Use the data scheme to load resources in the WebKitGTK+ implementation, rather than...

[wxWidgets.git] / src / png / example.c

diff --git a/src/png/example.c b/src/png/example.c
index 088aad3a764d5c073fc01b58c3286cfb636f5c23..d7391734de199df7f57f65165d7385bfabbd0986 100644 (file)
--- a/src/png/example.c
+++ b/src/png/example.c
@@ -1,20 +1,39 @@
 
 

-/* example.c - an example of using libpng */
+#if 0 /* in case someone actually tries to compile this */
+
+/* example.c - an example of using libpng
+ * Last changed in libpng 1.4.2 [May 6, 2010]
+ * This file has been placed in the public domain by the authors.
+ * Maintained 1998-2010 Glenn Randers-Pehrson
+ * Maintained 1996, 1997 Andreas Dilger)
+ * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ */

 
 /* This is an example of how to use libpng to read and write PNG files.
  * The file libpng.txt is much more verbose then this.  If you have not
  * read it, do so first.  This was designed to be a starting point of an
 
 /* This is an example of how to use libpng to read and write PNG files.
  * The file libpng.txt is much more verbose then this.  If you have not
  * read it, do so first.  This was designed to be a starting point of an

- * implementation.  This is not officially part of libpng, and therefore
- * does not require a copyright notice.
+ * implementation.  This is not officially part of libpng, is hereby placed
+ * in the public domain, and therefore does not require a copyright notice.

  *
  * This file does not currently compile, because it is missing certain
  * parts, like allocating memory to hold an image.  You will have to
  * supply these parts to get it to compile.  For an example of a minimal
  *
  * This file does not currently compile, because it is missing certain
  * parts, like allocating memory to hold an image.  You will have to
  * supply these parts to get it to compile.  For an example of a minimal

- * working PNG reader/writer, see pngtest.c, included in this distribution.
+ * working PNG reader/writer, see pngtest.c, included in this distribution;
+ * see also the programs in the contrib directory.

  */
 
 #include "png.h"
 
  */
 
 #include "png.h"
 

+ /* The png_jmpbuf() macro, used in error handling, became available in
+  * libpng version 1.0.6.  If you want to be able to run your code with older
+  * versions of libpng, you must define the macro yourself (but only if it
+  * is not already defined by libpng!).
+  */
+
+#ifndef png_jmpbuf
+#  define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
+#endif
+

 /* Check to see if a file is a PNG file using png_sig_cmp().  png_sig_cmp()
  * returns zero if the image is a PNG and nonzero if it isn't a PNG.
  *
 /* Check to see if a file is a PNG file using png_sig_cmp().  png_sig_cmp()
  * returns zero if the image is a PNG and nonzero if it isn't a PNG.
  *


@@ -41,7 +60,7 @@ int check_if_png(char *file_name, FILE **fp)
    char buf[PNG_BYTES_TO_CHECK];
 
    /* Open the prospective PNG file. */
    char buf[PNG_BYTES_TO_CHECK];
 
    /* Open the prospective PNG file. */

-   if ((*fp = fopen(file_name, "rb")) != NULL);
+   if ((*fp = fopen(file_name, "rb")) == NULL)

       return 0;
 
    /* Read in some of the signature bytes */
       return 0;
 
    /* Read in some of the signature bytes */


@@ -71,15 +90,16 @@ void read_png(char *file_name)  /* We need to open the file */
    FILE *fp;
 
    if ((fp = fopen(file_name, "rb")) == NULL)
    FILE *fp;
 
    if ((fp = fopen(file_name, "rb")) == NULL)

-      return;
+      return (ERROR);
+

 #else no_open_file /* prototype 2 */
 #else no_open_file /* prototype 2 */

-void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
+void read_png(FILE *fp, unsigned int sig_read)  /* File is already open */

 {
    png_structp png_ptr;
    png_infop info_ptr;
    png_uint_32 width, height;
    int bit_depth, color_type, interlace_type;
 {
    png_structp png_ptr;
    png_infop info_ptr;
    png_uint_32 width, height;
    int bit_depth, color_type, interlace_type;

