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+
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+#if 0 /* in case someone actually tries to compile this */
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+
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+/* example.c - an example of using libpng
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+ * Last changed in libpng 1.6.24 [August 4, 2016]
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+ * Maintained 1998-2016 Glenn Randers-Pehrson
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+ * Maintained 1996, 1997 Andreas Dilger)
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+ * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
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+ * To the extent possible under law, the authors have waived
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+ * all copyright and related or neighboring rights to this file.
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+ * This work is published from: United States.
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+ */
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+
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+/* This is an example of how to use libpng to read and write PNG files.
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+ * The file libpng-manual.txt is much more verbose then this. If you have not
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+ * read it, do so first. This was designed to be a starting point of an
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+ * implementation. This is not officially part of libpng, is hereby placed
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+ * in the public domain, and therefore does not require a copyright notice.
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+ *
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+ * This file does not currently compile, because it is missing certain
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+ * parts, like allocating memory to hold an image. You will have to
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+ * supply these parts to get it to compile. For an example of a minimal
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+ * working PNG reader/writer, see pngtest.c, included in this distribution;
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+ * see also the programs in the contrib directory.
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+ */
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+
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+/* The simple, but restricted, approach to reading a PNG file or data stream
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+ * just requires two function calls, as in the following complete program.
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+ * Writing a file just needs one function call, so long as the data has an
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+ * appropriate layout.
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+ *
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+ * The following code reads PNG image data from a file and writes it, in a
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+ * potentially new format, to a new file. While this code will compile there is
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+ * minimal (insufficient) error checking; for a more realistic version look at
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+ * contrib/examples/pngtopng.c
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+ */
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+#include <stddef.h>
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+#include <stdlib.h>
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+#include <string.h>
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+#include <stdio.h>
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+#include <png.h>
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+#include <zlib.h>
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+
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+int main(int argc, const char **argv)
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+{
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+ if (argc == 3)
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+ {
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+ png_image image; /* The control structure used by libpng */
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+
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+ /* Initialize the 'png_image' structure. */
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+ memset(&image, 0, (sizeof image));
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+ image.version = PNG_IMAGE_VERSION;
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+
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+ /* The first argument is the file to read: */
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+ if (png_image_begin_read_from_file(&image, argv[1]) != 0)
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+ {
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+ png_bytep buffer;
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+
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+ /* Set the format in which to read the PNG file; this code chooses a
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+ * simple sRGB format with a non-associated alpha channel, adequate to
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+ * store most images.
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+ */
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+ image.format = PNG_FORMAT_RGBA;
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+
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+ /* Now allocate enough memory to hold the image in this format; the
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+ * PNG_IMAGE_SIZE macro uses the information about the image (width,
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+ * height and format) stored in 'image'.
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+ */
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+ buffer = malloc(PNG_IMAGE_SIZE(image));
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+
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+ /* If enough memory was available read the image in the desired format
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+ * then write the result out to the new file. 'background' is not
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+ * necessary when reading the image because the alpha channel is
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+ * preserved; if it were to be removed, for example if we requested
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+ * PNG_FORMAT_RGB, then either a solid background color would have to
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+ * be supplied or the output buffer would have to be initialized to the
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+ * actual background of the image.
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+ *
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+ * The fourth argument to png_image_finish_read is the 'row_stride' -
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+ * this is the number of components allocated for the image in each
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+ * row. It has to be at least as big as the value returned by
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+ * PNG_IMAGE_ROW_STRIDE, but if you just allocate space for the
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+ * default, minimum, size using PNG_IMAGE_SIZE as above you can pass
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+ * zero.
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+ *
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+ * The final argument is a pointer to a buffer for the colormap;
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+ * colormaps have exactly the same format as a row of image pixels (so
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+ * you choose what format to make the colormap by setting
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+ * image.format). A colormap is only returned if
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+ * PNG_FORMAT_FLAG_COLORMAP is also set in image.format, so in this
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+ * case NULL is passed as the final argument. If you do want to force
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+ * all images into an index/color-mapped format then you can use:
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+ *
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+ * PNG_IMAGE_COLORMAP_SIZE(image)
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+ *
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+ * to find the maximum size of the colormap in bytes.
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+ */
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+ if (buffer != NULL &&
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+ png_image_finish_read(&image, NULL/*background*/, buffer,
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+ 0/*row_stride*/, NULL/*colormap*/) != 0)
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+ {
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+ /* Now write the image out to the second argument. In the write
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+ * call 'convert_to_8bit' allows 16-bit data to be squashed down to
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+ * 8 bits; this isn't necessary here because the original read was
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+ * to the 8-bit format.
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+ */
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+ if (png_image_write_to_file(&image, argv[2], 0/*convert_to_8bit*/,
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+ buffer, 0/*row_stride*/, NULL/*colormap*/) != 0)
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+ {
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+ /* The image has been written successfully. */
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+ exit(0);
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+ }
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+ }
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+
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+ else
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+ {
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+ /* Calling png_image_free is optional unless the simplified API was
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+ * not run to completion. In this case if there wasn't enough
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+ * memory for 'buffer' we didn't complete the read, so we must free
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+ * the image:
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+ */
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+ if (buffer == NULL)
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+ png_image_free(&image);
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+
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+ else
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+ free(buffer);
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+ }
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+
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+ /* Something went wrong reading or writing the image. libpng stores a
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+ * textual message in the 'png_image' structure:
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+ */
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+ fprintf(stderr, "pngtopng: error: %s\n", image.message);
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+ exit (1);
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+ }
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+
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+ fprintf(stderr, "pngtopng: usage: pngtopng input-file output-file\n");
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+ exit(1);
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+}
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+
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+/* That's it ;-) Of course you probably want to do more with PNG files than
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+ * just converting them all to 32-bit RGBA PNG files; you can do that between
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+ * the call to png_image_finish_read and png_image_write_to_file. You can also
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+ * ask for the image data to be presented in a number of different formats. You
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+ * do this by simply changing the 'format' parameter set before allocating the
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+ * buffer.
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+ *
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+ * The format parameter consists of five flags that define various aspects of
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+ * the image, you can simply add these together to get the format or you can use
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+ * one of the predefined macros from png.h (as above):
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+ *
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+ * PNG_FORMAT_FLAG_COLOR: if set the image will have three color components per
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+ * pixel (red, green and blue), if not set the image will just have one
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+ * luminance (grayscale) component.
