{"id":16905,"date":"2023-08-30T23:15:39","date_gmt":"2023-08-30T15:15:39","guid":{"rendered":"https:\/\/www.bookcard.net\/wordpress\/?p=16905"},"modified":"2023-08-30T23:15:39","modified_gmt":"2023-08-30T15:15:39","slug":"png","status":"publish","type":"post","link":"https:\/\/www.bookcard.net\/wordpress\/png\/","title":{"rendered":"\u5716\u6a94-PNG\u89e3\u6790"},"content":{"rendered":"
\"\u5716\u6a94-PNG\u89e3\u6790\"<\/a>
\u5716\u6a94-PNG\u89e3\u6790<\/figcaption><\/figure>\n

\u820a\u6642\u300e\u6e38\u6232\u7d0b\u7406\u300f\u518d\u7528\u300e.bmp\u683c\u5f0f\u300f, \u5187\u58d3\u7f29\u5373\u4f7f256\u8272\u76e4\u4f9d\u7136\u4f54\u7528\u5409\u9593.<\/p>\n

\u300e.PNG\u683c\u5f0f\u300f\u5229LZ77<\/a>\u4e14\u5187\u5931\u771f\u58d3\u7e2e. \u4e14\u58d3\u7e2e\u6975\u9ad8, \u914d\u5408256\u8272\u76e4,\u9002\u5b9c\u4f5c\u300e\u6e38\u6232\u7d0b\u7406\u300f.<\/p>\n\n\n\n\n\n\n\n\n
\u6578\u64da\u584a<\/td>\n\u6578\u503c<\/td>\n<\/tr>\n
PNG\u5716\u6a94\u6a19\u8a8c<\/td>\n0x89 0x50 0x4E 0x47 0x0D 0x0A 0x1A 0x0A<\/td>\n<\/tr>\n
\u5716\u6a94\u982d<\/td>\nIHDR<\/td>\n<\/tr>\n
\u8c03\u8272\u677f<\/td>\nPLTE<\/td>\n<\/tr>\n
\u56fe\u50cf\u6570\u636e<\/td>\nIDAT<\/td>\n<\/tr>\n
\u56fe\u50cf\u7ed3\u675f<\/td>\nIEND<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

PNG\u6578\u64da\u584a\u57fa\u672c\u7d50\u6784.<\/p>\n\n\n\n\n\n\n\n
\u6578\u64da\u584a\u7d50\u6784<\/td>\nsize<\/td>\n\u7c21\u4ecb<\/td>\n<\/tr>\n
LENGTH<\/td>\n\u6574\u65784\u5b57\u7bc0<\/td>\n\u6578\u64da\u9577\u5ea6<\/td>\n<\/tr>\n
CHUNK TYPE<\/td>\n\u6574\u65784\u5b57\u7bc0<\/td>\n\u985e\u578b\u6a19\u8a18<\/td>\n<\/tr>\n
CHUNK DATA<\/td>\n0~2^32\u5b57\u7bc0<\/td>\n\u6578\u64da<\/td>\n<\/tr>\n
CRC32<\/a><\/td>\n\u6574\u65784\u5b57\u7bc0<\/td>\nCRC32\u6821\u9a57<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u4e24\u5b57\u7bc0\u8086\u5b57\u7bc0\u6578\u64da,\u519a\u8fa6\u95cc\u7528\u300e\u7db2\u7edc\u5b57\u7bc0\u300f\u5b58\u5132,\u9700\u8f49\u300e\u4e3b\u6a5f\u5b57\u7bc0\u300f.<\/p>\n\n\n\n\n\n
\u300e\u7db2\u7edc\u5b57\u7bc0\u300f\u8f49\u300e\u4e3b\u6a5f\u5b57\u7bc0\u300f<\/td>\n<\/tr>\n
#define\u00a0 PNG_VALUE32(v)\u00a0 ((v & 0xff000000) >> 24 | (v & 0x00ff0000) >> 8 | (v & 0x0000ff00) << 8 | (v & 0x000000ff) << 24)<\/td>\n<\/tr>\n
#define\u00a0 PNG_VALUE16(v)\u00a0 ((v & 0xff00) >> 8 | (v & 0x00ff) << 8)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u6e38\u6232\u5f15\u64ce\u9700\u8b80PNG \u4f0d\u500b\u6578\u64da\u584a<\/p>\n\n\n\n\n\n\n\n\n\n
PNG\u6578\u64da\u584a<\/td>\n\u529f\u80fd\u7c21\u4ecb<\/td>\n<\/tr>\n
IHDR<\/td>\n\u6587\u6a94\u982d<\/td>\n<\/tr>\n
PLTE<\/td>\n\u8272\u76e4<\/td>\n<\/tr>\n
IDAT<\/td>\n\u5716\u50cf\u6578\u503c<\/td>\n<\/tr>\n
IEND<\/td>\n\u7d50\u675f<\/td>\n<\/tr>\n
tRNS<\/td>\n\u5716\u50cf\u900f\u660e<\/td>\n<\/tr>\n
bKGD<\/td>\n\u80cc\u666f\u8272<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

