x11shadowreader.cpp

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/*
    SPDX-FileCopyrightText: 2016 Martin Gräßlin <mgraesslin@kde.org>
 
    SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
*/
#include "utils/xcbutils.h"
 
#include <QApplication>
#include <QCommandLineParser>
#include <QDebug>
#include <QFormLayout>
#include <QLabel>
#include <QVBoxLayout>
#include <QWidget>
#include <private/qtx11extras_p.h>
 
static QList<uint32_t> readShadow(quint32 windowId)
{
    KWin::Xcb::Atom atom(QByteArrayLiteral("_KDE_NET_WM_SHADOW"), false, QX11Info::connection());
    QList<uint32_t> ret;
    if (windowId != XCB_WINDOW) {
        KWin::Xcb::Property property(false, windowId, atom, XCB_ATOM_CARDINAL, 0, 12);
        uint32_t *shadow = property.value<uint32_t *>();
        if (shadow) {
            ret.reserve(12);
            for (int i = 0; i < 12; ++i) {
                ret << shadow[i];
            }
        } else {
            qDebug() << "!!!! no shadow";
        }
    } else {
        qDebug() << "!!!! no window";
    }
    return ret;
}
 
static QList<QPixmap> getPixmaps(const QList<uint32_t> &data)
{
    QList<QPixmap> ret;
    static const int ShadowElementsCount = 8;
    QList<KWin::Xcb::WindowGeometry> pixmapGeometries(ShadowElementsCount);
    QList<xcb_get_image_cookie_t> getImageCookies(ShadowElementsCount);
    auto *c = KWin::connection();
    for (int i = 0; i < ShadowElementsCount; ++i) {
        pixmapGeometries[i] = KWin::Xcb::WindowGeometry(data[i]);
    }
    auto discardReplies = [&getImageCookies](int start) {
        for (int i = start; i < getImageCookies.size(); ++i) {
            xcb_discard_reply(KWin::connection(), getImageCookies.at(i).sequence);
        }
    };
    for (int i = 0; i < ShadowElementsCount; ++i) {
        auto &geo = pixmapGeometries[i];
        if (geo.isNull()) {
            discardReplies(0);
            return QList<QPixmap>();
        }
        getImageCookies[i] = xcb_get_image_unchecked(c, XCB_IMAGE_FORMAT_Z_PIXMAP, data[i],
                                                     0, 0, geo->width, geo->height, ~0);
    }
    for (int i = 0; i < ShadowElementsCount; ++i) {
        auto *reply = xcb_get_image_reply(c, getImageCookies.at(i), nullptr);
        if (!reply) {
            discardReplies(i + 1);
            return QList<QPixmap>();
        }
        auto &geo = pixmapGeometries[i];
        QImage image(xcb_get_image_data(reply), geo->width, geo->height, QImage::Format_ARGB32);
        ret << QPixmap::fromImage(image);
        free(reply);
    }
    return ret;
}
 
int main(int argc, char **argv)
{
    qputenv("QT_QPA_PLATFORM", "xcb");
    QApplication app(argc, argv);
    app.setProperty("x11Connection", QVariant::fromValue<void *>(QX11Info::connection()));
 
    QCommandLineParser parser;
    parser.addPositionalArgument(QStringLiteral("windowId"), QStringLiteral("The X11 windowId from which to read the shadow"));
    parser.addHelpOption();
    parser.process(app);
 
    if (parser.positionalArguments().count() != 1) {
        parser.showHelp(1);
    }
 
    bool ok = false;
    const auto shadow = readShadow(parser.positionalArguments().constFirst().toULongLong(&ok, 16));
    if (!ok) {
        qDebug() << "!!! Failed to read window id";
        return 1;
    }
    if (shadow.isEmpty()) {
        qDebug() << "!!!! Read shadow failed";
        return 1;
    }
    const auto pixmaps = getPixmaps(shadow);
    if (pixmaps.isEmpty()) {
        qDebug() << "!!!! Read pixmap failed";
        return 1;
    }
 
    std::unique_ptr<QWidget> widget(new QWidget());
    QFormLayout *layout = new QFormLayout(widget.get());
    for (const auto &pix : pixmaps) {
        QLabel *l = new QLabel(widget.get());
        l->setPixmap(pix);
        layout->addRow(QStringLiteral("%1x%2:").arg(pix.width()).arg(pix.height()), l);
    }
    widget->setLayout(layout);
    widget->show();
    return app.exec();
}