Revert "libpng 1.6.3"

This reverts commit 777c940a87944192afaa28904c30145bfeb54d09.

Many Blink LayoutTests starts failing after this patch.
http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20Blink&tests=canvas/philip/tests/security.dataURI.html,canvas/philip/tests/toDataURL.arguments.1.html,canvas/philip/tests/toDataURL.arguments.2.html,canvas/philip/tests/toDataURL.arguments.3.html,canvas/philip/tests/toDataURL.bogustype.html,canvas/philip/tests/toDataURL.default.html,canvas/philip/tests/toDataURL.lowercase.ascii.html,canvas/philip/tests/toDataURL.lowercase.unicode.html,canvas/philip/tests/toDataURL.nocontext.html,canvas/philip/tests/toDataURL.png.complexcolours.html,canvas/philip/tests/toDataURL.png.html,canvas/philip/tests/toDataURL.png.primarycolours.html,canvas/philip/tests/toDataURL.unrecognised.html,compositing/overflow/image-load-overflow-scrollbars.html,compositing/overflow/invisible-descendants-should-not-affect-opt-in.html,compositing/tiling/huge-layer-img.html,css2.1/20110323/inline-replaced-width-014.htm,css2.1/t0905-c414-flt-wrap-01-d-g.html,fast/backgrounds/bgCompositeCopy.html,fast/canvas/canvas-blending-color-over-image.html,fast/canvas/canvas-blending-color-over-pattern.html,fast/canvas/canvas-blending-gradient-over-image.html,fast/canvas/canvas-blending-gradient-over-pattern.html,fast/canvas/canvas-blending-image-over-color.html,fast/canvas/canvas-blending-image-over-gradient.html,fast/canvas/canvas-blending-image-over-image.html,fast/canvas/canvas-blending-image-over-pattern.html,fast/canvas/canvas-blending-pattern-over-color.html,fast/canvas/canvas-blending-pattern-over-gradient.html,fast/canvas/canvas-blending-pattern-over-image.html,fast/canvas/canvas-blending-pattern-over-pattern.html,fast/canvas/canvas-createImageBitmap-drawImage.html,fast/canvas/canvas-createImageBitmap-immutable.html,fast/canvas/canvas-createImageBitmap-invalid-args.html,fast/canvas/canvas-createImageBitmap-out-of-bounds-src.html,fast/canvas/canvas-createImageBitmap-recursive.html,fast/canvas/canvas-createPattern-fillRect-shadow.html,fast/canvas/canvas-drawImage-out-of-bounds-src.html,fast/canvas/canvas-drawImage-shadow.html,fast/canvas/canvas-scale-drawImage-shadow.html,fast/canvas/canvas-toDataURL-case-insensitive-mimetype.html,fast/canvas/check-stale-putImageData.html,fast/canvas/toDataURL-alpha.html,fast/canvas/toDataURL-supportedTypes.html,fast/canvas/webgl/gl-teximage.html,fast/canvas/webgl/tex-image-and-sub-image-2d-with-image-rgb565.html,fast/canvas/webgl/tex-image-and-sub-image-2d-with-image-rgba4444.html,fast/canvas/webgl/tex-image-and-sub-image-2d-with-image-rgba5551.html,fast/canvas/webgl/tex-image-and-sub-image-2d-with-image.html,fast/css/color-correction-on-backgrounds.html,fast/css/color-correction.html,fast/images/paint-subrect-grid.html,fast/images/png-suite/test.html,fast/images/png-with-color-profile.html,fast/images/rgb-png-with-cmyk-color-profile.html,inspector/profiler/canvas2d/canvas-get-resource-state.html,inspector/profiler/webgl/webgl-get-resource-state.html,svg/W3C-SVG-1.1/filters-blend-01-b.svg,svg/W3C-SVG-1.1/masking-path-04-b.svg,svg/dynamic-updates/SVGFEBlendElement-dom-in-attr.html,svg/dynamic-updates/SVGFEBlendElement-dom-in2-attr.html,svg/dynamic-updates/SVGFEBlendElement-dom-mode-attr.html,svg/dynamic-updates/SVGFEBlendElement-svgdom-in-prop.html,svg/dynamic-updates/SVGFEBlendElement-svgdom-in2