PNG\u5716\u6a94\u982d\u634c\u5b57\u7bc0\u6a19\u8a18,\u611b\u849e\u8b58\u522bPNG<\/p>\n\n\n\n\n
0x89<\/td>\n0x50<\/td>\n0x4E<\/td>\n0x47<\/td>\n0x0D<\/td>\n0x0A<\/td>\n0x1A<\/td>\n0x0A<\/td>\n<\/tr>\n
137<\/td>\nP<\/td>\nN<\/td>\nG<\/td>\n\\r<\/td>\n\\n<\/td>\n26<\/td>\n\\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u5c0d\u6bd4PNG\u6a19\u8b58<\/p>\n\n\n\n
\u00a0\u00a0\u00a0 if(memcmp(data,\u00a0 0x0A1A0A0D474E5089, 8) != 0)<\/p>\n

return false;\/\/ \u975epng\u5716\u6a94<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

CRC32<\/a>\u8a08\u7b97\u5fc5\u9700\u8a08\u300eCHUNK TYPE + CHUNK DATA\u300f, \u9577\u5ea6\u300elength + 4\u300f\u800c\u5f97.<\/p>\n\n\n\n\n\n\n
DWORD length = PNG_VALUE32(chunk->length) + 4;<\/td>\n\u9577<\/td>\n<\/tr>\n
DWORD64 crc = CRC32((PBYTE)(chunk) + 4,length);<\/td>\nCRC32\u8a08\u7b97<\/td>\n<\/tr>\n
DWORD64 crc_ = PNG_VALUE32(chunk->crc_);<\/td>\n\u8f49\u4e3b\u6a5f\u5b57\u7bc0<\/td>\n<\/tr>\n
\u00a0 if(crc_ == crc)<\/p>\n

return true;<\/p>\n

 <\/td>\n

\u6bd4\u8f03crc\u503c<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u9996\u5148\u5b9a\u7fa9PNG\u7d50\u6784<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n
typedef struct PNG_TAG{<\/td>\n <\/td>\n<\/tr>\n
int\u00a0\u00a0 width;<\/td>\n\u5716\u5bbd<\/td>\n<\/tr>\n
int\u00a0 \u00a0height;<\/td>\n\u5716\u9ad8<\/td>\n<\/tr>\n
int \u00a0bitCount;<\/td>\n\u4f4d\u5716\u50cf\u7d20bits 8\u4f4d,16\u4f4d,24\u4f4d,32\u4f4d<\/td>\n<\/tr>\n
PNG_RGBA\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 palette[256];<\/td>\n\u8c03\u8272\u677f<\/td>\n<\/tr>\n
PBYTE\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 buffer;<\/td>\n\u5716\u50cf\u6570\u636e<\/td>\n<\/tr>\n
int\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 buffer_size;<\/td>\n\u5716\u50cf\u6570\u636e\u9577\u5ea6<\/td>\n<\/tr>\n
int\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 length;<\/td>\n\u4e34\u6642\u8b8a\u91cf<\/td>\n<\/tr>\n
z_stream stream;<\/td>\nZLIB\u89e3\u58d3<\/a><\/td>\n<\/tr>\n
} PNG, *PNG_PTR;<\/td>\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u6587\u6a94\u982d\u7d50\u6784 IHDR<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
typedef struct PNG_IHDR_TAG{<\/td>\n\u6587\u6a94\u982d IHDR<\/td>\n<\/tr>\n
int length;<\/td>\nData\u9577\u5ea6<\/td>\n<\/tr>\n
DWORD type;<\/td>\n\u6a19\u8a18’IHDR’<\/td>\n<\/tr>\n
DWORD width;<\/td>\n\u50cf\u7d20\u5bec<\/td>\n<\/tr>\n
DWORD height;<\/td>\n\u50cf\u7d20\u9ad8<\/td>\n<\/tr>\n
BYTE\u00a0 BitDepth;<\/td>\n\u5716\u50cf\u6df1\u5ea6<\/td>\n<\/tr>\n
BYTE\u00a0 ColorType;<\/td>\n\u984f\u8272\u985e\u578b<\/td>\n<\/tr>\n
BYTE\u00a0 Compression;<\/td>\nLZ77\u6d3e\u751f\u6f14\u7b97\u6cd5<\/a> ,\u58f9\u5b9a\u4fc20<\/td>\n<\/tr>\n
BYTE\u00a0 Filter;<\/td>\n\u6ffe\u6ce2,\u6b62\u503c\u5b9a0. \u4e8b\u5be6\u300e0,1,2,3,4\u300f\u4f0d\u7a2e\u6ffe\u6ce2<\/td>\n<\/tr>\n
BYTE\u00a0 Interlace;<\/td>\n\u9694\u884c\u6383\u63cf0=\u5187\u6383\u63cf,1=(Adam7 interlace)<\/td>\n<\/tr>\n
DWORD CRC32;<\/td>\nCRC32\u6821\u9a57<\/a><\/td>\n<\/tr>\n
}PNG_IHDR,*PNG_IHDR_PTR;<\/td>\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

