(PictureFile.Open(sFilePathName, CFile::modeRead | CFile::typeBinary, &e))
{
nSize = PictureFile.GetLength();
BYTE* pBuffer = new BYTE[nSize];
if (PictureFile.Read(pBuffer, nSize) > 0 ) //从文件读到pBuffer
{ if(LoadPictureData(pBuffer, nSize)) bResult = TRUE; }//接作调用函数读pBuffer
PictureFile.Close();
delete [] pBuffer;
}
else // Open Failed...
{
TCHAR szCause[255];
e.GetErrorMessage(szCause, 255, NULL);
HWND hWnd = AfxGetApp()->GetMainWnd()->m_hWnd;
MessageBoxEx(hWnd, szCause, ERROR_TITLE, MB_OK | MB_ICONSTOP, LANG_ENGLISH);
bResult = FALSE;
}
m_Weight = nSize; // Update Picture Size Info...
if(m_IPicture != NULL) // Do Not Try To Read From Memory That Is Not Exist...
{
m_IPicture->get_Height(&m_Height);
m_IPicture->get_Width(&m_Width);
// Calculate Its Size On a "Standard" (96 DPI) Device Context
m_Height = MulDiv(m_Height, 96, HIMETRIC_INCH);
m_Width = MulDiv(m_Width, 96, HIMETRIC_INCH);
}
else // Picture Data Is Not a Known Picture Type
{
m_Height = 0;
m_Width = 0;
bResult = FALSE;
}
return(bResult);
}
//-----------------------------------------------------------------------------
// Does: Read The Picture Data From a Source (File / Resource)
// ~~~~ And Load It Into The Current IPicture Object In Use
//
// InPut: Buffer Of Data Source (File / Resource) And Its Size
// ~~~~~
//
// OutPut: Feed The IPicture Object With The Picture Data
// ~~~~~~ (Use Draw Functions To Show It On a Device Context)
// TRUE If Succeeded...
//-----------------------------------------------------------------------------
BOOL CPicture::LoadPictureData(BYTE *pBuffer, int nSize)
//=============================================================================
{
BOOL bResult = FALSE;
HGLOBAL hGlobal = GlobalAlloc(GMEM_MOVEABLE, nSize);
if(hGlobal == NULL)
{
HWND hWnd = AfxGetApp()->GetMainWnd()->m_hWnd;
MessageBoxEx(hWnd, "Can not allocate enough memory\t", ERROR_TITLE, MB_OK | MB_ICONSTOP, LANG_ENGLISH);
return(FALSE);
}
void* pData = GlobalLock(hGlobal);
memcpy(pData, pBuffer, nSize);
GlobalUnlock(hGlobal);
IStream* pStream = NULL;
if(CreateStreamOnHGlobal(hGlobal, TRUE, &pStream) == S_OK)
{
HRESULT hr;
if((hr = OleLoadPicture(pStream, nSize, FALSE, IID_IPicture, (LPVOID *)&m_IPicture)) == E_NOINTERFACE)
{
HWND hWnd = AfxGetApp()->GetMainWnd()->m_hWnd;
MessageBoxEx(hWnd, "IPicture interface is not supported\t", ERROR_TITLE, MB_OK | MB_ICONSTOP, LANG_ENGLISH);
return(FALSE);
}
else // S_OK
{
pStream->Release();
pStream = NULL;
bResult = TRUE;
}
}
FreeResource(hGlobal); // 16Bit Windows Needs This (32Bit - Automatic Release)
return(bResult);
}
//-----------------------------------------------------------------------------
// Does: Draw The Loaded Picture Direct To The Client DC
// ~~~~
//
// Note: Bigger OR Smaller Dimentions Than The Original Picture Size
// ~~~~ Will Draw The Picture Streached To Its New Given NEW Dimentions...
//
// InPut: pDC - Given DC To Draw On
// ~~~~~ DrawRect - Dimentions Of The Picture To Draw (As a Rectangle)
//
// OutPut: TRUE If Succeeded...
