WebViewX11.cpp

// SPDX-FileCopyrightText: 2023-2024 MOD Audio UG
// SPDX-License-Identifier: AGPL-3.0-or-later

#define QT_NO_VERSION_TAGGING
#include <QtCore/QChar>
#include <QtCore/QPoint>
#include <QtCore/QSize>
#undef signals

#include "WebView.hpp"

#include "ChildProcess.hpp"
#include "utils.hpp"

#include "extra/String.hpp"
#include "DistrhoPluginUtils.hpp"

#include <clocale>
#include <cstdio>
#include <dlfcn.h>
#include <functional>
#include <linux/limits.h>
#include <X11/Xlib.h>

START_NAMESPACE_DISTRHO

// -----------------------------------------------------------------------------------------------------------

struct WebViewX11 {
    ChildProcess p;
    ::Display* display;
    ::Window childWindow;
    ::Window ourWindow;
};

// -----------------------------------------------------------------------------------------------------------

void* addWebView(const uintptr_t parentWinId, const double scaleFactor, const uint port)
{
    char ldlinux[PATH_MAX] = {};
    {
        Dl_info info = {};
        dladdr(dlsym(nullptr, "_rtld_global"), &info);

        if (info.dli_fname[0] == '.')
        {
            getcwd(ldlinux, PATH_MAX - 1);
            std::strncat(ldlinux, info.dli_fname + 1, PATH_MAX - 1);
        }
        else if (info.dli_fname[0] != '/')
        {
            getcwd(ldlinux, PATH_MAX - 1);
            std::strncat(ldlinux, "/", PATH_MAX - 1);
            std::strncat(ldlinux, info.dli_fname, PATH_MAX - 1);
        }
        else
        {
            std::strncpy(ldlinux, info.dli_fname, PATH_MAX - 1);
        }
    }
    const char* const filename = getBinaryFilename();

    d_stdout("ld-linux is '%s'", ldlinux);
    d_stdout("filename is '%s'", filename);

    ::Display* const display = XOpenDisplay(nullptr);
    DISTRHO_SAFE_ASSERT_RETURN(display != nullptr, nullptr);

    // set up custom child environment
    uint envsize = 0;
    while (environ[envsize] != nullptr)
        ++envsize;

    char** const envp = new char*[envsize + 5];

    for (uint i = 0; i < envsize; ++i)
        envp[i] = strdup(environ[i]);

    for (uint i = 0; i < 5; ++i)
        envp[envsize + i] = nullptr;

    set_envp_value(envp, "LANG=en_US.UTF-8");
    set_envp_value(envp, "DPF_WEBVIEW_PORT", String(port));
    set_envp_value(envp, "DPF_WEBVIEW_SCALE_FACTOR", String(scaleFactor));
    set_envp_value(envp, "DPF_WEBVIEW_WIN_ID", String(parentWinId));

    WebViewX11* const ipc = new WebViewX11();
    ipc->display = display;
    ipc->childWindow = 0;
    ipc->ourWindow = parentWinId;

    const char* const args[] = { ldlinux, filename, "dpf-ld-linux-webview", nullptr };
    ipc->p.start(args, envp);

    for (uint i = 0; envp[i] != nullptr; ++i)
        std::free(envp[i]);
    delete[] envp;

    return ipc;
}

void destroyWebView(void* const webviewptr)
{
    WebViewX11* const ipc = static_cast<WebViewX11*>(webviewptr);

    XCloseDisplay(ipc->display);
    delete ipc;
}

void reloadWebView(void* const webviewptr, uint)
{
    WebViewX11* const ipc = static_cast<WebViewX11*>(webviewptr);

    ipc->p.signal(SIGUSR1);
}

void resizeWebView(void* const webviewptr, const uint offset, const uint width, const uint height)
{
    WebViewX11* const ipc = static_cast<WebViewX11*>(webviewptr);

    if (ipc->childWindow == 0)
    {
        ::Window rootWindow, parentWindow;
        ::Window* childWindows = nullptr;
        uint numChildren = 0;

        XFlush(ipc->display);
        XQueryTree(ipc->display, ipc->ourWindow, &rootWindow, &parentWindow, &childWindows, &numChildren);

        if (numChildren == 0 || childWindows == nullptr)
            return;

        ipc->childWindow = childWindows[0];
        XFree(childWindows);
    }

    XMoveResizeWindow(ipc->display, ipc->childWindow, 0, offset, width, height);
    XFlush(ipc->display);
}