PNG\u652f\u7de9\u4f0d\u6b3e\u984f\u8272\u985e\u578b<\/p>\n\n\n\n\n\n\n\n\n
ColorType<\/td>\n\u984f\u8272\u985e\u578b<\/td>\n\u50cf\u7d20<\/td>\n<\/tr>\n
0=Greyscale<\/td>\n\u7070\u5ea6\u5716\u50cf<\/td>\n1,2,4,8,16bit<\/td>\n<\/tr>\n
2=Truecolour<\/td>\n\u771f\u5f69\u8272\u5716\u50cf<\/td>\n8,16bit<\/td>\n<\/tr>\n
3=Indexed-colour<\/td>\n\u7d22\u5f15\u5f69\u8272\u5716\u50cf<\/td>\n1,2,4,8bit<\/td>\n<\/tr>\n
4=Greyscale with alpha<\/td>\n\u5e36\u03b1\u901a\u9053\u8cc7\u6599\u7070\u5ea6\u5716\u50cf<\/td>\n8,16bit<\/td>\n<\/tr>\n
6=Truecolour with alpha<\/td>\n\u5e36\u03b1\u901a\u9053\u8cc7\u6599\u771f\u5f69\u8272\u5716\u50cf<\/td>\n8,16bit<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u50cf\u7d20\u6392\u5217<\/p>\n\n\n\n\n\n\n\n\n
ColorType<\/td>\n\u50cf\u7d20\u6392\u5217<\/td>\n<\/tr>\n
Greyscale<\/td>\nY<\/td>\n<\/tr>\n
Truecolour<\/td>\nRGB<\/td>\n<\/tr>\n
Indexed-colour<\/td>\ni<\/td>\n<\/tr>\n
Greyscale with alpha<\/td>\nRGBA<\/td>\n<\/tr>\n
Truecolour with alpha<\/td>\nYA<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u89e3\u6790\u6587\u6a94\u982d IHDR, \u5206\u914d\u5716\u50cf\u6642\u5206, \u6bcf\u884c\u50cf\u7d20\u591a\u58f9\u5b57\u7bc0,\u8a18\u9304\u300eFilter\u300f\u6ffe\u6ce2\u503c,\u300e0,1,2,3,4\u300f\u4f0d\u7a2e\u6ffe\u6ce2;<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n
if(IHDR->ColorType == 0)<\/p>\n

png->bitCount = IHDR->BitDepth;<\/td>\n

0:Greyscale:\u7070\u5ea6\u5716\u50cf,1,2,4,8,16bit<\/td>\n<\/tr>\n
if(IHDR->ColorType == 2)<\/p>\n

png->bitCount = IHDR->BitDepth * 3;<\/td>\n

2:Truecolour:\u771f\u5f69\u8272\u5716\u50cf,8,16bit<\/td>\n<\/tr>\n
if(IHDR->ColorType == 3)<\/p>\n

png->bitCount = IHDR->BitDepth;<\/td>\n

3:Indexed-colour:\u7d22\u5f15\u5f69\u8272\u5716\u50cf,1,2,4,8bit<\/td>\n<\/tr>\n
if(IHDR->ColorType == 4)<\/p>\n

png->bitCount = IHDR->BitDepth * 2;<\/td>\n

4:Greyscale with alpha:\u5e36\u03b1\u901a\u9053\u8cc7\u6599\u7070\u5ea6\u5716\u50cf,8,16bit<\/td>\n<\/tr>\n
if(IHDR->ColorType == 6)<\/p>\n