// ~~~~~~
//-----------------------------------------------------------------------------
BOOL CPicture::Show(CDC *pDC, CRect DrawRect)
//=============================================================================
{
if (pDC == NULL || m_IPicture == NULL) return FALSE;
long Width = 0;
long Height = 0;
m_IPicture->get_Width(&Width);
m_IPicture->get_Height(&Height);
HRESULT hrP = NULL;
hrP = m_IPicture->Render(pDC->m_hDC,
DrawRect.left, // Left
DrawRect.top, // Top
DrawRect.right - DrawRect.left, // Right
DrawRect.bottom - DrawRect.top, // Bottom
0,
Height,
Width,
-Height,
&DrawRect);
if (SUCCEEDED(hrP)) return(TRUE);
HWND hWnd = AfxGetApp()->GetMainWnd()->m_hWnd;
MessageBoxEx(hWnd, "Can not allocate enough memory\t", ERROR_TITLE, MB_OK | MB_ICONSTOP, LANG_ENGLISH);
return(FALSE);
}
//-----------------------------------------------------------------------------
// Does: Draw The Loaded Picture Direct To The Client DC
// ~~~~
//
// Note: Bigger OR Smaller Dimentions Than The Original Picture Size
// ~~~~ Will Draw The Picture Streached To Its New Given Dimentions...
//
// InPut: pDC - Given DC To Draw On
// ~~~~~ LeftTop - Opening Point To Start Drawing (Left,Top)
// WidthHeight - Dimentions Of The Picture To Draw (Width,Height)
// MagnifyX - Magnify Pixel Width, 0 = Default (No Magnify)
// MagnifyY - Magnify Pixel Height, 0 = Default (No Magnify)
//
// OutPut: TRUE If Succeeded...
// ~~~~~~
//-----------------------------------------------------------------------------
BOOL CPicture::Show(CDC *pDC, CPoint LeftTop, CPoint WidthHeight, int MagnifyX, int MagnifyY)
//=============================================================================
{
if (pDC == NULL || m_IPicture == NULL) return FALSE;
long Width = 0;
long Height = 0;
m_IPicture->get_Width(&Width);
m_IPicture->get_Height(&Height);
if(MagnifyX == NULL) MagnifyX = 0;
if(MagnifyY == NULL) MagnifyY = 0;
MagnifyX = int(MulDiv(Width, pDC->GetDeviceCaps(LOGPIXELSX), HIMETRIC_INCH) * MagnifyX);
MagnifyY = int(MulDiv(Height,pDC->GetDeviceCaps(LOGPIXELSY), HIMETRIC_INCH) * MagnifyY);
CRect DrawRect(LeftTop.x, LeftTop.y, MagnifyX, MagnifyY);
HRESULT hrP = NULL;
hrP = m_IPicture->Render(pDC->m_hDC,
LeftTop.x, // Left
LeftTop.y, // Top
WidthHeight.x +MagnifyX, // Width
WidthHeight.y +MagnifyY, // Height
0,
Height,
Width,
-Height,
&DrawRect);
if(SUCCEEDED(hrP)) return(TRUE);
HWND hWnd = AfxGetApp()->GetMainWnd()->m_hWnd;
MessageBoxEx(hWnd, "Can not allocate enough memory\t", ERROR_TITLE, MB_OK | MB_ICONSTOP, LANG_ENGLISH);
return(FALSE);
}
//-----------------------------------------------------------------------------
// Does: Saves The Picture That Is Stored In The IPicture Object As a Bitmap
// ~~~~ (Converts From Any Known Picture Type To a Bitmap / Icon File)
//
// InPut: sFilePathName - Path And FileName Target To Save
// ~~~~~
//
// OutPut: TRUE If Succeeded...
// ~~~~~~
//-----------------------------------------------------------------------------
BOOL CPicture::SaveAsBitmap(CString sFilePathName)
//=============================================================================
{
BOOL bResult = FALSE;
ILockBytes *Buffer = 0;
IStorage *pStorage = 0;
IStream *FileStream = 0;
BYTE *BufferBytes;
STATSTG BytesStatistics;
DWORD OutData;
long OutStream;
CFile BitmapFile; CFileException e;
double SkipFloat = 0;
DWORD ByteSkip = 0;
_ULARGE_INTEGER RealData;
CreateILockBytesOnHGlobal(NULL, TRUE, &Buffer); // Create ILockBytes Buffer
HRESULT hr = ::StgCreateDocfileOnILockBytes(Buffer,
STGM_SHARE_EXCLUSIVE | STGM_CREATE | STGM_READWRITE, 0, &pStorage);
hr = pStorage->CreateStream(L"PICTURE",
STGM_SHARE_EXCLUSIVE | STGM_CREATE | STGM_READWRITE, 0, 0, &FileStream);
m_IPicture->SaveAsFile(FileStream, TRUE, &OutStream); // Copy Data Stream
FileStream->Release();
pStorage->Release();
Buffer->Flush();
// Get Statistics For Final Size Of Byte Array
Buffer->Stat(&BytesStatistics, STATFLAG_NONAME);
// Cut UnNeeded Data Coming From SaveAsFile() (Leave Only "Pure" Picture Data)
SkipFloat = (double(OutStream) / 512); // Must Be In a 512 Blocks...
