static bool jpeg_get_dimensions(FILE *f, // or:
const void *buf, uint32_t buflen,
int32_t *w, int32_t *h,
GError **err) {
bool result = false;
struct jpeg_decompress_struct cinfo;
struct _openslide_jpeg_error_mgr jerr;
jmp_buf env;
if (setjmp(env) == 0) {
cinfo.err = _openslide_jpeg_set_error_handler(&jerr, &env);
jpeg_create_decompress(&cinfo);
if (f) {
_openslide_jpeg_stdio_src(&cinfo, f);
} else {
_openslide_jpeg_mem_src(&cinfo, (void *) buf, buflen);
}
int header_result = jpeg_read_header(&cinfo, TRUE);
if ((header_result != JPEG_HEADER_OK
&& header_result != JPEG_HEADER_TABLES_ONLY)) {
g_set_error(err, OPENSLIDE_ERROR, OPENSLIDE_ERROR_FAILED,
"Couldn't read JPEG header");
goto DONE;
}
jpeg_calc_output_dimensions(&cinfo);
*w = cinfo.output_width;
*h = cinfo.output_height;
result = true;
} else {
// setjmp returned again
g_propagate_error(err, jerr.err);
}
DONE:
// free buffers
jpeg_destroy_decompress(&cinfo);
return result;
}
static bool jpeg_decode(FILE *f, // or:
const void *buf, uint32_t buflen,
void * const _dest, bool grayscale,
int32_t w, int32_t h,
GError **err) {
bool result = false;
struct jpeg_decompress_struct cinfo;
struct _openslide_jpeg_error_mgr jerr;
jmp_buf env;
volatile gsize row_size = 0; // preserve across longjmp
JSAMPARRAY buffer = g_slice_alloc0(sizeof(JSAMPROW) * MAX_SAMP_FACTOR);
if (setjmp(env) == 0) {
cinfo.err = _openslide_jpeg_set_error_handler(&jerr, &env);
jpeg_create_decompress(&cinfo);
// set up I/O
if (f) {
_openslide_jpeg_stdio_src(&cinfo, f);
} else {
_openslide_jpeg_mem_src(&cinfo, (void *) buf, buflen);
}
// read header
int header_result = jpeg_read_header(&cinfo, TRUE);
if ((header_result != JPEG_HEADER_OK
&& header_result != JPEG_HEADER_TABLES_ONLY)) {
g_set_error(err, OPENSLIDE_ERROR, OPENSLIDE_ERROR_FAILED,
"Couldn't read JPEG header");
goto DONE;
}
cinfo.out_color_space = grayscale ? JCS_GRAYSCALE : JCS_RGB;
jpeg_start_decompress(&cinfo);
// ensure buffer dimensions are correct
int32_t width = cinfo.output_width;
int32_t height = cinfo.output_height;
if (w != width || h != height) {
g_set_error(err, OPENSLIDE_ERROR, OPENSLIDE_ERROR_FAILED,
"Dimensional mismatch reading JPEG, "
"expected %dx%d, got %dx%d",
w, h, cinfo.output_width, cinfo.output_height);
goto DONE;
}
// allocate scanline buffers
row_size = sizeof(JSAMPLE) * cinfo.output_width * cinfo.output_components;
for (int i = 0; i < cinfo.rec_outbuf_height; i++) {
buffer[i] = g_slice_alloc(row_size);
}
// decompress
uint32_t *dest32 = _dest;
uint8_t *dest8 = _dest;
while (cinfo.output_scanline < cinfo.output_height) {
JDIMENSION rows_read = jpeg_read_scanlines(&cinfo,
buffer,
cinfo.rec_outbuf_height);
int cur_buffer = 0;
while (rows_read > 0) {
// copy a row
int32_t i;
if (cinfo.output_components == 1) {
// grayscale
for (i = 0; i < (int32_t) cinfo.output_width; i++) {
dest8[i] = buffer[cur_buffer][i];
}
dest8 += cinfo.output_width;
} else {
// RGB
for (i = 0; i < (int32_t) cinfo.output_width; i++) {