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+ *
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+ * PNG_FORMAT_FLAG_ALPHA: if set each pixel in the image will have an additional
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+ * alpha value; a linear value that describes the degree the image pixel
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+ * covers (overwrites) the contents of the existing pixel on the display.
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+ *
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+ * PNG_FORMAT_FLAG_LINEAR: if set the components of each pixel will be returned
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+ * as a series of 16-bit linear values, if not set the components will be
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+ * returned as a series of 8-bit values encoded according to the 'sRGB'
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+ * standard. The 8-bit format is the normal format for images intended for
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+ * direct display, because almost all display devices do the inverse of the
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+ * sRGB transformation to the data they receive. The 16-bit format is more
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+ * common for scientific data and image data that must be further processed;
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+ * because it is linear simple math can be done on the component values.
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+ * Regardless of the setting of this flag the alpha channel is always linear,
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+ * although it will be 8 bits or 16 bits wide as specified by the flag.
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+ *
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+ * PNG_FORMAT_FLAG_BGR: if set the components of a color pixel will be returned
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+ * in the order blue, then green, then red. If not set the pixel components
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+ * are in the order red, then green, then blue.
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+ *
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+ * PNG_FORMAT_FLAG_AFIRST: if set the alpha channel (if present) precedes the
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+ * color or grayscale components. If not set the alpha channel follows the
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+ * components.
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+ *
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+ * You do not have to read directly from a file. You can read from memory or,
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+ * on systems that support it, from a <stdio.h> FILE*. This is controlled by
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+ * the particular png_image_read_from_ function you call at the start. Likewise
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+ * on write you can write to a FILE* if your system supports it. Check the
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+ * macro PNG_STDIO_SUPPORTED to see if stdio support has been included in your
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+ * libpng build.
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+ *
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+ * If you read 16-bit (PNG_FORMAT_FLAG_LINEAR) data you may need to write it in
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+ * the 8-bit format for display. You do this by setting the convert_to_8bit
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+ * flag to 'true'.
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+ *
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+ * Don't repeatedly convert between the 8-bit and 16-bit forms. There is
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+ * significant data loss when 16-bit data is converted to the 8-bit encoding and
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+ * the current libpng implementation of conversion to 16-bit is also
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+ * significantly lossy. The latter will be fixed in the future, but the former
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+ * is unavoidable - the 8-bit format just doesn't have enough resolution.
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+ */
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+
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+/* If your program needs more information from the PNG data it reads, or if you
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+ * need to do more complex transformations, or minimize transformations, on the
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+ * data you read, then you must use one of the several lower level libpng
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+ * interfaces.
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+ *
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+ * All these interfaces require that you do your own error handling - your
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+ * program must be able to arrange for control to return to your own code any
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+ * time libpng encounters a problem. There are several ways to do this, but the
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+ * standard way is to use the ANSI-C (C90) <setjmp.h> interface to establish a
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+ * return point within your own code. You must do this if you do not use the
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+ * simplified interface (above).
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+ *
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+ * The first step is to include the header files you need, including the libpng
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+ * header file. Include any standard headers and feature test macros your
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+ * program requires before including png.h:
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+ */
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+#include <png.h>
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+
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+ /* The png_jmpbuf() macro, used in error handling, became available in
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+ * libpng version 1.0.6. If you want to be able to run your code with older
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+ * versions of libpng, you must define the macro yourself (but only if it
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+ * is not already defined by libpng!).
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+ */
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+
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+#ifndef png_jmpbuf
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+# define png_jmpbuf(png_ptr) ((png_ptr)->png_jmpbuf)
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+#endif
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+
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+/* Check to see if a file is a PNG file using png_sig_cmp(). png_sig_cmp()
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+ * returns zero if the image is a PNG and nonzero if it isn't a PNG.
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+ *
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+ * The function check_if_png() shown here, but not used, returns nonzero (true)
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+ * if the file can be opened and is a PNG, 0 (false) otherwise.
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+ *
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+ * If this call is successful, and you are going to keep the file open,
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+ * you should call png_set_sig_bytes(png_ptr, PNG_BYTES_TO_CHECK); once
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+ * you have created the png_ptr, so that libpng knows your application
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+ * has read that many bytes from the start of the file. Make sure you
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+ * don't call png_set_sig_bytes() with more than 8 bytes read or give it
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+ * an incorrect number of bytes read, or you will either have read too
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+ * many bytes (your fault), or you are telling libpng to read the wrong
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+ * number of magic bytes (also your fault).
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+ *
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+ * Many applications already read the first 2 or 4 bytes from the start
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+ * of the image to determine the file type, so it would be easiest just
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+ * to pass the bytes to png_sig_cmp() or even skip that if you know
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+ * you have a PNG file, and call png_set_sig_bytes().
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+ */
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+#define PNG_BYTES_TO_CHECK 4
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+int check_if_png(char *file_name, FILE **fp)
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+{
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+ char buf[PNG_BYTES_TO_CHECK];
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+
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+ /* Open the prospective PNG file. */
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+ if ((*fp = fopen(file_name, "rb")) == NULL)
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+ return 0;
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+
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+ /* Read in some of the signature bytes */
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+ if (fread(buf, 1, PNG_BYTES_TO_CHECK, *fp) != PNG_BYTES_TO_CHECK)
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+ return 0;
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+
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+ /* Compare the first PNG_BYTES_TO_CHECK bytes of the signature.
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+ Return nonzero (true) if they match */
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+
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+ return(!png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK));
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+}
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+
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+/* Read a PNG file. You may want to return an error code if the read
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+ * fails (depending upon the failure). There are two "prototypes" given
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+ * here - one where we are given the filename, and we need to open the
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+ * file, and the other where we are given an open file (possibly with
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+ * some or all of the magic bytes read - see comments above).