if(SkipFloat > DWORD(SkipFloat)) ByteSkip = (DWORD)SkipFloat + 1;
else ByteSkip = (DWORD)SkipFloat;
ByteSkip = ByteSkip * 512; // Must Be In a 512 Blocks...
// Find Difference Between The Two Values
ByteSkip = (DWORD)(BytesStatistics.cbSize.QuadPart - ByteSkip);
// Allocate Only The "Pure" Picture Data
RealData.LowPart = 0;
RealData.HighPart = 0;
RealData.QuadPart = ByteSkip;
BufferBytes = (BYTE*)malloc(OutStream);
if(BufferBytes == NULL)
{
Buffer->Release();
HWND hWnd = AfxGetApp()->GetMainWnd()->m_hWnd;
MessageBoxEx(hWnd, "Can not allocate enough memory\t", ERROR_TITLE, MB_OK | MB_ICONSTOP, LANG_ENGLISH);
}
Buffer->ReadAt(RealData, BufferBytes, OutStream, &OutData);
if(BitmapFile.Open(sFilePathName, CFile::typeBinary | CFile::modeCreate | CFile::modeWrite, &e))
{
BitmapFile.Write(BufferBytes, OutData);
BitmapFile.Close();
bResult = TRUE;
}
else // Write File Failed...
{
TCHAR szCause[255];
e.GetErrorMessage(szCause, 255, NULL);
HWND hWnd = AfxGetApp()->GetMainWnd()->m_hWnd;
MessageBoxEx(hWnd, szCause, ERROR_TITLE, MB_OK | MB_ICONSTOP, LANG_ENGLISH);
bResult = FALSE;
}
Buffer->Release();
free(BufferBytes);
return(bResult);
}
//-----------------------------------------------------------------------------
// Does: Draw a Bitmap Resource To The Client DC (Using Bitblt())
// ~~~~ It Will Use The Bitmap Resource Original Size (Width And Height)
// (.BMP .DIB)
//
// Note: This Function Is Just Another Simple Way Of Displaying a Bitmap Resource,
// ~~~~ It Is Not Connected With The IPicture Interface And Can Be Used
// As a StandAlone On Any Device Context (Directly)
//
// InPut: BMPResource - Resource Name As Defined In The Resources
// ~~~~~ pDC - Given DC To Draw On
// LeftTop - Opening Point To Start Drawing (Left,Top)
//
// OutPut: TRUE If Succeeded...
// ~~~~~~
//-----------------------------------------------------------------------------
BOOL CPicture::ShowBitmapResource(CDC *pDC, const int BMPResource, CPoint LeftTop)
//=============================================================================
{
if (pDC == NULL) return(FALSE);
CBitmap BMP;
if(BMP.LoadBitmap(BMPResource))
{
// Get Bitmap Details
BITMAP BMPInfo;
BMP.GetBitmap(&BMPInfo);
// Create An In-Memory DC Compatible With The Display DC We R Gonna Paint On
CDC DCMemory;
DCMemory.CreateCompatibleDC(pDC);
// Select The Bitmap Into The In-Memory DC
CBitmap* pOldBitmap = DCMemory.SelectObject(&BMP);
// Copy Bits From The In-Memory DC Into The On-Screen DC
pDC->BitBlt(LeftTop.x, LeftTop.y, BMPInfo.bmWidth, BMPInfo.bmHeight, &DCMemory, 0, 0, SRCCOPY);
DCMemory.SelectObject(pOldBitmap); // (As Shown In MSDN Example...)
}
else
{
TRACE0("ERROR: Can Not Find The Bitmap Resource\n");
return(FALSE);
}
return(TRUE);
}
//-----------------------------------------------------------------------------
// Does: Get The Original Picture Pixel Size (Ignor What Current DC Is Using)
// ~~~~ Pointer To a Device Context Is Needed For Pixel Calculation,
//
// Also Updates The Class's Height And Width Properties,
// (Coz Till Now We Had No Device Context To Work With...96 DPI Assumed)
//
// InPut: The Client DC (Needed To Check The Size Of The Pixels)
// ~~~~~
//
// OutPut: TRUE If Succeeded...
