/*!
* pixCopyColormap()
*
* Input: src and dest Pix
* Return: 0 if OK, 1 on error
*
* Notes:
* (1) This always destroys any colormap in pixd (except if
* the operation is a no-op.
*/
l_int32
pixCopyColormap(PIX *pixd,
PIX *pixs)
{
PIXCMAP *cmaps, *cmapd;
PROCNAME("pixCopyColormap");
if (!pixs)
return ERROR_INT("pixs not defined", procName, 1);
if (!pixd)
return ERROR_INT("pixd not defined", procName, 1);
if (pixs == pixd)
return 0; /* no-op */
pixDestroyColormap(pixd);
if ((cmaps = pixGetColormap(pixs)) == NULL) /* not an error */
return 0;
if ((cmapd = pixcmapCopy(cmaps)) == NULL)
return ERROR_INT("cmapd not made", procName, 1);
pixSetColormap(pixd, cmapd);
return 0;
}
/*!
* pixSetColormap()
*
* Input: pix
* colormap (to be assigned)
* Return: 0 if OK, 1 on error.
*
* Notes:
* (1) Unlike with the pix data field, pixSetColormap() destroys
* any existing colormap before assigning the new one.
* Because colormaps are not ref counted, it is important that
* the new colormap does not belong to any other pix.
*/
l_int32
pixSetColormap(PIX *pix,
PIXCMAP *colormap)
{
PROCNAME("pixSetColormap");
if (!pix)
return ERROR_INT("pix not defined", procName, 1);
pixDestroyColormap(pix);
pix->colormap = colormap;
return 0;
}
/*!
* pixFree()
*
* Input: pix
* Return: void
*
* Notes:
* (1) Decrements the ref count and, if 0, destroys the pix.
*/
static void
pixFree(PIX *pix)
{
l_uint32 *data;
char *text;
if (!pix) return;
pixChangeRefcount(pix, -1);
if (pixGetRefcount(pix) <= 0) {
if ((data = pixGetData(pix)) != NULL)
pix_free(data);
if ((text = pixGetText(pix)) != NULL)
FREE(text);
pixDestroyColormap(pix);
FREE(pix);
}
return;
}
/*!
* pixReadStreamPng()
*
* Input: stream
* Return: pix, or null on error
*
* Notes:
* (1) If called from pixReadStream(), the stream is positioned
* at the beginning of the file.
* (2) To do sequential reads of png format images from a stream,
* use pixReadStreamPng()
*/
PIX *
pixReadStreamPng(FILE *fp)
{
l_uint8 rval, gval, bval;
l_int32 i, j, k;
l_int32 wpl, d, spp, cindex;
l_uint32 png_transforms;
l_uint32 *data, *line, *ppixel;
int num_palette, num_text;
png_byte bit_depth, color_type, channels;
png_uint_32 w, h, rowbytes;
png_uint_32 xres, yres;
png_bytep rowptr;
png_bytep *row_pointers;
png_structp png_ptr;
png_infop info_ptr, end_info;
png_colorp palette;
png_textp text_ptr; /* ptr to text_chunk */
PIX *pix;
PIXCMAP *cmap;
PROCNAME("pixReadStreamPng");
if (!fp)
return (PIX *)ERROR_PTR("fp not defined", procName, NULL);
pix = NULL;
/* Allocate the 3 data structures */
if ((png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
(png_voidp)NULL, NULL, NULL)) == NULL)
return (PIX *)ERROR_PTR("png_ptr not made", procName, NULL);
if ((info_ptr = png_create_info_struct(png_ptr)) == NULL) {
png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
return (PIX *)ERROR_PTR("info_ptr not made", procName, NULL);
}
if ((end_info = png_create_info_struct(png_ptr)) == NULL) {
png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
return (PIX *)ERROR_PTR("end_info not made", procName, NULL);
}
/* Set up png setjmp error handling */
if (setjmp(png_jmpbuf(png_ptr))) {
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
return (PIX *)ERROR_PTR("internal png error", procName, NULL);
}
png_init_io(png_ptr, fp);
/* ---------------------------------------------------------- *
* Set the transforms flags. Whatever happens here,
* NEVER invert 1 bpp using PNG_TRANSFORM_INVERT_MONO.
