ImHex/main/gui/source/window/web_window.cpp

#include "window.hpp"

#if defined(OS_WEB)

#include <emscripten.h>
#include <emscripten/html5.h>

#include <hex/api/event_manager.hpp>

// Function used by c++ to get the size of the html canvas
EM_JS(int, canvas_get_width, (), {
    return Module.canvas.width;
});

// Function used by c++ to get the size of the html canvas
EM_JS(int, canvas_get_height, (), {
    return Module.canvas.height;
});

// Function called by javascript
EM_JS(void, resizeCanvas, (), {
    js_resizeCanvas();
});

EM_JS(void, setupThemeListener, (), {
    window.matchMedia('(prefers-color-scheme: dark)').addEventListener('change', event => {
        Module._handleThemeChange();
    });
});

EM_JS(bool, isDarkModeEnabled, (), {
    return window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches
});

EMSCRIPTEN_KEEPALIVE
extern "C" void handleThemeChange() {
    hex::EventOSThemeChanged::post();
}

namespace hex {

    void nativeErrorMessage(const std::string &message) {
        log::fatal(message);
        EM_ASM({
            alert(UTF8ToString($0));
        }, message.c_str());
    }

    void Window::initNative() {
        EM_ASM({
            // Save data directory
            FS.mkdir("/home/web_user/.local");
            FS.mount(IDBFS, {}, '/home/web_user/.local');

            FS.syncfs(true, function (err) {
                if (!err)
                    return;
                alert("Failed to load permanent file system: "+err);
            });
        });
    }

    void Window::setupNativeWindow() {
        resizeCanvas();
        setupThemeListener();

        bool themeFollowSystem = ImHexApi::System::usesSystemThemeDetection();
        EventOSThemeChanged::subscribe(this, [themeFollowSystem] {
            if (!themeFollowSystem) return;

            RequestChangeTheme::post(!isDarkModeEnabled() ? "Light" : "Dark");
        });

        if (themeFollowSystem)
            EventOSThemeChanged::post();
    }

    void Window::beginNativeWindowFrame() {
        static i32 prevWidth = 0;
        static i32 prevHeight = 0;

        auto width = canvas_get_width();
        auto height = canvas_get_height();

        if (prevWidth != width || prevHeight != height) {
            // Size has changed

            prevWidth  = width;
            prevHeight = height;
            this->resize(width, height);
        }
    }

    void Window::endNativeWindowFrame() {
    }

}

#endif