Misc (#19)

* get image returns optional<Mat> instead of unique_ptr<Mat>

* introduce complexity

* rename image load function

* add example for a basic reader for binary image files

* fix windows build?

* add a status bar underneath the menu bar

* use status bar in custom_0 example app

* clang formats

* packing w/ pragma push

* add "Save As" functions to image views

* resize over reserve

* rm local override uri

* add simple thread pool

* rename to simple_thread_pool

* get rid of useless renderlib

* document version inc

* extract hardcoded values to in-header

* clang format patch

* clone registered image in custom_0

* document binary-file header

* minor fixes

* clang format

* rm unused render cmake

lib/app/rendering/IPixelariumImageView.hpp

@@ -0,0 +1,40 @@
+#pragma once
+
+#include <memory>
+
+#include "imaging/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();
+
+   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