// ~~~~~~
//-----------------------------------------------------------------------------
BOOL CPicture::UpdateSizeOnDC(CDC *pDC)
//=============================================================================
{
if(pDC == NULL || m_IPicture == NULL) { m_Height = 0; m_Width = 0; return(FALSE); };
m_IPicture->get_Height(&m_Height);
m_IPicture->get_Width(&m_Width);
// Get Current DPI - Dot Per Inch
int CurrentDPI_X = pDC->GetDeviceCaps(LOGPIXELSX);
int CurrentDPI_Y = pDC->GetDeviceCaps(LOGPIXELSY);
// Use a "Standard" Print (When Printing)
if(pDC->IsPrinting())
{
CurrentDPI_X = 96;
CurrentDPI_Y = 96;
}
m_Height = MulDiv(m_Height, CurrentDPI_Y, HIMETRIC_INCH);
m_Width = MulDiv(m_Width, CurrentDPI_X, HIMETRIC_INCH);
return(TRUE);
}
3.在对话框头文件定义:
先包含头文件#include "Picture.h"
再定义
CPicture m_Pic;
4.给按钮的函数里写上:(注意,这个IDC_SHOWPIC)是你那个显示控件的ID号.
CRect rect;
GetDlgItem(IDC_SHOWPIC)->GetWindowRect(&rect);
ScreenToClient(&rect);
CFile f;
CString FilePathName;
CFileException e;
CFileDialog dlg(TRUE,NULL,NULL,0,_T("All Files (*.*)|*.*|BMP (*.bmp)|*.bmp|DIB (*.dib)|*.dib|EMF (*.emf)|*.emf|GIF (*.gif)|*.gif|ICO (*.ico)|*.ico|JPG (*.jpg)|*.jpg|WMF (*.wmf)|*.wmf||"),NULL);
if(dlg.DoModal()==IDOK)
{
FilePathName=dlg.GetPathName();
if(m_Pic.m_IPicture != NULL) m_Pic.FreePictureData();
m_Pic.Load(FilePathName);
CClientDC dc(this);
m_Pic.UpdateSizeOnDC(&dc);
m_Pic.Show(&dc, &rect);
}
热心网友
时间：2022-04-23 09:32
---- 一、BMP文件结构
---- 1. BMP文件组成
---- BMP文件由文件头、位图信息头、颜色信息和图形数据四部分组成。
---- 2. BMP文件头
---- BMP文件头数据结构含有BMP文件的类型、文件大小和位图起始位置等信息。
---- 其结构定义如下:
typedef struct tagBITMAPFILEHEADER
{
WORDbfType; // 位图文件的类型，必须为BM
DWORD bfSize; // 位图文件的大小，以字节为单位
WORDbfReserved1; // 位图文件保留字，必须为0
WORDbfReserved2; // 位图文件保留字，必须为0
DWORD bfOffBits; // 位图数据的起始位置，以相对于位图
// 文件头的偏移量表示，以字节为单位
} BITMAPFILEHEADER;
---- 3. 位图信息头
BMP位图信息头数据用于说明位图的尺寸等信息。
typedef struct tagBITMAPINFOHEADER{
DWORD biSize; // 本结构所占用字节数
LONGbiWidth; // 位图的宽度，以像素为单位
LONGbiHeight; // 位图的高度，以像素为单位
WORD biPlanes; // 目标设备的级别，必须为1
WORD biBitCount// 每个像素所需的位数，必须是1(双色),
// 4(16色)，8(256色)或24(真彩色)之一
DWORD biCompression; // 位图压缩类型，必须是 0(不压缩),
// 1(BI_RLE8压缩类型)或2(BI_RLE4压缩类型)之一
DWORD biSizeImage; // 位图的大小，以字节为单位
LONGbiXPelsPerMeter; // 位图水平分辨率，每米像素数
LONGbiYPelsPerMeter; // 位图垂直分辨率，每米像素数
DWORD biClrUsed;// 位图实际使用的颜色表中的颜色数
DWORD biClrImportant;// 位图显示过程中重要的颜色数
} BITMAPINFOHEADER;