-prop.html,svg/dynamic-updates/SVGFEBlendElement-svgdom-mode-prop.html,virtual/deferred/fast/images/paint-subrect-grid.html,virtual/deferred/fast/images/png-suite/test.html,virtual/deferred/fast/images/png-with-color-profile.html,virtual/deferred/fast/images/rgb-png-with-cmyk-color-profile.html,virtual/gpu/canvas/philip/tests/security.dataURI.html,virtual/gpu/canvas/philip/tests/toDataURL.arguments.1.html,virtual/gpu/canvas/philip/tests/toDataURL.arguments.2.html,virtual/gpu/canvas/philip/tests/toDataURL.arguments.3.html,virtual/gpu/canvas/philip/tests/toDataURL.bogustype.html,virtual/gpu/canvas/philip/tests/toDataURL.default.html,virtual/gpu/canvas/philip/tests/toDataURL.lowercase.ascii.html,virtual/gpu/canvas/philip/tests/toDataURL.lowercase.unicode.html,virtual/gpu/canvas/philip/tests/toDataURL.nocontext.html,virtual/gpu/canvas/philip/tests/toDataURL.png.complexcolours.html,virtual/gpu/canvas/philip/tests/toDataURL.png.html,virtual/gpu/canvas/philip/tests/toDataURL.png.primarycolours.html,virtual/gpu/canvas/philip/tests/toDataURL.unrecognised.html,virtual/gpu/compositedscrolling/overflow/image-load-overflow-scrollbars.html,virtual/gpu/compositedscrolling/overflow/invisible-descendants-should-not-affect-opt-in.html,virtual/gpu/fast/canvas/canvas-blending-color-over-image.html,virtual/gpu/fast/canvas/canvas-blending-color-over-pattern.html,virtual/gpu/fast/canvas/canvas-blending-gradient-over-image.html,virtual/gpu/fast/canvas/canvas-blending-gradient-over-pattern.html,virtual/gpu/fast/canvas/canvas-blending-image-over-color.html,virtual/gpu/fast/canvas/canvas-blending-image-over-gradient.html,virtual/gpu/fast/canvas/canvas-blending-image-over-image.html,virtual/gpu/fast/canvas/canvas-blending-image-over-pattern.html,virtual/gpu/fast/canvas/canvas-blending-pattern-over-color.html,virtual/gpu/fast/canvas/canvas-blending-pattern-over-gradient.html,virtual/gpu/fast/canvas/canvas-blending-pattern-over-image.html,virtual/gpu/fast/canvas/canvas-blending-pattern-over-pattern.html,virtual/gpu/fast/canvas/canvas-createImageBitmap-drawImage.html,virtual/gpu/fast/canvas/canvas-createImageBitmap-immutable.html,virtual/gpu/fast/canvas/canvas-createImageBitmap-invalid-args.html,virtual/gpu/fast/canvas/canvas-createImageBitmap-out-of-bounds-src.html,virtual/gpu/fast/canvas/canvas-createImageBitmap-recursive.html,virtual/gpu/fast/canvas/canvas-createPattern-fillRect-shadow.html,virtual/gpu/fast/canvas/canvas-drawImage-out-of-bounds-src.html,virtual/gpu/fast/canvas/canvas-scale-drawImage-shadow.html,virtual/gpu/fast/canvas/canvas-toDataURL-case-insensitive-mimetype.html,virtual/gpu/fast/canvas/check-stale-putImageData.html,virtual/gpu/fast/canvas/toDataURL-alpha.html,virtual/gpu/fast/canvas/toDataURL-supportedTypes.html,virtual/gpu/fast/canvas/webgl/gl-teximage.html,virtual/gpu/fast/canvas/webgl/premultiplyalpha-test.html,virtual/gpu/fast/canvas/webgl/tex-image-and-sub-image-2d-with-image-rgb565.html,virtual/gpu/fast/canvas/webgl/tex-image-and-sub-image-2d-with-image-rgba4444.html,virtual/gpu/fast/canvas/webgl/tex-image-and-sub-image-2d-with-image-rgba5551.html,virtual/gpu/fast/canvas/webgl/tex-image-and-sub-image-2d-with-image.html,virtual/softwarecompositing/overflow/image-load-overflow-scrollbars.html,virtual/softwarecompositing/overflow/invisible-descendants-should-not-affect-opt-in.html,virtual/softwarecompositing/tiling/huge-layer-img.html