-#endif no_open_file /* only use one prototype! */
+#endif no_open_file /* Only use one prototype! */

 
    /* Create and initialize the png_struct with the desired error handler
     * functions.  If you want to use the default stderr and longjump method,
 
    /* Create and initialize the png_struct with the desired error handler
     * functions.  If you want to use the default stderr and longjump method,


@@ -93,7 +113,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
    if (png_ptr == NULL)
    {
       fclose(fp);
    if (png_ptr == NULL)
    {
       fclose(fp);

-      return;
+      return (ERROR);

    }
 
    /* Allocate/initialize the memory for image information.  REQUIRED. */
    }
 
    /* Allocate/initialize the memory for image information.  REQUIRED. */


@@ -101,21 +121,22 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
    if (info_ptr == NULL)
    {
       fclose(fp);
    if (info_ptr == NULL)
    {
       fclose(fp);

-      png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
-      return;
+      png_destroy_read_struct(&png_ptr, NULL, NULL);
+      return (ERROR);

    }
 
    /* Set error handling if you are using the setjmp/longjmp method (this is
     * the normal method of doing things with libpng).  REQUIRED unless you
     * set up your own error handlers in the png_create_read_struct() earlier.
     */
    }
 
    /* Set error handling if you are using the setjmp/longjmp method (this is
     * the normal method of doing things with libpng).  REQUIRED unless you
     * set up your own error handlers in the png_create_read_struct() earlier.
     */

-   if (setjmp(png_ptr->jmpbuf))
+
+   if (setjmp(png_jmpbuf(png_ptr)))

    {
       /* Free all of the memory associated with the png_ptr and info_ptr */
    {
       /* Free all of the memory associated with the png_ptr and info_ptr */

-      png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
+      png_destroy_read_struct(&png_ptr, &info_ptr, NULL);

       fclose(fp);
       /* If we get here, we had a problem reading the file */
       fclose(fp);
       /* If we get here, we had a problem reading the file */

-      return;
+      return (ERROR);

    }
 
    /* One of the following I/O initialization methods is REQUIRED */
    }
 
    /* One of the following I/O initialization methods is REQUIRED */


@@ -134,6 +155,20 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
    /* If we have already read some of the signature */
    png_set_sig_bytes(png_ptr, sig_read);
 
    /* If we have already read some of the signature */
    png_set_sig_bytes(png_ptr, sig_read);
 

+#ifdef hilevel
+   /*
+    * If you have enough memory to read in the entire image at once,
+    * and you need to specify only transforms that can be controlled
+    * with one of the PNG_TRANSFORM_* bits (this presently excludes
+    * quantizing, filling, setting background, and doing gamma
+    * adjustment), then you can read the entire image (including
+    * pixels) into the info structure with this call:
+    */
+   png_read_png(png_ptr, info_ptr, png_transforms, NULL);
+
+#else
+   /* OK, you're doing it the hard way, with the lower-level functions */
+

    /* The call to png_read_info() gives us all of the information from the
     * PNG file before the first IDAT (image data chunk).  REQUIRED
     */
    /* The call to png_read_info() gives us all of the information from the
     * PNG file before the first IDAT (image data chunk).  REQUIRED
     */


@@ -142,16 +177,16 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
        &interlace_type, NULL, NULL);
 
    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
        &interlace_type, NULL, NULL);
 

-/**** 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.
- ****/
+   /* 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 bit/color files down to 8 bits/color */
+   /* Tell libpng to strip 16 bit/color files down to 8 bits/color */

    png_set_strip_16(png_ptr);
 
    png_set_strip_16(png_ptr);
 

-   /* Strip alpha bytes from the input data without combining with th
+   /* Strip alpha bytes from the input data without combining with the

     * background (not recommended).
     */
    png_set_strip_alpha(png_ptr);
     * background (not recommended).
     */
    png_set_strip_alpha(png_ptr);