// -----------------------------------------------------------------------------------------------------------

static std::function<void()> reloadFn;

// -----------------------------------------------------------------------------------------------------------

struct GtkContainer;
struct GtkPlug;
struct GtkWidget;
struct GtkWindow;
struct WebKitSettings;
struct WebKitWebView;

#define GTK_CONTAINER(p) reinterpret_cast<GtkContainer*>(p)
#define GTK_PLUG(p) reinterpret_cast<GtkPlug*>(p)
#define GTK_WINDOW(p) reinterpret_cast<GtkWindow*>(p)
#define WEBKIT_WEB_VIEW(p) reinterpret_cast<WebKitWebView*>(p)

struct QApplication;
struct QUrl;
struct QWebEngineView;
struct QWindow;

// -----------------------------------------------------------------------------------------------------------

#define JOIN(A, B) A ## B

#define AUTOSYM(S) \
    using JOIN(gtk3_, S) = decltype(&S); \
    JOIN(gtk3_, S) S = reinterpret_cast<JOIN(gtk3_, S)>(dlsym(nullptr, #S)); \
    DISTRHO_SAFE_ASSERT_RETURN(S != nullptr, false);

#define CSYM(S, NAME) \
    S NAME = reinterpret_cast<S>(dlsym(nullptr, #NAME)); \
    DISTRHO_SAFE_ASSERT_RETURN(NAME != nullptr, false);

#define CPPSYM(S, NAME, SN) \
    S NAME = reinterpret_cast<S>(dlsym(nullptr, #SN)); \
    DISTRHO_SAFE_ASSERT_RETURN(NAME != nullptr, false);

// -----------------------------------------------------------------------------------------------------------
// gtk3 variant

static bool gtk3(Display* const display, const Window winId, double scaleFactor, const char* const url)
{
    void* lib;
    if ((lib = dlopen("libwebkit2gtk-4.0.so.37", RTLD_NOW|RTLD_GLOBAL)) == nullptr ||
        (lib = dlopen("libwebkit2gtk-4.0.so", RTLD_NOW|RTLD_GLOBAL)) == nullptr)
        return false;

    using gdk_set_allowed_backends_t = void (*)(const char*);
    using gtk_container_add_t = void (*)(GtkContainer*, GtkWidget*);
    using gtk_init_check_t = bool (*)(int*, char***);
    using gtk_main_t = void (*)();
    using gtk_plug_get_id_t = Window (*)(GtkPlug*);
    using gtk_plug_new_t = GtkWidget* (*)(Window);
    using gtk_widget_show_all_t = void (*)(GtkWidget*);
    using gtk_window_move_t = void (*)(GtkWindow*, int, int);
    using gtk_window_set_default_size_t = void (*)(GtkWindow*, int, int);
    using webkit_settings_new_t = WebKitSettings* (*)();
    using webkit_settings_set_hardware_acceleration_policy_t = void (*)(WebKitSettings*, int);
    using webkit_settings_set_javascript_can_access_clipboard_t = void (*)(WebKitSettings*, bool);
    using webkit_web_view_load_uri_t = void (*)(WebKitWebView*, const char*);
    using webkit_web_view_new_with_settings_t = GtkWidget* (*)(WebKitSettings*);

    CSYM(gdk_set_allowed_backends_t, gdk_set_allowed_backends)
    CSYM(gtk_container_add_t, gtk_container_add)
    CSYM(gtk_init_check_t, gtk_init_check)
    CSYM(gtk_main_t, gtk_main)
    CSYM(gtk_plug_get_id_t, gtk_plug_get_id)
    CSYM(gtk_plug_new_t, gtk_plug_new)
    CSYM(gtk_widget_show_all_t, gtk_widget_show_all)
    CSYM(gtk_window_move_t, gtk_window_move)
    CSYM(gtk_window_set_default_size_t, gtk_window_set_default_size)
    CSYM(webkit_settings_new_t, webkit_settings_new)
    CSYM(webkit_settings_set_hardware_acceleration_policy_t, webkit_settings_set_hardware_acceleration_policy)
    CSYM(webkit_settings_set_javascript_can_access_clipboard_t, webkit_settings_set_javascript_can_access_clipboard)
    CSYM(webkit_web_view_load_uri_t, webkit_web_view_load_uri)
    CSYM(webkit_web_view_new_with_settings_t, webkit_web_view_new_with_settings)