BUG=none
TBR= dominikg@chromium.org, arv@chromium.org

Review URL: https://codereview.chromium.org/23494067

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224979 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 85 insertions, 140 deletions

diff --git a/third_party/libpng/pngwtran.c b/third_party/libpng/pngwtran.c
index 98703f8..0ce9b9b 100644
--- a/third_party/libpng/pngwtran.c
+++ b/third_party/libpng/pngwtran.c
@@ -1,8 +1,8 @@
 
 /* pngwtran.c - transforms the data in a row for PNG writers
  *
- * Last changed in libpng 1.6.0 [February 14, 2013]
- * Copyright (c) 1998-2013 Glenn Randers-Pehrson
+ * Last changed in libpng 1.2.43 [February 25, 2010]
+ * Copyright (c) 1998-2010 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -11,16 +11,16 @@
  * and license in png.h
  */
 
-#include "pngpriv.h"
-
+#define PNG_INTERNAL
+#define PNG_NO_PEDANTIC_WARNINGS
+#include "png.h"
 #ifdef PNG_WRITE_SUPPORTED
 
-#ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
 /* Transform the data according to the user's wishes.  The order of
  * transformations is significant.
  */
 void /* PRIVATE */
-png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info)
+png_do_write_transformations(png_structp png_ptr)
 {
    png_debug(1, "in png_do_write_transformations");
 
