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test-png: Also read images, to get interlace warnings

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Check output for "libpng warning:" lines; the tool also echos
its own "test-png warning" lines about other possible concerns
(e.g. strange bitdepths, etc.) which are not necessarily going
to cause Tux Paint to echo things to STDERR.
This commit is contained in:
Bill Kendrick 2022-07-03 19:42:00 -07:00
parent f56acbe34d
commit faa6746258
1 changed files with 83 additions and 6 deletions
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89
src/test-png.c
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@ -9,6 +9,10 @@
See https://sourceforge.net/p/tuxpaint/bugs/252/
Example:
./test-png data/images/icon.png
./test-png `find . -name "*.png"` | grep -B 2 libpng
Bill Kendrick <bill@newbreedsoftware.com>
(Based loosely on example code by Yoshimasa Niwa, https://gist.github.com/niw,
@ -26,10 +30,13 @@
#include <png.h>
int main(int argc, char * argv[]) {
int i;
int i, w, h, y;
FILE * fi;
png_structp png;
png_infop info;
png_byte ctype, depth;
png_bytep * rows;
/* Usage output */
if (argc == 1 || strcmp(argv[1], "--help") == 0) {
@ -78,13 +85,83 @@ int main(int argc, char * argv[]) {
png_init_io(png, fi);
png_read_info(png, info);
/* *** At this point, libpng would have reported issues *** */
/* *** At this point, libpng would have reported issues
about some chunks; e.g. "iCCP: too many profiles",
"sRGB: out of place", "bKGD: invalid gray level", etc. *** */
/* (We could do additional things, like reporting image
dimensions, color depth, etc., but I don't see any reason to
care right now. -bjk 2022.07.03) */
w = png_get_image_width(png, info);
h = png_get_image_height(png, info);
ctype = png_get_color_type(png, info);
depth = png_get_bit_depth(png, info);
/* If 16-bit, strip to 8-bit */
if (depth == 16) {
printf("test-png warning: 16-bit\n");
png_set_strip_16(png);
}
/* Switch palette to RGB */
if (ctype == PNG_COLOR_TYPE_PALETTE) {
printf("test-png warning: paletted\n");
png_set_palette_to_rgb(png);
}
/* Expand low-depth greyscale up to 8-bit */
if (ctype == PNG_COLOR_TYPE_GRAY && depth < 8) {
printf("test-png warning: greyscale with only %d-bit depth\n", depth);
png_set_expand_gray_1_2_4_to_8(png);
}
/* Expand tRNS chunks into alpha */
if (png_get_valid(png, info, PNG_INFO_tRNS)) {
printf("test-png warning: contains tRNS chunk\n");
png_set_tRNS_to_alpha(png);
}
/* Fill alpha channel if there is none */
if (ctype == PNG_COLOR_TYPE_RGB ||
ctype == PNG_COLOR_TYPE_GRAY ||
ctype == PNG_COLOR_TYPE_PALETTE) {
png_set_filler(png, 0xFF, PNG_FILLER_AFTER);
}
/* Expand grey to color */
if (ctype == PNG_COLOR_TYPE_GRAY ||
ctype == PNG_COLOR_TYPE_GRAY_ALPHA) {
printf("test-png warning: greyscale\n");
png_set_gray_to_rgb(png);
}
/* Update 'info' struct based on whatever was changed above */
png_read_update_info(png, info);
/* Allocate space */
rows = (png_bytep *) malloc(sizeof(png_bytep) * h);
if (!rows) {
fprintf(stderr, "Failed to malloc() space for image data rows!\n");
exit(1);
}
for (y = 0; y < h; y++) {
rows[y] = (png_byte *) malloc(png_get_rowbytes(png, info));
if (!rows[y]) {
fprintf(stderr, "Failed to malloc() space for image data row #%d!\n", y);
exit(1);
}
}
png_read_image(png, rows);
/* *** At this point, libpng would have reported issues while
loading the image, e.g.
"Interlace handling should be turned on when using png_read_image" */
/* Clean up and move on to the next file */
for (y = 0; y < h; y++)
free(rows[y]);
free(rows);
/* Close and move on to the next file */
png_destroy_read_struct(&png, &info, NULL);
fclose(fi);
}