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+ */
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+#ifdef open_file /* prototype 1 */
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+void read_png(char *file_name) /* We need to open the file */
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+{
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+ png_structp png_ptr;
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+ png_infop info_ptr;
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+ int sig_read = 0;
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+ png_uint_32 width, height;
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+ int bit_depth, color_type, interlace_type;
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+ FILE *fp;
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+
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+ if ((fp = fopen(file_name, "rb")) == NULL)
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+ return (ERROR);
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+
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+#else no_open_file /* prototype 2 */
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+void read_png(FILE *fp, int sig_read) /* File is already open */
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+{
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+ png_structp png_ptr;
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+ png_infop info_ptr;
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+ png_uint_32 width, height;
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+ int bit_depth, color_type, interlace_type;
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+#endif no_open_file /* Only use one prototype! */
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+
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+ /* Create and initialize the png_struct with the desired error handler
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+ * functions. If you want to use the default stderr and longjump method,
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+ * you can supply NULL for the last three parameters. We also supply the
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+ * the compiler header file version, so that we know if the application
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+ * was compiled with a compatible version of the library. REQUIRED
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+ */
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+ png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
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+ png_voidp user_error_ptr, user_error_fn, user_warning_fn);
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+
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+ if (png_ptr == NULL)
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+ {
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+ fclose(fp);
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+ return (ERROR);
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+ }
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+
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+ /* Allocate/initialize the memory for image information. REQUIRED. */
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+ info_ptr = png_create_info_struct(png_ptr);
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+ if (info_ptr == NULL)
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+ {
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+ fclose(fp);
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+ png_destroy_read_struct(&png_ptr, NULL, NULL);
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+ return (ERROR);
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+ }
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+
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+ /* Set error handling if you are using the setjmp/longjmp method (this is
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+ * the normal method of doing things with libpng). REQUIRED unless you
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+ * set up your own error handlers in the png_create_read_struct() earlier.
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+ */
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+
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+ if (setjmp(png_jmpbuf(png_ptr)))
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+ {
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+ /* Free all of the memory associated with the png_ptr and info_ptr */
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+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
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+ fclose(fp);
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+ /* If we get here, we had a problem reading the file */
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+ return (ERROR);
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+ }
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+
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+ /* One of the following I/O initialization methods is REQUIRED */
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+#ifdef streams /* PNG file I/O method 1 */
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+ /* Set up the input control if you are using standard C streams */
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+ png_init_io(png_ptr, fp);
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+
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+#else no_streams /* PNG file I/O method 2 */
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+ /* If you are using replacement read functions, instead of calling
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+ * png_init_io() here you would call:
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+ */
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+ png_set_read_fn(png_ptr, (void *)user_io_ptr, user_read_fn);
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+ /* where user_io_ptr is a structure you want available to the callbacks */
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+#endif no_streams /* Use only one I/O method! */
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+
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+ /* If we have already read some of the signature */
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+ png_set_sig_bytes(png_ptr, sig_read);
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+
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+#ifdef hilevel
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+ /*
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+ * If you have enough memory to read in the entire image at once,
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+ * and you need to specify only transforms that can be controlled
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+ * with one of the PNG_TRANSFORM_* bits (this presently excludes
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+ * quantizing, filling, setting background, and doing gamma
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+ * adjustment), then you can read the entire image (including
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+ * pixels) into the info structure with this call:
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+ */
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+ png_read_png(png_ptr, info_ptr, png_transforms, NULL);
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+
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+#else
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+ /* OK, you're doing it the hard way, with the lower-level functions */
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+
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+ /* The call to png_read_info() gives us all of the information from the
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+ * PNG file before the first IDAT (image data chunk). REQUIRED
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+ */
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+ png_read_info(png_ptr, info_ptr);
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+
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+ png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
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+ &interlace_type, NULL, NULL);
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|
|
+
|
|
|
+ /* Set up the data transformations you want. Note that these are all
|
|
|
+ * optional. Only call them if you want/need them. Many of the
|
|
|
+ * transformations only work on specific types of images, and many
|
|
|
+ * are mutually exclusive.
|
|
|
+ */
|
|
|
+
|
|
|
+ /* Tell libpng to strip 16 bits/color files down to 8 bits/color.
|
|
|
+ * Use accurate scaling if it's available, otherwise just chop off the
|
|
|
+ * low byte.
|
|
|
+ */
|
|
|
+#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
|
|
|
+ png_set_scale_16(png_ptr);
|
|
|
+#else
|
|
|
+ png_set_strip_16(png_ptr);
|
|
|
+#endif
|
|
|
+
|
|
|
+ /* Strip alpha bytes from the input data without combining with the
|
|
|
+ * background (not recommended).
|
|
|
+ */
|
|
|
+ png_set_strip_alpha(png_ptr);
|
|
|
+
|
|
|
+ /* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
|
|
|
+ * byte into separate bytes (useful for paletted and grayscale images).
|
|
|
+ */
|
|
|
+ png_set_packing(png_ptr);
|
|
|
+
|
|
|
+ /* Change the order of packed pixels to least significant bit first
|
|
|
+ * (not useful if you are using png_set_packing). */
|
|
|
+ png_set_packswap(png_ptr);
|
|
|
+
|
|
|
+ /* Expand paletted colors into true RGB triplets */
|
|
|
+ if (color_type == PNG_COLOR_TYPE_PALETTE)
|
|
|
+ png_set_palette_to_rgb(png_ptr);
|
|
|
+
|
|
|
+ /* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */
|
|
|
+ if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
|
|
|
+ png_set_expand_gray_1_2_4_to_8(png_ptr);
|
|
|
+
|
|
|
+ /* Expand paletted or RGB images with transparency to full alpha channels
|
|
|
+ * so the data will be available as RGBA quartets.
|
|
|
+ */
|
|
|
+ if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) != 0)
|
|
|
+ png_set_tRNS_to_alpha(png_ptr);
|
|
|
+
|
|
|
+ /* Set the background color to draw transparent and alpha images over.
|
|
|
+ * It is possible to set the red, green, and blue components directly
|
|
|
+ * for paletted images instead of supplying a palette index. Note that
|
|
|
+ * even if the PNG file supplies a background, you are not required to
|
|
|
+ * use it - you should use the (solid) application background if it has one.
|
|
|
+ */
|
|
|
+
|
|
|
+ png_color_16 my_background, *image_background;
|
|
|
+
|
|
|
+ if (png_get_bKGD(png_ptr, info_ptr, &image_background) != 0)
|
|
|
+ png_set_background(png_ptr, image_background,
|
|
|
+ PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
|
|
|
+ else
|
|
|
+ png_set_background(png_ptr, &my_background,
|
|
|
+ PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
|
|
|
+
|
|
|
+ /* Some suggestions as to how to get a screen gamma value
|
|
|
+ *
|
|
|
+ * Note that screen gamma is the display_exponent, which includes
|
|
|
+ * the CRT_exponent and any correction for viewing conditions
|
|
|
+ */
|
|
|
+ if (/* We have a user-defined screen gamma value */)
|
|
|
+ {
|
|
|
+ screen_gamma = user-defined screen_gamma;
|
|
|
+ }
|
|
|
+ /* This is one way that applications share the same screen gamma value */
|
|
|
+ else if ((gamma_str = getenv("SCREEN_GAMMA")) != NULL)
|
|
|
+ {
|
|
|
+ screen_gamma = atof(gamma_str);
|
|
|
+ }
|
|
|
+ /* If we don't have another value */
|
|
|
+ else
|
|
|
+ {
|
|
|
+ screen_gamma = PNG_DEFAULT_sRGB; /* A good guess for a PC monitor
|
|
|
+ in a dimly lit room */
|
|
|
+ screen_gamma = PNG_GAMMA_MAC_18 or 1.0; /* Good guesses for Mac systems */
|
|
|
+ }
|
|
|
+
|
|
|
+ /* Tell libpng to handle the gamma conversion for you. The final call
|
|
|
+ * is a good guess for PC generated images, but it should be configurable
|
|
|
+ * by the user at run time by the user. It is strongly suggested that
|
|
|
+ * your application support gamma correction.