@@ -30,65 +30,56 @@ png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info)
 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
    if (png_ptr->transformations & PNG_USER_TRANSFORM)
       if (png_ptr->write_user_transform_fn != NULL)
-         (*(png_ptr->write_user_transform_fn)) /* User write transform
+        (*(png_ptr->write_user_transform_fn)) /* User write transform
                                                  function */
-             (png_ptr,  /* png_ptr */
-             row_info,  /* row_info: */
-                /*  png_uint_32 width;       width of row */
-                /*  png_size_t rowbytes;     number of bytes in row */
-                /*  png_byte color_type;     color type of pixels */
-                /*  png_byte bit_depth;      bit depth of samples */
-                /*  png_byte channels;       number of channels (1-4) */
-                /*  png_byte pixel_depth;    bits per pixel (depth*channels) */
-             png_ptr->row_buf + 1);      /* start of pixel data for row */
+          (png_ptr,                    /* png_ptr */
+           &(png_ptr->row_info),       /* row_info:     */
+             /*  png_uint_32 width;          width of row */
+             /*  png_uint_32 rowbytes;       number of bytes in row */
+             /*  png_byte color_type;        color type of pixels */
+             /*  png_byte bit_depth;         bit depth of samples */
+             /*  png_byte channels;          number of channels (1-4) */
+             /*  png_byte pixel_depth;       bits per pixel (depth*channels) */
+           png_ptr->row_buf + 1);      /* start of pixel data for row */
 #endif
-
 #ifdef PNG_WRITE_FILLER_SUPPORTED
    if (png_ptr->transformations & PNG_FILLER)
-      png_do_strip_channel(row_info, png_ptr->row_buf + 1,
-         !(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
+      png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
+         png_ptr->flags);
 #endif
-
 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
    if (png_ptr->transformations & PNG_PACKSWAP)
-      png_do_packswap(row_info, png_ptr->row_buf + 1);
+      png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
-
 #ifdef PNG_WRITE_PACK_SUPPORTED
    if (png_ptr->transformations & PNG_PACK)
-      png_do_pack(row_info, png_ptr->row_buf + 1,
-          (png_uint_32)png_ptr->bit_depth);
+      png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1,
+         (png_uint_32)png_ptr->bit_depth);
 #endif
-
 #ifdef PNG_WRITE_SWAP_SUPPORTED
    if (png_ptr->transformations & PNG_SWAP_BYTES)
-      png_do_swap(row_info, png_ptr->row_buf + 1);
+      png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
-
 #ifdef PNG_WRITE_SHIFT_SUPPORTED
    if (png_ptr->transformations & PNG_SHIFT)
-      png_do_shift(row_info, png_ptr->row_buf + 1,
-          &(png_ptr->shift));
+      png_do_shift(&(png_ptr->row_info), png_ptr->row_buf + 1,
+         &(png_ptr->shift));
 #endif
-
 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
    if (png_ptr->transformations & PNG_SWAP_ALPHA)
-      png_do_write_swap_alpha(row_info, png_ptr->row_buf + 1);
+      png_do_write_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
-
 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
    if (png_ptr->transformations & PNG_INVERT_ALPHA)
-      png_do_write_invert_alpha(row_info, png_ptr->row_buf + 1);
+      png_do_write_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
-
 #ifdef PNG_WRITE_BGR_SUPPORTED
    if (png_ptr->transformations & PNG_BGR)
-      png_do_bgr(row_info, png_ptr->row_buf + 1);
+      png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
-
 #ifdef PNG_WRITE_INVERT_SUPPORTED
    if (png_ptr->transformations & PNG_INVERT_MONO)
-      png_do_invert(row_info, png_ptr->row_buf + 1);
+      png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
 }
 
@@ -103,6 +94,9 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
    png_debug(1, "in png_do_pack");
 
    if (row_info->bit_depth == 8 &&
+#ifdef PNG_USELESS_TESTS_SUPPORTED
+       row != NULL && row_info != NULL &&
+#endif
       row_info->channels == 1)
    {
       switch ((int)bit_depth)
@@ -123,12 +117,9 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
             {
                if (*sp != 0)
                   v |= mask;
-
                sp++;
-
                if (mask > 1)
                   mask >>= 1;
-
                else
                {
                   mask = 0x80;
@@ -137,13 +128,10 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
                   v = 0;
                }
             }
-
             if (mask != 0x80)
                *dp = (png_byte)v;
-
             break;
          }
-
          case 2:
          {
             png_bytep sp, dp;
@@ -155,14 +143,12 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
             dp = row;
             shift = 6;
             v = 0;
-
             for (i = 0; i < row_width; i++)
             {
                png_byte value;
 
                value = (png_byte)(*sp & 0x03);
                v |= (value << shift);
-
                if (shift == 0)
                {
                   shift = 6;
@@ -170,19 +156,14 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
                   dp++;
                   v = 0;
                }
-
                else
                   shift -= 2;
-
                sp++;
             }
-
             if (shift != 6)
                *dp = (png_byte)v;
-
             break;
          }
-
          case 4:
          {
             png_bytep sp, dp;
@@ -194,7 +175,6 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
             dp = row;
             shift = 4;
             v = 0;
-
             for (i = 0; i < row_width; i++)
             {
                png_byte value;
@@ -209,27 +189,20 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
                   dp++;
                   v = 0;
                }
-
                else
                   shift -= 4;
 
                sp++;
             }
-
             if (shift != 4)
                *dp = (png_byte)v;
-
             break;
          }
-
-         default:
-            break;
       }
-
       row_info->bit_depth = (png_byte)bit_depth;
       row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
       row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
-          row_info->width);
+         row_info->width);
    }
 }
 #endif
@@ -243,12 +216,16 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
  * data to 0 to 15.
  */
 void /* PRIVATE */
-png_do_shift(png_row_infop row_info, png_bytep row,
-    png_const_color_8p bit_depth)
+png_do_shift(png_row_infop row_info, png_bytep row, png_color_8p bit_depth)
 {
    png_debug(1, "in png_do_shift");
 
