From f9fa9c24612a6395bfb0c6796b833fd4c2a3a464 Mon Sep 17 00:00:00 2001
From: Dane Springmeyer <dane@dbsgeo.com>
Date: Sun, 4 Nov 2012 06:58:25 -0500
Subject: [PATCH] Add support for missing user ability to set Z_FIXED zlib
 strategy

---
 CHANGELOG.md       | 2 ++
 src/image_util.cpp | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 73f77691e..e64aec429 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,8 @@ For a complete change history, see the git log.
 
 ## Future
 
+- Added support for setting zlib `Z_FIXED` strategy with format string: `png:z=fixed`
+
 - Fixed handling of transparency level option in Octree-based PNG encoding (#1556)
 
 - Faster rendering of rasters by reducing memory allocation of temporary buffers (#1516)
diff --git a/src/image_util.cpp b/src/image_util.cpp
index 623cf267d..53824e462 100644
--- a/src/image_util.cpp
+++ b/src/image_util.cpp
@@ -198,6 +198,10 @@ void handle_png_options(std::string const& type,
                 {
                     *strategy = Z_RLE;
                 }
+                else if (s == "fixed")
+                {
+                    *strategy = Z_FIXED;
+                }
                 else
                 {
                     throw ImageWriterException("invalid compression strategy parameter: " + s);