@@ -167,17 +202,17 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
 
    /* Expand paletted colors into true RGB triplets */
    if (color_type == PNG_COLOR_TYPE_PALETTE)
 
    /* Expand paletted colors into true RGB triplets */
    if (color_type == PNG_COLOR_TYPE_PALETTE)

-      png_set_expand(png_ptr);
+      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)
 
    /* 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(png_ptr);
+      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))
 
    /* 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))

-      png_set_expand(png_ptr);
+      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
 
    /* Set the background color to draw transparent and alpha images over.
     * It is possible to set the red, green, and blue components directly


@@ -195,9 +230,11 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
       png_set_background(png_ptr, &my_background,
                          PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
 
       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 (display_gamma/viewing_gamma) */
+   /* 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;
    if (/* We have a user-defined screen gamma value */)
    {
       screen_gamma = user-defined screen_gamma;


@@ -210,12 +247,12 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
    /* If we don't have another value */
    else
    {
    /* If we don't have another value */
    else
    {

-      screen_gamma = 2.2;  /* A good guess for a PC monitors in a dimly
+      screen_gamma = 2.2;  /* A good guess for a PC monitor in a dimly

                               lit room */
       screen_gamma = 1.7 or 1.0;  /* A good guess for Mac systems */
    }
 
                               lit room */
       screen_gamma = 1.7 or 1.0;  /* A good guess for Mac systems */
    }
 

-   /* Tell libpng to handle the gamma conversion for you.  The second call
+   /* 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.
     * 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.


@@ -224,7 +261,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
    int intent;
 
    if (png_get_sRGB(png_ptr, info_ptr, &intent))
    int intent;
 
    if (png_get_sRGB(png_ptr, info_ptr, &intent))

-      png_set_sRGB(png_ptr, intent, 0);
+      png_set_gamma(png_ptr, screen_gamma, 0.45455);

    else
    {
       double image_gamma;
    else
    {
       double image_gamma;


@@ -234,36 +271,39 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
          png_set_gamma(png_ptr, screen_gamma, 0.45455);
    }
 
          png_set_gamma(png_ptr, screen_gamma, 0.45455);
    }
 

-   /* Dither RGB files down to 8 bit palette or reduce palettes
+#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)
    {
     * to the number of colors available on your screen.
     */
    if (color_type & PNG_COLOR_MASK_COLOR)
    {

-      png_uint_32 num_palette;
+      int num_palette;

       png_colorp palette;
 
       /* This reduces the image to the application supplied palette */
       png_colorp palette;
 
       /* This reduces the image to the application supplied palette */

-      if (/* we have our own palette */)
+      if (/* We have our own palette */)

       {
       {

-         /* An array of colors to which the image should be dithered */
+         /* An array of colors to which the image should be quantized */

          png_color std_color_cube[MAX_SCREEN_COLORS];
 
          png_color std_color_cube[MAX_SCREEN_COLORS];
 

-         png_set_dither(png_ptr, std_color_cube, MAX_SCREEN_COLORS,
+         /* Prior to libpng-1.4.2, this was png_set_dither(). */
+         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))
       {
             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))
       {

-         png_color16p histogram;
+         png_uint_16p histogram = NULL;

 
          png_get_hIST(png_ptr, info_ptr, &histogram);
 
 
          png_get_hIST(png_ptr, info_ptr, &histogram);
 

-         png_set_dither(png_ptr, palette, num_palette,
+         png_set_quantize(png_ptr, palette, num_palette,

                         max_screen_colors, histogram, 0);
       }
    }
                         max_screen_colors, histogram, 0);
       }
    }

+#endif /* PNG_READ_QUANTIZE_SUPPORTED */

 
 

-   /* invert monocrome files to have 0 as white and 1 as black */
+   /* 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
    png_set_invert_mono(png_ptr);
 
    /* If you want to shift the pixel values from the range [0,255] or


@@ -272,19 +312,20 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
     */
    if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT))
    {
     */
    if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT))
    {

