BMP位图之代码实现

V2AS问路

BMP位图之代码实现

阅读原文时间：2023年07月10日阅读：2

从16位开始，不存在调色板，顶多存在一个RGBQUAD的掩码。

16位位图，我没有拿到对应的素材，但是根据官方文档的描述和代码验证后，我总结为下：

当biCompression为BI_RGB时，此时是RGB555格式，不存在调色板。

当biCompression为BI_BITFIELDS时，16位位图时RGB565格式，对应的32位是带掩码的格式，两种都有一个RGBQUAD的数据存在于调色板。

24位位图，只有BI_RGB存储方式。

代码实现如下

enum { bitmap_undefined, bitmap_unknown, bitmap1, bitmap4, bitmap4_RLE4,
bitmap8, bitmap8_RLE8, bitmap16_RGB555, bitmap16_RGB565, bitmap24, bitmap32, bitmap32_mask};//所有bmp类型

class Bitmap {
public:
Bitmap();
virtual ~Bitmap();
HBITMAP BitCreate(HDC hDC, LPTSTR szFilename);//从文件载入
HBITMAP BitCreate(HDC hDC, HINSTANCE hInstance, UINT rscID);//从资源载入
PBITMAPFILEHEADER GetBitFileheader(PBYTE pBitmap = NULL);//位图头
PBITMAPINFOHEADER GetBitInfoheader(PBYTE pBitmap = NULL);//位图INFO结构
LPRGBQUAD GetBitPalette(PBYTE pBitmap = NULL);//位图画板，不存在返回NULL
PVOID GetBitData(PBYTE pBitmap = NULL);//位图数据
void BitDraw(HDC hDC, int x, int y, HBITMAP hBitmap);//将位图画到自己的窗口
protected:
void BitErrorshow(DWORD errorID);//错误提示
void BitTypedefined();//类型定义
void BitFree();//资源释放
HBITMAP BitLoad(HDC hDC, PBYTE pBitmap = NULL);//载入的数据，转换为HBITMAP句柄，方便操作
private:
HGLOBAL m_hGlablebitmap;
HANDLE m_hFilemapping;
PBYTE m_pBitmap;
int m_iWidth, m_iHeight, m_iFilesize;
int m_iType;
};

对应的实现代码

Bitmap::Bitmap() {
m_hFilemapping = m_hGlablebitmap = NULL;
m_pBitmap = NULL;
m_iFilesize = m_iWidth = m_iHeight = 0;
m_iType = bitmap_undefined;
}

Bitmap::~Bitmap() {
BitFree();
}

void Bitmap::BitTypedefined() {
PBITMAPINFOHEADER bInfoheader;
bInfoheader = GetBitInfoheader();
m_iWidth = bInfoheader->biWidth;
m_iHeight = bInfoheader->biHeight;
WORD bitCount = bInfoheader->biBitCount;
DWORD bitCompression = bInfoheader->biCompression;
if (bitCompression == BI_RGB) {
switch (bitCount) {
case 1:
m_iType = bitmap1; break;
case 4:
m_iType = bitmap4; break;
case 8:
m_iType = bitmap8; break;
case 16:
m_iType = bitmap16_RGB555; break;
case 24:
m_iType = bitmap24; break;
case 32:
m_iType = bitmap32; break;
default:
m_iType = bitmap_unknown;
}
}
else if (bitCompression == BI_BITFIELDS) {
switch (bitCount) {
case 16:
m_iType = bitmap16_RGB565; break;
case 32:
m_iType = bitmap32_mask; break;
default:
m_iType = bitmap_unknown;
}
}
else if (bitCompression == BI_RLE4)
m_iType = bitmap4_RLE4;
else if (bitCompression == BI_RLE8)
m_iType = bitmap8_RLE8;
else
m_iType = bitmap_unknown;
}

HBITMAP Bitmap::BitLoad(HDC hDC, PBYTE pBitmap) {
PBITMAPINFOHEADER pBitmapinfo = GetBitInfoheader(pBitmap);
PBYTE pBitmapdata = (PBYTE)GetBitData(pBitmap), pDIBData = NULL;
HBITMAP hBitmap = CreateDIBSection(hDC, (PBITMAPINFO)pBitmapinfo, DIB_RGB_COLORS, (void **)&pDIBData,
NULL, 0);
DWORD sizeImage = m_iFilesize - (DWORD)(pBitmapdata - pBitmap);//永远自己计算数据大小，因为位图INFO头中的biSizeImage字段可能为0.
CopyMemory(pDIBData, pBitmapdata, sizeImage);
return hBitmap;
}

void Bitmap::BitErrorshow(DWORD errorID) {
TCHAR szCaption[64];
LPVOID lpMsgBuf;
wsprintf(szCaption, L"错误代码：0x%08x", errorID);
FormatMessage(
FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
NULL,
errorID,
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
(LPTSTR)&lpMsgBuf,
0, NULL);
MessageBox(NULL, (LPTSTR)lpMsgBuf, szCaption, MB_OK | MB_ICONSTOP);
LocalFree(lpMsgBuf);
}

