mewin/libpng
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Imported from libpng-0.86.tar

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This commit is contained in:
Guy Schalnat
1996-01-10 02:56:49 -06:00
committed by Glenn Randers-Pehrson
parent 6d76471acd
commit 69b1448f19
21 changed files with 572 additions and 410 deletions
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62
example.c
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@@ -79,13 +79,21 @@ void read_png(char *file_name)
png_info_init(info_ptr);
png_read_init(png_ptr);
/* set up the input control */
/* set up the input control if you are using standard C streams */
png_init_io(png_ptr, fp);
/* read the file information */
png_read_info(png_ptr, info_ptr);
/* if you are using replacement read functions, here you would call */
png_set_read_fn(png_ptr, (void *)io_ptr, user_read_fn);
/* where io_ptr is a structure you want available to the callbacks */
/* set up the transformations you want. Note that these are
/* if you are using replacement message functions, here you would call */
png_set_message_fn(png_ptr, (void *)msg_ptr, user_error_fn, user_warning_fn);
/* where msg_ptr is a structure you want available to the callbacks */
/* read the file information */
png_read_info(png_ptr, info_ptr);
/* set up the transformations you want. Note that these are
all optional. Only call them if you want them */
/* expand paletted colors into true rgb */
@@ -102,7 +110,7 @@ void read_png(char *file_name)
png_set_expand(png_ptr);
/* Set the background color to draw transparent and alpha
images over */
images over */
png_color_16 my_background;
if (info_ptr->valid & PNG_INFO_bKGD)
@@ -120,7 +128,7 @@ void read_png(char *file_name)
/* tell libpng to strip 16 bit depth files down to 8 bits */
if (info_ptr->bit_depth == 16)
png_set_strip_16(png_ptr);
png_set_strip_16(png_ptr);
/* dither rgb files down to 8 bit palettes & reduce palettes
to the number of colors available on your screen */
@@ -138,7 +146,7 @@ void read_png(char *file_name)
png_set_dither(png_ptr, std_color_cube, MAX_SCREEN_COLORS,
MAX_SCREEN_COLORS, NULL);
}
}
}
/* invert monocrome files */
if (info_ptr->bit_depth == 1 &&
@@ -156,7 +164,7 @@ void read_png(char *file_name)
/* flip the rgb pixels to bgr */
if (info_ptr->color_type == PNG_COLOR_TYPE_RGB ||
info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
png_set_bgr(png_ptr);
/* swap bytes of 16 bit files to least significant bit first */
@@ -174,7 +182,7 @@ void read_png(char *file_name)
else
number_passes = 1;
/* optional call to update palette with transformations */
/* optional call to update palette with transformations */
png_start_read_image(png_ptr);
/* optional call to update the info structure */
@@ -192,7 +200,7 @@ void read_png(char *file_name)
for (pass = 0; pass < number_passes; pass++)
{
/* Read the image using the "sparkle" effect. */
png_read_rows(png_ptr, row_pointers, NULL, number_of_rows);
png_read_rows(png_ptr, row_pointers, NULL, number_of_rows);
/* If you are only reading on row at a time, this works */
for (y = 0; y < height; y++)
@@ -210,7 +218,7 @@ void read_png(char *file_name)
/* read the rest of the file, getting any additional chunks
in info_ptr */
png_read_end(png_ptr, info_ptr);
png_read_end(png_ptr, info_ptr);
/* clean up after the read, and free any memory allocated */
png_read_destroy(png_ptr, info_ptr, (png_infop)0);
@@ -262,7 +270,7 @@ initialize_png_reader()
function callbacks, even if you aren't using them all.
You can put a void pointer in place of the NULL, and
retrieve the pointer from inside the callbacks using
the function png_get_msg_ptr(png_ptr); */
the function png_get_progressive_ptr(png_ptr); */
png_set_progressive_read_fn(png_ptr, NULL,
info_callback, row_callback, end_callback);
@@ -372,7 +380,7 @@ void write_png(char *file_name, ... other image information ...)
}
/* set error handling */
if (setjmp(png_ptr->jmpbuf))
if (setjmp(png_ptr->jmpbuf))
{
png_write_destroy(png_ptr);
fclose(fp);
@@ -386,10 +394,18 @@ void write_png(char *file_name, ... other image information ...)
png_info_init(info_ptr);
png_write_init(png_ptr);
/* set up the output control */
/* set up the output control if you are using standard C streams */
png_init_io(png_ptr, fp);
/* set the file information here */
/* if you are using replacement write functions, here you would call */
png_set_write_fn(png_ptr, (void *)io_ptr, user_write_fn, user_flush_fn);
/* where io_ptr is a structure you want available to the callbacks */
/* if you are using replacement message functions, here you would call */
png_set_message_fn(png_ptr, (void *)msg_ptr, user_error_fn, user_warning_fn);
/* where msg_ptr is a structure you want available to the callbacks */
/* set the file information here */
info_ptr->width = ;
info_ptr->height = ;
etc.
@@ -402,10 +418,18 @@ void write_png(char *file_name, ... other image information ...)
/* optional significant bit chunk */
info_ptr->valid |= PNG_INFO_sBIT;
info_ptr->sig_bit = true_bit_depth;
/* optional gamma chunk */
info_ptr->valid |= PNG_INFO_gAMA;
/* if we are dealing with a grayscale image then */
info_ptr->sig_bit.gray = true_bit_depth;
/* otherwise, if we are dealing with a color image then */
info_ptr->sig_bit.red = true_red_bit_depth;
info_ptr->sig_bit.green = true_green_bit_depth;
info_ptr->sig_bit.blue = true_blue_bit_depth;
/* if the image has an alpha channel then */
info_ptr->sig_bit.alpha = true_alpha_bit_depth;
/* optional gamma chunk is strongly suggested if you have any guess
as to the correct gamma of the image */
info_ptr->valid |= PNG_INFO_gAMA;
info_ptr->gamma = gamma;
/* other optional chunks */