📄 coding.cpp
字号:
LONG lWidth = m_clsDIB.DIBWidth(lpDIB);
// 找到DIB图像象素起始位置
LPBYTE lpDIBBits = m_clsDIB.FindDIBBits(lpDIB);
// 计算每行字节数
LONG lWidthBytes = DWORD_WBYTES(lWidth * 8);
// 给GIFCVar结构赋值
GIFCVar.wWidth = (WORD)lWidth;
GIFCVar.wDepth = (WORD)lHeight;
GIFCVar.wBits = m_clsDIB.DIBBitCount(lpDIB);
GIFCVar.wLineBytes = (WORD)BYTE_WBYTES((DWORD)GIFCVar.wWidth * (DWORD)GIFCVar.wBits);
// 计算颜色数目
LONG lColors = 1 << GIFCVar.wBits;
// 获取指向BITMAPINFO结构的指针（Win3.0）
lpbmi = (LPBITMAPINFO)lpDIB;
// 获取指向BITMAPCOREINFO结构的指针
lpbmc = (LPBITMAPCOREINFO)lpDIB;
// 判断是否是WIN3.0的DIB
bWinStyleDIB = IS_WIN30_DIB(lpDIB);
// 给调色板赋值
if (bWinStyleDIB)
{
j = 0;
for (i = 0; i < lColors; i++)
{
// 读取红色分量
byGIF_Pal[j++] = lpbmi->bmiColors[i].rgbRed;
// 读取绿色分量
byGIF_Pal[j++] = lpbmi->bmiColors[i].rgbGreen;
// 读取蓝色分量
byGIF_Pal[j++] = lpbmi->bmiColors[i].rgbBlue;
}
}
else
{
j = 0;
for (i = 0; i < lColors; i++)
{
// 读取红色分量
byGIF_Pal[j++] = lpbmc->bmciColors[i].rgbtRed;
// 读取绿色分量
byGIF_Pal[j++] = lpbmc->bmciColors[i].rgbtGreen;
// 读取红色分量
byGIF_Pal[j++] = lpbmc->bmciColors[i].rgbtBlue;
}
}
////////////////////////////////////////////////////////////////////////////////////////
// 开始写GIF文件
// 写GIF文件头
GIFH.bySignature[0] = 'G';
GIFH.bySignature[1] = 'I';
GIFH.bySignature[2] = 'F';
GIFH.byVersion[0]='8';
GIFH.byVersion[1]='9';
GIFH.byVersion[2]='a';
file.Write((LPBYTE)&GIFH, 6);
// 写GIF逻辑屏幕描述块
GIFS.wWidth = GIFCVar.wWidth;
GIFS.wDepth = GIFCVar.wDepth;
GIFS.GlobalFlag.PalBits = GIFCVar.wBits - 1;
GIFS.GlobalFlag.SortFlag = 0x00;
GIFS.GlobalFlag.ColorRes = GIFCVar.wBits - 1;
GIFS.GlobalFlag.GlobalPal = 0x01;
GIFS.byBackground = 0x00;
GIFS.byAspect = 0x00;
file.Write(&GIFS, 7);
// 写GIF全局调色板
file.Write(byGIF_Pal, (lColors * 3));
// 写GIF图像描述间隔符
byChar = 0x2C;
file.Write(&byChar, 1);
// 写GIF图像描述块
GIFI.wLeft = 0;
GIFI.wTop = 0;
GIFI.wWidth = GIFCVar.wWidth;
GIFI.wDepth = GIFCVar.wDepth;
GIFI.LocalFlag.PalBits = 0x00;
GIFI.LocalFlag.Reserved = 0x00;
GIFI.LocalFlag.SortFlag = 0x00;
GIFI.LocalFlag.Interlace = bInterlace ? 0x01 : 0x00;
GIFI.LocalFlag.LocalPal = 0x00;
file.Write(&GIFI, 9);
// 写GIF图像压缩数据
HANDLE hSrcBuff = GlobalAlloc(GHND, (DWORD)MAX_BUFF_SIZE);
GIFCVar.lpDataBuff = (LPBYTE)GlobalLock(hSrcBuff);
GIFCVar.lpEndBuff = GIFCVar.lpDataBuff;
GIFCVar.dwTempCode = 0UL;
GIFCVar.wByteCnt = 0;
GIFCVar.wBlockNdx = 1;
GIFCVar.byLeftBits = 0x00;
