Linux compilation with gcc

Rgb2Hires_PC/CMakeLists.txt

@@ -31,6 +31,7 @@ else()
 	find_package(ImageMagick 6.9 EXACT REQUIRED COMPONENTS Magick++ )
 endif(WIN32)
 find_package(SDL2 REQUIRED)
+find_package(Threads REQUIRED)
 
 # directories
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY_DEBUG ${CMAKE_CURRENT_SOURCE_DIR}/bin/debug)
@@ -55,9 +56,12 @@ target_include_directories(${PROJECT_NAME} PRIVATE ${ImageMagick_INCLUDE_DIRS} $
 
 # Application Picture
 add_executable(Picture src/App_Picture.cpp)
+if(NOT WIN32)
+		set_target_properties(Picture PROPERTIES COMPILE_FLAGS -pthread LINK_FLAGS -pthread)
+endif()
 target_compile_definitions(Picture PUBLIC MAGICKCORE_QUANTUM_DEPTH=16 MAGICKCORE_HDRI_ENABLE=0)
 target_include_directories(Picture PRIVATE src ${ImageMagick_INCLUDE_DIRS})
-target_link_libraries(Picture ${ImageMagick_LIBRARIES} ${SDL2_LIBRARIES} ${PROJECT_NAME})    
+target_link_libraries(Picture ${ImageMagick_LIBRARIES}  ${CMAKE_THREAD_LIBS_INIT} ${PROJECT_NAME} ${SDL2_LIBRARIES})  # SDL2 must be at the end
 set_property(TARGET Picture PROPERTY RUNTIME_OUTPUT_DIRECTORY ${CMAKE_RUNTIME_OUTPUT_DIRECTORY_DEBUG})
 
 # Application Tile

Rgb2Hires_PC/src/Display.cpp

@@ -2,6 +2,8 @@
 #include <stdexcept>
 #include <iostream>
 #include <chrono>
+
+#define SDL_MAIN_HANDLED
 #include <SDL.h>
 
 #include "Picture.h"
@@ -175,7 +177,7 @@ namespace RgbToHires
 
 
 		//===========================================================================
-// RGB videocards HGR
+		// RGB videocards HGR
 		
 		//! @details Adapted from AppleWin: https://github.com/AppleWin/AppleWin
 		//!					 A 14-dot block is used to draw a 7-pixel block (2 * 3.5-pixel blocks)

Rgb2Hires_PC/src/Display.h

@@ -19,6 +19,7 @@
 #define _DISPLAY_H_
 
 #include <thread>
+#include <atomic>
 
 #include "ImageQuantized.h"
 #include "HiRes.h"