|
|
|
+ */
|
|
|
+
|
|
|
+ int intent;
|
|
|
+
|
|
|
+ if (png_get_sRGB(png_ptr, info_ptr, &intent) != 0)
|
|
|
+ png_set_gamma(png_ptr, screen_gamma, PNG_DEFAULT_sRGB);
|
|
|
+ else
|
|
|
+ {
|
|
|
+ double image_gamma;
|
|
|
+ if (png_get_gAMA(png_ptr, info_ptr, &image_gamma) != 0)
|
|
|
+ png_set_gamma(png_ptr, screen_gamma, image_gamma);
|
|
|
+ else
|
|
|
+ png_set_gamma(png_ptr, screen_gamma, 0.45455);
|
|
|
+ }
|
|
|
+
|
|
|
+#ifdef PNG_READ_QUANTIZE_SUPPORTED
|
|
|
+ /* Quantize RGB files down to 8-bit palette or reduce palettes
|
|
|
+ * to the number of colors available on your screen.
|
|
|
+ */
|
|
|
+ if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
|
|
|
+ {
|
|
|
+ int num_palette;
|
|
|
+ png_colorp palette;
|
|
|
+
|
|
|
+ /* This reduces the image to the application supplied palette */
|
|
|
+ if (/* We have our own palette */)
|
|
|
+ {
|
|
|
+ /* An array of colors to which the image should be quantized */
|
|
|
+ png_color std_color_cube[MAX_SCREEN_COLORS];
|
|
|
+
|
|
|
+ png_set_quantize(png_ptr, std_color_cube, MAX_SCREEN_COLORS,
|
|
|
+ MAX_SCREEN_COLORS, NULL, 0);
|
|
|
+ }
|
|
|
+ /* This reduces the image to the palette supplied in the file */
|
|
|
+ else if (png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette) != 0)
|
|
|
+ {
|
|
|
+ png_uint_16p histogram = NULL;
|
|
|
+
|
|
|
+ png_get_hIST(png_ptr, info_ptr, &histogram);
|
|
|
+
|
|
|
+ png_set_quantize(png_ptr, palette, num_palette,
|
|
|
+ max_screen_colors, histogram, 0);
|
|
|
+ }
|
|
|
+ }
|
|
|
+#endif /* READ_QUANTIZE */
|
|
|
+
|
|
|
+ /* Invert monochrome files to have 0 as white and 1 as black */
|
|
|
+ png_set_invert_mono(png_ptr);
|
|
|
+
|
|
|
+ /* If you want to shift the pixel values from the range [0,255] or
|
|
|
+ * [0,65535] to the original [0,7] or [0,31], or whatever range the
|
|
|
+ * colors were originally in:
|
|
|
+ */
|
|
|
+ if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT) != 0)
|
|
|
+ {
|
|
|
+ png_color_8p sig_bit_p;
|
|
|
+
|
|
|
+ png_get_sBIT(png_ptr, info_ptr, &sig_bit_p);
|
|
|
+ png_set_shift(png_ptr, sig_bit_p);
|
|
|
+ }
|
|
|
+
|
|
|
+ /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
|
|
|
+ if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
|
|
|
+ png_set_bgr(png_ptr);
|
|
|
+
|
|
|
+ /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
|
|
|
+ png_set_swap_alpha(png_ptr);
|
|
|
+
|
|
|
+ /* Swap bytes of 16-bit files to least significant byte first */
|
|
|
+ png_set_swap(png_ptr);
|
|
|
+
|
|
|
+ /* Add filler (or alpha) byte (before/after each RGB triplet) */
|
|
|
+ png_set_filler(png_ptr, 0xffff, PNG_FILLER_AFTER);
|
|
|
+
|
|
|
+#ifdef PNG_READ_INTERLACING_SUPPORTED
|
|
|
+ /* Turn on interlace handling. REQUIRED if you are not using
|
|
|
+ * png_read_image(). To see how to handle interlacing passes,
|
|
|
+ * see the png_read_row() method below:
|
|
|
+ */
|
|
|
+ number_passes = png_set_interlace_handling(png_ptr);
|
|
|
+#else /* !READ_INTERLACING */
|
|
|
+ number_passes = 1;
|
|
|
+#endif /* READ_INTERLACING */
|
|
|
+
|
|
|
+
|
|
|
+ /* Optional call to gamma correct and add the background to the palette
|
|
|
+ * and update info structure. REQUIRED if you are expecting libpng to
|
|
|
+ * update the palette for you (ie you selected such a transform above).