    const int gdkScale = std::fmod(scaleFactor, 1.0) >= 0.75
                       ? static_cast<int>(scaleFactor + 0.5)
                       : static_cast<int>(scaleFactor);

    if (gdkScale != 1)
    {
        char scale[8] = {};
        std::snprintf(scale, 7, "%d", gdkScale);
        setenv("GDK_SCALE", scale, 1);

        std::snprintf(scale, 7, "%.2f", (1.0 / scaleFactor) * 1.2);
        setenv("GDK_DPI_SCALE", scale, 1);
    }
    else if (scaleFactor > 1.0)
    {
        char scale[8] = {};
        std::snprintf(scale, 7, "%.2f", (1.0 / scaleFactor) * 1.4);
        setenv("GDK_DPI_SCALE", scale, 1);
    }

    scaleFactor /= gdkScale;

    gdk_set_allowed_backends("x11");

    if (! gtk_init_check (nullptr, nullptr))
        return false;

    GtkWidget* const window = gtk_plug_new(winId);
    DISTRHO_SAFE_ASSERT_RETURN(window != nullptr, false);

    gtk_window_set_default_size(GTK_WINDOW(window),
                                DISTRHO_UI_DEFAULT_WIDTH * scaleFactor,
                                (DISTRHO_UI_DEFAULT_HEIGHT - kVerticalOffset) * scaleFactor);
    gtk_window_move(GTK_WINDOW(window), 0, kVerticalOffset * scaleFactor);

    WebKitSettings* const settings = webkit_settings_new();
    DISTRHO_SAFE_ASSERT_RETURN(settings != nullptr, false);

    webkit_settings_set_javascript_can_access_clipboard(settings, true);
    webkit_settings_set_hardware_acceleration_policy(settings, 2 /* WEBKIT_HARDWARE_ACCELERATION_POLICY_NEVER */);

    GtkWidget* const webview = webkit_web_view_new_with_settings(settings);
    DISTRHO_SAFE_ASSERT_RETURN(webview != nullptr, false);

    webkit_web_view_load_uri(WEBKIT_WEB_VIEW (webview), url);

    gtk_container_add(GTK_CONTAINER(window), webview);

    gtk_widget_show_all(window);

    Window wid = gtk_plug_get_id(GTK_PLUG(window));
    XMapWindow(display, wid);
    XFlush(display);

    reloadFn = [=](){
        webkit_web_view_load_uri(WEBKIT_WEB_VIEW (webview), url);
    };

    gtk_main();

    dlclose(lib);
    return true;
}

// -----------------------------------------------------------------------------------------------------------
// qt5webengine variant

static bool qt5webengine(const Window winId, const double scaleFactor, const char* const url)
{
    void* lib;
    if ((lib = dlopen("libQt5WebEngineWidgets.so.5", RTLD_NOW|RTLD_GLOBAL)) == nullptr ||
        (lib = dlopen("libQt5WebEngineWidgets.so", RTLD_NOW|RTLD_GLOBAL)) == nullptr)
        return false;

    using QApplication__init_t = void (*)(QApplication*, int&, char**, int);
    using QApplication_exec_t = void (*)();
    using QApplication_setAttribute_t = void (*)(Qt::ApplicationAttribute, bool);
    using QString__init_t = void (*)(void*, const QChar*, ptrdiff_t);
    using QUrl__init_t = void (*)(void*, const QString&, int /* QUrl::ParsingMode */);
    using QWebEngineView__init_t = void (*)(QWebEngineView*, void*);
    using QWebEngineView_move_t = void (*)(QWebEngineView*, const QPoint&);
    using QWebEngineView_resize_t = void (*)(QWebEngineView*, const QSize&);
    using QWebEngineView_setUrl_t = void (*)(QWebEngineView*, const QUrl&);
    using QWebEngineView_show_t = void (*)(QWebEngineView*);
    using QWebEngineView_winId_t = ulonglong (*)(QWebEngineView*);
    using QWebEngineView_windowHandle_t = QWindow* (*)(QWebEngineView*);
    using QWindow_fromWinId_t = QWindow* (*)(ulonglong);
    using QWindow_setParent_t = void (*)(QWindow*, void*);