-   if (row_info->color_type != PNG_COLOR_TYPE_PALETTE)
+#ifdef PNG_USELESS_TESTS_SUPPORTED
+   if (row != NULL && row_info != NULL &&
+#else
+   if (
+#endif
+      row_info->color_type != PNG_COLOR_TYPE_PALETTE)
    {
       int shift_start[4], shift_dec[4];
       int channels = 0;
@@ -258,23 +235,19 @@ png_do_shift(png_row_infop row_info, png_bytep row,
          shift_start[channels] = row_info->bit_depth - bit_depth->red;
          shift_dec[channels] = bit_depth->red;
          channels++;
-
          shift_start[channels] = row_info->bit_depth - bit_depth->green;
          shift_dec[channels] = bit_depth->green;
          channels++;
-
          shift_start[channels] = row_info->bit_depth - bit_depth->blue;
          shift_dec[channels] = bit_depth->blue;
          channels++;
       }
-
       else
       {
          shift_start[channels] = row_info->bit_depth - bit_depth->gray;
          shift_dec[channels] = bit_depth->gray;
          channels++;
       }
-
       if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
       {
          shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
@@ -286,40 +259,33 @@ png_do_shift(png_row_infop row_info, png_bytep row,
       if (row_info->bit_depth < 8)
       {
          png_bytep bp = row;
-         png_size_t i;
-         unsigned int mask;
-         png_size_t row_bytes = row_info->rowbytes;
+         png_uint_32 i;
+         png_byte mask;
+         png_uint_32 row_bytes = row_info->rowbytes;
 
          if (bit_depth->gray == 1 && row_info->bit_depth == 2)
             mask = 0x55;
-
          else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
             mask = 0x11;
-
          else
             mask = 0xff;
 
          for (i = 0; i < row_bytes; i++, bp++)
          {
+            png_uint_16 v;
             int j;
-            unsigned int v, out;
 
             v = *bp;
-            out = 0;
-
+            *bp = 0;
             for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
             {
                if (j > 0)
-                  out |= v << j;
-
+                  *bp |= (png_byte)((v << j) & 0xff);
                else
-                  out |= (v >> (-j)) & mask;
+                  *bp |= (png_byte)((v >> (-j)) & mask);
             }
-
-            *bp = (png_byte)(out & 0xff);
          }
       }
-
       else if (row_info->bit_depth == 8)
       {
          png_bytep bp = row;
@@ -329,26 +295,21 @@ png_do_shift(png_row_infop row_info, png_bytep row,
          for (i = 0; i < istop; i++, bp++)
          {
 
-            const unsigned int c = i%channels;
+            png_uint_16 v;
             int j;
-            unsigned int v, out;
+            int c = (int)(i%channels);
 
             v = *bp;
-            out = 0;
-
+            *bp = 0;
             for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
             {
                if (j > 0)
-                  out |= v << j;
-
+                  *bp |= (png_byte)((v << j) & 0xff);
                else
-                  out |= v >> (-j);
+                  *bp |= (png_byte)((v >> (-j)) & 0xff);
             }
-
-            *bp = (png_byte)(out & 0xff);
          }
       }
-
       else
       {
          png_bytep bp;
@@ -357,22 +318,20 @@ png_do_shift(png_row_infop row_info, png_bytep row,
 
          for (bp = row, i = 0; i < istop; i++)
          {
-            const unsigned int c = i%channels;
+            int c = (int)(i%channels);
+            png_uint_16 value, v;
             int j;
-            unsigned int value, v;
 
