Managed to compile qzint with png save support included

backend_qt4/backend_qt4.pro

@@ -19,12 +19,11 @@ TARGET = QtZint
 INCLUDEPATH += ../backend
 
 #EDIT THIS !!!!
-DEFINES += ZINT_VERSION="\\\"2.3.0\\\"" NO_PNG
+DEFINES += ZINT_VERSION="\\\"2.5.0\\\""
 
 !contains(DEFINES, NO_PNG) {
-    LIBS += -llibpng
+    INCLUDEPATH += ../../lpng
-    INCLUDEPATH += ../../../support/lpng169
+    INCLUDEPATH += ../../zlib
-    QMAKE_LIBDIR+=../../../support/lpng169/projects/visualc71/Win32_LIB_Release ../../../support/lpng169/projects/visualc71/Win32_LIB_Release/ZLib
 }
 
 contains(DEFINES, QR_SYSTEM){
@@ -104,7 +103,7 @@ SOURCES += ../backend/2of5.c \
            ../backend/png.c \
            qzint.cpp
 
-VERSION = 2.3.0
+VERSION = 2.5.0
 
 #DESTDIR = .
 

frontend_qt4/frontend_qt4.pro

@@ -7,7 +7,6 @@ TEMPLATE = app
 TARGET = qtZint
 DEPENDPATH += . debug release
 INCLUDEPATH += .
-DEFINES += NO_PNG
 
 # Input
 HEADERS += barcodeitem.h \
@@ -56,4 +55,11 @@ CONFIG += warn_on thread qt uitools
 INCLUDEPATH += ../backend_qt4 ../backend
 
 LIBS += -lqtzint -lQtCore
-QMAKE_LIBDIR += ../backend_qt4/release
+QMAKE_LIBDIR += ../backend_qt4/release
+
+!contains(DEFINES, NO_PNG) {
+    LIBS += -llibpng -lzlib
+    QMAKE_LIBDIR+=../../lpng\projects\visualc71_converted_to_9\Win32_LIB_Release ../../lpng\projects\visualc71_converted_to_9\Win32_LIB_Release\zlib
+#    LIBS += -llibpng16 -lzlib1
+#    QMAKE_LIBDIR+=../../lpng\projects\visualc71_converted_to_9\Win32_DLL_Release ../../lpng\projects\visualc71_converted_to_9\Win32_DLL_Release\zlib
+}

frontend_qt4/howto_build_qzint_using_msvs9.txt

@@ -0,0 +1,55 @@
+Harald Oehlmann
+2016-02-28
+
+How to build qzint.exe using:
+- QT 4
+- MS Visual Studio 2008 (VC9)
+
+Folder structure:
+- zint source files in $ZH
+  -> this file is in $ZH\frontend_qt4
+- png1620.zip unzipped in $ZH\..\lpng
+  -> $ZH\..\lpng\png.h exists
+- zlib128.zip inzipped in folder $ZH\..\zlib
+  -> $ZH\..\zlib\zlib.h exists
+
+Prepare qt for static build
+
+- Start "Visual Studio 2008 Command Line" (or execute "%VS90COMNTOOLS%vsvars32.bat" )
+- cd c:\qt\4.8.6
+- configure -static -release -qt-zlib  -qt-libpng -qt-libjpeg
+- nmake
+  -> took around 2 hours for me
+
+Build pnglib and zlib
+- cd $ZH\..\lpng\projects
+- copy visual71 visual71_converted_to_9
+- Start Visual Studio 2..8 (CV9)
+- open Project: $ZH\..\lpng\projects\visualc71_converted_to_9\libpng.sln
+- convert it as proposed by the IDE (no backup, we have made a copy before)
+- select "LIB Release" configuration
+- go to project "libpng" and open project options (ALT-F7)
+- On the left, select "C/C++->Code generation"
+- On the right change "Run time library" from "Multi-Treaded (/MT)" to "Multithread-DLL (/MD)"
+- also do the upper steps for the project "zlib" (change /MT to /MD)
+- Build libpng and zlib project using the Buildall menu entry
+  -> this compiles png in the static lib:
+   lpng\projects\visualc71_converted_to_9\Win32_LIB_Release\libpng.lib
+   and zlib into the static lib
+   lpng\projects\visualc71_converted_to_9\Win32_LIB_Release\zlib\zlib.lib
+
+Build zint
+
+- Start "Visual Studio 2008 Command Line" (or execute "%VS90COMNTOOLS%vsvars32.bat" )
+- C:\Qt\4.8.6\bin\qtvars.bat
+- cd $ZH
+- cd backend_qt4
+- qmake backend_qt4.pro
+- nmake clean
+- nmake release
+    
+- cd ..\frontend_qt4
+- qmake frontend_qt4.pro
+- nmake clean
+- nmake release
+  -> qzint.exe is in the release folder