Support for libpng > 1.2.

  * Add conditional defines for deprecated NULL type casts.
  * Use wrapper functions for accessing png_structp & png_infop fields
    (direct access is deprecated).

Tested on Fedora 17 (libpng 1.5) and Ubuntu 12.04 (libpng 1.2).

Note: there is one png_structp direct field acces left in
SkPNGImageDecoder::onDecodeRegion() for which libpng does not provide a
wrapper method (png_ptr->pass = 0). That should be OK for now as the code
is only enabled when SK_BUILD_FOR_ANDROID is set, and the Android libpng
version is striclty controlled. But it may become an issue in the future
when/if Android decides to update libpng, so we should investigate a
solution.


R=scroggo@google.com, reed@google.com, djsollen@google.com

Author: fmalita@google.com

Review URL: https://chromiumcodereview.appspot.com/14645018

git-svn-id: http://skia.googlecode.com/svn/trunk@8956 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 35 insertions, 11 deletions

diff --git a/src/images/SkImageDecoder_libpng.cpp b/src/images/SkImageDecoder_libpng.cpp
index aec8948945..0e02ccf08d 100644
--- a/src/images/SkImageDecoder_libpng.cpp
+++ b/src/images/SkImageDecoder_libpng.cpp
@@ -23,6 +23,23 @@ extern "C" {
 #include "png.h"
 }
 
+/* These were dropped in libpng >= 1.4 */
+#ifndef png_infopp_NULL
+#define png_infopp_NULL NULL
+#endif
+
+#ifndef png_bytepp_NULL
+#define png_bytepp_NULL NULL
+#endif
+
+#ifndef int_p_NULL
+#define int_p_NULL NULL
+#endif
+
+#ifndef png_flush_ptr_NULL
+#define png_flush_ptr_NULL NULL
+#endif
+
 class SkPNGImageIndex {
 public:
     SkPNGImageIndex(png_structp png_ptr, png_infop info_ptr) {
@@ -90,7 +107,7 @@ private:
 };
 
 static void sk_read_fn(png_structp png_ptr, png_bytep data, png_size_t length) {
-    SkStream* sk_stream = (SkStream*) png_ptr->io_ptr;
+    SkStream* sk_stream = (SkStream*) png_get_io_ptr(png_ptr);
     size_t bytes = sk_stream->read(data, length);
     if (bytes != length) {
         png_error(png_ptr, "Read Error!");
@@ -99,7 +116,7 @@ static void sk_read_fn(png_structp png_ptr, png_bytep data, png_size_t length) {
 
 #ifdef SK_BUILD_FOR_ANDROID
 static void sk_seek_fn(png_structp png_ptr, png_uint_32 offset) {
-    SkStream* sk_stream = (SkStream*) png_ptr->io_ptr;
+    SkStream* sk_stream = (SkStream*) png_get_io_ptr(png_ptr);
     sk_stream->rewind();
     (void)sk_stream->skip(offset);
 }
@@ -240,7 +257,7 @@ bool SkPNGImageDecoder::onDecodeInit(SkStream* sk_stream, png_structp *png_ptrp,
     }
     /* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */
     if (colorType == PNG_COLOR_TYPE_GRAY && bitDepth < 8) {
-        png_set_gray_1_2_4_to_8(png_ptr);
+        png_set_expand_gray_1_2_4_to_8(png_ptr);
     }
 
     /* Make a grayscale image into RGB. */
@@ -437,16 +454,16 @@ bool SkPNGImageDecoder::getBitmapConfig(png_structp png_ptr, png_infop info_ptr,
 
     // check for sBIT chunk data, in case we should disable dithering because
     // our data is not truely 8bits per component
-    if (*doDitherp) {
+    png_color_8p sig_bit;
+    if (*doDitherp && png_get_sBIT(png_ptr, info_ptr, &sig_bit)) {
 #if 0
-        SkDebugf("----- sBIT %d %d %d %d\n", info_ptr->sig_bit.red,
-                 info_ptr->sig_bit.green, info_ptr->sig_bit.blue,
-                 info_ptr->sig_bit.alpha);
+        SkDebugf("----- sBIT %d %d %d %d\n", sig_bit->red, sig_bit->green,
+                 sig_bit->blue, sig_bit->alpha);
 #endif
         // 0 seems to indicate no information available
-        if (pos_le(info_ptr->sig_bit.red, SK_R16_BITS) &&
-            pos_le(info_ptr->sig_bit.green, SK_G16_BITS) &&
-            pos_le(info_ptr->sig_bit.blue, SK_B16_BITS)) {
+        if (pos_le(sig_bit->red, SK_R16_BITS) &&
+            pos_le(sig_bit->green, SK_G16_BITS) &&
+            pos_le(sig_bit->blue, SK_B16_BITS)) {
             *doDitherp = false;
         }
     }
@@ -709,7 +726,14 @@ bool SkPNGImageDecoder::onDecodeRegion(SkBitmap* bm, const SkIRect& region) {
     * and update info structure.  REQUIRED if you are expecting libpng to
     * update the palette for you (ie you selected such a transform above).
     */
+
+    // Direct access to png_ptr fields is deprecated in libpng > 1.2.
+#if defined(PNG_1_0_X) || defined (PNG_1_2_X)
     png_ptr->pass = 0;
+#else
+    // FIXME: Figure out what (if anything) to do when Android moves to
+    // libpng > 1.2.
+#endif
     png_read_update_info(png_ptr, info_ptr);
 
     int actualTop = rect.fTop;
@@ -817,7 +841,7 @@ bool SkPNGImageDecoder::onDecodeRegion(SkBitmap* bm, const SkIRect& region) {
 #include "SkUnPreMultiply.h"
 
 static void sk_write_fn(png_structp png_ptr, png_bytep data, png_size_t len) {
-    SkWStream* sk_stream = (SkWStream*)png_ptr->io_ptr;
+    SkWStream* sk_stream = (SkWStream*)png_get_io_ptr(png_ptr);
     if (!sk_stream->write(data, len)) {
         png_error(png_ptr, "sk_write_fn Error!");
     }