    CPPSYM(QApplication__init_t, QApplication__init, _ZN12QApplicationC1ERiPPci)
    CPPSYM(QApplication_exec_t, QApplication_exec, _ZN15QGuiApplication4execEv)
    CPPSYM(QApplication_setAttribute_t, QApplication_setAttribute, _ZN16QCoreApplication12setAttributeEN2Qt20ApplicationAttributeEb)
    CPPSYM(QString__init_t, QString__init, _ZN7QStringC2EPK5QChari)
    CPPSYM(QUrl__init_t, QUrl__init, _ZN4QUrlC1ERK7QStringNS_11ParsingModeE)
    CPPSYM(QWebEngineView__init_t, QWebEngineView__init, _ZN14QWebEngineViewC1EP7QWidget)
    CPPSYM(QWebEngineView_move_t, QWebEngineView_move, _ZN7QWidget4moveERK6QPoint)
    CPPSYM(QWebEngineView_resize_t, QWebEngineView_resize, _ZN7QWidget6resizeERK5QSize)
    CPPSYM(QWebEngineView_setUrl_t, QWebEngineView_setUrl, _ZN14QWebEngineView6setUrlERK4QUrl)
    CPPSYM(QWebEngineView_show_t, QWebEngineView_show, _ZN7QWidget4showEv)
    CPPSYM(QWebEngineView_winId_t, QWebEngineView_winId, _ZNK7QWidget5winIdEv)
    CPPSYM(QWebEngineView_windowHandle_t, QWebEngineView_windowHandle, _ZNK7QWidget12windowHandleEv)
    CPPSYM(QWindow_fromWinId_t, QWindow_fromWinId, _ZN7QWindow9fromWinIdEy)
    CPPSYM(QWindow_setParent_t, QWindow_setParent, _ZN7QWindow9setParentEPS_)

    unsetenv("QT_FONT_DPI");
    unsetenv("QT_SCREEN_SCALE_FACTORS");
    unsetenv("QT_USE_PHYSICAL_DPI");
    setenv("QT_AUTO_SCREEN_SCALE_FACTOR", "0", 1);

    char scale[8] = {};
    std::snprintf(scale, 7, "%.2f", scaleFactor);
    setenv("QT_SCALE_FACTOR", scale, 1);

    QApplication_setAttribute(Qt::AA_X11InitThreads, true);
    QApplication_setAttribute(Qt::AA_EnableHighDpiScaling, true);
    QApplication_setAttribute(Qt::AA_UseHighDpiPixmaps, true);

    static int argc = 0;
    static char* argv[] = { nullptr };

    uint8_t _app[64]; // sizeof(QApplication) == 16
    QApplication* const app = reinterpret_cast<QApplication*>(_app);
    QApplication__init(app, argc, argv, 0);

    uint8_t _qstrurl[32]; // sizeof(QString) == 8
    QString* const qstrurl(reinterpret_cast<QString*>(_qstrurl));

    {
        const size_t url_len = std::strlen(url);
        QChar* const url_qchar = new QChar[url_len + 1];

        for (size_t i = 0; i < url_len; ++i)
            url_qchar[i] = QChar(url[i]);

        url_qchar[url_len] = 0;

        QString__init(qstrurl, url_qchar, url_len);
    }

    uint8_t _qurl[32]; // sizeof(QUrl) == 8
    QUrl* const qurl(reinterpret_cast<QUrl*>(_qurl));
    QUrl__init(qurl, *qstrurl, 1 /* QUrl::StrictMode */);

    uint8_t _webview[128]; // sizeof(QWebEngineView) == 56
    QWebEngineView* const webview = reinterpret_cast<QWebEngineView*>(_webview);
    QWebEngineView__init(webview, nullptr);

    QWebEngineView_move(webview, QPoint(0, kVerticalOffset));
    QWebEngineView_resize(webview, QSize(DISTRHO_UI_DEFAULT_WIDTH, DISTRHO_UI_DEFAULT_HEIGHT - kVerticalOffset));
    QWebEngineView_winId(webview);
    QWindow_setParent(QWebEngineView_windowHandle(webview), QWindow_fromWinId(winId));
    QWebEngineView_setUrl(webview, *qurl);
    QWebEngineView_show(webview);

    reloadFn = [=](){
        QWebEngineView_setUrl(webview, *qurl);
    };