-      png_color8p sig_bit;
+      png_color_8p sig_bit_p;

 
 

-      png_get_sBIT(png_ptr, info_ptr, &sig_bit);
-      png_set_shift(png_ptr, sig_bit);
+      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) */
-   png_set_bgr(png_ptr);
+   /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
+   if (color_type & PNG_COLOR_MASK_COLOR)
+      png_set_bgr(png_ptr);

 
 

-   /* swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
+   /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */

    png_set_swap_alpha(png_ptr);
 
    png_set_swap_alpha(png_ptr);
 

-   /* swap bytes of 16 bit files to least significant byte first */
+   /* 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_swap(png_ptr);
 
    /* Add filler (or alpha) byte (before/after each RGB triplet) */


@@ -307,10 +348,13 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
    /* The easiest way to read the image: */
    png_bytep row_pointers[height];
 
    /* The easiest way to read the image: */
    png_bytep row_pointers[height];
 

+   /* Clear the pointer array */

    for (row = 0; row < height; row++)
    for (row = 0; row < height; row++)

-   {
-      row_pointers[row] = malloc(png_get_rowbytes(png_ptr, info_ptr));
-   }
+      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 */
 
    /* Now it's time to read the image.  One of these methods is REQUIRED */
 #ifdef entire /* Read the entire image in one go */


@@ -331,34 +375,36 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
       for (y = 0; y < height; y += number_of_rows)
       {
 #ifdef sparkle /* Read the image using the "sparkle" effect. */
       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);
-
-         png_read_rows(png_ptr, NULL, row_pointers[y], number_of_rows);
+         png_read_rows(png_ptr, &row_pointers[y], NULL,
+            number_of_rows);

 #else no_sparkle /* Read the image using the "rectangle" effect */
 #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 */
+         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 */
+      /* 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 */
+#endif no_entire /* Use only one of these two methods */

 
 

-   /* read rest of file, and get additional chunks in info_ptr - REQUIRED */
+   /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */

    png_read_end(png_ptr, info_ptr);
    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, (png_infopp)NULL);
+   /* Clean up after the read, and free any memory allocated - REQUIRED */
+   png_destroy_read_struct(&png_ptr, &info_ptr, NULL);

 
 

-   /* close the file */
+   /* Close the file */

    fclose(fp);
 
    fclose(fp);
 

-   /* that's it */
-   return;
+   /* That's it */
+   return (OK);

 }
 
 }
 

-/* progressively read a file */
+/* Progressively read a file */

 
 int
 initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
 
 int
 initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)


@@ -375,21 +421,21 @@ initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
    if (*png_ptr == NULL)
    {
       *info_ptr = NULL;
    if (*png_ptr == NULL)
    {
       *info_ptr = NULL;

-      return ERROR;
+      return (ERROR);

    }
 
    *info_ptr = png_create_info_struct(png_ptr);
 
    if (*info_ptr == NULL)
    {
    }
 
    *info_ptr = png_create_info_struct(png_ptr);
 
    if (*info_ptr == NULL)
    {

-      png_destroy_read_struct(png_ptr, info_ptr, (png_infopp)NULL);
-      return ERROR;
+      png_destroy_read_struct(png_ptr, info_ptr, NULL);
+      return (ERROR);

    }
 
    }
 

-   if (setjmp((*png_ptr)->jmpbuf))
+   if (setjmp(png_jmpbuf((*png_ptr))))

    {
    {

-      png_destroy_read_struct(png_ptr, info_ptr, (png_infopp)NULL);
-      return ERROR;
+      png_destroy_read_struct(png_ptr, info_ptr, NULL);
+      return (ERROR);

    }
 
    /* This one's new.  You will need to provide all three
    }
 
    /* This one's new.  You will need to provide all three


@@ -407,23 +453,23 @@ initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
    png_set_progressive_read_fn(*png_ptr, (void *)stream_data,
       info_callback, row_callback, end_callback);
 
    png_set_progressive_read_fn(*png_ptr, (void *)stream_data,
       info_callback, row_callback, end_callback);
 

