Changeset 561 for trunk/src/3rdparty/libpng/example.c

Timestamp:

Feb 11, 2010, 11:19:06 PM (15 years ago)

Author:

Dmitry A. Kuminov

Message:

trunk: Merged in qt 4.6.1 sources.

Location:

trunk

Files:

• . (modified) (1 prop)
• src/3rdparty/libpng/example.c (modified) (30 diffs)

trunk/src/3rdparty/libpng/example.c

@@ -3 +3 @@
 
 /* example.c - an example of using libpng
- * Last changed in libpng 1.2.1 December 7, 2001.
+ * Last changed in libpng 1.2.37 [June 4, 2009]
  * This file has been placed in the public domain by the authors.
- * Maintained 1998-2007 Glenn Randers-Pehrson
+ * Maintained 1998-2009 Glenn Randers-Pehrson
  * Maintained 1996, 1997 Andreas Dilger)
  * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -92 +92 @@
    if ((fp = fopen(file_name, "rb")) == NULL)
       return (ERROR);
+
 #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;
@@ -99 +100 @@
    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
@@ -165 +166 @@
     */
    png_read_png(png_ptr, info_ptr, png_transforms, png_voidp_NULL);
+
 #else
    /* OK, you're doing it the hard way, with the lower-level functions */
@@ -176 +178 @@
        &interlace_type, int_p_NULL, int_p_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.
- */
-
-   /* tell libpng to strip 16 bit/color files down to 8 bits/color */
+   /* 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 */
    png_set_strip_16(png_ptr);
 
@@ -205 +207 @@
    /* 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
@@ -229 +231 @@
                          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 */)
    {
@@ -245 +248 @@
    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 */
@@ -278 +281 @@
 
       /* 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 */
@@ -298 +301 @@
    }
 
-   /* 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);
 
@@ -307 +310 @@
    if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT))
    {
-      png_color_8p sig_bit;
-
-      png_get_sBIT(png_ptr, info_ptr, &sig_bit);
-      png_set_shift(png_ptr, sig_bit);
-   }
-
-   /* flip the RGB pixels to BGR (or RGBA to BGRA) */
+      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)
       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);
 
-   /* 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);
 
@@ -343 +346 @@
    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 */
@@ -373 +378 @@
          png_read_rows(png_ptr, png_bytepp_NULL, &row_pointers[y],
             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 */
-   }
-#endif no_entire /* use only one of these two methods */
-
-   /* read rest of file, and get additional chunks in info_ptr - REQUIRED */
+      /* 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
@@ -388 +392 @@
    /* At this point you have read the entire image */
 
-   /* clean up after the read, and free any memory allocated - REQUIRED */
+   /* Clean up after the read, and free any memory allocated - REQUIRED */
    png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL);
 
-   /* close the file */
+   /* Close the file */
    fclose(fp);
 
-   /* that's it */
+   /* That's it */
    return (OK);
 }
 
-/* progressively read a file */
+/* Progressively read a file */
 
 int
@@ -463 +467 @@
    /* 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
@@ -477 +481 @@
 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.
+    */
 }
 
@@ -489 +493 @@
    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:
- */
+   /*
+    * 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))
+   if ((row_num >= 0) && (row_num < height))
    {
      /* Get pointer to corresponding row in our
@@ -516 +521 @@
       * data to the corresponding row data.
       */
-     if((old_row != NULL) && (new_row != NULL))
+     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:
- */
+   /*
+    * 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.
- */
+   /* 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)
 {
-/* 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 ... */)
 {
@@ -564 +569 @@
    png_colorp palette;
 
-   /* open the file */
+   /* Open the file */
    fp = fopen(file_name, "wb");
    if (fp == NULL)
@@ -598 +603 @@
    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);
@@ -605 +610 @@
 
    /* 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 */
+   /* 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 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 */
-#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 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_write_png(png_ptr, info_ptr, png_transforms, png_voidp_NULL);
+
 #else
    /* This is the hard way */
@@ -636 +645 @@
       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
-             * 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
-      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 */
+    * 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 */
+   /* 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 */
+   /* If the image has an alpha channel then */
    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);
 
 
@@ -679 +690 @@
    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 */
@@ -693 +707 @@
     *   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.
     */
@@ -703 +717 @@
     */
 
-   /* 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.
     */
 
-   /* invert monochrome pixels */
+   /* Invert monochrome pixels */
    png_set_invert_mono(png_ptr);
 
@@ -715 +729 @@
    png_set_shift(png_ptr, &sig_bit);
 
-   /* pack pixels into bytes */
+   /* Pack pixels into bytes */
    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);
 
@@ -726 +740 @@
    png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
 
-   /* flip BGR pixels to RGB */
+   /* Flip BGR pixels to RGB */
    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);
 
-   /* 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);
 
-   /* 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);
@@ -756 +770 @@
 
    /* 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);
 
-   /* the other way to write the image - deal with interlacing */
-
-#else no_entire /* write out the image data by one or more scanlines */
+   /* 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.
@@ -772 +788 @@
       /* 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 */
+   }
+#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 1.1.0 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.
@@ -789 +803 @@
 
    /* 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);
-   palette=NULL;
+   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_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;
-
-   /* clean up after the write, and free any memory allocated */
+   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 */
+   /* Close the file */
    fclose(fp);
 
-   /* that's it */
+   /* That's it */
    return (OK);
 }