[vtk-developers] VTK with system libpng >= 1.4

[Chuck Atkins]

It looks like when building VTK against the system libpng >= 1.4, it's still
trying to use the old 1.3 API for png_set_gray_1_2_4_to_8.

I propose the following patch deal with this accordingly.  Comments,
criticisms?

- Chuck

>From 110f26909454b8b51672fb246b992e93cd723276 Mon Sep 17 00:00:00 2001
From: Chuck Atkins <chuck.atkins at kitware.com>
Date: Wed, 21 Apr 2010 13:59:49 -0400
Subject: [PATCH] ENH: Accommodate libpng API change from 1.3 -> 1.4

A macro was added to replace calls to png_set_gray_1_2_4_to_8 with calls to
png_set_expand_gray_1_2_4_to_8 as per the API change in libpng 1.3 -> libpng
1.4.  The macro preserves backwards compatibility with 1.3 and should only
take effect when using the system libpng instead of the included libpng.
---
 IO/vtkPNGReader.cxx |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/IO/vtkPNGReader.cxx b/IO/vtkPNGReader.cxx
index 9ef592c..465b007 100644
--- a/IO/vtkPNGReader.cxx
+++ b/IO/vtkPNGReader.cxx
@@ -20,6 +20,15 @@
 #include "vtkPointData.h"
 #include "vtk_png.h"

+// If the system libpng is newer than 1.3 then adjust the set_gray call
+// to conform to the new API
+#if !defined(png_set_gray_1_2_4_to_8) && \
+    defined(PNG_LIBPNG_VER_MAJOR) && defined(PNG_LIBPNG_VER_MINOR) && \
+    (PNG_LIBPNG_VER_MAJOR > 1 || \
+     (PNG_LIBPNG_VER_MAJOR == 1 && PNG_LIBPNG_VER_MINOR >= 4))
+#define png_set_gray_1_2_4_to_8 png_set_expand_gray_1_2_4_to_8
+#endif
+
 vtkCxxRevisionMacro(vtkPNGReader, "1.27");
 vtkStandardNewMacro(vtkPNGReader);

-- 
1.7.0.5
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