/* ** m_png.cpp ** Routines for manipulating PNG files. ** **--------------------------------------------------------------------------- ** Copyright 2002-2006 Randy Heit ** All rights reserved. ** ** Redistribution and use in source and binary forms, with or without ** modification, are permitted provided that the following conditions ** are met: ** ** 1. Redistributions of source code must retain the above copyright ** notice, this list of conditions and the following disclaimer. ** 2. Redistributions in binary form must reproduce the above copyright ** notice, this list of conditions and the following disclaimer in the ** documentation and/or other materials provided with the distribution. ** 3. The name of the author may not be used to endorse or promote products ** derived from this software without specific prior written permission. ** ** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR ** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES ** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. ** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT ** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF ** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. **--------------------------------------------------------------------------- ** */ // HEADER FILES ------------------------------------------------------------ #include #include #include #ifdef _MSC_VER #include // for alloca() #endif #include "m_crc32.h" #include "m_swap.h" #include "c_cvars.h" #include "r_defs.h" #include "v_video.h" #include "m_png.h" #include "templates.h" #include "files.h" // MACROS ------------------------------------------------------------------ // The maximum size of an IDAT chunk ZDoom will write. This is also the // size of the compression buffer it allocates on the stack. #define PNG_WRITE_SIZE 32768 // Set this to 1 to use a simple heuristic to select the filter to apply // for each row of RGB image saves. As it turns out, it seems no filtering // is the best for Doom screenshots, no matter what the heuristic might // determine, so that's why this is 0 here. #define USE_FILTER_HEURISTIC 0 // TYPES ------------------------------------------------------------------- struct IHDR { uint32_t Width; uint32_t Height; uint8_t BitDepth; uint8_t ColorType; uint8_t Compression; uint8_t Filter; uint8_t Interlace; }; PNGHandle::PNGHandle (FILE *file) : File(0), bDeleteFilePtr(true), ChunkPt(0) { File = new FileReader(file); } PNGHandle::PNGHandle (FileReader *file, bool takereader) : File(file), bDeleteFilePtr(takereader), ChunkPt(0) {} PNGHandle::~PNGHandle () { for (unsigned int i = 0; i < TextChunks.Size(); ++i) { delete[] TextChunks[i]; } if (bDeleteFilePtr) { delete File; } } // EXTERNAL FUNCTION PROTOTYPES -------------------------------------------- // PUBLIC FUNCTION PROTOTYPES ---------------------------------------------- // PRIVATE FUNCTION PROTOTYPES --------------------------------------------- static inline void MakeChunk (void *where, uint32_t type, size_t len); static inline void StuffPalette (const PalEntry *from, uint8_t *to); static bool WriteIDAT (FileWriter *file, const uint8_t *data, int len); static void UnfilterRow (int width, uint8_t *dest, uint8_t *stream, uint8_t *prev, int bpp); static void UnpackPixels (int width, int bytesPerRow, int bitdepth, const uint8_t *rowin, uint8_t *rowout, bool grayscale); // EXTERNAL DATA DECLARATIONS ---------------------------------------------- // PUBLIC DATA DEFINITIONS ------------------------------------------------- CUSTOM_CVAR(Int, png_level, 5, CVAR_ARCHIVE|CVAR_GLOBALCONFIG) { if (self < 0) self = 0; else if (self > 9) self = 9; } CVAR(Float, png_gamma, 0.f, CVAR_ARCHIVE|CVAR_GLOBALCONFIG) // PRIVATE DATA DEFINITIONS ------------------------------------------------ // CODE -------------------------------------------------------------------- //========================================================================== // // M_CreatePNG // // Passed a newly-created file, writes the PNG signature and IHDR, gAMA, and // PLTE chunks. Returns true if everything went as expected. // //========================================================================== bool M_CreatePNG (FileWriter *file, const uint8_t *buffer, const PalEntry *palette, ESSType color_type, int width, int height, int pitch, float gamma) { uint8_t work[8 + // signature 12+2*4+5 + // IHDR 12+4 + // gAMA 12+256*3]; // PLTE uint32_t *const sig = (uint32_t *)&work[0]; IHDR *const ihdr = (IHDR *)&work[8 + 8]; uint32_t *const gama = (uint32_t *)((uint8_t *)ihdr + 2*4+5 + 12); uint8_t *const plte = (uint8_t *)gama + 4 + 12; size_t work_len; sig[0] = MAKE_ID(137,'P','N','G'); sig[1] = MAKE_ID(13,10,26,10); ihdr->Width = BigLong(width); ihdr->Height = BigLong(height); ihdr->BitDepth = 8; ihdr->ColorType = color_type == SS_PAL ? 3 : 2; ihdr->Compression = 0; ihdr->Filter = 0; ihdr->Interlace = 0; MakeChunk (ihdr, MAKE_ID('I','H','D','R'), 2*4+5); // Assume a display exponent of 2.2 (100000/2.2 ~= 45454.5) *gama = BigLong (int (45454.5f * (png_gamma == 0.f ? gamma : png_gamma))); MakeChunk (gama, MAKE_ID('g','A','M','A'), 4); if (color_type == SS_PAL) { StuffPalette (palette, plte); MakeChunk (plte, MAKE_ID('P','L','T','E'), 256*3); work_len = sizeof(work); } else { work_len = sizeof(work) - (12+256*3); } if (file->Write (work, work_len) != work_len) return false; return M_SaveBitmap (buffer, color_type, width, height, pitch, file); } //========================================================================== // // M_CreateDummyPNG // // Like M_CreatePNG, but the image is always a grayscale 1x1 black square. // //========================================================================== bool M_CreateDummyPNG (FileWriter *file) { static const uint8_t dummyPNG[] = { 137,'P','N','G',13,10,26,10, 0,0,0,13,'I','H','D','R', 0,0,0,1,0,0,0,1,8,0,0,0,0,0x3a,0x7e,0x9b,0x55, 0,0,0,10,'I','D','A','T', 104,222,99,96,0,0,0,2,0,1,0x9f,0x65,0x0e,0x18 }; return file->Write (dummyPNG, sizeof(dummyPNG)) == sizeof(dummyPNG); } //========================================================================== // // M_FinishPNG // // Writes an IEND chunk to a PNG file. The file is left opened. // //========================================================================== bool M_FinishPNG (FileWriter *file) { static const uint8_t iend[12] = { 0,0,0,0,73,69,78,68,174,66,96,130 }; return file->Write (iend, 12) == 12; } //========================================================================== // // M_AppendPNGChunk // // Writes a PNG-compliant chunk to the file. // //========================================================================== bool M_AppendPNGChunk (FileWriter *file, uint32_t chunkID, const uint8_t *chunkData, uint32_t len) { uint32_t head[2] = { BigLong((unsigned int)len), chunkID }; uint32_t crc; if (file->Write (head, 8) == 8 && (len == 0 || file->Write (chunkData, len) == len)) { crc = CalcCRC32 ((uint8_t *)&head[1], 4); if (len != 0) { crc = AddCRC32 (crc, chunkData, len); } crc = BigLong((unsigned int)crc); return file->Write (&crc, 4) == 4; } return false; } //========================================================================== // // M_AppendPNGText // // Appends a PNG tEXt chunk to the file // //========================================================================== bool M_AppendPNGText (FileWriter *file, const char *keyword, const char *text) { struct { uint32_t len, id; char key[80]; } head; int len = (int)strlen (text); int keylen = MIN ((int)strlen (keyword), 79); uint32_t crc; head.len = BigLong(len + keylen + 1); head.id = MAKE_ID('t','E','X','t'); memset (&head.key, 0, sizeof(head.key)); strncpy (head.key, keyword, keylen); head.key[keylen] = 0; if ((int)file->Write (&head, keylen + 9) == keylen + 9 && (int)file->Write (text, len) == len) { crc = CalcCRC32 ((uint8_t *)&head+4, keylen + 5); if (len != 0) { crc = AddCRC32 (crc, (uint8_t *)text, len); } crc = BigLong((unsigned int)crc); return file->Write (&crc, 4) == 4; } return false; } //========================================================================== // // M_FindPNGChunk // // Finds a chunk in a PNG file. The file pointer will be positioned at the // beginning of the chunk data, and its length will be returned. A return // value of 0 indicates the chunk was either not present or had 0 length. // This means there is no way to conclusively determine if a chunk is not // present in a PNG file with this function, but since we're only // interested in chunks with content, that's okay. The file pointer will // be left sitting at the start of the chunk's data if it was found. // //========================================================================== unsigned int M_FindPNGChunk (PNGHandle *png, uint32_t id) { png->ChunkPt = 0; return M_NextPNGChunk (png, id); } //========================================================================== // // M_NextPNGChunk // // Like M_FindPNGChunk, but it starts it search at the current chunk. // //========================================================================== unsigned int M_NextPNGChunk (PNGHandle *png, uint32_t id) { for ( ; png->ChunkPt < png->Chunks.Size(); ++png->ChunkPt) { if (png->Chunks[png->ChunkPt].ID == id) { // Found the chunk png->File->Seek (png->Chunks[png->ChunkPt++].Offset, SEEK_SET); return png->Chunks[png->ChunkPt - 1].Size; } } return 0; } //========================================================================== // // M_GetPNGText // // Finds a PNG text chunk with the given signature and returns a pointer // to a NULL-terminated string if present. Returns NULL on failure. // //========================================================================== char *M_GetPNGText (PNGHandle *png, const char *keyword) { unsigned int i; size_t keylen, textlen; for (i = 0; i < png->TextChunks.Size(); ++i) { if (strncmp (keyword, png->TextChunks[i], 80) == 0) { // Woo! A match was found! keylen = MIN (80, strlen (keyword) + 1); textlen = strlen (png->TextChunks[i] + keylen) + 1; char *str = new char[textlen]; strcpy (str, png->TextChunks[i] + keylen); return str; } } return NULL; } // This version copies it to a supplied buffer instead of allocating a new one. bool M_GetPNGText (PNGHandle *png, const char *keyword, char *buffer, size_t buffsize) { unsigned int i; size_t keylen; for (i = 0; i < png->TextChunks.Size(); ++i) { if (strncmp (keyword, png->TextChunks[i], 80) == 0) { // Woo! A match was found! keylen = MIN (80, strlen (keyword) + 1); strncpy (buffer, png->TextChunks[i] + keylen, buffsize); return true; } } return false; } //========================================================================== // // M_VerifyPNG // // Returns a PNGHandle if the file is a PNG or NULL if not. CRC checking of // chunks is not done in order to save time. // //========================================================================== PNGHandle *M_VerifyPNG (FileReader *filer, bool takereader) { PNGHandle::Chunk chunk; PNGHandle *png; uint32_t data[2]; bool sawIDAT = false; if (filer->Read(&data, 8) != 8) { if (takereader) delete filer; return NULL; } if (data[0] != MAKE_ID(137,'P','N','G') || data[1] != MAKE_ID(13,10,26,10)) { // Does not have PNG signature if (takereader) delete filer; return NULL; } if (filer->Read (&data, 8) != 8) { if (takereader) delete filer; return NULL; } if (data[1] != MAKE_ID('I','H','D','R')) { // IHDR must be the first chunk if (takereader) delete filer; return NULL; } // It looks like a PNG so far, so start creating a PNGHandle for it png = new PNGHandle (filer, takereader); chunk.ID = data[1]; chunk.Offset = 16; chunk.Size = BigLong((unsigned int)data[0]); png->Chunks.Push (chunk); filer->Seek (16, SEEK_SET); while (filer->Seek (chunk.Size + 4, SEEK_CUR) == 0) { // If the file ended before an IEND was encountered, it's not a PNG. if (filer->Read (&data, 8) != 8) { break; } // An IEND chunk terminates the PNG and must be empty if (data[1] == MAKE_ID('I','E','N','D')) { if (data[0] == 0 && sawIDAT) { return png; } break; } // A PNG must include an IDAT chunk if (data[1] == MAKE_ID('I','D','A','T')) { sawIDAT = true; } chunk.ID = data[1]; chunk.Offset = filer->Tell(); chunk.Size = BigLong((unsigned int)data[0]); png->Chunks.Push (chunk); // If this is a text chunk, also record its contents. if (data[1] == MAKE_ID('t','E','X','t')) { char *str = new char[chunk.Size + 1]; if (filer->Read (str, chunk.Size) != (long)chunk.Size) { delete[] str; break; } str[chunk.Size] = 0; png->TextChunks.Push (str); chunk.Size = 0; // Don't try to seek past its contents again. } } delete png; return NULL; } //========================================================================== // // M_FreePNG // // Just deletes the PNGHandle. The file is not closed. // //========================================================================== void M_FreePNG (PNGHandle *png) { delete png; } //========================================================================== // // ReadIDAT // // Reads image data out of a PNG // //========================================================================== bool M_ReadIDAT (FileReader *file, uint8_t *buffer, int width, int height, int pitch, uint8_t bitdepth, uint8_t colortype, uint8_t interlace, unsigned int chunklen) { // Uninterlaced images are treated as a conceptual eighth pass by these tables. static const uint8_t passwidthshift[8] = { 3, 3, 2, 2, 1, 1, 0, 0 }; static const uint8_t passheightshift[8] = { 3, 3, 3, 2, 2, 1, 1, 0 }; static const uint8_t passrowoffset[8] = { 0, 0, 4, 0, 2, 0, 1, 0 }; static const uint8_t passcoloffset[8] = { 0, 4, 0, 2, 0, 1, 0, 0 }; Byte *inputLine, *prev, *curr, *adam7buff[3], *bufferend; Byte chunkbuffer[4096]; z_stream stream; int err; int i, pass, passbuff, passpitch, passwidth; bool lastIDAT; int bytesPerRowIn, bytesPerRowOut; int bytesPerPixel; bool initpass; switch (colortype) { case 2: bytesPerPixel = 3; break; // RGB case 4: bytesPerPixel = 2; break; // LA case 6: bytesPerPixel = 4; break; // RGBA default: bytesPerPixel = 1; break; } bytesPerRowOut = width * bytesPerPixel; i = 4 + bytesPerRowOut * 2; if (interlace) { i += bytesPerRowOut * 2; } inputLine = (Byte *)alloca (i); adam7buff[0] = inputLine + 4 + bytesPerRowOut; adam7buff[1] = adam7buff[0] + bytesPerRowOut; adam7buff[2] = adam7buff[1] + bytesPerRowOut; bufferend = buffer + pitch * height; stream.next_in = Z_NULL; stream.avail_in = 0; stream.zalloc = Z_NULL; stream.zfree = Z_NULL; err = inflateInit (&stream); if (err != Z_OK) { return false; } lastIDAT = false; initpass = true; pass = interlace ? 