-   return OK;
+   return (OK);

 }
 
 int
 process_data(png_structp *png_ptr, png_infop *info_ptr,
    png_bytep buffer, png_uint_32 length)
 {
 }
 
 int
 process_data(png_structp *png_ptr, png_infop *info_ptr,
    png_bytep buffer, png_uint_32 length)
 {

-   if (setjmp((*png_ptr)->jmpbuf))
+   if (setjmp(png_jmpbuf((*png_ptr))))

    {
       /* Free the png_ptr and info_ptr memory on error */
    {
       /* Free the png_ptr and info_ptr memory on error */

-      png_destroy_read_struct(png_ptr, info_ptr, (png_infopp)NULL);
-      return 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).
    }
 
    /* 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.
+    * 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
     * 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


@@ -432,75 +478,100 @@ process_data(png_structp *png_ptr, png_infop *info_ptr,
     * callback, if you aren't already displaying them there.
     */
    png_process_data(*png_ptr, *info_ptr, buffer, length);
     * callback, if you aren't already displaying them there.
     */
    png_process_data(*png_ptr, *info_ptr, buffer, length);

-   return OK;
+   return (OK);

 }
 
 info_callback(png_structp png_ptr, png_infop info)
 {
 }
 
 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.
- */
+   /* 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)
 {
 }
 
 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 interlacing, and you turned on the interlace handler,
- * this function will be called for every row in every pass.
- * Some of these rows will not be changed from the previous pass.
- * When the row is not changed, the new_row variable will be NULL.
- * 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 row and the
- * old row.  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:
- */
+   /*
+    * 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];

 
 

+   /* 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);
 
    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, and the function will combine the
- * old row and the 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 png_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.
+    */

 }
 
 end_callback(png_structp png_ptr, png_infop info)
 {
 }
 
 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.
- */
+   /* 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 */
+/* Write a png file */

 void write_png(char *file_name /* , ... other image information ... */)
 {
    FILE *fp;
    png_structp png_ptr;
    png_infop info_ptr;
 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 */
+   /* Open the file */

    fp = fopen(file_name, "wb");
    if (fp == NULL)
    fp = fopen(file_name, "wb");
    if (fp == NULL)

-      return;
+      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,
 
    /* Create and initialize the png_struct with the desired error handler
     * functions.  If you want to use the default stderr and longjump method,


@@ -514,7 +585,7 @@ void write_png(char *file_name /* , ... other image information ... */)
    if (png_ptr == NULL)
    {
       fclose(fp);
    if (png_ptr == NULL)
    {
       fclose(fp);

-      return;
+      return (ERROR);

    }
 
    /* Allocate/initialize the image information data.  REQUIRED */
    }
 
    /* Allocate/initialize the image information data.  REQUIRED */


@@ -522,32 +593,45 @@ void write_png(char *file_name /* , ... other image information ... */)
    if (info_ptr == NULL)
    {
       fclose(fp);
    if (info_ptr == NULL)
    {
       fclose(fp);

-      png_destroy_write_struct(&png_ptr,  (png_infopp)NULL);
-      return;
+      png_destroy_write_struct(&png_ptr,  NULL);
+      return (ERROR);

    }
 
    /* Set error handling.  REQUIRED if you aren't supplying your own
    }
 
    /* Set error handling.  REQUIRED if you aren't supplying your own

-    * error hadnling functions in the png_create_write_struct() call.
+    * error handling functions in the png_create_write_struct() call.