png->bitCount = IHDR->BitDepth * 4;<\/td>\n

6:Truecolour with alpha:\u5e36\u03b1\u901a\u9053\u8cc7\u6599\u771f\u5f69\u8272\u5716\u50cf,8,16bit<\/td>\n<\/tr>\n
png->width\u00a0 = PNG_VALUE32(IHDR->width);<\/td>\n\u50cf\u7d20\u5bec<\/td>\n<\/tr>\n
png->height = PNG_VALUE32(IHDR->height);<\/td>\n\u50cf\u7d20\u9ad8<\/td>\n<\/tr>\n
int byte_count\u00a0 = (float)png->bitCount \/ 8.0f;<\/td>\n\u50cf\u7d20\u5927\u5c0f BIT to BYTE<\/td>\n<\/tr>\n
png->buffer_size = (png->width * png->height * byte_count) + (png->height * 1);<\/td>\n\u5716\u50cf\u6570\u636e\u9577\u5ea6,\u6bcf\u884c\u591a\u58f9\u5b57\u7bc0<\/td>\n<\/tr>\n
png->buffer = (PBYTE)malloc(png->buffer_size);<\/td>\n\u5716\u50cf\u6570\u636e<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u5b9a\u7fa9\u8272\u76e4RGB<\/p>\n\n\n\n\n\n\n\n
typedef struct PNG_RGB_TYP {<\/td>\n\u8272\u76e43\u5b57\u7bc0<\/td>\n<\/tr>\n
\u00a0\u00a0\u00a0 BYTE red;<\/td>\n\u7d05<\/td>\n<\/tr>\n
\u00a0\u00a0\u00a0 BYTE green;<\/td>\n\u9304<\/td>\n<\/tr>\n
\u00a0\u00a0\u00a0 BYTE blue;<\/td>\n\u84dd<\/td>\n<\/tr>\n
} PNG_RGB, *PNG_RGB_PTR;<\/td>\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u5b9a\u7fa9\u8272\u76e4RGBA<\/p>\n\n\n\n\n\n\n\n\n
typedef struct PNG_RGBA_TYP {<\/td>\n\u8272\u76e44\u5b57\u7bc0<\/td>\n<\/tr>\n
\u00a0\u00a0\u00a0 BYTE red;<\/td>\n\u7d05<\/td>\n<\/tr>\n
\u00a0\u00a0\u00a0 BYTE green;<\/td>\n\u9304<\/td>\n<\/tr>\n
\u00a0\u00a0\u00a0 BYTE blue;<\/td>\n\u84dd<\/td>\n<\/tr>\n
\u00a0\u00a0\u00a0 BYTE alpha;<\/td>\n\u900f\u660e\u6df7\u5408,\u900f\u660e0x00~\u5be6\u9ad40xFF<\/td>\n<\/tr>\n
} PNG_RGBA, *PNG_RGBA_PTR;<\/td>\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u5b9a\u7fa9PNG\u8272\u76e4\u7d50\u6784 ‘PLTE’<\/p>\n\n\n\n\n\n\n\n\n
typedef struct PNG_PLTE_TYP {<\/td>\n <\/td>\n<\/tr>\n
int length;<\/td>\nData\u9577\u5ea6<\/td>\n<\/tr>\n
DWORD type;<\/td>\n\u6a19\u8a18’PLTE’<\/td>\n<\/tr>\n
PNG_RGB palette[256];<\/td>\n\u81f3\u591a256\u8272\u76e4<\/td>\n<\/tr>\n
DWORD CRC32;<\/td>\nCRC32\u6821\u9a57<\/a><\/td>\n<\/tr>\n
} PNG_PLTE, *PNG_PLTE_PTR;<\/td>\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u5206\u6790PNG\u8272\u76e4 ‘PLTE’<\/p>\n\n\n\n\n\n\n\n\n\n
int length = PNG_VALUE32(chunk->length);<\/td>\n\u9577\u5ea6<\/td>\n<\/tr>\n
int count = length \/ 3;<\/td>\n\u8272\u76e4\u91cf<\/td>\n<\/tr>\n
for(int index = 0; index < count; ++index){<\/td>\n <\/td>\n<\/tr>\n
png->palette[index].red\u00a0\u00a0\u00a0 \u00a0\u00a0= PLTE->palette[index].red ;<\/td>\n\u7d05<\/td>\n<\/tr>\n
png->palette[index].green\u00a0 = PLTE->palette[index].green ;<\/td>\n\u9304<\/td>\n<\/tr>\n
png->palette[index].blue\u00a0\u00a0 \u00a0= PLTE->palette[index].blue ;<\/td>\n\u84dd<\/td>\n<\/tr>\n
png->palette[index].alpha\u00a0 = 0xff;\u00a0\u00a0\u00a0 }<\/td>\n\u900f\u660e0x00~\u5be6\u9ad40xFF<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u5b9a\u7fa9\u900f\u660e\u50cf\u7d20\u7d50\u6784’tRNS’<\/p>\n\n\n\n\n\n\n\n\n\n\n\n
typedef struct PNG_tRNS_TYP{<\/td>\n <\/td>\n<\/tr>\n
int length;<\/td>\n\u6578\u64da\u9577\u5ea6<\/td>\n<\/tr>\n
DWORD type;<\/td>\n\u6a19\u8a18’tRNS’<\/td>\n<\/tr>\n
union {<\/td>\n <\/td>\n<\/tr>\n
WORD grey;<\/td>\n\u984f\u8272\u985e\u578b 0<\/td>\n<\/tr>\n
struct {WORD Red,Green,Blue;};<\/td>\n\u984f\u8272\u985e\u578b \u00a02<\/td>\n<\/tr>\n
BYTE palette[256];<\/td>\n\u984f\u8272\u985e\u578b \u00a03<\/td>\n<\/tr>\n
DWORD CRC32;<\/td>\nCRC32\u6821\u9a57<\/a><\/td>\n<\/tr>\n
}PNG_tRNS,*PNG_tRNS_PTR;<\/td>\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u5206\u6790\u900f\u660e\u50cf\u7d20<\/p>\n\n\n\n\n\n\n\n
PNG_tRNS_PTR tRNS;<\/td>\n\u900f\u660e\u50cf\u7d20<\/td>\n<\/tr>\n
tRNS->length = PNG_VALUE32(tRNS->length);<\/td>\n\u6578\u64da\u9577\u5ea6<\/td>\n<\/tr>\n
if(IHDR->ColorType == 0 )<\/p>\n

tRNS->grey = PNG_VALUE16(tRNS->grey);<\/td>\n

0:Greyscale:\u7070\u5ea6\u5716\u50cf,1,2,4,8,16bit<\/td>\n<\/tr>\n
if(IHDR->ColorType == 2\u00a0 ) {<\/p>\n

tRNS->Red\u00a0\u00a0 = PNG_VALUE16(tRNS->Red);<\/p>\n

tRNS->Green = PNG_VALUE16(tRNS->Green);<\/p>\n

tRNS->Blue\u00a0 = PNG_VALUE16(tRNS->Blue);<\/p>\n

}<\/td>\n

2:Truecolour:\u771f\u5f69\u8272\u5716\u50cf,8,16bit<\/td>\n<\/tr>\n
if(IHDR->ColorType == 3) {<\/p>\n