0 : 7; // Silence GCC warnings. Due to initpass being true, these will be set // before they're used, but it doesn't know that. curr = prev = 0; passwidth = passpitch = bytesPerRowIn = 0; passbuff = 0; while (err != Z_STREAM_END && pass < 8 - interlace) { if (initpass) { int rowoffset, coloffset; initpass = false; pass--; do { pass++; rowoffset = passrowoffset[pass]; coloffset = passcoloffset[pass]; } while ((rowoffset >= height || coloffset >= width) && pass < 7); if (pass == 7 && interlace) { break; } passwidth = (width + (1 << passwidthshift[pass]) - 1 - coloffset) >> passwidthshift[pass]; prev = adam7buff[0]; passbuff = 1; memset (prev, 0, passwidth * bytesPerPixel); switch (bitdepth) { case 8: bytesPerRowIn = passwidth * bytesPerPixel; break; case 4: bytesPerRowIn = (passwidth+1)/2; break; case 2: bytesPerRowIn = (passwidth+3)/4; break; case 1: bytesPerRowIn = (passwidth+7)/8; break; default: return false; } curr = buffer + rowoffset*pitch + coloffset*bytesPerPixel; passpitch = pitch << passheightshift[pass]; stream.next_out = inputLine; stream.avail_out = bytesPerRowIn + 1; } if (stream.avail_in == 0 && chunklen > 0) { stream.next_in = chunkbuffer; stream.avail_in = (uInt)file->Read (chunkbuffer, MIN(chunklen,sizeof(chunkbuffer))); chunklen -= stream.avail_in; } err = inflate (&stream, Z_SYNC_FLUSH); if (err != Z_OK && err != Z_STREAM_END) { // something unexpected happened inflateEnd (&stream); return false; } if (stream.avail_out == 0) { if (pass >= 6) { // Store pixels directly into the output buffer UnfilterRow (bytesPerRowIn, curr, inputLine, prev, bytesPerPixel); prev = curr; } else { const uint8_t *in; uint8_t *out; int colstep, x; // Store pixels into a temporary buffer UnfilterRow (bytesPerRowIn, adam7buff[passbuff], inputLine, prev, bytesPerPixel); prev = adam7buff[passbuff]; passbuff ^= 1; in = prev; if (bitdepth < 8) { UnpackPixels (passwidth, bytesPerRowIn, bitdepth, in, adam7buff[2], colortype == 0); in = adam7buff[2]; } // Distribute pixels into the output buffer out = curr; colstep = bytesPerPixel << passwidthshift[pass]; switch (bytesPerPixel) { case 1: for (x = passwidth; x > 0; --x) { *out = *in; out += colstep; in += 1; } break; case 2: for (x = passwidth; x > 0; --x) { *(uint16_t *)out = *(uint16_t *)in; out += colstep; in += 2; } break; case 3: for (x = passwidth; x > 0; --x) { out[0] = in[0]; out[1] = in[1]; out[2] = in[2]; out += colstep; in += 3; } break; case 4: for (x = passwidth; x > 0; --x) { *(uint32_t *)out = *(uint32_t *)in; out += colstep; in += 4; } break; } } if ((curr += passpitch) >= bufferend) { ++pass; initpass = true; } stream.next_out = inputLine; stream.avail_out = bytesPerRowIn + 1; } if (chunklen == 0 && !lastIDAT) { uint32_t x[3]; if (file->Read (x, 12) != 12) { lastIDAT = true; } else if (x[2] != MAKE_ID('I','D','A','T')) { lastIDAT = true; } else { chunklen = BigLong((unsigned int)x[1]); } } } inflateEnd (&stream); if (bitdepth < 8) { // Noninterlaced images must be unpacked completely. // Interlaced images only need their final pass unpacked. passpitch = pitch << interlace; for (curr = buffer + pitch * interlace; curr <= prev; curr += passpitch) { UnpackPixels (width, bytesPerRowIn, bitdepth, curr, curr, colortype == 0); } } return true; } // PRIVATE CODE ------------------------------------------------------------ //========================================================================== // // MakeChunk // // Prepends the chunk length and type and appends the chunk's CRC32. // There must be 8 bytes available before the chunk passed and 4 bytes // after the chunk. // //========================================================================== static