     */
     */

-   if (setjmp(png_ptr->jmpbuf))
+   if (setjmp(png_jmpbuf(png_ptr)))

    {
    {

-      /* If we get here, we had a problem reading the file */
+      /* If we get here, we had a problem writing the file */

       fclose(fp);
       fclose(fp);

-      png_destroy_write_struct(&png_ptr,  (png_infopp)NULL);
-      return;
+      png_destroy_write_struct(&png_ptr, &info_ptr);
+      return (ERROR);

    }
 
    /* One of the following I/O initialization functions is REQUIRED */
    }
 
    /* One of the following I/O initialization functions is REQUIRED */

+

 #ifdef streams /* I/O initialization method 1 */
 #ifdef streams /* I/O initialization method 1 */

-   /* set up the output control if you are using standard C streams */
+   /* Set up the output control if you are using standard C streams */

    png_init_io(png_ptr, fp);
    png_init_io(png_ptr, fp);

+

 #else no_streams /* I/O initialization method 2 */
 #else no_streams /* I/O initialization method 2 */

-   /* If you are using replacement read functions, instead of calling
-    * png_init_io() here you would call */
+   /* 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 */
    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 */
+#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
 
    /* 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


@@ -560,21 +644,27 @@ void write_png(char *file_name /* , ... other image information ... */)
    png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, PNG_COLOR_TYPE_???,
       PNG_INTERLACE_????, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
 
    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, 256 * sizeof (png_color));
-   /* ... set palette colors ... */
-   png_set_PLTE(png_ptr, info_ptr, palette, 256);
+   /* Set the palette if there is one.  REQUIRED for indexed-color images */
+   palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH
+             * png_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 chunk */
-   /* if we are dealing with a grayscale image then */
+   /* 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;
    sig_bit.gray = true_bit_depth;

-   /* otherwise, if we are dealing with a color image then */
+   /* 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;
    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 */
+   /* If the image has an alpha channel then */

    sig_bit.alpha = true_alpha_bit_depth;
    sig_bit.alpha = true_alpha_bit_depth;

-   png_set_sBIT(png_ptr, info_ptr, sig_bit);
+   png_set_sBIT(png_ptr, info_ptr, &sig_bit);

 
 
    /* Optional gamma chunk is strongly suggested if you have any guess
 
 
    /* Optional gamma chunk is strongly suggested if you have any guess


@@ -592,26 +682,48 @@ void write_png(char *file_name /* , ... other image information ... */)
    text_ptr[2].key = "Description";
    text_ptr[2].text = "<long text>";
    text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt;
    text_ptr[2].key = "Description";
    text_ptr[2].text = "<long text>";
    text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt;

+#ifdef PNG_iTXt_SUPPORTED
+   text_ptr[0].lang = NULL;
+   text_ptr[0].lang_key = NULL;
+   text_ptr[1].lang = NULL;
+   text_ptr[1].lang_key = NULL;
+   text_ptr[2].lang = NULL;
+   text_ptr[2].lang_key = NULL;
+#endif

    png_set_text(png_ptr, info_ptr, text_ptr, 3);
 
    png_set_text(png_ptr, info_ptr, text_ptr, 3);
 

-   /* other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs, */
-   /* note that if sRGB is present the cHRM chunk must be ignored
-    * on read and must be written in accordance with the sRGB profile */
+   /* 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);
 
 
    /* 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
     * chunks 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.
     */
 
    /* Once we write out the header, the compression type on the text
     * chunks 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
+   /* Set up the transformations you want.  Note that these are

     * all optional.  Only call them if you want them.
     */
 
     * all optional.  Only call them if you want them.
     */
 

-   /* invert monocrome pixels */
+   /* Invert monochrome pixels */

    png_set_invert_mono(png_ptr);
 
    /* Shift the pixels up to a legal bit depth and fill in
    png_set_invert_mono(png_ptr);
 
    /* Shift the pixels up to a legal bit depth and fill in


@@ -619,10 +731,10 @@ void write_png(char *file_name /* , ... other image information ... */)
     */
    png_set_shift(png_ptr, &sig_bit);
 
     */
    png_set_shift(png_ptr, &sig_bit);
 

-   /* pack pixels into bytes */
+   /* Pack pixels into bytes */

    png_set_packing(png_ptr);
 
    png_set_packing(png_ptr);
 