HBITMAP Bitmap::BitCreate(HDC hDC, LPTSTR szFilename) {
HANDLE hFile = NULL;
BitFree();//释放之前数据
__try {
hFile = CreateFile(szFilename, GENERIC_READ, FILE_SHARE_READ, NULL,
OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
m_hFilemapping = CreateFileMapping(hFile, NULL, PAGE_READONLY, 0, 0, NULL);
m_pBitmap = (PBYTE)MapViewOfFile(m_hFilemapping, FILE_MAP_READ, 0, 0, 0);
m_iFilesize = GetFileSize(hFile, 0);
BitTypedefined();
}__except (EXCEPTION_EXECUTE_HANDLER) {
BitErrorshow(GetLastError());
CloseHandle(hFile);
BitFree();
return NULL;
}
CloseHandle(hFile);
return BitLoad(hDC, m_pBitmap);
}

HBITMAP Bitmap::BitCreate(HDC hDC, HINSTANCE hInstance, UINT rscID) {
HRSRC hResInfo = NULL;
BitFree();//释放之前数据
__try {
hResInfo = FindResource(hInstance, MAKEINTRESOURCE(rscID), RT_BITMAP);
m_hGlablebitmap = LoadResource(hInstance, hResInfo);
m_pBitmap = (PBYTE)LockResource(m_hGlablebitmap);
m_iFilesize = SizeofResource(hInstance, hResInfo);
BitTypedefined();
}__except (EXCEPTION_EXECUTE_HANDLER) {
BitErrorshow(GetLastError());
BitFree();
return NULL;
}
return BitLoad(hDC, m_pBitmap);
}

void Bitmap::BitFree() {
if (m_hFilemapping != NULL) {
UnmapViewOfFile(m_pBitmap);
CloseHandle(m_hFilemapping);
m_hFilemapping = NULL;
}
else if (m_hGlablebitmap != NULL) {
UnlockResource(m_hGlablebitmap);
FreeResource(m_hGlablebitmap);
m_hGlablebitmap = NULL;
}
m_pBitmap = NULL;
m_iType = bitmap_undefined;
m_iFilesize = m_iHeight = m_iWidth = 0;
}

PBITMAPFILEHEADER Bitmap::GetBitFileheader(PBYTE pBitmap) {
if (m_hFilemapping != NULL)
return pBitmap ? (PBITMAPFILEHEADER)pBitmap : (PBITMAPFILEHEADER)m_pBitmap;
return NULL;
}

PBITMAPINFOHEADER Bitmap::GetBitInfoheader(PBYTE pBitmap) {
DWORD offset = 0;
if (m_hFilemapping != NULL)
offset = sizeof(BITMAPFILEHEADER);
return pBitmap ? (PBITMAPINFOHEADER)(pBitmap + offset) : (PBITMAPINFOHEADER)(m_pBitmap + offset);
}

LPRGBQUAD Bitmap::GetBitPalette(PBYTE pBitmap) {
PBITMAPINFOHEADER pBitmapinfo = GetBitInfoheader(pBitmap);
PBYTE pPalette = (PBYTE)pBitmapinfo + sizeof(PBITMAPINFOHEADER), pData = (PBYTE)GetBitData(pBitmap);
if (pPalette == pData)//不存在调色板
return NULL;
return (LPRGBQUAD)pPalette;
}

PVOID Bitmap::GetBitData(PBYTE pBitmap) {
DWORD offset = 0, n;
PBITMAPINFOHEADER pBitmapinfo = GetBitInfoheader(pBitmap);
n = pBitmapinfo->biClrUsed ? pBitmapinfo->biClrUsed : pBitmapinfo->biBitCount;
switch (m_iType) {
case bitmap1:
case bitmap4:
case bitmap4_RLE4:
case bitmap8:
case bitmap8_RLE8:
offset = (DWORD)pow(2, n); break;
case bitmap16_RGB565:
case bitmap32_mask:
offset = 1; break;
}
return (PBYTE)pBitmapinfo + offset * sizeof(RGBQUAD)+sizeof (BITMAPINFOHEADER);
}

void Bitmap::BitDraw(HDC hDC, int x, int y, HBITMAP hBitmap){
if (hBitmap != NULL) {
HDC hMemDC = CreateCompatibleDC(hDC);
HBITMAP hOldBitmap = (HBITMAP)SelectObject(hMemDC, hBitmap);//载入位图
BitBlt(hDC, x, y, m_iWidth, m_iHeight, hMemDC, 0, 0, SRCCOPY);
SelectObject(hMemDC, hOldBitmap);//还原位图
DeleteDC(hMemDC);
}
}

代码测试图

1位位图：