Proper image rendering ux (#5)

* can draw from selection

* add light-weight render manager to render many images simultaneously

* [debug me] currently the image close button does not do

* the unselected image can be closed now

* can close images and manually open them on demand

* cosmetic

* image view stuff in render subdirectory

* cosmetic

* generate docs

* review

windows support

some cosmetics

💅 and pin libCZI module

lib/rendering/PixelariumImageView.cpp

@@ -0,0 +1,70 @@
+#include "PixelariumImageView.hpp"
+
+#include <format>
+
+#include "imgui.h"
+
+/// @brief Checks if the dimensions of two ImVec2 vectors have changed significantly.
+/// @param ref_rect The reference ImVec2 vector.
+/// @param new_rect The new ImVec2 vector to compare against.
+/// @return True if the absolute difference between the y-coordinates is greater than 5 or the x-coordinates are
+/// different; otherwise, false.
+static bool dim_changed_p(const ImVec2& ref_rect, const ImVec2& new_rect)
+{
+    if (std::abs(ref_rect.y - new_rect.y) > 5 || std::abs(ref_rect.x - new_rect.x))
+    {
+        return true;
+    }
+
+    return false;
+}
+
+/// @brief Calculates dimensions to maintain aspect ratio.
+/// @param img The input image.
+/// @param curr_dim The current dimensions.
+/// @return The calculated dimensions maintaining aspect ratio.
+ImVec2 aspect_const_dimensions(const pixelarium::imaging::PixelariumImage& img, const ImVec2& curr_dim)
+{
+    const auto w_fact = (static_cast<float>(curr_dim.x) / img.GetImage().cols);
+    const auto h_fact = (static_cast<float>(curr_dim.y) / img.GetImage().rows);
+
+    const auto fact = w_fact < h_fact ? w_fact : h_fact;
+
+    return ImVec2(img.GetImage().cols * fact, img.GetImage().rows * fact);
+}
+
+/// @brief Displays the image in an ImGui window.
+///
+/// If the image is null, empty, or has an empty name, the function returns immediately.  Otherwise, it creates an ImGui
+/// window with a horizontal scrollbar and menu bar. The image is rendered using the CvMatRender object, resizing it to
+/// fit the available window space.  The raw and rendered dimensions are displayed below the image.
+void pixelarium::render::PixelariumImageView::ShowImage()
+{
+    if (this->img_ == nullptr || this->img_->Empty() || this->img_->Name().empty())
+    {
+        // do nothing
+        return;
+    }
+
+    ImGui::Begin(img_->Name().c_str(), &this->open_p, ImGuiWindowFlags_HorizontalScrollbar | ImGuiWindowFlags_MenuBar);
+
+    this->curr_dim_ = ImGui::GetContentRegionAvail();
+    auto new_dim = ImGui::GetContentRegionAvail();
+    auto texture =
+        dim_changed_p(this->curr_dim_, new_dim)
+            ? this->render_.Render(static_cast<size_t>(this->curr_dim_.x), static_cast<size_t>(this->curr_dim_.y))
+            : this->render_.Render();
+
+    this->curr_dim_ = new_dim;
+
+    ImVec2 dim(this->img_->GetImage().cols, this->img_->GetImage().rows);
+
+    ImGui::Image(reinterpret_cast<ImTextureID>(reinterpret_cast<void*>(texture)),
+                 aspect_const_dimensions(*this->img_, new_dim));
+
+    ImGui::Separator();
+    ImGui::Text("%s", std::format("   Raw Dimensions W : {}, H: {}", dim.x, dim.y).c_str());
+    ImGui::Text("%s", std::format("Render Dimensions W : {}, H: {}", curr_dim_.x, curr_dim_.y).c_str());
+
+    ImGui::End();
+}