* ---------------------------------------------------------- */
/* To strip 16 --> 8 bit depth, use PNG_TRANSFORM_STRIP_16 */
if (var_PNG_STRIP_16_TO_8 == 1) /* our default */
png_transforms = PNG_TRANSFORM_STRIP_16;
else
png_transforms = PNG_TRANSFORM_IDENTITY;
/* To remove alpha channel, use PNG_TRANSFORM_STRIP_ALPHA */
if (var_PNG_STRIP_ALPHA == 1) /* our default */
png_transforms |= PNG_TRANSFORM_STRIP_ALPHA;
/* Read it */
png_read_png(png_ptr, info_ptr, png_transforms, NULL);
row_pointers = png_get_rows(png_ptr, info_ptr);
w = png_get_image_width(png_ptr, info_ptr);
h = png_get_image_height(png_ptr, info_ptr);
bit_depth = png_get_bit_depth(png_ptr, info_ptr);
rowbytes = png_get_rowbytes(png_ptr, info_ptr);
color_type = png_get_color_type(png_ptr, info_ptr);
channels = png_get_channels(png_ptr, info_ptr);
spp = channels;
if (spp == 1)
d = bit_depth;
else if (spp == 2) {
d = 2 * bit_depth;
L_WARNING("there shouldn't be 2 spp!", procName);
}
else /* spp == 3 (rgb), spp == 4 (rgba) */
d = 4 * bit_depth;
/* Remove if/when this is implemented for all bit_depths */
if (spp == 3 && bit_depth != 8) {
fprintf(stderr, "Help: spp = 3 and depth = %d != 8\n!!", bit_depth);
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
return (PIX *)ERROR_PTR("not implemented for this depth",
procName, NULL);
}
if (color_type == PNG_COLOR_TYPE_PALETTE ||
color_type == PNG_COLOR_MASK_PALETTE) { /* generate a colormap */
png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette);
cmap = pixcmapCreate(d); /* spp == 1 */
for (cindex = 0; cindex < num_palette; cindex++) {
rval = palette[cindex].red;
gval = palette[cindex].green;
bval = palette[cindex].blue;
pixcmapAddColor(cmap, rval, gval, bval);
}
}
else
cmap = NULL;
if ((pix = pixCreate(w, h, d)) == NULL) {
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
return (PIX *)ERROR_PTR("pix not made", procName, NULL);
}
wpl = pixGetWpl(pix);
data = pixGetData(pix);
pixSetColormap(pix, cmap);
if (spp == 1) { /* copy straight from buffer to pix */
for (i = 0; i < h; i++) {
line = data + i * wpl;
rowptr = row_pointers[i];
for (j = 0; j < rowbytes; j++) {
SET_DATA_BYTE(line, j, rowptr[j]);
}
}
}
else { /* spp == 3 or spp == 4 */
for (i = 0; i < h; i++) {
ppixel = data + i * wpl;
rowptr = row_pointers[i];
for (j = k = 0; j < w; j++) {
SET_DATA_BYTE(ppixel, COLOR_RED, rowptr[k++]);
SET_DATA_BYTE(ppixel, COLOR_GREEN, rowptr[k++]);
SET_DATA_BYTE(ppixel, COLOR_BLUE, rowptr[k++]);
if (spp == 4)
SET_DATA_BYTE(ppixel, L_ALPHA_CHANNEL, rowptr[k++]);
ppixel++;
}
}
}
#if DEBUG
if (cmap) {
for (i = 0; i < 16; i++) {
fprintf(stderr, "[%d] = %d\n", i,
((l_uint8 *)(cmap->array))[i]);
}
}
#endif /* DEBUG */
/* If there is no colormap, PNG defines black = 0 and
* white = 1 by default for binary monochrome. Therefore,
* since we use the opposite definition, we must invert
* the image colors in either of these cases:
* (i) there is no colormap (default)
* (ii) there is a colormap which defines black to
* be 0 and white to be 1.
* We cannot use the PNG_TRANSFORM_INVERT_MONO flag
* because that flag (since version 1.0.9) inverts 8 bpp
* grayscale as well, which we don't want to do.
* (It also doesn't work if there is a colormap.)
* If there is a colormap that defines black = 1 and
* white = 0, we don't need to do anything.
*
* How do we check the polarity of the colormap?
* The colormap determines the values of black and
* white pixels in the following way:
* if black = 1 (255), white = 0
* 255, 255, 255, 0, 0, 0, 0, 0, 0
* if black = 0, white = 1 (255)
* 0, 0, 0, 0, 255, 255, 255, 0
* So we test the first byte to see if it is 0;
* if so, invert the colors.
*
* If there is a colormap, after inverting the pixels it is
* necessary to destroy the colormap. Otherwise, if someone were
* to call pixRemoveColormap(), this would cause the pixel
* values to be inverted again!
*/
if (d == 1 && (!cmap || (cmap && ((l_uint8 *)(cmap->array))[0] == 0x0))) {
/* fprintf(stderr, "Inverting binary data on png read\n"); */
pixInvert(pix, pix);
pixDestroyColormap(pix);
}
xres = png_get_x_pixels_per_meter(png_ptr, info_ptr);
yres = png_get_y_pixels_per_meter(png_ptr, info_ptr);
pixSetXRes(pix, (l_int32)((l_float32)xres / 39.37 + 0.5)); /* to ppi */
pixSetYRes(pix, (l_int32)((l_float32)yres / 39.37 + 0.5)); /* to ppi */
/* Get the text if there is any */
png_get_text(png_ptr, info_ptr, &text_ptr, &num_text);
if (num_text && text_ptr)
pixSetText(pix, text_ptr->text);
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
return pix;
}
