build system and module refactoring + simple histogram scratch (#20)

* scratch adding histogram to image views

Histograms should come from some sort of histogram service. This is
currently just a POC.

* custom logger implementation w/o spdlog

* missing cmake file

* fix tests

* use operator<< over direct stream exposure

* rm print header

* add threading test + refactor towards interface libraries

omits the need for =target_include_directories= calls /everywhere/

* rm print header

* rm constexpr

* templated thread_pool

* fix doxyfile

* default enable doc building

* czi reader refactor

* rm erroneous include expression

* clang-format

* single lib include with PUBLIC visibility

* compile imgui stdlib

* clang format

* documentation update

centralize `LogLevelToString` to `ILog.hpp`

update docs and examples

lib/app/rendering/include/CvMatRender.hpp

@@ -0,0 +1,52 @@
+#pragma once
+// windows.h must come before GL/GL.h here.
+// clang format would change this, effectively rendering the build broken.
+// clang-format off
+#ifdef _WIN32
+#include <windows.h>
+#include <GL/GL.h>
+#else
+#define GL_SILENCE_DEPRECATION
+#if defined(IMGUI_IMPL_OPENGL_ES2)
+#include <GLES2/gl2.h>
+#endif
+#include <GLFW/glfw3.h>  // Will drag system OpenGL headers
+#endif
+#include <opencv2/core/mat.hpp>
+// clang-format on
+
+namespace pixelarium::application
+{
+/// @brief Renders cv::Mat bitmaps as OpenGL textures.
+class CvMatRender
+{
+   public:
+    // we want the default constructor for the time being
+    // (although it does not make much sense and should
+    // get removed in the future)
+    // as the using AppGLFW constructs it empty as a member
+    // when coming to life.
+    // CvMatRender() = default;
+    CvMatRender(CvMatRender&) = delete;
+    CvMatRender(const CvMatRender&) = delete;
+    CvMatRender(CvMatRender&&) = delete;
+    CvMatRender& operator=(CvMatRender&) = delete;
+    CvMatRender& operator=(CvMatRender&& other) = delete;
+    ~CvMatRender();
+    explicit CvMatRender(const cv::Mat& img);
+
+   public:
+    GLuint Render();
+    GLuint Render(float factor);
+    GLuint Render(size_t width, size_t height);
+    void ResetRenderImage();
+
+   private:
+    cv::Mat img_;
+    const cv::Mat& base_;
+    GLuint texture_;
+
+    GLuint uploadTexture();
+};
+
+}  // namespace pixelarium::application

lib/app/rendering/include/IPixelariumImageView.hpp

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <memory>
+
+#include "IPixelariumImage.hpp"
+#include "imgui.h"
+
+namespace pixelarium::application
+{
+/// @brief An interface defining the contract on views to dedicated implementations of IPixelariumImage
+class IPixelariumImageView
+{
+   public:
+    virtual ~IPixelariumImageView() = default;
+    virtual void ShowImage() = 0;
+
+    // default implemented
+   public:
+    virtual const bool* GetStatus() const noexcept { return &this->open_p; }
+    virtual void ForceUpdate() noexcept { this->is_dirty_ = true; }
+
+    // this must be called immediately before a "ImGui::Begin" context
+    // as it will affect the next window and result in undeterministic effects
+    // when called "out of sync"
+    virtual void SetInitialSize(float width = 700.0f, float height = 700.0f)
+    {
+        ImGui::SetNextWindowSize({width, height});
+    }
+
+   protected:
+    virtual void ImageViewMenuBar();
+    virtual void ImageViewMenuBarAdditions() {};
+
+   protected:
+    std::shared_ptr<imaging::IPixelariumImageCvMat> img_{};
+    cv::Mat cached_image_{};
+    bool open_p{true};
+    bool is_dirty_{true};
+    bool first_render_{true};
+};
+}  // namespace pixelarium::application

lib/app/rendering/include/ImageViewFactory.hpp

@@ -0,0 +1,25 @@
+#pragma once
+
+#include "ILog.hpp"
+#include "IPixelariumImageView.hpp"
+#include "resource.hpp"
+
+namespace pixelarium::application
+{
+/// @brief Factory for instantiating matching views to different implementations of IPixelariumImage.
+class ImageViewFactory
+{
+    using Image = imaging::IPixelariumImageCvMat;
+    using Pool = resources::ImageResourcePool;
+    using Log = utils::log::ILog;
+
+   public:
+    explicit ImageViewFactory(Pool& pool, const Log& log) : image_pool_(pool), log_(log) {}
+
+    std::unique_ptr<IPixelariumImageView> RenderImage(resources::ResourceKey id);
+
+   private:
+    Pool& image_pool_;
+    const Log& log_;
+};
+}  // namespace pixelarium::application