|
|
|
+ */
|
|
|
+ png_read_update_info(png_ptr, info_ptr);
|
|
|
+
|
|
|
+ /* Allocate the memory to hold the image using the fields of info_ptr. */
|
|
|
+
|
|
|
+ /* The easiest way to read the image: */
|
|
|
+ png_bytep row_pointers[height];
|
|
|
+
|
|
|
+ /* Clear the pointer array */
|
|
|
+ for (row = 0; row < height; row++)
|
|
|
+ row_pointers[row] = NULL;
|
|
|
+
|
|
|
+ for (row = 0; row < height; row++)
|
|
|
+ row_pointers[row] = png_malloc(png_ptr, png_get_rowbytes(png_ptr,
|
|
|
+ info_ptr));
|
|
|
+
|
|
|
+ /* Now it's time to read the image. One of these methods is REQUIRED */
|
|
|
+#ifdef entire /* Read the entire image in one go */
|
|
|
+ png_read_image(png_ptr, row_pointers);
|
|
|
+
|
|
|
+#else no_entire /* Read the image one or more scanlines at a time */
|
|
|
+ /* The other way to read images - deal with interlacing: */
|
|
|
+
|
|
|
+ for (pass = 0; pass < number_passes; pass++)
|
|
|
+ {
|
|
|
+#ifdef single /* Read the image a single row at a time */
|
|
|
+ for (y = 0; y < height; y++)
|
|
|
+ {
|
|
|
+ png_read_rows(png_ptr, &row_pointers[y], NULL, 1);
|
|
|
+ }
|
|
|
+
|
|
|
+#else no_single /* Read the image several rows at a time */
|
|
|
+ for (y = 0; y < height; y += number_of_rows)
|
|
|
+ {
|
|
|
+#ifdef sparkle /* Read the image using the "sparkle" effect. */
|
|
|
+ png_read_rows(png_ptr, &row_pointers[y], NULL,
|
|
|
+ number_of_rows);
|
|
|
+#else no_sparkle /* Read the image using the "rectangle" effect */
|
|
|
+ png_read_rows(png_ptr, NULL, &row_pointers[y],
|
|
|
+ number_of_rows);
|
|
|
+#endif no_sparkle /* Use only one of these two methods */
|
|
|
+ }
|
|
|
+
|
|
|
+ /* If you want to display the image after every pass, do so here */
|
|
|
+#endif no_single /* Use only one of these two methods */
|
|
|
+ }
|
|
|
+#endif no_entire /* Use only one of these two methods */
|
|
|
+
|
|
|
+ /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
|
|
|
+ png_read_end(png_ptr, info_ptr);
|
|
|
+#endif hilevel
|
|
|
+
|
|
|
+ /* At this point you have read the entire image */
|
|
|
+
|
|
|
+ /* Clean up after the read, and free any memory allocated - REQUIRED */
|
|
|
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
|
|
|
+
|
|
|
+ /* Close the file */
|
|
|
+ fclose(fp);
|
|
|
+
|
|
|
+ /* That's it */
|
|
|
+ return (OK);
|
|
|
+}
|
|
|
+
|
|
|
+/* Progressively read a file */
|
|
|
+
|
|
|
+int
|
|
|
+initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
|
|
|
+{
|
|
|
+ /* Create and initialize the png_struct with the desired error handler
|
|
|
+ * functions. If you want to use the default stderr and longjump method,
|
|
|
+ * you can supply NULL for the last three parameters. We also check that
|
|
|
+ * the library version is compatible in case we are using dynamically
|
|
|
+ * linked libraries.
|
|
|
+ */
|
|
|
+ *png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
|
|
|
+ png_voidp user_error_ptr, user_error_fn, user_warning_fn);
|
|
|
+
|
|
|
+ if (*png_ptr == NULL)
|
|
|
+ {
|
|
|
+ *info_ptr = NULL;
|
|
|
+ return (ERROR);
|
|
|
+ }
|
|
|
+
|
|
|
+ *info_ptr = png_create_info_struct(png_ptr);
|
|
|
+
|
|
|
+ if (*info_ptr == NULL)
|
|
|
+ {
|
|
|
+ png_destroy_read_struct(png_ptr, info_ptr, NULL);
|
|
|
+ return (ERROR);
|
|
|
+ }
|
|
|
+
|
|
|
+ if (setjmp(png_jmpbuf((*png_ptr))))
|
|
|
+ {
|
|
|
+ png_destroy_read_struct(png_ptr, info_ptr, NULL);
|
|
|
+ return (ERROR);
|
|
|
+ }
|
|
|
+
|
|
|
+ /* This one's new. You will need to provide all three
|
|
|
+ * function callbacks, even if you aren't using them all.
|
|
|
+ * If you aren't using all functions, you can specify NULL
|
|
|
+ * parameters. Even when all three functions are NULL,
|
|
|
+ * you need to call png_set_progressive_read_fn().
|
|
|
+ * These functions shouldn't be dependent on global or
|
|
|
+ * static variables if you are decoding several images
|
|
|
+ * simultaneously. You should store stream specific data
|
|
|
+ * in a separate struct, given as the second parameter,
|
|
|
+ * and retrieve the pointer from inside the callbacks using
|
|
|
+ * the function png_get_progressive_ptr(png_ptr).
|
|
|
+ */
|
|
|
+ png_set_progressive_read_fn(*png_ptr, (void *)stream_data,
|
|
|
+ info_callback, row_callback, end_callback);
|
|
|
+
|
|
|
+ return (OK);
|
|
|
+}
|
|
|
+
|
|
|
+int
|
|
|
+process_data(png_structp *png_ptr, png_infop *info_ptr,
|
|
|
+ png_bytep buffer, png_uint_32 length)
|
|
|
+{
|
|
|
+ if (setjmp(png_jmpbuf((*png_ptr))))
|
|
|
+ {
|
|
|
+ /* Free the png_ptr and info_ptr memory on error */
|
|
|
+ png_destroy_read_struct(png_ptr, info_ptr, NULL);
|
|
|
+ return (ERROR);
|
|
|
+ }
|
|
|
+
|
|
|
+ /* This one's new also. Simply give it chunks of data as
|
|
|
+ * they arrive from the data stream (in order, of course).
|
|
|
+ * On segmented machines, don't give it any more than 64K.
|
|
|
+ * The library seems to run fine with sizes of 4K, although
|
|
|
+ * you can give it much less if necessary (I assume you can
|
|
|
+ * give it chunks of 1 byte, but I haven't tried with less
|
|
|
+ * than 256 bytes yet). When this function returns, you may
|
|
|
+ * want to display any rows that were generated in the row
|
|
|
+ * callback, if you aren't already displaying them there.
|
|
|
+ */
|
|
|
+ png_process_data(*png_ptr, *info_ptr, buffer, length);
|
|
|
+ return (OK);
|
|
|
+}
|
|
|
+
|
|
|
+info_callback(png_structp png_ptr, png_infop info)
|
|
|
+{
|
|
|
+ /* Do any setup here, including setting any of the transformations
|
|
|
+ * mentioned in the Reading PNG files section. For now, you _must_
|
|
|
+ * call either png_start_read_image() or png_read_update_info()
|
|
|
+ * after all the transformations are set (even if you don't set
|
|
|
+ * any). You may start getting rows before png_process_data()
|
|
|
+ * returns, so this is your last chance to prepare for that.