// 进行GIF_LZW编码
LZW_Encode(lpDIBBits, file, &GIFCVar, (WORD)lWidthBytes, bInterlace);
// 判断是否编码成功
if (GIFCVar.wByteCnt)
{
// 写入文件
file.Write(GIFCVar.lpDataBuff, GIFCVar.wByteCnt);
}
// 释放内存
GlobalUnlock(hSrcBuff);
GlobalFree(hSrcBuff);
// 写GIF Block Terminator
byChar = 0x00;
file.Write(&byChar,1);
//写GIF文件结尾块
byChar = 0x3B;
file.Write(&byChar,1);
// 解除锁定
::GlobalUnlock((HGLOBAL) hDIB);
// 恢复光标
EndWaitCursor();
// 返回
return TRUE;
}
/*************************************************************************
*
* 函数名称：
* LZW_Encode()
*
* 参数:
* LPBYTE lpDIBBits - 指向源DIB图像指针
* CFile& file - 要保存的文件
* LPGIFC_VAR lpGIFCVar - 指向GIFC_VAR结构的指针
* WORD wWidthBytes - 每行图像字节数
* BOOL bInterlace - 是否按照交错方式保存
*
* 返回值:
* 无
*
* 说明:
* 该函数对图像进行GIF_LZW编码。
*
*************************************************************************/
void CCoding::LZW_Encode(LPBYTE lpDIBBits, CFile &file, LPGIFC_VAR lpGIFCVar, WORD wWidthBytes, BOOL bInterlace)
{
// 内存分配句柄
HANDLE hTableNdx;
HANDLE hPrefix;
HANDLE hSuffix;
// 指向字串表指针
LPWORD lpwTableNdx;
// 用于字串表搜索的索引
LPWORD lpwPrefix;
LPBYTE lpbySuffix;
// 指向当前编码像素的指针
LPBYTE lpImage;
// 计算当前数据图像的偏移量
DWORD dwDataNdx;
// LZW_CLEAR
WORD wLZW_CLEAR;
// LZW_EOI
WORD wLZW_EOI;
// LZW_MinCodeLen
BYTE byLZW_MinCodeLen;
// 字串表索引
WORD wPreTableNdx;
WORD wNowTableNdx;
WORD wTopTableNdx;
// 哈希表索引
WORD wHashNdx;
WORD wHashGap;
WORD wPrefix;
WORD wShiftBits;
// 当前图像的行数
WORD wRowNum;
WORD wWidthCnt;
// 循环变量
WORD wi;
WORD wj;
// 交错方式存储时每次增加的行数
WORD wIncTable[5] = {8, 8, 4, 2, 0};
// 交错方式存储时起始行数
WORD wBgnTable[5] = {0, 4, 2, 1, 0 };
BOOL bStart;
BYTE bySuffix;
BYTE bySubBlock[256];
BYTE byCurrentBits;
BYTE byMask;
BYTE byChar;
BYTE byPass;
// 临时字节变量
BYTE byTemp;
// 给字串表分配内存
hTableNdx = GlobalAlloc(GHND,(DWORD)(MAX_HASH_SIZE<<1));
hPrefix = GlobalAlloc(GHND,(DWORD)(MAX_HASH_SIZE<<1));
hSuffix = GlobalAlloc(GHND,(DWORD)MAX_HASH_SIZE);
// 锁定内存
lpwTableNdx = (LPWORD)GlobalLock(hTableNdx);
lpwPrefix = (LPWORD)GlobalLock(hPrefix);
lpbySuffix = (LPBYTE)GlobalLock(hSuffix);
// 计算LZW_MinCodeLen
byLZW_MinCodeLen = (lpGIFCVar->wBits>1) ? lpGIFCVar->wBits : 0x02;
// 写GIF LZW最小代码大小
file.Write(&byLZW_MinCodeLen, 1);
wRowNum = 0;
bStart = TRUE;
byPass = 0x00;
// 计算LZW_CLEAR
wLZW_CLEAR = 1 << byLZW_MinCodeLen;
// 计算LZW_EOI
wLZW_EOI = wLZW_CLEAR + 1;
// 初始化字串表
byCurrentBits = byLZW_MinCodeLen + 0x01;
wNowTableNdx = wLZW_CLEAR + 2;