-            v = png_get_uint_16(bp);
+            v = (png_uint_16)(((png_uint_16)(*bp) << 8) + *(bp + 1));
             value = 0;
-
             for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
             {
                if (j > 0)
-                  value |= v << j;
-
+                  value |= (png_uint_16)((v << j) & (png_uint_16)0xffff);
                else
-                  value |= v >> (-j);
+                  value |= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff);
             }
-            *bp++ = (png_byte)((value >> 8) & 0xff);
+            *bp++ = (png_byte)(value >> 8);
             *bp++ = (png_byte)(value & 0xff);
          }
       }
@@ -386,16 +345,18 @@ png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_write_swap_alpha");
 
+#ifdef PNG_USELESS_TESTS_SUPPORTED
+   if (row != NULL && row_info != NULL)
+#endif
    {
       if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
       {
+         /* This converts from ARGB to RGBA */
          if (row_info->bit_depth == 8)
          {
-            /* This converts from ARGB to RGBA */
             png_bytep sp, dp;
             png_uint_32 i;
             png_uint_32 row_width = row_info->width;
-
             for (i = 0, sp = dp = row; i < row_width; i++)
             {
                png_byte save = *(sp++);
@@ -405,11 +366,9 @@ png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
                *(dp++) = save;
             }
          }
-
-#ifdef PNG_WRITE_16BIT_SUPPORTED
+         /* This converts from AARRGGBB to RRGGBBAA */
          else
          {
-            /* This converts from AARRGGBB to RRGGBBAA */
             png_bytep sp, dp;
             png_uint_32 i;
             png_uint_32 row_width = row_info->width;
@@ -429,14 +388,12 @@ png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
                *(dp++) = save[1];
             }
          }
-#endif /* PNG_WRITE_16BIT_SUPPORTED */
       }
-
       else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
       {
+         /* This converts from AG to GA */
          if (row_info->bit_depth == 8)
          {
-            /* This converts from AG to GA */
             png_bytep sp, dp;
             png_uint_32 i;
             png_uint_32 row_width = row_info->width;
@@ -448,11 +405,9 @@ png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
                *(dp++) = save;
             }
          }
-
-#ifdef PNG_WRITE_16BIT_SUPPORTED
+         /* This converts from AAGG to GGAA */
          else
          {
-            /* This converts from AAGG to GGAA */
             png_bytep sp, dp;
             png_uint_32 i;
             png_uint_32 row_width = row_info->width;
@@ -468,7 +423,6 @@ png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
                *(dp++) = save[1];
             }
          }
-#endif /* PNG_WRITE_16BIT_SUPPORTED */
       }
    }
 }
@@ -480,16 +434,18 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_write_invert_alpha");
 
+#ifdef PNG_USELESS_TESTS_SUPPORTED
+   if (row != NULL && row_info != NULL)
+#endif
    {
       if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
       {
+         /* This inverts the alpha channel in RGBA */
          if (row_info->bit_depth == 8)
          {
-            /* This inverts the alpha channel in RGBA */
             png_bytep sp, dp;
             png_uint_32 i;
             png_uint_32 row_width = row_info->width;
-
             for (i = 0, sp = dp = row; i < row_width; i++)
             {
                /* Does nothing
@@ -501,11 +457,9 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
                *(dp++) = (png_byte)(255 - *(sp++));
             }
          }
-
-#ifdef PNG_WRITE_16BIT_SUPPORTED
+         /* This inverts the alpha channel in RRGGBBAA */
          else
          {
-            /* This inverts the alpha channel in RRGGBBAA */
             png_bytep sp, dp;
             png_uint_32 i;
             png_uint_32 row_width = row_info->width;
@@ -525,14 +479,12 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
                *(dp++) = (png_byte)(255 - *(sp++));
             }
          }
-#endif /* PNG_WRITE_16BIT_SUPPORTED */
       }
-
       else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
       {
+         /* This inverts the alpha channel in GA */
          if (row_info->bit_depth == 8)
          {
-            /* This inverts the alpha channel in GA */
             png_bytep sp, dp;
             png_uint_32 i;
             png_uint_32 row_width = row_info->width;
@@ -543,11 +495,9 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
                *(dp++) = (png_byte)(255 - *(sp++));
             }
          }
-
-#ifdef PNG_WRITE_16BIT_SUPPORTED
+         /* This inverts the alpha channel in GGAA */
          else
          {
-            /* This inverts the alpha channel in GGAA */
             png_bytep sp, dp;
             png_uint_32 i;
             png_uint_32 row_width = row_info->width;
@@ -563,12 +513,10 @@ png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
                *(dp++) = (png_byte)(255 - *(sp++));
             }
          }
-#endif /* PNG_WRITE_16BIT_SUPPORTED */
       }
    }
 }
 #endif
-#endif /* PNG_WRITE_TRANSFORMS_SUPPORTED */
 
