Enhance image type support (#18)

* adds tiff support

* doc update

* adds memory-based =IPixelariumImage= implementation

* add usage example for custom user control

* enhance

* clang-format

fix readme

fix docs

lib/imaging/impl/PixelariumMem.cpp

@@ -0,0 +1,26 @@
+#include "PixelariumMem.hpp"
+
+#include <filesystem>
+#include <memory>
+#include <opencv2/imgcodecs.hpp>
+#include <string>
+
+pixelarium::imaging::PixelariumMem::PixelariumMem(const cv::Mat& img, const std::string& name, const Log& log)
+    : img_(img), log_(log), name_(name)
+{
+    this->is_empty_ = false;
+    this->uri_ = std::filesystem::path();
+}
+
+std::unique_ptr<cv::Mat> pixelarium::imaging::PixelariumMem::TryGetImage()
+{
+    // ToDo: this craving for a revision of the whole concept:
+    // the interface requires a unique_ptr here. This concept was designed to "create an in-memory image on demand" sort
+    // of.
+    // I.e., it only makes sense for the file types that do not already manage a cv::Mat in memory.
+    // PixelariumMem is meant for exactly this in-memory management of a cv::Mat though.
+    // So, returning a unique_ptr from it in the following semantic essentially calls the
+    // copy constructor of cv::Mat. This is potentially not "super bad", but at least it requires attention at some
+    // point.
+    return std::make_unique<cv::Mat>(this->img_);
+}

lib/imaging/impl/PixelariumMem.hpp

@@ -0,0 +1,47 @@
+#pragma once
+
+#include <stdexcept>
+#include <string>
+
+#include "../IPixelariumImage.hpp"
+#include "utilities/ILog.hpp"
+
+namespace pixelarium::imaging
+{
+/// @brief Implements support for in-memory images in the realm of IPixelariumImage
+class PixelariumMem : public IPixelariumImage
+{
+    using Log = pixelarium::utils::log::ILog;
+
+   public:
+    explicit PixelariumMem(const cv::Mat& img, const std::string& name, const Log& log);
+
+    // IPixelariumImage member implementations
+   public:
+    std::unique_ptr<cv::Mat> TryGetImage() override;
+
+    std::unique_ptr<cv::Mat> TryGetImage(const IImageQuery&) override { throw std::runtime_error("Not implemented."); }
+
+    std::vector<std::unique_ptr<cv::Mat>> TryGetImages(const IImageQuery&) override
+    {
+        throw std::runtime_error("Not implemented.");
+    }
+
+    void SetImage(const cv::Mat& img) { this->img_ = img; }
+
+    std::string Name() const noexcept override { return this->name_; }
+
+    bool Empty() const noexcept override { return this->is_empty_; }
+
+   public:
+    const static ImageFileType type_{ImageFileType::kMemory};
+
+   private:
+    // this should be set by each image getter
+    // after a new cv::Mat could be instantiated
+    bool is_empty_{true};
+    cv::Mat img_;
+    const Log& log_;
+    std::string name_;
+};
+}  // namespace pixelarium::imaging

lib/imaging/impl/PixelariumTiff.cpp

@@ -0,0 +1,34 @@
+#include "PixelariumTiff.hpp"
+
+#include <filesystem>
+#include <memory>
+#include <opencv2/imgcodecs.hpp>
+#include <string>
+
+pixelarium::imaging::PixelariumTiff::PixelariumTiff(const std::string& uri, const Log& log) : log_(log)
+{
+    if (!std::filesystem::exists(uri))
+    {
+        throw std::runtime_error("Render file not found.");
+    }
+
+    this->is_empty_ = false;
+    this->uri_ = std::filesystem::path(uri);
+}
+
+std::unique_ptr<cv::Mat> pixelarium::imaging::PixelariumTiff::TryGetImage()
+{
+    try
+    {
+        auto img = std::make_unique<cv::Mat>(cv::imread(this->uri_.string()));
+
+        this->is_empty_ = false;
+
+        return img;
+    }
+    catch (const std::exception& e)
+    {
+        this->is_empty_ = true;
+        return {};
+    }
+}

lib/imaging/impl/PixelariumTiff.hpp

@@ -0,0 +1,46 @@
+#pragma once
+
+#include <stdexcept>
+#include <string>
+
+#include "../IPixelariumImage.hpp"
+#include "utilities/ILog.hpp"
+
+namespace pixelarium::imaging
+{
+/// @brief Implements support for .tiff-images in the realm of IPixelariumImage
+class PixelariumTiff : public IPixelariumImage
+{
+    using Log = pixelarium::utils::log::ILog;
+
+   public:
+    explicit PixelariumTiff(const std::string& uri, const Log& log);
+
+    // IPixelariumImage member implementations
+   public:
+    std::unique_ptr<cv::Mat> TryGetImage() override;
+
+    std::unique_ptr<cv::Mat> TryGetImage(const IImageQuery&) override
+    {
+        // ToDo: proper error
+        throw std::runtime_error("Not possible with tiff.");
+    }
+
+    std::vector<std::unique_ptr<cv::Mat>> TryGetImages(const IImageQuery&) override
+    {
+        // ToDo: proper error
+        throw std::runtime_error("Not possible with tiff.");
+    }
+
+    bool Empty() const noexcept override { return this->is_empty_; }
+
+   public:
+    const static ImageFileType type_{ImageFileType::kTiff};
+
+   private:
+    // this should be set by each image getter
+    // after a new cv::Mat could be instantiated
+    bool is_empty_{true};
+    const Log& log_;
+};
+}  // namespace pixelarium::imaging