length = tRNS->length;<\/p>\n

for(int i = 0; i < length; ++i) {<\/p>\n

index = tRNS->palette[i];<\/p>\n

png->palette[index].alpha = 0x00;<\/p>\n

}<\/td>\n

3:Indexed-colour:\u7d22\u5f15\u5f69\u8272\u5716\u50cf,1,2,4,8bit<\/p>\n

\u900f\u660e0x00~\u5be6\u9ad40xFF<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u5b9a\u7fa9\u80cc\u666f\u8272\u7d50\u6784 ‘bKGD’<\/p>\n\n\n\n\n\n\n\n\n\n\n\n
typedef struct PNG_bKGD_TYP{<\/td>\n <\/td>\n<\/tr>\n
int length;<\/td>\nData\u9577\u5ea6<\/td>\n<\/tr>\n
DWORD type;<\/td>\n\u6a19\u8a18’bKGD’<\/td>\n<\/tr>\n
union {<\/td>\n <\/td>\n<\/tr>\n
WORD Greyscale;<\/td>\n\u984f\u8272\u985e\u578b0 and 4\u7070\u5ea6<\/td>\n<\/tr>\n
struct{WORD Red,Green,Blue;};<\/td>\n\u984f\u8272\u985e\u578b2 and 6 -RGB\u4e09\u8272<\/td>\n<\/tr>\n
BYTE Palette_Index;};<\/td>\n\u984f\u8272\u985e\u578b3\u8272\u76e4\u7d22\u5f15<\/td>\n<\/tr>\n
DWORD CRC32;<\/td>\nCRC32\u6821\u9a57<\/a><\/td>\n<\/tr>\n
}PNG_bKGD,*PNG_bKGD_PTR;<\/td>\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u5206\u6790\u80cc\u666f\u8272’bKGD’<\/p>\n\n\n\n\n\n\n
int length = PNG_VALUE32(bKGD->length);<\/td>\n\u9577\u5ea6<\/td>\n<\/tr>\n
if(IHDR->ColorType == 0 || IHDR->ColorType == 4)<\/p>\n

bKGD->Greyscale = PNG_VALUE16(bKGD->Greyscale);<\/td>\n

\u7070\u5ea6\u5716\u50cf – \u5e36\u03b1\u901a\u9053\u8cc7\u6599\u7070\u5ea6\u5716\u50cf<\/td>\n<\/tr>\n
if(IHDR->ColorType == 2 || IHDR->ColorType == 6) {<\/p>\n

bKGD->Red = PNG_VALUE16(bKGD->Red);<\/p>\n

bKGD->Green = PNG_VALUE16(bKGD->Green);<\/p>\n

bKGD->Blue = PNG_VALUE16(bKGD->Blue);<\/p>\n

}<\/td>\n

\u771f\u5f69\u8272\u5716\u50cf – \u5e36\u03b1\u901a\u9053\u8cc7\u6599\u771f\u5f69\u8272\u5716\u50cf<\/td>\n<\/tr>\n
if(IHDR->ColorType == 3)<\/p>\n

bKGD->Palette_Index = bKGD->Palette_Index;<\/td>\n

\u7d22\u5f15\u5f69\u8272\u5716\u50cf<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u5b9a\u7fa9\u5716\u50cf\u6578\u503c\u7d50\u6784 ‘IDAT’, \u6b62\u6578\u64da\u584a\u53ef\u80fd\u6709\u591a\u500b.<\/p>\n\n\n\n\n\n\n\n\n
typedef struct PNG_IDAT_TYP {<\/td>\n <\/td>\n<\/tr>\n
int length;<\/td>\n\u00a0Data\u9577\u5ea6<\/td>\n<\/tr>\n
DWORD type;<\/td>\n\u6a19\u8a18’PLTE’<\/td>\n<\/tr>\n
BYTE data[1];<\/td>\n\u7d93\u58d3\u7e2e\u5716\u50cf\u6578\u64da<\/td>\n<\/tr>\n
DWORD CRC32;<\/td>\nCRC32\u6821\u9a57<\/a><\/td>\n<\/tr>\n
} PNG_IDAT, *PNG_IDAT_PTR;<\/td>\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u6bcf\u884c\u50cf\u7d20\u591a\u58f9\u5b57\u7bc0,\u8a18\u9304\u300eFilter\u300f\u6ffe\u6ce2\u503c,\u300e0,1,2,3,4\u300f\u4f0d\u7a2e\u6ffe\u6ce2;<\/p>\n\n\n\n\n\n\n
int length = PNG_VALUE32(IDAT->length);<\/td>\n\u9577\u5ea6<\/td>\n<\/tr>\n
int size = png->buffer_size – png->length;<\/td>\n\u5269\u4f59\u8a18\u61b6\u9ad4<\/td>\n<\/tr>\n
Uncompress_Data_gZip<\/a>(png->buffer + png->length, &size,<\/p>\n

IDAT->data,length,<\/p>\n

&png->stream);<\/td>\n

\u89e3\u538b<\/td>\n<\/tr>\n
png->length =\u00a0 png->length + size;<\/td>\n\u7d2f\u7a4d\u7a4d\u6578\u64da\u9577\u5ea6<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u7d50\u675f IEND,\u6aa2\u6e2c\u5230’IEND’\u6578\u64da\u584a,\u5df1\u5230\u6587\u6a94\u672a\u7aef.<\/p>\n\n\n\n\n\n\n\n
typedef struct PNG_IEND_TAG{<\/td>\n <\/td>\n<\/tr>\n
int length;<\/td>\nData\u9577\u5ea60<\/td>\n<\/tr>\n
DWORD type;<\/td>\n\u6a19\u8a18’IEND’<\/td>\n<\/tr>\n
DWORD CRC32;<\/td>\nCRC32\u6821\u9a57<\/a><\/td>\n<\/tr>\n
}PNG_IEND, *PNG_IEND_PTR;<\/td>\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u4ee5\u984f\u8272\u985e\u578b\u5206\u5225\u9032\u884c\u300e\u53cd\u6ffe\u6ce2\u300f, \u4fc2\u6bcf\u884c\u50cf\u7d20\u9996\u5b57\u7bc0\u300e\u6ffe\u6ce2\u300f\u503c,\u6709\u300e0,1,2,3,4\u300f\u4f0d\u6b3e\u6ffe\u6ce2, \u4ee5\u6bcf\u7c92\u50cf\u7d20\u55ae\u7368\u300e\u5fa9\u4f4d\u300f,\u5e36\u03b1\u901a\u9053\u771f\u5f69\u8272\u5716\u50cf8bit\u70ba\u4f8b.<\/p>\n

