pixelarium/lib/app/rendering/PixelariumImageViewDefault.cpp

#include "PixelariumImageViewDefault.hpp"

#include <opencv2/core/hal/interface.h>

#include <cstdio>
#include <format>
#include <iostream>
#include <opencv2/core.hpp>
#include <opencv2/imgproc.hpp>
#include <ostream>
#include <ranges>
#include <utility>

#include "IPixelariumImage.hpp"
#include "RenderHelpers.hpp"
#include "app_resources_default.h"
#include "imgui.h"
#include "implot.h"
#include "simple_thread_pool.hpp"

void pixelarium::application::PixelariumImageViewDefault::RefreshCachedImage()
{
    if (this->cached_image_.empty() || this->is_dirty_)
    {
        this->cached_image_ = this->img_->TryGetImage().value_or(cv::Mat{});
        this->is_dirty_ = false;
    }
}

void pixelarium::application::PixelariumImageViewDefault::ImageViewMenuBarAdditions()
{
    ImGui::MenuItem("Histogram", NULL, &this->show_hists_);
}

/// @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::application::PixelariumImageViewDefault::ShowImage()
{
    RefreshCachedImage();

    if (this->img_->Empty() || this->img_->type_ == imaging::ImageFileType::kUnknown || this->cached_image_.empty() ||
        this->img_->Name().empty())
    {
        // do nothing
        return;
    }

    if (first_render_)
    {
        first_render_ = false;

        const auto cached_width{cached_image_.cols};
        const auto cached_heigth{cached_image_.rows};
        const auto ratio{static_cast<float>(cached_heigth) / cached_width};
        SetInitialSize(kInitialWindowWidth, (kInitialWindowWidth * ratio + 100));
        utils::pixelarium_pool::enqueue([this]() { GenerateHistogram(); });
    }

    ImGui::Begin(this->img_->Name().c_str(), &this->open_p,
                 ImGuiWindowFlags_HorizontalScrollbar | ImGuiWindowFlags_MenuBar);

    ImageViewMenuBar();

    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(cached_image_.cols, cached_image_.rows);

    ImGui::Image(reinterpret_cast<ImTextureID>(reinterpret_cast<void*>(texture)),
                 aspect_const_dimensions(dim, new_dim));

    ImGui::Separator();

    if (show_hists_ && hist_available_)
    {
        if (ImPlot::BeginPlot("Histogram"))
        {
            ImPlot::SetupAxes(nullptr, nullptr, ImPlotAxisFlags_AutoFit, ImPlotAxisFlags_AutoFit);
            using style_pair = std::pair<const char*, ImVec4>;

            constexpr std::array<style_pair, 3> names = {
                {{"Blue", ImVec4(0, 0, 1, 1)}, {"Green", ImVec4(0, 1, 0, 1)}, {"Red", ImVec4(1, 0, 0, 1)}}};
            // for (auto& e : hist_planes_)
            // {
            //     ImPlot::PlotHistogram(name.c_str(), e.data, e.rows * e.cols, 16);
            //     for (auto& e : name)
            //     {
            //         e++;
            //     }
            // }
            for (size_t i{0}; i < hist_planes_.size(); ++i)
            {
                if (hist_planes_.at(i).type() == CV_32F)
                {
                    // ImPlot::PlotHistogram(names.at(i % 3), reinterpret_cast<float*>(hist_planes_[i].data),
                    //                       hist_planes_[i].rows * hist_planes_[i].cols, 16, 1.0, ImPlotRange(),
                    //                       ImPlotHistogramFlags_Horizontal);
                    ImPlot::PushStyleColor(ImPlotCol_Line, names.at(i % 3).second);
                    ImPlot::PlotLine(std::format("{}-line", names.at(i % 3).first).c_str(),
                                     reinterpret_cast<float*>(hist_planes_[i].data),
                                     hist_planes_[i].rows * hist_planes_[i].cols);
                    ImPlot::PopStyleColor();
                }
            }

            ImPlot::PushStyleVar(ImPlotStyleVar_FillAlpha, 0.25f);
            ImPlot::SetNextMarkerStyle(ImPlotMarker_Square, 6, ImPlot::GetColormapColor(1), IMPLOT_AUTO,
                                       ImPlot::GetColormapColor(1));

            ImPlot::EndPlot();
        }
    }

    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();
}

auto pixelarium::application::PixelariumImageViewDefault::GenerateHistogram() -> void
{
    cv::split(cached_image_, bgr_planes_);
    hist_planes_.resize(bgr_planes_.size());

    int histSize = 256;
    float range[] = {0, 256};  // the upper boundary is exclusive
    const float* histRange[] = {range};

    for (auto [bgr, hist] : std::ranges::views::zip(bgr_planes_, hist_planes_))
    {
        cv::calcHist(&bgr, 1, 0, cv::Mat(), hist, 1, &histSize, histRange, true, false);
        // cv::normalize(hist, hist);
    }

    hist_available_ = true;
}