|
|
|
+ */
|
|
|
+}
|
|
|
+
|
|
|
+row_callback(png_structp png_ptr, png_bytep new_row,
|
|
|
+ png_uint_32 row_num, int pass)
|
|
|
+{
|
|
|
+ /*
|
|
|
+ * This function is called for every row in the image. If the
|
|
|
+ * image is interlaced, and you turned on the interlace handler,
|
|
|
+ * this function will be called for every row in every pass.
|
|
|
+ *
|
|
|
+ * In this function you will receive a pointer to new row data from
|
|
|
+ * libpng called new_row that is to replace a corresponding row (of
|
|
|
+ * the same data format) in a buffer allocated by your application.
|
|
|
+ *
|
|
|
+ * The new row data pointer "new_row" may be NULL, indicating there is
|
|
|
+ * no new data to be replaced (in cases of interlace loading).
|
|
|
+ *
|
|
|
+ * If new_row is not NULL then you need to call
|
|
|
+ * png_progressive_combine_row() to replace the corresponding row as
|
|
|
+ * shown below:
|
|
|
+ */
|
|
|
+
|
|
|
+ /* Get pointer to corresponding row in our
|
|
|
+ * PNG read buffer.
|
|
|
+ */
|
|
|
+ png_bytep old_row = ((png_bytep *)our_data)[row_num];
|
|
|
+
|
|
|
+#ifdef PNG_READ_INTERLACING_SUPPORTED
|
|
|
+ /* If both rows are allocated then copy the new row
|
|
|
+ * data to the corresponding row data.
|
|
|
+ */
|
|
|
+ if ((old_row != NULL) && (new_row != NULL))
|
|
|
+ png_progressive_combine_row(png_ptr, old_row, new_row);
|
|
|
+
|
|
|
+ /*
|
|
|
+ * The rows and passes are called in order, so you don't really
|
|
|
+ * need the row_num and pass, but I'm supplying them because it
|
|
|
+ * may make your life easier.
|
|
|
+ *
|
|
|
+ * For the non-NULL rows of interlaced images, you must call
|
|
|
+ * png_progressive_combine_row() passing in the new row and the
|
|
|
+ * old row, as demonstrated above. You can call this function for
|
|
|
+ * NULL rows (it will just return) and for non-interlaced images
|
|
|
+ * (it just does the memcpy for you) if it will make the code
|
|
|
+ * easier. Thus, you can just do this for all cases:
|
|
|
+ */
|
|
|
+
|
|
|
+ png_progressive_combine_row(png_ptr, old_row, new_row);
|
|
|
+
|
|
|
+ /* where old_row is what was displayed for previous rows. Note
|
|
|
+ * that the first pass (pass == 0 really) will completely cover
|
|
|
+ * the old row, so the rows do not have to be initialized. After
|
|
|
+ * the first pass (and only for interlaced images), you will have
|
|
|
+ * to pass the current row as new_row, and the function will combine
|
|
|
+ * the old row and the new row.
|
|
|
+ */
|
|
|
+#endif /* READ_INTERLACING */
|
|
|
+}
|
|
|
+
|
|
|
+end_callback(png_structp png_ptr, png_infop info)
|
|
|
+{
|
|
|
+ /* This function is called when the whole image has been read,
|
|
|
+ * including any chunks after the image (up to and including
|
|
|
+ * the IEND). You will usually have the same info chunk as you
|
|
|
+ * had in the header, although some data may have been added
|
|
|
+ * to the comments and time fields.
|
|
|
+ *
|
|
|
+ * Most people won't do much here, perhaps setting a flag that
|
|
|
+ * marks the image as finished.
|
|
|
+ */
|
|
|
+}
|
|
|
+
|
|
|
+/* Write a png file */
|
|
|
+void write_png(char *file_name /* , ... other image information ... */)
|
|
|
+{
|
|
|
+ FILE *fp;
|
|
|
+ png_structp png_ptr;
|
|
|
+ png_infop info_ptr;
|
|
|
+ png_colorp palette;
|
|
|
+
|
|
|
+ /* Open the file */
|
|
|
+ fp = fopen(file_name, "wb");
|
|
|
+ if (fp == NULL)
|
|
|
+ return (ERROR);
|
|
|
+
|
|
|
+ /* Create and initialize the png_struct with the desired error handler
|
|
|
+ * functions. If you want to use the default stderr and longjump method,
|
|
|
+ * you can supply NULL for the last three parameters. We also check that
|
|
|
+ * the library version is compatible with the one used at compile time,
|
|
|
+ * in case we are using dynamically linked libraries. REQUIRED.
|
|
|
+ */
|
|
|
+ png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
|
|
|
+ png_voidp user_error_ptr, user_error_fn, user_warning_fn);
|
|
|
+
|
|
|
+ if (png_ptr == NULL)
|
|
|
+ {
|
|
|
+ fclose(fp);
|
|
|
+ return (ERROR);
|
|
|
+ }
|
|
|
+
|
|
|
+ /* Allocate/initialize the image information data. REQUIRED */
|
|
|
+ info_ptr = png_create_info_struct(png_ptr);
|
|
|
+ if (info_ptr == NULL)
|
|
|
+ {
|
|
|
+ fclose(fp);
|
|
|
+ png_destroy_write_struct(&png_ptr, NULL);
|
|
|
+ return (ERROR);
|
|
|
+ }
|
|
|
+
|
|
|
+ /* Set error handling. REQUIRED if you aren't supplying your own
|
|
|
+ * error handling functions in the png_create_write_struct() call.
|
|
|
+ */
|
|
|
+ if (setjmp(png_jmpbuf(png_ptr)))
|
|
|
+ {
|
|
|
+ /* If we get here, we had a problem writing the file */
|
|
|
+ fclose(fp);
|
|
|
+ png_destroy_write_struct(&png_ptr, &info_ptr);
|
|
|
+ return (ERROR);
|
|
|
+ }
|
|
|
+
|
|
|
+ /* One of the following I/O initialization functions is REQUIRED */
|
|
|
+
|
|
|
+#ifdef streams /* I/O initialization method 1 */
|
|
|
+ /* Set up the output control if you are using standard C streams */
|
|
|
+ png_init_io(png_ptr, fp);
|
|
|
+
|
|
|
+#else no_streams /* I/O initialization method 2 */
|
|
|
+ /* If you are using replacement write functions, instead of calling
|
|
|
+ * png_init_io() here you would call
|
|
|
+ */
|
|
|
+ png_set_write_fn(png_ptr, (void *)user_io_ptr, user_write_fn,
|
|
|
+ user_IO_flush_function);
|
|
|
+ /* where user_io_ptr is a structure you want available to the callbacks */
|
|
|
+#endif no_streams /* Only use one initialization method */
|
|
|
+
|
|
|
+#ifdef hilevel
|
|
|
+ /* This is the easy way. Use it if you already have all the
|
|
|
+ * image info living in the structure. You could "|" many
|
|
|
+ * PNG_TRANSFORM flags into the png_transforms integer here.