    QApplication_exec();

    dlclose(lib);
    return true;
}

// -----------------------------------------------------------------------------------------------------------
// qt6webengine variant (same as qt5 but `QString__init_t` has different arguments)

static bool qt6webengine(const Window winId, const double scaleFactor, const char* const url)
{
    void* lib;
    if ((lib = dlopen("libQt6WebEngineWidgets.so.6", RTLD_NOW|RTLD_GLOBAL)) == nullptr ||
        (lib = dlopen("libQt6WebEngineWidgets.so", RTLD_NOW|RTLD_GLOBAL)) == nullptr)
        return false;

    using QApplication__init_t = void (*)(QApplication*, int&, char**, int);
    using QApplication_exec_t = void (*)();
    using QApplication_setAttribute_t = void (*)(Qt::ApplicationAttribute, bool);
    using QString__init_t = void (*)(void*, const QChar*, long long);
    using QUrl__init_t = void (*)(void*, const QString&, int /* QUrl::ParsingMode */);
    using QWebEngineView__init_t = void (*)(QWebEngineView*, void*);
    using QWebEngineView_move_t = void (*)(QWebEngineView*, const QPoint&);
    using QWebEngineView_resize_t = void (*)(QWebEngineView*, const QSize&);
    using QWebEngineView_setUrl_t = void (*)(QWebEngineView*, const QUrl&);
    using QWebEngineView_show_t = void (*)(QWebEngineView*);
    using QWebEngineView_winId_t = ulonglong (*)(QWebEngineView*);
    using QWebEngineView_windowHandle_t = QWindow* (*)(QWebEngineView*);
    using QWindow_fromWinId_t = QWindow* (*)(ulonglong);
    using QWindow_setParent_t = void (*)(QWindow*, void*);

    CPPSYM(QApplication__init_t, QApplication__init, _ZN12QApplicationC1ERiPPci)
    CPPSYM(QApplication_exec_t, QApplication_exec, _ZN15QGuiApplication4execEv)
    CPPSYM(QApplication_setAttribute_t, QApplication_setAttribute, _ZN16QCoreApplication12setAttributeEN2Qt20ApplicationAttributeEb)
    CPPSYM(QString__init_t, QString__init, _ZN7QStringC2EPK5QCharx)
    CPPSYM(QUrl__init_t, QUrl__init, _ZN4QUrlC1ERK7QStringNS_11ParsingModeE)
    CPPSYM(QWebEngineView__init_t, QWebEngineView__init, _ZN14QWebEngineViewC1EP7QWidget)
    CPPSYM(QWebEngineView_move_t, QWebEngineView_move, _ZN7QWidget4moveERK6QPoint)
    CPPSYM(QWebEngineView_resize_t, QWebEngineView_resize, _ZN7QWidget6resizeERK5QSize)
    CPPSYM(QWebEngineView_setUrl_t, QWebEngineView_setUrl, _ZN14QWebEngineView6setUrlERK4QUrl)
    CPPSYM(QWebEngineView_show_t, QWebEngineView_show, _ZN7QWidget4showEv)
    CPPSYM(QWebEngineView_winId_t, QWebEngineView_winId, _ZNK7QWidget5winIdEv)
    CPPSYM(QWebEngineView_windowHandle_t, QWebEngineView_windowHandle, _ZNK7QWidget12windowHandleEv)
    CPPSYM(QWindow_fromWinId_t, QWindow_fromWinId, _ZN7QWindow9fromWinIdEy)
    CPPSYM(QWindow_setParent_t, QWindow_setParent, _ZN7QWindow9setParentEPS_)

    unsetenv("QT_FONT_DPI");
    unsetenv("QT_SCREEN_SCALE_FACTORS");
    unsetenv("QT_USE_PHYSICAL_DPI");
    setenv("QT_AUTO_SCREEN_SCALE_FACTOR", "0", 1);

    char scale[8] = {};
    std::snprintf(scale, 7, "%.2f", scaleFactor);
    setenv("QT_SCALE_FACTOR", scale, 1);