-   /* swap location of alpha bytes from ARGB to RGBA */
+   /* 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
    png_set_swap_alpha(png_ptr);
 
    /* Get rid of filler (OR ALPHA) bytes, pack XRGB/RGBX/ARGB/RGBA into


@@ -630,16 +742,16 @@ void write_png(char *file_name /* , ... other image information ... */)
     */
    png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
 
     */
    png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
 

-   /* flip BGR pixels to RGB */
+   /* Flip BGR pixels to RGB */

    png_set_bgr(png_ptr);
 
    png_set_bgr(png_ptr);
 

-   /* swap bytes of 16-bit files to most significant byte first */
+   /* Swap bytes of 16-bit files to most significant byte first */

    png_set_swap(png_ptr);
 
    png_set_swap(png_ptr);
 

-   /* swap bits of 1, 2, 4 bit packed pixel formats */
+   /* Swap bits of 1, 2, 4 bit packed pixel formats */

    png_set_packswap(png_ptr);
 
    png_set_packswap(png_ptr);
 

-   /* turn on interlace handling if you are not using png_write_image() */
+   /* Turn on interlace handling if you are not using png_write_image() */

    if (interlacing)
       number_passes = png_set_interlace_handling(png_ptr);
    else
    if (interlacing)
       number_passes = png_set_interlace_handling(png_ptr);
    else


@@ -650,18 +762,24 @@ void write_png(char *file_name /* , ... other image information ... */)
     * use the first method if you aren't handling interlacing yourself.
     */
    png_uint_32 k, height, width;
     * use the first method if you aren't handling interlacing yourself.
     */
    png_uint_32 k, height, width;

-   png_byte image[height][width];
+   png_byte image[height][width*bytes_per_pixel];

    png_bytep row_pointers[height];
    png_bytep row_pointers[height];

+
+   if (height > PNG_UINT_32_MAX/png_sizeof(png_bytep))
+     png_error (png_ptr, "Image is too tall to process in memory");
+

    for (k = 0; k < height; k++)
    for (k = 0; k < height; k++)

-     row_pointers[k] = image + k*width;
+     row_pointers[k] = image + k*width*bytes_per_pixel;

 
    /* One of the following output methods is REQUIRED */
 
    /* One of the following output methods is REQUIRED */

-#ifdef entire /* write out the entire image data in one call */
+
+#ifdef entire /* Write out the entire image data in one call */

    png_write_image(png_ptr, row_pointers);
 
    png_write_image(png_ptr, row_pointers);
 

-   /* the other way to write the image - deal with interlacing */
+   /* The other way to write the image - deal with interlacing */
+
+#else no_entire /* Write out the image data by one or more scanlines */

 
 

-#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.
     */
    /* The number of passes is either 1 for non-interlaced images,
     * or 7 for interlaced images.
     */


@@ -672,31 +790,49 @@ void write_png(char *file_name /* , ... other image information ... */)
 
       /* If you are only writing one row at a time, this works */
       for (y = 0; y < height; y++)
 
       /* 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);
          png_write_rows(png_ptr, &row_pointers[y], 1);

-      }

    }
    }

-#endif no_entire /* use only one output method */
+#endif no_entire /* Use only one output method */

 
    /* You can write optional chunks like tEXt, zTXt, and tIME at the end
 
    /* You can write optional chunks like tEXt, zTXt, and tIME at the end

-    * as well.
+    * 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);
     */
 
    /* 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 malloced the palette, free it here */
-   free(info_ptr->palette);
+   /* 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;

 
 

-   /* if you allocated any text comments, free them here */
+   /* 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, (png_infopp)NULL);
+   /* Clean up after the write, and free any memory allocated */
+   png_destroy_write_struct(&png_ptr, &info_ptr);

 
 

-   /* close the file */
+   /* Close the file */

    fclose(fp);
 
    fclose(fp);
 

-   /* that's it */
-   return;
+   /* That's it */
+   return (OK);

 }
 
 }
 

+#endif /* if 0 */