|
|
|
+ */
|
|
|
+ png_write_png(png_ptr, info_ptr, png_transforms, NULL);
|
|
|
+
|
|
|
+#else
|
|
|
+ /* This is the hard way */
|
|
|
+
|
|
|
+ /* Set the image information here. Width and height are up to 2^31,
|
|
|
+ * bit_depth is one of 1, 2, 4, 8, or 16, but valid values also depend on
|
|
|
+ * the color_type selected. color_type is one of PNG_COLOR_TYPE_GRAY,
|
|
|
+ * PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB,
|
|
|
+ * or PNG_COLOR_TYPE_RGB_ALPHA. interlace is either PNG_INTERLACE_NONE or
|
|
|
+ * PNG_INTERLACE_ADAM7, and the compression_type and filter_type MUST
|
|
|
+ * currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED
|
|
|
+ */
|
|
|
+ png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, PNG_COLOR_TYPE_???,
|
|
|
+ PNG_INTERLACE_????, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
|
|
|
+
|
|
|
+ /* Set the palette if there is one. REQUIRED for indexed-color images */
|
|
|
+ palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH
|
|
|
+ * (sizeof (png_color)));
|
|
|
+ /* ... Set palette colors ... */
|
|
|
+ png_set_PLTE(png_ptr, info_ptr, palette, PNG_MAX_PALETTE_LENGTH);
|
|
|
+ /* You must not free palette here, because png_set_PLTE only makes a link to
|
|
|
+ * the palette that you malloced. Wait until you are about to destroy
|
|
|
+ * the png structure.
|
|
|
+ */
|
|
|
+
|
|
|
+ /* Optional significant bit (sBIT) chunk */
|
|
|
+ png_color_8 sig_bit;
|
|
|
+
|
|
|
+ /* If we are dealing with a grayscale image then */
|
|
|
+ sig_bit.gray = true_bit_depth;
|
|
|
+
|
|
|
+ /* Otherwise, if we are dealing with a color image then */
|
|
|
+ sig_bit.red = true_red_bit_depth;
|
|
|
+ sig_bit.green = true_green_bit_depth;
|
|
|
+ sig_bit.blue = true_blue_bit_depth;
|
|
|
+
|
|
|
+ /* If the image has an alpha channel then */
|
|
|
+ sig_bit.alpha = true_alpha_bit_depth;
|
|
|
+
|
|
|
+ png_set_sBIT(png_ptr, info_ptr, &sig_bit);
|
|
|
+
|
|
|
+
|
|
|
+ /* Optional gamma chunk is strongly suggested if you have any guess
|
|
|
+ * as to the correct gamma of the image.
|
|
|
+ */
|
|
|
+ png_set_gAMA(png_ptr, info_ptr, gamma);
|
|
|
+
|
|
|
+ /* Optionally write comments into the image */
|
|
|
+ {
|
|
|
+ png_text text_ptr[3];
|
|
|
+
|
|
|
+ char key0[]="Title";
|
|
|
+ char text0[]="Mona Lisa";
|
|
|
+ text_ptr[0].key = key0;
|
|
|
+ text_ptr[0].text = text0;
|
|
|
+ text_ptr[0].compression = PNG_TEXT_COMPRESSION_NONE;
|
|
|
+ text_ptr[0].itxt_length = 0;
|
|
|
+ text_ptr[0].lang = NULL;
|
|
|
+ text_ptr[0].lang_key = NULL;
|
|
|
+
|
|
|
+ char key1[]="Author";
|
|
|
+ char text1[]="Leonardo DaVinci";
|
|
|
+ text_ptr[1].key = key1;
|
|
|
+ text_ptr[1].text = text1;
|
|
|
+ text_ptr[1].compression = PNG_TEXT_COMPRESSION_NONE;
|
|
|
+ text_ptr[1].itxt_length = 0;
|
|
|
+ text_ptr[1].lang = NULL;
|
|
|
+ text_ptr[1].lang_key = NULL;
|
|
|
+
|
|
|
+ char key2[]="Description";
|
|
|
+ char text2[]="<long text>";
|
|
|
+ text_ptr[2].key = key2;
|
|
|
+ text_ptr[2].text = text2;
|
|
|
+ text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt;
|
|
|
+ text_ptr[2].itxt_length = 0;
|
|
|
+ text_ptr[2].lang = NULL;
|
|
|
+ text_ptr[2].lang_key = NULL;
|
|
|
+
|
|
|
+ png_set_text(write_ptr, write_info_ptr, text_ptr, 3);
|
|
|
+ }
|
|
|
+
|
|
|
+ /* Other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs */
|
|
|
+
|
|
|
+ /* Note that if sRGB is present the gAMA and cHRM chunks must be ignored
|
|
|
+ * on read and, if your application chooses to write them, they must
|
|
|
+ * be written in accordance with the sRGB profile
|
|
|
+ */
|
|
|
+
|
|
|
+ /* Write the file header information. REQUIRED */
|
|
|
+ png_write_info(png_ptr, info_ptr);
|
|
|
+
|
|
|
+ /* If you want, you can write the info in two steps, in case you need to
|
|
|
+ * write your private chunk ahead of PLTE:
|
|
|
+ *
|
|
|
+ * png_write_info_before_PLTE(write_ptr, write_info_ptr);
|
|
|
+ * write_my_chunk();
|
|
|
+ * png_write_info(png_ptr, info_ptr);
|
|
|
+ *
|
|
|
+ * However, given the level of known- and unknown-chunk support in 1.2.0
|
|
|
+ * and up, this should no longer be necessary.
|
|
|
+ */
|
|
|
+
|
|
|
+ /* Once we write out the header, the compression type on the text
|
|
|
+ * chunk gets changed to PNG_TEXT_COMPRESSION_NONE_WR or
|
|
|
+ * PNG_TEXT_COMPRESSION_zTXt_WR, so it doesn't get written out again
|
|
|
+ * at the end.
|
|
|
+ */
|
|
|
+
|
|
|
+ /* Set up the transformations you want. Note that these are
|
|
|
+ * all optional. Only call them if you want them.