dest32[i] = 0xFF000000 | // A
buffer[cur_buffer][i * 3 + 0] << 16 | // R
buffer[cur_buffer][i * 3 + 1] << 8 | // G
buffer[cur_buffer][i * 3 + 2]; // B
}
dest32 += cinfo.output_width;
}
// advance 1 row
rows_read--;
cur_buffer++;
}
}
result = true;
} else {
// setjmp has returned again
g_propagate_error(err, jerr.err);
}
DONE:
// free buffers
for (int i = 0; i < cinfo.rec_outbuf_height; i++) {
g_slice_free1(row_size, buffer[i]);
}
g_slice_free1(sizeof(JSAMPROW) * MAX_SAMP_FACTOR, buffer);
jpeg_destroy_decompress(&cinfo);
return result;
}
// returns w and h and tw and th and comment as a convenience
static bool verify_jpeg(FILE *f, int32_t *w, int32_t *h,
int32_t *tw, int32_t *th,
char **comment, GError **err) {
struct jpeg_decompress_struct cinfo;
struct _openslide_jpeg_error_mgr jerr;
jmp_buf env;
bool success = false;
*w = 0;
*h = 0;
*tw = 0;
*th = 0;
if (comment) {
*comment = NULL;
}
if (setjmp(env) == 0) {
cinfo.err = _openslide_jpeg_set_error_handler(&jerr, &env);
jpeg_create_decompress(&cinfo);
_openslide_jpeg_stdio_src(&cinfo, f);
int header_result;
if (comment) {
// extract comment
jpeg_save_markers(&cinfo, JPEG_COM, 0xFFFF);
}
header_result = jpeg_read_header(&cinfo, TRUE);
if (header_result != JPEG_HEADER_OK
&& header_result != JPEG_HEADER_TABLES_ONLY) {
g_set_error(err, OPENSLIDE_ERROR, OPENSLIDE_ERROR_BAD_DATA,
"Couldn't read JPEG header");
goto DONE;
}
if (cinfo.num_components != 3) {
g_set_error(err, OPENSLIDE_ERROR, OPENSLIDE_ERROR_BAD_DATA,
"JPEG color components != 3");
goto DONE;
}
if (cinfo.restart_interval == 0) {
g_set_error(err, OPENSLIDE_ERROR, OPENSLIDE_ERROR_BAD_DATA,
"No restart markers");
goto DONE;
}
jpeg_start_decompress(&cinfo);
if (comment) {
if (cinfo.marker_list) {
// copy everything out
char *com = g_strndup((const gchar *) cinfo.marker_list->data,
cinfo.marker_list->data_length);
// but only really save everything up to the first '\0'
*comment = g_strdup(com);
g_free(com);
}
jpeg_save_markers(&cinfo, JPEG_COM, 0); // stop saving
}
*w = cinfo.output_width;
*h = cinfo.output_height;
if (cinfo.restart_interval > cinfo.MCUs_per_row) {
g_set_error(err, OPENSLIDE_ERROR, OPENSLIDE_ERROR_BAD_DATA,
"Restart interval greater than MCUs per row");
goto DONE;
}
*tw = *w / (cinfo.MCUs_per_row / cinfo.restart_interval);
*th = *h / cinfo.MCU_rows_in_scan;
int leftover_mcus = cinfo.MCUs_per_row % cinfo.restart_interval;
if (leftover_mcus != 0) {
g_set_error(err, OPENSLIDE_ERROR, OPENSLIDE_ERROR_BAD_DATA,
"Inconsistent restart marker spacing within row");
goto DONE;
}
// g_debug("w: %d, h: %d, restart_interval: %d\n"
// "mcus_per_row: %d, mcu_rows_in_scan: %d\n"
// "leftover mcus: %d",
// cinfo.output_width, cinfo.output_height,
// cinfo.restart_interval,
// cinfo.MCUs_per_row, cinfo.MCU_rows_in_scan,
// leftover_mcus);
} else {
// setjmp has returned again
g_propagate_error(err, jerr.err);
goto DONE;
}
success = true;
DONE:
jpeg_destroy_decompress(&cinfo);
return success;
}