lib/app/rendering/include/PixelariumImageViewCzi.hpp

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <memory>
+#include <unordered_map>
+
+#include "CvMatRender.hpp"
+#include "ILog.hpp"
+#include "IPixelariumImage.hpp"
+#include "IPixelariumImageView.hpp"
+#include "imgui.h"
+#include "libCZI_DimCoordinate.h"
+
+namespace pixelarium::application
+{
+/// @brief A CZI-specific implementation of IPixelariumImageView.
+class PixelariumImageViewCzi : public IPixelariumImageView
+{
+    using Image = imaging::IPixelariumImageCvMat;
+    using Log = utils::log::ILog;
+
+   public:
+    explicit PixelariumImageViewCzi(std::shared_ptr<Image> img, const Log& log);
+    PixelariumImageViewCzi() = delete;
+    PixelariumImageViewCzi(PixelariumImageViewCzi&) = delete;
+    PixelariumImageViewCzi(const PixelariumImageViewCzi&) = delete;
+    PixelariumImageViewCzi(PixelariumImageViewCzi&&) = delete;
+    PixelariumImageViewCzi& operator=(PixelariumImageViewCzi&) = delete;
+    PixelariumImageViewCzi& operator=(PixelariumImageViewCzi&&) = delete;
+
+    void ShowImage() override;
+
+   private:
+    ImVec2 curr_dim_{};
+    const Log& log_;
+    std::unordered_map<libCZI::DimensionIndex, int> dimension_map_;
+    std::unique_ptr<CvMatRender> render_;
+
+   private:
+    void RefreshCachedImage();
+};
+}  // namespace pixelarium::application

lib/app/rendering/include/PixelariumImageViewDefault.hpp

@@ -0,0 +1,46 @@
+#pragma once
+
+#include <memory>
+#include <vector>
+
+#include "CvMatRender.hpp"
+#include "IPixelariumImage.hpp"
+#include "IPixelariumImageView.hpp"
+#include "imgui.h"
+
+namespace pixelarium::application
+{
+/// @brief A default implementation of IPixelariumImageView.
+/// This is sufficient for single dimension images like png or jpg.
+class PixelariumImageViewDefault : public IPixelariumImageView
+{
+    using Image = imaging::IPixelariumImageCvMat;
+
+   public:
+    explicit PixelariumImageViewDefault(std::shared_ptr<Image> img) : render_(*img->TryGetImage()) { img_ = img; }
+
+    PixelariumImageViewDefault() = delete;
+    PixelariumImageViewDefault(PixelariumImageViewDefault&) = delete;
+    PixelariumImageViewDefault(const PixelariumImageViewDefault&) = delete;
+    PixelariumImageViewDefault(PixelariumImageViewDefault&&) = delete;
+    PixelariumImageViewDefault& operator=(PixelariumImageViewDefault&) = delete;
+    PixelariumImageViewDefault& operator=(PixelariumImageViewDefault&&) = delete;
+
+    void ShowImage() override;
+
+    void ImageViewMenuBarAdditions() override;
+
+    void GenerateHistogram();
+
+   private:
+    ImVec2 curr_dim_{};
+    CvMatRender render_;
+    bool show_hists_{false};
+    bool hist_available_{false};
+    std::vector<cv::Mat> bgr_planes_;
+    std::vector<cv::Mat> hist_planes_;
+
+   private:
+    void RefreshCachedImage();
+};
+}  // namespace pixelarium::application

lib/app/rendering/include/RenderHelpers.hpp

@@ -0,0 +1,10 @@
+#pragma once
+
+#include "imgui.h"
+
+namespace pixelarium::application
+{
+bool dim_changed_p(const ImVec2& ref_rect, const ImVec2& new_rect);
+
+ImVec2 aspect_const_dimensions(const ImVec2& raw_dim, const ImVec2& curr_dim);
+};  // namespace pixelarium::application

lib/app/rendering/include/RenderImageManager.hpp

@@ -0,0 +1,75 @@
+#pragma once
+#include <memory>
+#include <mutex>
+#include <unordered_map>
+#include <unordered_set>
+
+#include "ILog.hpp"
+#include "IPixelariumImageView.hpp"
+#include "ImageViewFactory.hpp"
+#include "resource.hpp"
+
+// This is intended as an additional abstraction
+// aggregating views that should be rendered (or not)
+namespace pixelarium::application
+{
+/// @brief Instead of directly using the view, we
+/// proxy it through a wrapper. This allows for arbitrary additional data
+/// to be added in future
+struct RenderImageStateWrapper
+{
+    std::unique_ptr<IPixelariumImageView> view;
+    const bool* show_state;
+};
+
+/// @brief Manage instances of IPixelariumImageView.
+///
+/// This class is used to keep track of what must be rendered.
+/// It manages a set of IPixelariumImageView instances that can be traversed
+/// via its Enumerate() function.
+/// Views that shall not be rendered anymore should be marked for deletion
+/// with MarkForDeletion()
+class RenderImageManager
+{
+    using Pool = resources::ImageResourcePool;
+
+   public:
+    explicit RenderImageManager(Pool& pool, const utils::log::ILog& log)
+        : view_factory_(std::make_unique<ImageViewFactory>(pool, log)), log_(log)
+    {
+    }
+
+    void Clear() noexcept;
+
+    void Add(resources::ResourceKey key) noexcept;
+
+    bool Remove(resources::ResourceKey key) noexcept;
+
+    // can't be const because func mutates the state
+    template <typename Callable>
+        requires std::invocable<Callable, resources::ResourceKey, RenderImageStateWrapper&>
+    void Enumerate(Callable&& func)
+    {
+        for (auto& [key, val] : this->render_image_map_)
+        {
+            if (val.view != nullptr)
+            {
+                func(key, val);
+            }
+        }
+    }
+
+    void MarkForDeletion(resources::ResourceKey key);
+
+    void UpdateCollection();
+
+   private:
+    std::unordered_map<resources::ResourceKey, RenderImageStateWrapper> render_image_map_;
+    std::unique_ptr<ImageViewFactory> view_factory_;
+    std::mutex mut_;
+    std::unordered_set<resources::ResourceKey> keys_to_delete_;
+    std::unordered_set<resources::ResourceKey> failed_keys_cache_;
+
+    const utils::log::ILog& log_;
+};
+}  // namespace pixelarium::application