    QApplication_setAttribute(Qt::AA_X11InitThreads, true);
    QApplication_setAttribute(Qt::AA_EnableHighDpiScaling, true);
    QApplication_setAttribute(Qt::AA_UseHighDpiPixmaps, true);

    static int argc = 0;
    static char* argv[] = { nullptr };

    uint8_t _app[64]; // sizeof(QApplication) == 16
    QApplication* const app = reinterpret_cast<QApplication*>(_app);
    QApplication__init(app, argc, argv, 0);

    uint8_t _qstrurl[32]; // sizeof(QString) == 8
    QString* const qstrurl(reinterpret_cast<QString*>(_qstrurl));

    {
        const size_t url_len = std::strlen(url);
        QChar* const url_qchar = new QChar[url_len + 1];

        for (size_t i = 0; i < url_len; ++i)
            url_qchar[i] = QChar(url[i]);

        url_qchar[url_len] = 0;

        QString__init(qstrurl, url_qchar, url_len);
    }

    uint8_t _qurl[32]; // sizeof(QUrl) == 8
    QUrl* const qurl(reinterpret_cast<QUrl*>(_qurl));
    QUrl__init(qurl, *qstrurl, 1 /* QUrl::StrictMode */);

    uint8_t _webview[128]; // sizeof(QWebEngineView) == 56
    QWebEngineView* const webview = reinterpret_cast<QWebEngineView*>(_webview);
    QWebEngineView__init(webview, nullptr);

    QWebEngineView_move(webview, QPoint(0, kVerticalOffset));
    QWebEngineView_resize(webview, QSize(DISTRHO_UI_DEFAULT_WIDTH, DISTRHO_UI_DEFAULT_HEIGHT - kVerticalOffset));
    QWebEngineView_winId(webview);
    QWindow_setParent(QWebEngineView_windowHandle(webview), QWindow_fromWinId(winId));
    QWebEngineView_setUrl(webview, *qurl);
    QWebEngineView_show(webview);

    reloadFn = [=](){
        QWebEngineView_setUrl(webview, *qurl);
    };

    QApplication_exec();

    dlclose(lib);
    return true;
}

// -----------------------------------------------------------------------------------------------------------
// startup via ld-linux

static void signalHandler(const int sig)
{
    DISTRHO_SAFE_ASSERT_RETURN(sig == SIGUSR1,);

    reloadFn();
}

int dpf_webview_start(int /* argc */, char** /* argv[] */)
{
    uselocale(newlocale(LC_NUMERIC_MASK, "C", nullptr));

    const char* const envPort = std::getenv("DPF_WEBVIEW_PORT");
    DISTRHO_SAFE_ASSERT_RETURN(envPort != nullptr, 1);

    const char* const envScaleFactor = std::getenv("DPF_WEBVIEW_SCALE_FACTOR");
    DISTRHO_SAFE_ASSERT_RETURN(envScaleFactor != nullptr, 1);

    const char* const envWinId = std::getenv("DPF_WEBVIEW_WIN_ID");
    DISTRHO_SAFE_ASSERT_RETURN(envWinId != nullptr, 1);

    const Window winId = std::strtoul(envWinId, nullptr, 10);
    DISTRHO_SAFE_ASSERT_RETURN(winId != 0, 1);

    const double scaleFactor = std::atof(envScaleFactor);
    DISTRHO_SAFE_ASSERT_RETURN(scaleFactor > 0.0, 1);

    Display* const display = XOpenDisplay(nullptr);
    DISTRHO_SAFE_ASSERT_RETURN(display != nullptr, 1);

    char url[32] = {};
    std::snprintf(url, 31, "http://127.0.0.1:%s/", envPort);

    struct sigaction sig = {};
    sig.sa_handler = signalHandler;
    sig.sa_flags = SA_RESTART;
    sigemptyset(&sig.sa_mask);
    sigaction(SIGUSR1, &sig, nullptr);

    qt5webengine(winId, scaleFactor, url) ||
    qt6webengine(winId, scaleFactor, url) ||
    gtk3(display, winId, scaleFactor, url);

    XCloseDisplay(display);

    return 0;
}

// -----------------------------------------------------------------------------------------------------------

END_NAMESPACE_DISTRHO