- cmake: remove zintconfig.h.in for now as incompatible with MSVC

project builds (will add back in future if go fully CMake)
- NO_PNG -> ZINT_NO_PNG and new API function `Zint_NoPng()` to
  determine if no PNG support in libzint; replace use in GUI with
  backend_qt method `noPng()`

backend_qt/backend_qt.pro

@@ -19,7 +19,7 @@ INCLUDEPATH += ../backend
 #EDIT THIS !!!!
 DEFINES += ZINT_VERSION="\\\"2.11.1.9\\\""
 
-!contains(DEFINES, NO_PNG) {
+!contains(DEFINES, ZINT_NO_PNG) {
     INCLUDEPATH += ../../lpng
     INCLUDEPATH += ../../zlib
 }

backend_qt/backend_vc8.pro

@@ -13,7 +13,7 @@ INCLUDEPATH += ../backend d:\\opt\\include
 
 DEFINES +=  _CRT_SECURE_NO_WARNINGS _CRT_NONSTDC_NO_WARNINGS ZINT_VERSION=\\\"$$VERSION\\\" include=""
 
-!contains(DEFINES, NO_PNG) {
+!contains(DEFINES, ZINT_NO_PNG) {
     SOURCES += ../backend/png.c
 }
 

backend_qt/qzint.cpp

@@ -682,6 +682,10 @@ namespace Zint {
         return m_lastError.length();
     }
 
+    bool QZint::noPng() const {
+        return ZBarcode_NoPng() == 1;
+    }
+
     int QZint::getVersion() const {
         return ZBarcode_Version();
     }

backend_qt/qzint.h

@@ -196,6 +196,9 @@ public:
     /* Note: legacy argument `mode` is not used */
     void render(QPainter& painter, const QRectF& paintRect, AspectRatioMode mode = IgnoreAspectRatio);
 
+    /* Whether Zint library "libzint" built with PNG support or not (`ZBarcode_NoPng()`) */
+    bool noPng() const;
+
     int getVersion() const;
 
     /* Translate settings into Command Line equivalent. Set `win` to use Windows escaping of data.