make imgcodecs optional for highgui

modules/highgui/CMakeLists.txt

@@ -1,9 +1,9 @@
 set(the_description "High-level GUI")
 
 if(ANDROID)
-  ocv_add_module(highgui opencv_imgproc opencv_imgcodecs OPTIONAL opencv_videoio WRAP python)
+  ocv_add_module(highgui opencv_imgproc OPTIONAL opencv_imgcodecs opencv_videoio WRAP python)
 else()
-  ocv_add_module(highgui opencv_imgproc opencv_imgcodecs OPTIONAL opencv_videoio WRAP python java)
+  ocv_add_module(highgui opencv_imgproc OPTIONAL opencv_imgcodecs opencv_videoio WRAP python java)
 endif()
 
 include(${CMAKE_CURRENT_LIST_DIR}/cmake/plugin.cmake)

modules/highgui/src/plugin_wrapper.impl.hpp

@@ -235,12 +235,15 @@ std::vector<FileSystemPath_t> getPluginCandidates(const std::string& baseName)
     return results;
 }
 
-// NB: require loading of imgcodecs module
+#ifdef HAVE_OPENCV_IMGCODECS // NB: require loading of imgcodecs module
 static void* g_imwrite = (void*)imwrite;
+#endif
 
 void PluginUIBackendFactory::loadPlugin()
 {
+#ifdef HAVE_OPENCV_IMGCODECS
     CV_Assert(g_imwrite);
+#endif
     for (const FileSystemPath_t& plugin : getPluginCandidates(baseName_))
     {
         auto lib = std::make_shared<cv::plugin::impl::DynamicLib>(plugin);

modules/highgui/src/precomp.hpp

@@ -60,8 +60,6 @@
 #include "opencv2/imgproc/imgproc_c.h"
 #include "opencv2/highgui/highgui_c.h"
 
-#include "opencv2/imgcodecs.hpp"
-
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>

modules/highgui/src/window_w32.cpp

@@ -2132,6 +2132,7 @@ cvDestroyAllWindows(void)
 
 static void showSaveDialog(CvWindow& window)
 {
+#ifdef HAVE_OPENCV_IMGCODECS
     if (!window.image)
         return;
 
@@ -2193,6 +2194,11 @@ static void showSaveDialog(CvWindow& window)
         cv::flip(cv::Mat(sz.cy, sz.cx, CV_8UC(channels), data, (sz.cx * channels + 3) & -4), tmp, 0);
         cv::imwrite(szFileName, tmp);
     }
+#else
+    CV_UNUSED(window);
+    CV_LOG_WARNING("Save dialog requires enabled 'imgcodecs' module.");
+    return;
+#endif
 }
 
 /*