\u4ee5cbax\u50cf\u7d20\u6392\u5217\u652f\u7f13\u4f0d\u6b3e\u6ffe\u6ce2<\/p>\n\n\n\n\n
c<\/td>\nb<\/td>\n<\/tr>\n
a<\/td>\nx<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u6ffe\u6ce2\u7b97\u6cd5<\/p>\n\n\n\n\n\n\n\n\n
filter\u6ffe\u6ce2<\/td>\n\u6ffe\u6ce2<\/td>\n\u5fa9\u4f4d<\/td>\n<\/tr>\n
0= None<\/td>\nFilt(x) = Orig(x)<\/td>\nRecon(x) = Filt(x)<\/td>\n<\/tr>\n
1= Sub<\/td>\nFilt(x) = Orig(x) – Orig(a)<\/td>\nRecon(x) = Filt(x) + Recon(a)<\/td>\n<\/tr>\n
2= Up<\/td>\nFilt(x) = Orig(x) – Orig(b)<\/td>\nRecon(x) = Filt(x) + Recon(b)<\/td>\n<\/tr>\n
3= Average<\/td>\nFilt(x) = Orig(x) – floor((Orig(a) + Orig(b)) \/ 2)<\/td>\nRecon(x) = Filt(x) + floor((Recon(a) + Recon(b)) \/ 2)<\/td>\n<\/tr>\n
4= Paeth<\/td>\nFilt(x) = Orig(x) – PaethPredictor(Orig(a), Orig(b), Orig(c))<\/td>\nRecon(x) = Filt(x) + PaethPredictor(Recon(a), Recon(b), Recon(c))<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u5fa9\u4f4d\u7b97\u6cd5<\/p>\n\n\n\n\n\n\n\n\n\n\n
int byte_count\u00a0\u00a0 = 4;<\/td>\n\u6bcf\u7c92\u50cf\u7d204\u5b57\u7bc0<\/td>\n<\/tr>\n
int pixel_size = png->width * png->height;<\/td>\n\u7e3d\u50cf\u7d20\u91cf<\/td>\n<\/tr>\n
int buffer_size = png->width * png->height * byte_count;<\/td>\n\u7e3d\u5b57\u7bc0\u91cf<\/td>\n<\/tr>\n
PBYTE buffer = (PBYTE)malloc(buffer_size);<\/td>\n\u53cd\u6ffe\u6ce2\u5f71\u50cf\u6578\u64da<\/td>\n<\/tr>\n
int col_size_recon = (png->width * 4) ;<\/td>\n\u5fa9\u4f4d\u5f8c\u6bcf\u884c\u5b57\u7bc0\u91cf<\/td>\n<\/tr>\n
int col_size_filt\u00a0 = (png->width * 4)\u00a0 + 1;<\/td>\n\u6ffe\u6ce2\u5f8c\u6bcf\u884c\u5b57\u7bc0\u91cf<\/td>\n<\/tr>\n
for(int j = 0; j < png->height ; ++j)<\/td>\n\u6bcf\u884c\u50cf\u7d20<\/td>\n<\/tr>\n
int filter = png->buffer[col_size_filt * j];<\/td>\n\u884c\u9996\u6ffe\u6ce2=1 byte<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u8655\u7406filter\u6ffe\u6ce20= None<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n
if(filter == 0) {<\/td>\nNone<\/td>\n<\/tr>\n
for(int i = 0; i < png->width; ++i){<\/td>\n\u9010\u50cf\u7d20\u5fa9\u4f4d<\/td>\n<\/tr>\n
Red = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 0];<\/td>\nx\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
Green = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 1];<\/td>\nx\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
Blue = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 2];<\/td>\nx\u50cf\u7d20\u9304\u8272<\/td>\n<\/tr>\n
Alpha = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 3];<\/td>\nx\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 0] = Red;<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 1] = Green;<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 2] = Blue;<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u7da0\u8272<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 3] = Alpha;\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 }}<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u8655\u7406filter\u6ffe\u6ce21 =Sub<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
if(filter == 1)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 {<\/td>\nSub<\/td>\n<\/tr>\n
for(int i = 0; i < png->width; ++i){<\/td>\n\u9010\u50cf\u7d20\u5fa9\u4f4d<\/td>\n<\/tr>\n
Red = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 0];<\/td>\nx\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
Green = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 1];<\/td>\nx\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
Blue = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 2];<\/td>\nx\u50cf\u7d20\u9304\u8272<\/td>\n<\/tr>\n
Alpha = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 3];<\/td>\nx\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n
aRed = aGreen = aBlue = aAlpha = 0;<\/td>\n\u6e05\u96f6<\/td>\n<\/tr>\n
if(i > 0) {<\/td>\n <\/td>\n<\/tr>\n
aRed = buffer[(col_size_recon * j) + ((i-1) * 4) + 0];<\/td>\na\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
aGreen = buffer[(col_size_recon * j) + ((i-1) * 4) + 1];<\/td>\na\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
aBlue = buffer[(col_size_recon * j) + ((i-1) * 4) + 2];<\/td>\na\u50cf\u7d20\u7da0\u8272<\/td>\n<\/tr>\n
aAlpha = buffer[(col_size_recon * j) + ((i-1) * 4) + 3]; }<\/td>\na\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 0] = Red + aRed;<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 1] = Green + aGreen;<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 2] = Blue + aBlue;<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u7da0\u8272<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 3] = Alpha + aAlpha; }}<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u8655\u7406filter\u6ffe\u6ce22 =Up<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