---- 4. 颜色表
---- 颜色表用于说明位图中的颜色，它有若干个表项，每一个表项是一个RGBQUAD类型的结构，定义一种颜色。RGBQUAD结构的定义如下:
typedef struct tagRGBQUAD {
BYTErgbBlue;// 蓝色的亮度(值范围为0-255)
BYTErgbGreen; // 绿色的亮度(值范围为0-255)
BYTErgbRed; // 红色的亮度(值范围为0-255)
BYTErgbReserved;// 保留，必须为0
} RGBQUAD;
颜色表中RGBQUAD结构数据的个数有biBitCount来确定:
当biBitCount=1,4,8时，分别有2,16,256个表项;
当biBitCount=24时，没有颜色表项。
位图信息头和颜色表组成位图信息，BITMAPINFO结构定义如下:
typedef struct tagBITMAPINFO {
BITMAPINFOHEADER bmiHeader; // 位图信息头
RGBQUAD bmiColors[1]; // 颜色表
} BITMAPINFO;
---- 5. 位图数据
---- 位图数据记录了位图的每一个像素值，记录顺序是在扫描行内是从左到右,扫描行之间是从下到上。位图的一个像素值所占的字节数:
当biBitCount=1时，8个像素占1个字节;
当biBitCount=4时，2个像素占1个字节;
当biBitCount=8时，1个像素占1个字节;
当biBitCount=24时,1个像素占3个字节;
Windows规定一个扫描行所占的字节数必须是 4的倍数(即以long为单位),不足的以0填充，
一个扫描行所占的字节数计算方法: DataSizePerLine= (biWidth* biBitCount+31)/8;
// 一个扫描行所占的字节数 DataSizePerLine= DataSizePerLine/4*4; // 字节数必须是4的倍数
位图数据的大小(不压缩情况下): DataSize= DataSizePerLine* biHeight;
---- 二、BMP位图一般显示方法
---- 1. 申请内存空间用于存放位图文件
---- GlobalAlloc(GHND，FileLength);
---- 2. 位图文件读入所申请内存空间中
---- LoadFileToMemory( mpBitsSrc，mFileName);
---- 3. 在OnPaint等函数中用创建显示用位图
---- 用CreateDIBitmap()创建显示用位图，用CreateCompatibleDC()创建兼容DC,
---- 用SelectBitmap()选择显示位图。
---- 4. 用BitBlt或StretchBlt等函数显示位图
---- 5. 用DeleteObject()删除所创建的位图
---- 以上方法的缺点是: 1)显示速度慢; 2) 内存占用大; 3) 位图在缩小显示时图形失真大,(可通过安装字体平滑软件来解决); 4) 在低颜色位数的设备上(如256显示模式)显示高颜色位数的图形(如真彩色)图形失真严重。
---- 三、BMP位图缩放显示
---- 用DrawDib视频函数来显示位图，内存占用少，速度快，而且还可以对图形进行淡化(Dithering )处理。淡化处理是一种图形算法，可以用来在一个支持比图像所用颜色要少的设备上显示彩色图像。BMP位图显示方法如下:
---- 1. 打开视频函数DrawDibOpen()，一般放在在构造函数中
---- 2. 申请内存空间用于存放位图文件
---- GlobalAlloc(GHND，FileLength);
---- 3. 位图文件读入所申请内存空间中
---- LoadFileToMemory( mpBitsSrc，mFileName);
---- 4. 在OnPaint等函数中用DrawDibRealize()，DrawDibDraw()显示位图
---- 5. 关闭视频函数DrawDibClose(),一般放在在析构函数中
---- 以上方法的优点是: 1)显示速度快; 2) 内存占用少; 3) 缩放显示时图形失真小,4) 在低颜色位数的设备上显示高颜色位数的图形图形时失真小; 5) 通过直接处理位图数据，可以制作简单动画。
---- 四、CViewBimap类编程要点
---- 1. 在CViewBimap类中添加视频函数等成员
HDRAWDIB m_hDrawDib; // 视频函数
HANDLEmhBitsSrc; // 位图文件句柄(内存)
LPSTR mpBitsSrc; // 位图文件地址(内存)
BITMAPINFOHEADER *mpBitmapInfo; // 位图信息头
---- 2. 在CViewBimap类构造函数中添加打开视频函数
---- m_hDrawDib= DrawDibOpen();
---- 3. 在CViewBimap类析构函数中添加关闭视频函数
if( m_hDrawDib != NULL)
{
DrawDibClose( m_hDrawDib);
m_hDrawDib = NULL;
}
---- 4. 在CViewBimap类图形显示函数OnPaint中添加GraphicDraw()
voidCViewBitmap::OnPaint()
{
CPaintDC dc(this); // device context for painting
