Ensure that scrollbars are shown in scrolled popup in the popup sample.

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

diff --git a/src/png/example.c b/src/png/example.c
index 08158731a69bcf373de8e20b07b1ca5c7724452b..ec53a8cdee3c819d34ad35ba419edb9a1c43e119 100644 (file)
--- a/src/png/example.c
+++ b/src/png/example.c
@@ -2,18 +2,19 @@
 #if 0 /* in case someone actually tries to compile this */
 
 /* 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 1.2.1 December 7, 2001.
- * This file has been placed in the public domain by the authors.
- * Maintained 1998-2007 Glenn Randers-Pehrson
- * Maintained 1996, 1997 Andreas Dilger)
- * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Last changed in libpng 1.5.7 [December 15, 2011]
+ * Maintained 1998-2011 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.
  */
 
 /* 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
+ * The file libpng-manual.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, is hereby placed
  * in the public domain, and therefore does not require a copyright notice.
  * read it, do so first.  This was designed to be a starting point of an
  * implementation.  This is not officially part of libpng, is hereby placed
  * in the public domain, and therefore does not require a copyright notice.

+ * To the extent possible under law, the authors have waived all copyright and
+ * related or neighboring rights to this file.

  *
  * This file does not currently compile, because it is missing certain
  * parts, like allocating memory to hold an image.  You will have to
  *
  * This file does not currently compile, because it is missing certain
  * parts, like allocating memory to hold an image.  You will have to


@@ -22,6 +23,10 @@
  * see also the programs in the contrib directory.
  */
 
  * see also the programs in the contrib directory.
  */
 

+#define _POSIX_SOURCE 1  /* libpng and zlib are POSIX-compliant.  You may
+                          * change this if your application uses non-POSIX
+                          * extensions. */
+

 #include "png.h"
 
  /* The png_jmpbuf() macro, used in error handling, became available in
 #include "png.h"
 
  /* The png_jmpbuf() macro, used in error handling, became available in


@@ -31,7 +36,7 @@
   */
 
 #ifndef png_jmpbuf
   */
 
 #ifndef png_jmpbuf

-#  define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
+#  define png_jmpbuf(png_ptr) ((png_ptr)->png_jmpbuf)

 #endif
 
 /* Check to see if a file is a PNG file using png_sig_cmp().  png_sig_cmp()
 #endif
 
 /* Check to see if a file is a PNG file using png_sig_cmp().  png_sig_cmp()


@@ -91,14 +96,15 @@ void read_png(char *file_name)  /* We need to open the file */
 
    if ((fp = fopen(file_name, "rb")) == NULL)
       return (ERROR);
 
    if ((fp = fopen(file_name, "rb")) == NULL)
       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,


@@ -120,7 +126,7 @@ 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);
+      png_destroy_read_struct(&png_ptr, NULL, NULL);

       return (ERROR);
    }
 
       return (ERROR);
    }
 


@@ -132,7 +138,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
    if (setjmp(png_jmpbuf(png_ptr)))
    {
       /* Free all of the memory associated with the png_ptr and info_ptr */
    if (setjmp(png_jmpbuf(png_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 */
       return (ERROR);
       fclose(fp);
       /* If we get here, we had a problem reading the file */
       return (ERROR);


@@ -159,11 +165,12 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
     * 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
     * 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

-    * dithering, filling, setting background, and doing gamma
+    * quantizing, filling, setting background, and doing gamma

     * adjustment), then you can read the entire image (including
     * pixels) into the info structure with this call:
     */
     * 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, png_voidp_NULL);
+   png_read_png(png_ptr, info_ptr, png_transforms, NULL);
+

 #else
    /* OK, you're doing it the hard way, with the lower-level functions */
 
 #else
    /* OK, you're doing it the hard way, with the lower-level functions */
 


@@ -173,16 +180,23 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
    png_read_info(png_ptr, info_ptr);
 
    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
    png_read_info(png_ptr, info_ptr);
 
    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,

-       &interlace_type, int_p_NULL, int_p_NULL);
+       &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.
+    * 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);
    png_set_strip_16(png_ptr);

+#endif

 
    /* Strip alpha bytes from the input data without combining with the
     * background (not recommended).
 
    /* Strip alpha bytes from the input data without combining with the
     * background (not recommended).


@@ -204,7 +218,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
 
    /* 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_gray_1_2_4_to_8(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.
 
    /* Expand paletted or RGB images with transparency to full alpha channels
     * so the data will be available as RGBA quartets.