inline void MakeChunk (void *where, uint32_t type, size_t len) { uint8_t *const data = (uint8_t *)where; *(uint32_t *)(data - 8) = BigLong ((unsigned int)len); *(uint32_t *)(data - 4) = type; *(uint32_t *)(data + len) = BigLong ((unsigned int)CalcCRC32 (data-4, (unsigned int)(len+4))); } //========================================================================== // // StuffPalette // // Converts 256 4-byte palette entries to 3 bytes each. // //========================================================================== static void StuffPalette (const PalEntry *from, uint8_t *to) { for (int i = 256; i > 0; --i) { to[0] = from->r; to[1] = from->g; to[2] = from->b; from += 1; to += 3; } } //========================================================================== // // CalcSum // // //========================================================================== uint32_t CalcSum(Byte *row, int len) { uint32_t sum = 0; while (len-- != 0) { sum += (char)*row++; } return sum; } //========================================================================== // // SelectFilter // // Performs the heuristic recommended by the PNG spec to decide the // (hopefully) best filter to use for this row. To quate: // // Select the filter that gives the smallest sum of absolute values of // outputs. (Consider the output bytes as signed differences for this // test.) // //========================================================================== #if USE_FILTER_HEURISTIC static int SelectFilter(Byte row[5][1 + MAXWIDTH*3], Byte prior[MAXWIDTH*3], int width) { // As it turns out, it seems no filtering is the best for Doom screenshots, // no matter what the heuristic might determine. return 0; uint32_t sum; uint32_t bestsum; int bestfilter; int x; width *= 3; // The first byte of each row holds the filter type, filled in by the caller. // However, the prior row does not contain a filter type, since it's always 0. bestsum = 0; bestfilter = 0; // None for (x = 1; x <= width; ++x) { bestsum += abs((char)row[0][x]); } // Sub row[1][1] = row[0][1]; row[1][2] = row[0][2]; row[1][3] = row[0][3]; sum = abs((char)row[0][1]) + abs((char)row[0][2]) + abs((char)row[0][3]); for (x = 4; x <= width; ++x) { row[1][x] = row[0][x] - row[0][x - 3]; sum += abs((char)row[1][x]); if (sum >= bestsum) { // This isn't going to be any better. break; } } if (sum < bestsum) { bestsum = sum; bestfilter = 1; } // Up sum = 0; for (x = 1; x <= width; ++x) { row[2][x] = row[0][x] - prior[x - 1]; sum += abs((char)row[2][x]); if (sum >= bestsum) { // This isn't going to be any better. break; } } if (sum < bestsum) { bestsum = sum; bestfilter = 2; } // Average row[3][1] = row[0][1] - prior[0] / 2; row[3][2] = row[0][2] - prior[1] / 2; row[3][3] = row[0][3] - prior[2] / 2; sum = abs((char)row[3][1]) + abs((char)row[3][2]) + abs((char)row[3][3]); for (x = 4; x <= width; ++x) { row[3][x] = row[0][x] - (row[0][x - 3] + prior[x - 1]) / 2; sum += (char)row[3][x]; if (sum >= bestsum) { // This isn't going to be any better. break; } } if (sum < bestsum) { bestsum = sum; bestfilter = 3; } // Paeth row[4][1] = row[0][1] - prior[0]; row[4][2] = row[0][2] - prior[1]; row[4][3] = row[0][3] - prior[2]; sum = abs((char)row[4][1]) + abs((char)row[4][2]) + abs((char)row[4][3]); for (x = 4; x <= width; ++x) { Byte a = row[0][x - 3]; Byte b = prior[x - 1]; Byte c = prior[x - 4]; int p = a + b - c; int pa = abs(p - a); int pb = abs(p - b); int pc = abs(p - c); if (pa <= pb && pa <= pc) { row[4][x] = row[0][x] - a; } else if (pb <= pc) { row[4][x] = row[0][x] - b; } else { row[4][x] = row[0][x] - c; } sum += (char)row[4][x]; if (sum >= bestsum) { // This isn't going to be any better. break; } } if (sum < bestsum) { bestfilter = 4; } return bestfilter; } #else #define SelectFilter(x,y,z) 0 #endif //========================================================================== // // M_SaveBitmap // // Given a bitmap, creates one or more IDAT chunks in the given file. // Returns true on success. // //========================================================================== bool M_SaveBitmap(const uint8_t *from, ESSType color_type, int width, int height, int pitch, FileWriter *file) { #if USE_FILTER_HEURISTIC Byte prior[MAXWIDTH*3]; Byte temprow[5][1 + MAXWIDTH*3]; #else Byte temprow[1][1 + MAXWIDTH*3]; #endif Byte buffer[PNG_WRITE_SIZE]; z_stream stream; int err; int y; stream.next_in = Z_NULL; stream.avail_in = 0; stream.zalloc = Z_NULL; stream.zfree = Z_NULL; err = deflateInit (&stream, png_level); if (err != Z_OK) { return false; } y = height; stream.next_out = buffer; stream.avail_out = sizeof(buffer); temprow[0][0] = 0; #if USE_FILTER_HEURISTIC temprow[1][0] = 1; temprow[2][0] = 2; temprow[3][0] = 3; temprow[4][0] = 4; // Fill the prior row with 0 for RGB images. Paletted is always filter 0, // so it doesn't need this. if (color_type != SS_PAL) { memset(prior, 0, width * 3); } #endif while (y-- > 0 && err == Z_OK) { switch (color_type) { case SS_PAL: memcpy(&temprow[0][1], from, width); // always use filter type 0 for paletted images stream.next_in = temprow[0]; stream.avail_in = width + 1; break; case SS_RGB: memcpy(&temprow[0][1], from, width*3); stream.next_in = temprow[SelectFilter(temprow, prior, width)]; stream.avail_in = width * 3 + 1; break; case SS_BGRA: for (int x = 0; x < width; ++x) { temprow[0][x*3 + 1] = from[x*4 + 2]; temprow[0][x*3 + 2] = from[x*4 + 1]; temprow[0][x*3 + 3] = from[x*4]; } stream.next_in = temprow[SelectFilter(temprow, prior, width)]; stream.avail_in = width * 3 + 1; break; } #if USE_FILTER_HEURISTIC if (color_type != SS_PAL) { // Save this row for filter calculations on the next row. memcpy (prior, &temprow[0][1], stream.avail_in - 1); } #endif from += pitch; err = deflate (&stream, (y == 0) ? Z_FINISH : 0); if (err != Z_OK) { break; } while (stream.avail_out == 0) { if (!WriteIDAT (file, buffer, sizeof(buffer))) { return false; } stream.next_out = buffer; stream.avail_out = sizeof(buffer); if (stream.avail_in != 0) { err = deflate (&stream, (y == 0) ? Z_FINISH : 0); if (err != Z_OK) { break; } } } } while (err == Z_OK) { err = deflate (&stream, Z_FINISH); if (err != Z_OK) { break; } if (stream.avail_out == 0) { if (!WriteIDAT (file, buffer, sizeof(buffer))) { return false; } stream.next_out = buffer; stream.avail_out = sizeof(buffer); } } deflateEnd (&stream); if (err != Z_STREAM_END) { return false; } return WriteIDAT (file, buffer, sizeof(buffer)-stream.avail_out); } //========================================================================== // // WriteIDAT // // Writes a single IDAT chunk to the file. Returns true on success. // //========================================================================== static bool WriteIDAT (FileWriter *file, const uint8_t *data, int len) { uint32_t foo[2], crc; foo[0] = BigLong (len); foo[1] = MAKE_ID('I','D','A','T'); crc = CalcCRC32 ((uint8_t *)&foo[1], 4); crc = BigLong ((unsigned int)AddCRC32 (crc, data, len)); if (file->Write (foo, 8) != 8 || file->Write (data, len) != (size_t)len || file->Write (&crc, 4) != 4) { return false; } return true; } //========================================================================== // // UnfilterRow // // Unfilters the given row. Unknown filter types are silently ignored. // bpp is bytes per pixel, not bits per pixel. // width is in bytes, not pixels. // //========================================================================== void UnfilterRow (int width, uint8_t *dest, uint8_t *row, uint8_t *prev, int bpp) { int x; switch (*row++) { case 1: // Sub x = bpp; do { *dest++ = *row++; } while (--x); for (x = width - bpp; x > 0; --x) { *dest = *row++ + *(dest - bpp); dest++; } break; case 2: // Up x = width; do { *dest++ = *row++ + *prev++; } while (--x); break; case 3: // Average x = bpp; do { *dest++ = *row++ + (*prev++)/2; } while (--x); for (x = width - bpp; x > 0; --x) { *dest = *row++ + (uint8_t)((unsigned(*(dest - bpp)) + unsigned(*prev++)) >> 1); dest++; } break; case 4: // Paeth x = bpp; do { *dest++ = *row++ + *prev++; } while (--x); for (x = width - bpp; x > 0; --x) { int a, b, c, pa, pb, pc; a = *(dest - bpp); b = *(prev); c = *(prev - bpp); pa = b - c; pb = a - c; pc = abs (pa + pb); pa = abs (pa); pb = abs (pb); *dest = *row + (uint8_t)((pa <= pb && pa <= pc) ? a : (pb <= pc) ? b : c); dest++; row++; prev++; } break; default: // Treat everything else as filter type 0 (none) memcpy (dest, row, width); break; } } //========================================================================== // // UnpackPixels // // Unpacks a row of pixels whose depth is less than 8 so that each pixel // occupies a single byte. The outrow must be "width" bytes long. // "bytesPerRow" is the number of bytes for the packed row. The in and out // rows may overlap, but only if rowin == rowout. // //========================================================================== static void UnpackPixels (int width, int bytesPerRow, int bitdepth, const uint8_t *rowin, uint8_t *rowout, bool grayscale) { const uint8_t *in; uint8_t *out; uint8_t pack; int lastbyte; assert(bitdepth == 1 || bitdepth == 2 || bitdepth == 4); out = rowout + width; in = rowin + bytesPerRow; switch (bitdepth) { case 1: lastbyte = width & 7; if (lastbyte != 0) { in--; pack = *in; out -= lastbyte; out[0] = (pack >> 7) & 1; if (lastbyte >= 2) out[1] = (pack >> 6) & 1; if (lastbyte >= 3) out[2] = (pack >> 5) & 1; if (lastbyte >= 4) out[3] = (pack >> 4) & 1; if (lastbyte >= 5) out[4] = (pack >> 3) & 1; if (lastbyte >= 6) out[5] = (pack >> 2) & 1; if (lastbyte == 7) out[6] = (pack >> 1) & 1; } while (in-- > rowin) { pack = *in; out -= 8; out[0] = (pack >> 7) & 1; out[1] = (pack >> 6) & 1; out[2] = (pack >> 5) & 1; out[3] = (pack >> 4) & 1; out[4] = (pack >> 3) & 1; out[5] = (pack >> 2) & 1; out[6] = (pack >> 1) & 1; out[7] = pack & 1; } break; case 2: lastbyte = width & 3; if (lastbyte != 0) { in--; pack = *in; out -= lastbyte; out[0] = pack >> 6; if (lastbyte >= 2) out[1] = (pack >> 4) & 3; if (lastbyte == 3) out[2] = (pack >> 2) & 3; } while (in-- > rowin) { pack = *in; out -= 4; out[0] = pack >> 6; out[1] = (pack >> 4) & 3; out[2] = (pack >> 2) & 3; out[3] = pack & 3; } break; case 4: lastbyte = width & 1; if (lastbyte != 0) { in--; pack = *in; out -= lastbyte; out[0] = pack >> 4; } while (in-- > rowin) { pack = *in; out -= 2; out[0] = pack >> 4; out[1] = pack & 15; } break; } // Expand grayscale to 8bpp if (grayscale) { // Put the 2-bit lookup table on the stack, since it's probably already // in a cache line. union { uint32_t bits2l; uint8_t bits2[4]; }; out = rowout + width; switch (bitdepth) { case 1: while (--out >= rowout) { // 1 becomes -1 (0xFF), and 0 remains untouched. *out = 0 - *out; } break; case 2: bits2l = MAKE_ID(0x00,0x55,0xAA,0xFF); while (--out >= rowout) { *out = bits2[*out]; } break; case 4: while (--out >= rowout) { *out |= (*out << 4); } break; } } }