if(filter == 2){<\/td>\nUp<\/td>\n<\/tr>\n
for( i = 0; i < png->width; ++i){<\/td>\n\u9010\u50cf\u7d20\u5fa9\u4f4d<\/td>\n<\/tr>\n
Red = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 0];<\/td>\nx\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
Green = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 1];<\/td>\nx\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
Blue = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 2];<\/td>\nx\u50cf\u7d20\u9304\u8272<\/td>\n<\/tr>\n
Alpha = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 3];<\/td>\nx\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n
bRed = bGreen = bBlue = bAlpha = 0;<\/td>\n\u6e05\u96f6<\/td>\n<\/tr>\n
if(j > 0) {<\/td>\n <\/td>\n<\/tr>\n
bRed = buffer[(col_size_recon * (j-1)) + (i * 4) + 0];<\/td>\nb\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
bGreen = buffer[(col_size_recon * (j-1)) + (i * 4) + 1];<\/td>\nb\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
bBlue = buffer[(col_size_recon * (j-1)) + (i * 4) + 2];<\/td>\nb\u50cf\u7d20\u7da0\u8272<\/td>\n<\/tr>\n
bAlpha = buffer[(col_size_recon * (j-1)) + (i * 4) + 3];}<\/td>\nb\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 0] = Red + bRed;<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 1] = Green + bGreen;<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 2] = Blue + bBlue;<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u7da0\u8272<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 3] = Alpha + bAlpha; }}<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u8655\u7406filter\u6ffe\u6ce23 = Average<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
if(filter == 3)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 {<\/td>\nAverage<\/td>\n<\/tr>\n
for( i = 0; i < png->width; ++i){<\/td>\n\u9010\u50cf\u7d20\u5fa9\u4f4d<\/td>\n<\/tr>\n
Red = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 0];<\/td>\nx\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
Green = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 1];<\/td>\nx\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
Blue = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 2];<\/td>\nx\u50cf\u7d20\u9304\u8272<\/td>\n<\/tr>\n
Alpha = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 3];<\/td>\nx\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n
aRed = aGreen = aBlue = aAlpha = 0;<\/td>\n\u6e05\u96f6<\/td>\n<\/tr>\n
bRed = bGreen = bBlue = bAlpha = 0;<\/td>\n\u6e05\u96f6<\/td>\n<\/tr>\n
if(i > 0) {<\/td>\n <\/td>\n<\/tr>\n
aRed = buffer[(col_size_recon * j) + ((i-1) * 4) + 0];<\/td>\na\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
aGreen = buffer[(col_size_recon * j) + ((i-1) * 4) + 1];<\/td>\na\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
aBlue = buffer[(col_size_recon * j) + ((i-1) * 4) + 2];<\/td>\na\u50cf\u7d20\u7da0\u8272<\/td>\n<\/tr>\n
aAlpha = buffer[(col_size_recon * j) + ((i-1) * 4) + 3]; }<\/td>\na\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n
if(j > 0) {<\/td>\n <\/td>\n<\/tr>\n
bRed = buffer[(col_size_recon * (j-1)) + (i * 4) + 0];<\/td>\nb\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
bGreen = buffer[(col_size_recon * (j-1)) + (i * 4) + 1];<\/td>\nb\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
bBlue = buffer[(col_size_recon * (j-1)) + (i * 4) + 2];<\/td>\nb\u50cf\u7d20\u7da0\u8272<\/td>\n<\/tr>\n
bAlpha = buffer[(col_size_recon * (j-1)) + (i * 4) + 3];}<\/td>\nb\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 0] = Red + ((aRed+bRed)\/2);<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 1] = Green + ((aGreen+bGreen)\/2);<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 2] = Blue + ((aBlue+bBlue)\/2);<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u7da0\u8272<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 3] = Alpha + ((aAlpha+bAlpha)\/2); }}<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Paeth\u9810\u6e2c\u51fd\u5f0f<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n
BYTE PaethPredictor_PNG(BYTE a,BYTE b,BYTE c){<\/td>\n\u9810\u6e2c\u51fd\u5f0f<\/td>\n<\/tr>\n
int p;<\/td>\n <\/td>\n<\/tr>\n
int pa,pb,pc;<\/td>\n <\/td>\n<\/tr>\n
p = a + b – c;<\/td>\n <\/td>\n<\/tr>\n
pa = abs(p – a);<\/td>\n <\/td>\n<\/tr>\n
pb = abs(p – b);<\/td>\n <\/td>\n<\/tr>\n
pc = abs(p – c);<\/td>\n <\/td>\n<\/tr>\n
if (pa <= pb && pa <= pc ) \u00a0return a;<\/td>\n <\/td>\n<\/tr>\n
else if (pb <= pc ) return b;<\/td>\n <\/td>\n<\/tr>\n
else return c;}<\/td>\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u8655\u7406filter\u6ffe\u6ce24 =Paeth\u9810\u6e2c<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
if(filter == 3)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 {<\/td>\nAverage<\/td>\n<\/tr>\n