@@ -228,10 +242,11 @@ 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 the display_exponent, which includes
-    * the CRT_exponent and any correction for viewing conditions */
+   /* 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;


@@ -244,7 +259,7 @@ 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 */
    }


@@ -268,7 +283,8 @@ 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)


@@ -277,13 +293,13 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
       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,
-            MAX_SCREEN_COLORS, png_uint_16p_NULL, 0);
+         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))
       }
       /* This reduces the image to the palette supplied in the file */
       else if (png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette))


@@ -292,12 +308,13 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
 
          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 monochrome 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


@@ -306,30 +323,35 @@ 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_color_8p 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) */
+   /* Flip the RGB pixels to BGR (or RGBA to BGRA) */

    if (color_type & PNG_COLOR_MASK_COLOR)
       png_set_bgr(png_ptr);
 
    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_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
 
    png_set_swap(png_ptr);
 
    /* Add filler (or alpha) byte (before/after each RGB triplet) */
    png_set_filler(png_ptr, 0xff, 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);
    /* 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
+   number_passes = 1;
+#endif /* PNG_READ_INTERLACING_SUPPORTED */
+

 
    /* Optional call to gamma correct and add the background to the palette
     * and update info structure.  REQUIRED if you are expecting libpng to
 
    /* Optional call to gamma correct and add the background to the palette
     * and update info structure.  REQUIRED if you are expecting libpng to


@@ -342,11 +364,13 @@ 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++)
+      row_pointers[row] = NULL;
+

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

-   {

       row_pointers[row] = png_malloc(png_ptr, png_get_rowbytes(png_ptr,
          info_ptr));
       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 */


@@ -360,44 +384,43 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
 #ifdef single /* Read the image a single row at a time */
       for (y = 0; y < height; y++)
       {
 #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], png_bytepp_NULL, 1);
+         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. */
       }
 
 #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], png_bytepp_NULL,
+         png_read_rows(png_ptr, &row_pointers[y], NULL,

             number_of_rows);
 #else no_sparkle /* Read the image using the "rectangle" effect */
             number_of_rows);
 #else no_sparkle /* Read the image using the "rectangle" effect */

-         png_read_rows(png_ptr, png_bytepp_NULL, &row_pointers[y],
+         png_read_rows(png_ptr, NULL, &row_pointers[y],

             number_of_rows);
             number_of_rows);

-#endif no_sparkle /* use only one of these two methods */
+#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);
 #endif hilevel
 
    /* At this point you have read the entire image */
 
    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 */
+   /* That's it */

    return (OK);
 }
 
    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)


@@ -421,13 +444,13 @@ initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
 
    if (*info_ptr == NULL)
    {
 
    if (*info_ptr == NULL)
    {

-      png_destroy_read_struct(png_ptr, info_ptr, png_infopp_NULL);
+      png_destroy_read_struct(png_ptr, info_ptr, NULL);

       return (ERROR);
    }
 
    if (setjmp(png_jmpbuf((*png_ptr))))
    {
       return (ERROR);
    }
 
    if (setjmp(png_jmpbuf((*png_ptr))))
    {

-      png_destroy_read_struct(png_ptr, info_ptr, png_infopp_NULL);
+      png_destroy_read_struct(png_ptr, info_ptr, NULL);

       return (ERROR);
    }
 
       return (ERROR);
    }
 


@@ -456,13 +479,13 @@ process_data(png_structp *png_ptr, png_infop *info_ptr,
    if (setjmp(png_jmpbuf((*png_ptr))))
    {
       /* Free the png_ptr and info_ptr memory on error */
    if (setjmp(png_jmpbuf((*png_ptr))))
    {
       /* Free the png_ptr and info_ptr memory on error */

-      png_destroy_read_struct(png_ptr, info_ptr, png_infopp_NULL);
+      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).
       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.
+    * 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


@@ -476,86 +499,86 @@ process_data(png_structp *png_ptr, png_infop *info_ptr,
 
 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 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:
- */
-   /* Check if row_num is in bounds. */
-   if((row_num >= 0) && (row_num < height))
-   {
-     /* 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);
-   }
-/*
- * 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:
- */
+   /*
+    * 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);
 
    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.
- */
+   /*
+    * 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.
+    */
+#endif /* PNG_READ_INTERLACING_SUPPORTED */

 }
 
 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;
 void write_png(char *file_name /* , ... other image information ... */)
 {
    FILE *fp;


@@ -563,7 +586,7 @@ void write_png(char *file_name /* , ... other image information ... */)
    png_infop info_ptr;
    png_colorp palette;
 
    png_infop info_ptr;
    png_colorp palette;
 