wTopTableNdx = 1 << byCurrentBits;
for(wi = 0; wi < MAX_HASH_SIZE; wi++)
{
// 初始化为0xFFFF
*(lpwTableNdx + wi) = 0xFFFF;
}
// 输出LZW_CLEAR
OutputCode(file, wLZW_CLEAR, bySubBlock, &byCurrentBits, lpGIFCVar);
// 逐行编码
for(wi=0; wi < lpGIFCVar->wDepth; wi++)
{
// 计算当前偏移量
dwDataNdx = (DWORD)(lpGIFCVar->wDepth - 1 - wRowNum) * (DWORD)wWidthBytes;
// 指向当前行图像的指针
lpImage = lpDIBBits + dwDataNdx;
wWidthCnt = 0;
wShiftBits = 8 - lpGIFCVar->wBits;
byMask = (lpGIFCVar->wBits == 1) ? 0x80 : 0xF0;
if (bStart)
{
// 判断是否是256色位图（一个像素一字节）
if (lpGIFCVar->wBits == 8)
{
// 256色，直接赋值即可
byTemp = *lpImage++;
}
else
{
// 非256色，需要移位获取像素值
wShiftBits = 8 - lpGIFCVar->wBits;
byMask = (lpGIFCVar->wBits == 1) ? 0x80 : 0xF0;
byTemp = (*lpImage & byMask) >> wShiftBits;
byMask >>= lpGIFCVar->wBits;
wShiftBits -= lpGIFCVar->wBits;
}
wPrefix = (WORD)byTemp;
bStart = FALSE;
wWidthCnt++;
}
// 每行编码
while(wWidthCnt < lpGIFCVar->wWidth)
{
// 判断是否是256色位图（一个像素一字节）
if (lpGIFCVar->wBits == 8)
{
// 256色，直接赋值即可
byTemp = *lpImage++;
}
else
{
// 非256色，需要移位获取像素值
byChar = *lpImage;
byTemp = (byChar & byMask) >> wShiftBits;
if (wShiftBits)
{
byMask >>= lpGIFCVar->wBits;
wShiftBits -= lpGIFCVar->wBits;
}
else
{
wShiftBits = 8 - lpGIFCVar->wBits;
byMask = (lpGIFCVar->wBits==1) ? 0x80 : 0xF0;
lpImage++;
}
}
bySuffix = byTemp;
wWidthCnt ++;
// 查找当前字符串是否存在于字串表中
wHashNdx = wPrefix ^ ((WORD)bySuffix << 4);
wHashGap = (wHashNdx ? (MAX_HASH_SIZE - wHashNdx) : 1);
// 判断当前字符串是否在字串表中
while(TRUE)
{
// 当前字符串不在字串表中
if (*(lpwTableNdx + wHashNdx) == 0xFFFF)
{
// 新字符串，退出循环
break;
}
// 判断是否找到该字符串
if ((*(lpwPrefix+wHashNdx) == wPrefix) &&
(*(lpbySuffix+wHashNdx) == bySuffix))
{
// 找到，退出循环
break;
}
// 第二哈希表
if (wHashNdx < wHashGap)
{
wHashNdx += MAX_HASH_SIZE;
}
wHashNdx -= wHashGap;
}
// 判断是否是新字符串
if (*(lpwTableNdx+wHashNdx) != 0xFFFF)
{
// 不是新字符串
wPrefix = *(lpwTableNdx + wHashNdx);
}
else
{
// 新字符串
// 输出该编码
OutputCode(file, wPrefix, bySubBlock, &byCurrentBits, lpGIFCVar);
// 将该新字符串添加到字串表中
wPreTableNdx = wNowTableNdx;
// 判断是否达到最大字串表大小
if (wNowTableNdx < MAX_TABLE_SIZE)
{
*(lpwTableNdx+wHashNdx) = wNowTableNdx++;
*(lpwPrefix+wHashNdx) = wPrefix;
*(lpbySuffix+wHashNdx) = bySuffix;
}
if (wPreTableNdx == wTopTableNdx)
{
if (byCurrentBits<12)
{
byCurrentBits ++;
wTopTableNdx <<= 1;
}
else
{
// 字串表到达最大长度
// 输出LZW_CLEAR
OutputCode(file, wLZW_CLEAR, bySubBlock, &byCurrentBits, lpGIFCVar);