|
|
|
+ */
|
|
|
+
|
|
|
+ /* Invert monochrome pixels */
|
|
|
+ png_set_invert_mono(png_ptr);
|
|
|
+
|
|
|
+ /* Shift the pixels up to a legal bit depth and fill in
|
|
|
+ * as appropriate to correctly scale the image.
|
|
|
+ */
|
|
|
+ png_set_shift(png_ptr, &sig_bit);
|
|
|
+
|
|
|
+ /* Pack pixels into bytes */
|
|
|
+ png_set_packing(png_ptr);
|
|
|
+
|
|
|
+ /* Swap location of alpha bytes from ARGB to RGBA */
|
|
|
+ png_set_swap_alpha(png_ptr);
|
|
|
+
|
|
|
+ /* Get rid of filler (OR ALPHA) bytes, pack XRGB/RGBX/ARGB/RGBA into
|
|
|
+ * RGB (4 channels -> 3 channels). The second parameter is not used.
|
|
|
+ */
|
|
|
+ png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
|
|
|
+
|
|
|
+ /* Flip BGR pixels to RGB */
|
|
|
+ png_set_bgr(png_ptr);
|
|
|
+
|
|
|
+ /* Swap bytes of 16-bit files to most significant byte first */
|
|
|
+ png_set_swap(png_ptr);
|
|
|
+
|
|
|
+ /* Swap bits of 1-bit, 2-bit, 4-bit packed pixel formats */
|
|
|
+ png_set_packswap(png_ptr);
|
|
|
+
|
|
|
+ /* Turn on interlace handling if you are not using png_write_image() */
|
|
|
+ if (interlacing != 0)
|
|
|
+ number_passes = png_set_interlace_handling(png_ptr);
|
|
|
+
|
|
|
+ else
|
|
|
+ number_passes = 1;
|
|
|
+
|
|
|
+ /* The easiest way to write the image (you may have a different memory
|
|
|
+ * layout, however, so choose what fits your needs best). You need to
|
|
|
+ * use the first method if you aren't handling interlacing yourself.
|
|
|
+ */
|
|
|
+ png_uint_32 k, height, width;
|
|
|
+
|
|
|
+ /* In this example, "image" is a one-dimensional array of bytes */
|
|
|
+
|
|
|
+ /* Guard against integer overflow */
|
|
|
+ if (height > PNG_SIZE_MAX/(width*bytes_per_pixel)) {
|
|
|
+ png_error(png_ptr, "Image_data buffer would be too large");
|
|
|
+ }
|
|
|
+ png_byte image[height*width*bytes_per_pixel];
|
|
|
+
|
|
|
+ png_bytep row_pointers[height];
|
|
|
+
|
|
|
+ if (height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
|
|
|
+ png_error (png_ptr, "Image is too tall to process in memory");
|
|
|
+
|
|
|
+ /* Set up pointers into your "image" byte array */
|
|
|
+ for (k = 0; k < height; k++)
|
|
|
+ row_pointers[k] = image + k*width*bytes_per_pixel;
|
|
|
+
|
|
|
+ /* One of the following output methods is REQUIRED */
|
|
|
+
|
|
|
+#ifdef entire /* Write out the entire image data in one call */
|
|
|
+ png_write_image(png_ptr, row_pointers);
|
|
|
+
|
|
|
+ /* The other way to write the image - deal with interlacing */
|
|
|
+
|
|
|
+#else no_entire /* Write out the image data by one or more scanlines */
|
|
|
+
|
|
|
+ /* The number of passes is either 1 for non-interlaced images,
|
|
|
+ * or 7 for interlaced images.
|
|
|
+ */
|
|
|
+ for (pass = 0; pass < number_passes; pass++)
|
|
|
+ {
|
|
|
+ /* Write a few rows at a time. */
|
|
|
+ png_write_rows(png_ptr, &row_pointers[first_row], number_of_rows);
|
|
|
+
|
|
|
+ /* If you are only writing one row at a time, this works */
|
|
|
+ for (y = 0; y < height; y++)
|
|
|
+ png_write_rows(png_ptr, &row_pointers[y], 1);
|
|
|
+ }
|
|
|
+#endif no_entire /* Use only one output method */
|
|
|
+
|
|
|
+ /* You can write optional chunks like tEXt, zTXt, and tIME at the end
|
|
|
+ * as well. Shouldn't be necessary in 1.2.0 and up as all the public
|
|
|
+ * chunks are supported and you can use png_set_unknown_chunks() to
|
|
|
+ * register unknown chunks into the info structure to be written out.
|
|
|
+ */
|
|
|
+
|
|
|
+ /* It is REQUIRED to call this to finish writing the rest of the file */
|
|
|
+ png_write_end(png_ptr, info_ptr);
|
|
|
+#endif hilevel
|
|
|
+
|
|
|
+ /* If you png_malloced a palette, free it here (don't free info_ptr->palette,
|
|
|
+ * as recommended in versions 1.0.5m and earlier of this example; if
|
|
|
+ * libpng mallocs info_ptr->palette, libpng will free it). If you
|
|
|
+ * allocated it with malloc() instead of png_malloc(), use free() instead
|
|
|
+ * of png_free().
|
|
|
+ */
|
|
|
+ png_free(png_ptr, palette);
|
|
|
+ palette = NULL;
|
|
|
+
|
|
|
+ /* Similarly, if you png_malloced any data that you passed in with
|
|
|
+ * png_set_something(), such as a hist or trans array, free it here,
|
|
|
+ * when you can be sure that libpng is through with it.
|
|
|
+ */
|
|
|
+ png_free(png_ptr, trans);
|
|
|
+ trans = NULL;
|
|
|
+ /* Whenever you use png_free() it is a good idea to set the pointer to
|
|
|
+ * NULL in case your application inadvertently tries to png_free() it
|
|
|
+ * again. When png_free() sees a NULL it returns without action, thus
|
|
|
+ * avoiding the double-free security problem.
|
|
|
+ */
|
|
|
+
|
|
|
+ /* Clean up after the write, and free any memory allocated */
|
|
|
+ png_destroy_write_struct(&png_ptr, &info_ptr);
|
|
|
+
|
|
|
+ /* Close the file */
|
|
|
+ fclose(fp);
|
|
|
+
|
|
|
+ /* That's it */
|
|
|
+ return (OK);
|
|
|
+}
|
|
|
+
|
|
|
+#endif /* if 0 */
|
Areloch