-   /* open the file */
+   /* Open the file */

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


@@ -588,7 +611,7 @@ 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);
+      png_destroy_write_struct(&png_ptr,  NULL);

       return (ERROR);
    }
 
       return (ERROR);
    }
 


@@ -597,30 +620,34 @@ void write_png(char *file_name /* , ... other image information ... */)
     */
    if (setjmp(png_jmpbuf(png_ptr)))
    {
     */
    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);
       png_destroy_write_struct(&png_ptr, &info_ptr);
       return (ERROR);
    }
 
    /* One of the following I/O initialization functions is REQUIRED */
       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 */
 #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
 
 #ifdef hilevel
    /* This is the easy way.  Use it if you already have all the

-    * image info living info in the structure.  You could "|" many
+    * image info living in the structure.  You could "|" many

     * PNG_TRANSFORM flags into the png_transforms integer here.
     */
     * PNG_TRANSFORM flags into the png_transforms integer here.
     */

-   png_write_png(png_ptr, info_ptr, png_transforms, png_voidp_NULL);
+   png_write_png(png_ptr, info_ptr, png_transforms, NULL);
+

 #else
    /* This is the hard way */
 
 #else
    /* This is the hard way */
 


@@ -635,25 +662,31 @@ 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 */
+   /* Set the palette if there is one.  REQUIRED for indexed-color images */

    palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH
    palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH

-             * png_sizeof (png_color));
-   /* ... set palette colors ... */
+             * 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
    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. */
+    * 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;

 
 

-   /* optional significant bit chunk */
-   /* if we are dealing with a grayscale image then */
+   /* 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


@@ -665,22 +698,29 @@ void write_png(char *file_name /* , ... other image information ... */)
    text_ptr[0].key = "Title";
    text_ptr[0].text = "Mona Lisa";
    text_ptr[0].compression = PNG_TEXT_COMPRESSION_NONE;
    text_ptr[0].key = "Title";
    text_ptr[0].text = "Mona Lisa";
    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;

    text_ptr[1].key = "Author";
    text_ptr[1].text = "Leonardo DaVinci";
    text_ptr[1].compression = PNG_TEXT_COMPRESSION_NONE;
    text_ptr[1].key = "Author";
    text_ptr[1].text = "Leonardo DaVinci";
    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;

    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[1].lang = NULL;
+   text_ptr[2].itxt_length = 0;

    text_ptr[2].lang = NULL;
    text_ptr[2].lang = NULL;

-#endif
+   text_ptr[2].lang_key = NULL;

    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 gAMA and cHRM chunks 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);


@@ -692,7 +732,7 @@ void write_png(char *file_name /* , ... other image information ... */)
     *   write_my_chunk();
     *   png_write_info(png_ptr, info_ptr);
     *
     *   write_my_chunk();
     *   png_write_info(png_ptr, info_ptr);
     *

-    * However, given the level of known- and unknown-chunk support in 1.1.0
+    * However, given the level of known- and unknown-chunk support in 1.2.0

     * and up, this should no longer be necessary.
     */
 
     * and up, this should no longer be necessary.
     */
 


@@ -702,11 +742,11 @@ void write_png(char *file_name /* , ... other image information ... */)
     * at the end.
     */
 
     * 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 monochrome 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


@@ -714,10 +754,10 @@ 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


@@ -725,18 +765,19 @@ 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);
    if (interlacing)
       number_passes = png_set_interlace_handling(png_ptr);

+

    else
       number_passes = 1;
 
    else
       number_passes = 1;
 


@@ -755,12 +796,14 @@ void write_png(char *file_name /* , ... other image information ... */)
      row_pointers[k] = image + k*width*bytes_per_pixel;
 
    /* One of the following output methods is REQUIRED */
      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 */
+
+#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.
     */


@@ -771,14 +814,12 @@ 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.  Shouldn't be necessary in 1.1.0 and up as all the public
+    * 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.
     */
     * chunks are supported and you can use png_set_unknown_chunks() to
     * register unknown chunks into the info structure to be written out.
     */


@@ -788,26 +829,33 @@ void write_png(char *file_name /* , ... other image information ... */)
 #endif hilevel
 
    /* If you png_malloced a palette, free it here (don't free info_ptr->palette,
 #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(). */
+    * 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);
    png_free(png_ptr, palette);

-   palette=NULL;
+   palette = NULL;

 
    /* Similarly, if you png_malloced any data that you passed in with
 
    /* 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_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);
    png_free(png_ptr, trans);

-   trans=NULL;
+   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 */
+   /* Clean up after the write, and free any memory allocated */

    png_destroy_write_struct(&png_ptr, &info_ptr);
 
    png_destroy_write_struct(&png_ptr, &info_ptr);
 

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

    fclose(fp);
 
    fclose(fp);
 

-   /* that's it */
+   /* That's it */

    return (OK);
 }
 
    return (OK);
 }