 #ifdef PNG_MNG_FEATURES_SUPPORTED
 /* Undoes intrapixel differencing  */
@@ -577,7 +525,11 @@ png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_write_intrapixel");
 
-   if ((row_info->color_type & PNG_COLOR_MASK_COLOR))
+   if (
+#ifdef PNG_USELESS_TESTS_SUPPORTED
+       row != NULL && row_info != NULL &&
+#endif
+       (row_info->color_type & PNG_COLOR_MASK_COLOR))
    {
       int bytes_per_pixel;
       png_uint_32 row_width = row_info->width;
@@ -588,21 +540,17 @@ png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
 
          if (row_info->color_type == PNG_COLOR_TYPE_RGB)
             bytes_per_pixel = 3;
-
          else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
             bytes_per_pixel = 4;
-
          else
             return;
 
          for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
          {
-            *(rp)     = (png_byte)((*rp       - *(rp + 1)) & 0xff);
-            *(rp + 2) = (png_byte)((*(rp + 2) - *(rp + 1)) & 0xff);
+            *(rp)   = (png_byte)((*rp     - *(rp+1))&0xff);
+            *(rp+2) = (png_byte)((*(rp+2) - *(rp+1))&0xff);
          }
       }
-
-#ifdef PNG_WRITE_16BIT_SUPPORTED
       else if (row_info->bit_depth == 16)
       {
          png_bytep rp;
@@ -610,27 +558,24 @@ png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
 
          if (row_info->color_type == PNG_COLOR_TYPE_RGB)
             bytes_per_pixel = 6;
-
          else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
             bytes_per_pixel = 8;
-
          else
             return;
 
          for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
          {
-            png_uint_32 s0   = (*(rp    ) << 8) | *(rp + 1);
-            png_uint_32 s1   = (*(rp + 2) << 8) | *(rp + 3);
-            png_uint_32 s2   = (*(rp + 4) << 8) | *(rp + 5);
+            png_uint_32 s0   = (*(rp  ) << 8) | *(rp+1);
+            png_uint_32 s1   = (*(rp+2) << 8) | *(rp+3);
+            png_uint_32 s2   = (*(rp+4) << 8) | *(rp+5);
             png_uint_32 red  = (png_uint_32)((s0 - s1) & 0xffffL);
             png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
-            *(rp    ) = (png_byte)((red >> 8) & 0xff);
-            *(rp + 1) = (png_byte)(red & 0xff);
-            *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
-            *(rp + 5) = (png_byte)(blue & 0xff);
+            *(rp  ) = (png_byte)((red >> 8) & 0xff);
+            *(rp+1) = (png_byte)(red & 0xff);
+            *(rp+4) = (png_byte)((blue >> 8) & 0xff);
+            *(rp+5) = (png_byte)(blue & 0xff);
          }
       }
-#endif /* PNG_WRITE_16BIT_SUPPORTED */
    }
 }
 #endif /* PNG_MNG_FEATURES_SUPPORTED */