for( i = 0; i < png->width; ++i){<\/td>\n\u9010\u50cf\u7d20\u5fa9\u4f4d<\/td>\n<\/tr>\n
Red = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 0];<\/td>\nx\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
Green = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 1];<\/td>\nx\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
Blue = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 2];<\/td>\nx\u50cf\u7d20\u9304\u8272<\/td>\n<\/tr>\n
Alpha = png->buffer[(col_size_filt * j) + 1 + (i * 4) + 3];<\/td>\nx\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n
aRed = aGreen = aBlue = aAlpha = 0;<\/td>\n\u6e05\u96f6<\/td>\n<\/tr>\n
bRed = bGreen = bBlue = bAlpha = 0;<\/td>\n\u6e05\u96f6<\/td>\n<\/tr>\n
cRed = cGreen = cBlue = cAlpha = 0;<\/td>\n\u6e05\u96f6<\/td>\n<\/tr>\n
if(i > 0) {<\/td>\n <\/td>\n<\/tr>\n
aRed = buffer[(col_size_recon * j) + ((i-1) * 4) + 0];<\/td>\na\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
aGreen = buffer[(col_size_recon * j) + ((i-1) * 4) + 1];<\/td>\na\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
aBlue = buffer[(col_size_recon * j) + ((i-1) * 4) + 2];<\/td>\na\u50cf\u7d20\u7da0\u8272<\/td>\n<\/tr>\n
aAlpha = buffer[(col_size_recon * j) + ((i-1) * 4) + 3]; }<\/td>\na\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n
if(j > 0) {<\/td>\n <\/td>\n<\/tr>\n
bRed = buffer[(col_size_recon * (j-1)) + (i * 4) + 0];<\/td>\nb\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
bGreen = buffer[(col_size_recon * (j-1)) + (i * 4) + 1];<\/td>\nb\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
bBlue = buffer[(col_size_recon * (j-1)) + (i * 4) + 2];<\/td>\nb\u50cf\u7d20\u7da0\u8272<\/td>\n<\/tr>\n
bAlpha = buffer[(col_size_recon * (j-1)) + (i * 4) + 3];}<\/td>\nb\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n
if(i > 0 && j > 0) {<\/td>\n <\/td>\n<\/tr>\n
cRed = buffer[(col_size_recon * (j-1)) + ((i-1) * 4) + 0];<\/td>\nc\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
cGreen = buffer[(col_size_recon * (j-1)) + ((i-1) * 4) + 1];<\/td>\nc\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
cBlue = buffer[(col_size_recon * (j-1)) + ((i-1) * 4) + 2];<\/td>\nc\u50cf\u7d20\u7da0\u8272<\/td>\n<\/tr>\n
cAlpha = buffer[(col_size_recon * (j-1)) + ((i-1) * 4) + 3];}<\/td>\nc\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 0] = Red + PaethPredictor_PNG(aRed,bRed,cRed);<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u7d05\u8272<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 1] = Green + PaethPredictor_PNG(aGreen,bGreen,cGreen);<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u85cd\u8272<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 2] = Blue + PaethPredictor_PNG(aBlue,bBlue,cBlue);<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u7da0\u8272<\/td>\n<\/tr>\n
buffer[(col_size_recon * j) + (i * 4) + 3] = Alpha + PaethPredictor_PNG(aAlpha,bAlpha,cAlpha);}}<\/td>\n\u5fa9\u4f4d\u50cf\u7d20\u900f\u660e<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u91ca\u653e\u5716\u50cf<\/p>\n\n\n\n\n\n\n
free(png->buffer);<\/td>\n\u91ca\u653e<\/td>\n<\/tr>\n
png->buffer = buffer;<\/td>\n\u66ff\u6362\u5fa9\u4f4d\u5716\u50cf<\/td>\n<\/tr>\n
png->bitCount = 32;<\/td>\nrgba<\/td>\n<\/tr>\n
png->buffer_size = buffer_size;<\/td>\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

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\u7e7c\u7e8c\u95b1\u8b80 \u5716\u6a94-PNG\u89e3\u6790<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[13],"tags":[42],"class_list":["post-16905","post","type-post","status-publish","format-standard","hentry","category-pc","tag-computer","entry"],"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/www.bookcard.net\/wordpress\/wp-json\/wp\/v2\/posts\/16905","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bookcard.net\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bookcard.net\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bookcard.net\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bookcard.net\/wordpress\/wp-json\/wp\/v2\/comments?post=16905"}],"version-history":[{"count":1,"href":"https:\/\/www.bookcard.net\/wordpress\/wp-json\/wp\/v2\/posts\/16905\/revisions"}],"predecessor-version":[{"id":16907,"href":"https:\/\/www.bookcard.net\/wordpress\/wp-json\/wp\/v2\/posts\/16905\/revisions\/16907"}],"wp:attachment":[{"href":"https:\/\/www.bookcard.net\/wordpress\/wp-json\/wp\/v2\/media?parent=16905"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bookcard.net\/wordpress\/wp-json\/wp\/v2\/categories?post=16905"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bookcard.net\/wordpress\/wp-json\/wp\/v2\/tags?post=16905"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}