GraphicDraw( );
}
voidCViewBitmap::GraphicDraw( void )
{
CClientDC dc(this); // device context for painting
BITMAPFILEHEADER *pBitmapFileHeader;
ULONG bfoffBits= 0;
CPoint Wid;
// 图形文件名有效 (=0 BMP)
if( mBitmapFileType < ID_BITMAP_BMP ) return;
// 图形文件名有效 (=0 BMP)
// 准备显示真彩位图
pBitmapFileHeader= (BITMAPFILEHEADER *) mpBitsSrc;
bfoffBits= pBitmapFileHeader->bfOffBits;
// 使用普通函数显示位图
if( m_hDrawDib == NULL || mDispMethod == 0)
{
HBITMAP hBitmap=::CreateDIBitmap(dc.m_hDC,
mpBitmapInfo, CBM_INIT, mpBitsSrc+bfoffBits,
(LPBITMAPINFO) mpBitmapInfo,DIB_RGB_COLORS);
// 建立位图
HDC hMemDC=::CreateCompatibleDC(dc.m_hDC);// 建立内存
HBITMAP hBitmapOld= SelectBitmap(hMemDC, hBitmap); // 选择对象
// 成员CRect mDispR用于指示图形显示区域的大小.
// 成员CPoint mPos用于指示图形显示起始位置坐标.
if( mPos.x > (mpBitmapInfo- >biWidth - mDispR.Width() ))
mPos.x= mpBitmapInfo->biWidth - mDispR.Width() ;
if( mPos.y > (mpBitmapInfo- >biHeight- mDispR.Height()))
mPos.y= mpBitmapInfo- >biHeight- mDispR.Height();
if( mPos.x < 0 ) mPos.x= 0;
if( mPos.y < 0 ) mPos.y= 0;
if( mFullViewTog == 0)
{
// 显示真彩位图
::BitBlt(dc.m_hDC,0,0, mDispR.Width(), mDispR.Height(),
hMemDC,mPos.x,mPos.y, SRCCOPY);
} else {
::StretchBlt(dc.m_hDC,0,0, mDispR.Width(), mDispR.Height(),
hMemDC,0,0, mpBitmapInfo- >biWidth, mpBitmapInfo-
>biHeight, SRCCOPY);
}
// 结束显示真彩位图
::DeleteObject(SelectObject(hMemDC,hBitmapOld));
// 删 除 位 图
} else {
// 使用视频函数显示位图
if( mPos.x > (mpBitmapInfo- >biWidth - mDispR.Width() ))
mPos.x= mpBitmapInfo- >biWidth - mDispR.Width() ;
if( mPos.y > (mpBitmapInfo- >biHeight- mDispR.Height()))
mPos.y= mpBitmapInfo- >biHeight- mDispR.Height();
if( mPos.x < 0 ) mPos.x= 0;
if( mPos.y < 0 ) mPos.y= 0;
热心网友
时间：2022-04-23 11:06
BITMAP BM;
CDC MemDC;
CClientDC ClientDC(this);
MemDC.CreateCompatibleDC(&ClientDC);
hBitmap=(HBITMAP*)::LoadImage(
AfxGetInstanceHandle(), // 取得应用程序句柄
"demo1.bmp", // 位图文件名
IMAGE_BITMAP, // 类型为Windows位图
0,0,
LR_LOADFROMFILE
);
// 从文件中取位图数据
MemDC.SelectObject(hBitmap);
::GetObject(hBitmap，sizeof(BM), &BM);
ClientDC.BitBlt(
X,Y, // 目标设备逻辑横、纵坐标
BM.bmWidth, BM.bmHeight, // 显示位图的像素宽、高度
&MemDC, // 待显示位图数据的设备情境对象
0,0, // 源数据中的横、纵坐标
SRCCOPY // 位操作方式
);
热心网友
时间：2022-04-23 12:58
1 读取文件，转换成位图对象
2 获得空间的hdc，在hdc上绘制这个位图
www.codeproject.com 上面有大量的例子可以看
热心网友
时间：2022-04-23 15:06
参考资料：http://www.vckbase.com/code/downcode.asp?id=1972