// 重新初始化字串表
byCurrentBits = byLZW_MinCodeLen + 0x01;
wLZW_CLEAR = 1 << byLZW_MinCodeLen;
wLZW_EOI = wLZW_CLEAR + 1;
wNowTableNdx = wLZW_CLEAR + 2;
wTopTableNdx = 1 << byCurrentBits;
for(wj = 0; wj < MAX_HASH_SIZE; wj++)
{
// 初始化为0xFFFF
*(lpwTableNdx+wj) = 0xFFFF;
}
}
}
wPrefix = (WORD)bySuffix;
}
}
// 判断是否是交错方式
if (bInterlace)
{
// 交错方式，计算下一行位置
wRowNum += wIncTable[byPass];
if (wRowNum >= lpGIFCVar->wDepth)
{
byPass++;
wRowNum = wBgnTable[byPass];
}
}
else
{
// 非交错方式，直接将行数加一即可
wRowNum ++;
}
}
// 输出当前编码
OutputCode(file, wPrefix, bySubBlock, &byCurrentBits, lpGIFCVar);
// 输出LZW_EOI
OutputCode(file, wLZW_EOI, bySubBlock, &byCurrentBits, lpGIFCVar);
if (lpGIFCVar->byLeftBits)
{
// 加入该字符
bySubBlock[lpGIFCVar->wBlockNdx++] = (BYTE)lpGIFCVar->dwTempCode;
// 判断是否超出MAX_SUBBLOCK_SIZE
if (lpGIFCVar->wBlockNdx > MAX_SUBBLOCK_SIZE)
{
// 判断wByteCnt + 256是否超过MAX_BUFF_SIZE
if ((lpGIFCVar->wByteCnt + 256) >= MAX_BUFF_SIZE)
{
// 输出
file.Write(lpGIFCVar->lpDataBuff, lpGIFCVar->wByteCnt);
lpGIFCVar->lpEndBuff = lpGIFCVar->lpDataBuff;
lpGIFCVar->wByteCnt = 0;
}
bySubBlock[0] = (lpGIFCVar->wBlockNdx - 1);
memcpy(lpGIFCVar->lpEndBuff, bySubBlock, lpGIFCVar->wBlockNdx);
lpGIFCVar->lpEndBuff += lpGIFCVar->wBlockNdx;
lpGIFCVar->wByteCnt += lpGIFCVar->wBlockNdx;
lpGIFCVar->wBlockNdx = 1;
}
lpGIFCVar->dwTempCode = 0UL;
lpGIFCVar->byLeftBits = 0x00;
}
if (lpGIFCVar->wBlockNdx > 1)
{
// 判断wByteCnt + 256是否超过MAX_BUFF_SIZE
if ((lpGIFCVar->wByteCnt + 256) >= MAX_BUFF_SIZE)
{
// 输出
file.Write(lpGIFCVar->lpDataBuff, lpGIFCVar->wByteCnt);
lpGIFCVar->lpEndBuff = lpGIFCVar->lpDataBuff;
lpGIFCVar->wByteCnt = 0;
}
bySubBlock[0] = lpGIFCVar->wBlockNdx - 1;
memcpy(lpGIFCVar->lpEndBuff, bySubBlock, lpGIFCVar->wBlockNdx);
lpGIFCVar->lpEndBuff += lpGIFCVar->wBlockNdx;
lpGIFCVar->wByteCnt += lpGIFCVar->wBlockNdx;
lpGIFCVar->wBlockNdx = 1;
}
// 解除锁定
GlobalUnlock(hTableNdx);
GlobalUnlock(hPrefix);
GlobalUnlock(hSuffix);
// 释放内存
GlobalFree(hTableNdx);
GlobalFree(hPrefix);
GlobalFree(hSuffix);
// 退出
return;
}
/*************************************************************************
*
* 函数名称：
* OutputCode()
*
* 参数:
* CFile& file - 要保存的文件
* WORD wCode - 要添加的编码
* LPBYTE lpbySubBlock - 子块
* LPBYTE lpbyCurrentBits - 当前位数
* LPGIFC_VAR lpGIFCVar - 指向GIFC_VAR结构的指针
*
* 返回值:
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -