diff options
Diffstat (limited to 'source/blender/blendthumb/src/blendthumb_extract.cc')
| -rw-r--r-- | source/blender/blendthumb/src/blendthumb_extract.cc | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/source/blender/blendthumb/src/blendthumb_extract.cc b/source/blender/blendthumb/src/blendthumb_extract.cc new file mode 100644 index 00000000000..99b13c89994 --- /dev/null +++ b/source/blender/blendthumb/src/blendthumb_extract.cc @@ -0,0 +1,257 @@ +/* + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software Foundation, + * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + * + * The Original Code is Copyright (C) 2008 Blender Foundation. + * All rights reserved. + */ + +/** \file + * \ingroup blendthumb + * + * Expose #blendthumb_create_thumb_from_file that creates the PNG data + * but does not write it to a file. + */ + +#include <cstring> + +#include "BLI_alloca.h" +#include "BLI_endian_defines.h" +#include "BLI_endian_switch.h" +#include "BLI_fileops.h" +#include "BLI_filereader.h" +#include "BLI_string.h" + +#include "blendthumb.hh" + +static bool blend_header_check_magic(const char header[12]) +{ + /* Check magic string at start of file. */ + if (!BLI_str_startswith(header, "BLENDER")) { + return false; + } + /* Check pointer size and endianness indicators. */ + if (((header[7] != '_') && (header[7] != '-')) || ((header[8] != 'v') && (header[8] != 'V'))) { + return false; + } + /* Check version number. */ + if (!isdigit(header[9]) || !isdigit(header[10]) || !isdigit(header[11])) { + return false; + } + return true; +} + +static bool blend_header_is_version_valid(const char header[12]) +{ + /* Thumbnails are only in files with version >= 2.50 */ + char num[4]; + memcpy(num, header + 9, 3); + num[3] = 0; + return atoi(num) >= 250; +} + +static int blend_header_pointer_size(const char header[12]) +{ + return header[7] == '_' ? 4 : 8; +} + +static bool blend_header_is_endian_switch_needed(const char header[12]) +{ + return (((header[8] == 'v') ? L_ENDIAN : B_ENDIAN) != ENDIAN_ORDER); +} + +static void thumb_data_vertical_flip(Thumbnail *thumb) +{ + uint32_t *rect = (uint32_t *)thumb->data.data(); + int x = thumb->width, y = thumb->height; + uint32_t *top = rect; + uint32_t *bottom = top + ((y - 1) * x); + uint32_t *line = (uint32_t *)malloc(x * sizeof(uint32_t)); + + y >>= 1; + for (; y > 0; y--) { + memcpy(line, top, x * sizeof(uint32_t)); + memcpy(top, bottom, x * sizeof(uint32_t)); + memcpy(bottom, line, x * sizeof(uint32_t)); + bottom -= x; + top += x; + } + free(line); +} + +static int32_t bytes_to_native_i32(const uint8_t bytes[4], bool endian_switch) +{ + int32_t data; + memcpy(&data, bytes, 4); + if (endian_switch) { + BLI_endian_switch_int32(&data); + } + return data; +} + +static bool file_read(FileReader *file, uint8_t *buf, size_t buf_len) +{ + return (file->read(file, buf, buf_len) == buf_len); +} + +static bool file_seek(FileReader *file, size_t len) +{ + if (file->seek != nullptr) { + if (file->seek(file, len, SEEK_CUR) == -1) { + return false; + } + return true; + } + + /* File doesn't support seeking (e.g. gzip), so read and discard in chunks. */ + constexpr size_t dummy_data_size = 4096; + blender::Array<char> dummy_data(dummy_data_size); + while (len > 0) { + const size_t len_chunk = std::min(len, dummy_data_size); + if ((size_t)file->read(file, dummy_data.data(), len_chunk) != len_chunk) { + return false; + } + len -= len_chunk; + } + return true; +} + +static eThumbStatus blendthumb_extract_from_file_impl(FileReader *file, + Thumbnail *thumb, + const size_t bhead_size, + const bool endian_switch) +{ + /* Iterate over file blocks until we find the thumbnail or run out of data. */ + uint8_t *bhead_data = (uint8_t *)BLI_array_alloca(bhead_data, bhead_size); + while (file_read(file, bhead_data, bhead_size)) { + /* Parse type and size from `BHead`. */ + const int32_t block_size = bytes_to_native_i32(&bhead_data[4], endian_switch); + + /* We're looking for the thumbnail, so skip any other block. */ + switch (*((int32_t *)bhead_data)) { + case MAKE_ID('T', 'E', 'S', 'T'): { + uint8_t shape[8]; + if (!file_read(file, shape, sizeof(shape))) { + return BT_INVALID_THUMB; + } + thumb->width = bytes_to_native_i32(&shape[0], endian_switch); + thumb->height = bytes_to_native_i32(&shape[4], endian_switch); + + /* Verify that image dimensions and data size make sense. */ + size_t data_size = block_size - 8; + const size_t expected_size = thumb->width * thumb->height * 4; + if (thumb->width < 0 || thumb->height < 0 || data_size != expected_size) { + return BT_INVALID_THUMB; + } + + thumb->data = blender::Array<uint8_t>(data_size); + if (!file_read(file, thumb->data.data(), data_size)) { + return BT_INVALID_THUMB; + } + return BT_OK; + } + case MAKE_ID('R', 'E', 'N', 'D'): { + if (!file_seek(file, block_size)) { + return BT_INVALID_THUMB; + } + /* Check the next block. */ + break; + } + default: { + /* Early exit if there are no `TEST` or `REND` blocks. + * This saves scanning the entire blend file which could be slow. */ + return BT_INVALID_THUMB; + } + } + } + + return BT_INVALID_THUMB; +} + +/** + * This function extracts the thumbnail from the .blend file into thumb. + * Returns #BT_OK for success and the relevant error code otherwise. + */ +eThumbStatus blendthumb_create_thumb_from_file(FileReader *rawfile, Thumbnail *thumb) +{ + /* Read header in order to identify file type. */ + char header[12]; + if (rawfile->read(rawfile, header, sizeof(header)) != sizeof(header)) { + rawfile->close(rawfile); + return BT_ERROR; + } + + /* Rewind the file after reading the header. */ + rawfile->seek(rawfile, 0, SEEK_SET); + + /* Try to identify the file type from the header. */ + FileReader *file = nullptr; + if (BLI_str_startswith(header, "BLENDER")) { + file = rawfile; + rawfile = nullptr; + } + else if (BLI_file_magic_is_gzip(header)) { + file = BLI_filereader_new_gzip(rawfile); + if (file != nullptr) { + rawfile = nullptr; /* The Gzip #FileReader takes ownership of raw-file. */ + } + } + else if (BLI_file_magic_is_zstd(header)) { + file = BLI_filereader_new_zstd(rawfile); + if (file != nullptr) { + rawfile = nullptr; /* The Zstd #FileReader takes ownership of raw-file. */ + } + } + + /* Clean up rawfile if it wasn't taken over. */ + if (rawfile != nullptr) { + rawfile->close(rawfile); + } + + if (file == nullptr) { + return BT_ERROR; + } + + /* Re-read header in case we had compression. */ + if (file->read(file, header, sizeof(header)) != sizeof(header)) { + file->close(file); + return BT_ERROR; + } + + /* Check if the header format is valid for a .blend file. */ + if (!blend_header_check_magic(header)) { + file->close(file); + return BT_INVALID_FILE; + } + + /* Check if the file is new enough to contain a thumbnail. */ + if (!blend_header_is_version_valid(header)) { + file->close(file); + return BT_EARLY_VERSION; + } + + /* Depending on where it was saved, the file can use different pointer size or endianness. */ + int bhead_size = 16 + blend_header_pointer_size(header); + const bool endian_switch = blend_header_is_endian_switch_needed(header); + + /* Read the thumbnail. */ + eThumbStatus err = blendthumb_extract_from_file_impl(file, thumb, bhead_size, endian_switch); + file->close(file); + if (err != BT_OK) { + return err; + } + + thumb_data_vertical_flip(thumb); + return BT_OK; +} |