Modularize imiv: split app into multiple sources

Refactor the imiv viewer by extracting large portions of imiv_app into separate, modular source/header files and adding missing components. New files added under src/imiv include imiv_actions, imiv_frame, imiv_navigation, imiv_test_engine, imiv_types, imiv_ui, imiv_viewer and several Vulkan helpers (imiv_vulkan_runtime/Setup/Texture). CMakeLists updated to read OIIO_IMIV_NFD_ROOT from the environment and to include the new source files in the build. Also minor updates to shader sources. This organizes the codebase for better separation of concerns (actions, UI, navigation, Vulkan runtime, test engine) and prepares for easier maintenance and further development.

Author: ssh4net

src/imiv/CMakeLists.txt

@@ -6,7 +6,7 @@ set (OIIO_IMIV_IMGUI_ROOT "${PROJECT_SOURCE_DIR}/../imgui" CACHE PATH
      "Path to Dear ImGui repository checkout used by imiv")
 set (OIIO_IMIV_TEST_ENGINE_ROOT "${PROJECT_SOURCE_DIR}/../imgui_test_engine" CACHE PATH
      "Path to Dear ImGui Test Engine repository checkout used by imiv tests")
-set (OIIO_IMIV_NFD_ROOT "/mnt/f/GH/oiio-builder/developer/nativefiledialog-extended" CACHE PATH
+set (OIIO_IMIV_NFD_ROOT "$ENV{OIIO_IMIV_NFD_ROOT}" CACHE PATH
      "Path hint for nativefiledialog-extended source/build/install root used by imiv")
 set (OIIO_IMIV_NFD_INCLUDE_DIR "" CACHE PATH
      "Optional explicit include directory containing nfd.h")
@@ -62,8 +62,17 @@ endif ()
 record_build_dependency (ImGui FOUND)
 
 set (_imiv_core_sources
+     imiv_actions.cpp
      imiv_app.cpp
      imiv_file_dialog.cpp
+     imiv_frame.cpp
+     imiv_navigation.cpp
+     imiv_ui.cpp
+     imiv_viewer.cpp
+     imiv_vulkan_setup.cpp
+     imiv_vulkan_runtime.cpp
+     imiv_vulkan_texture.cpp
+     imiv_test_engine.cpp
      imiv_main.cpp)
 
 set (_imiv_shader_src "${CMAKE_CURRENT_SOURCE_DIR}/shaders/imiv_upload_to_rgba.comp")