[tests] Tool to read the X11 shadow on a window

Summary:
This new helper tool allows to read the X11 shadow from a window
and visualize the individual parts.

Reviewers: #kwin

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D2101

tests/CMakeLists.txt

@@ -33,3 +33,6 @@ if (HAVE_INPUT)
     add_definitions(-DKWIN_BUILD_TESTING)
     target_link_libraries(libinputtest Qt5::Core Qt5::DBus Libinput::Libinput ${UDEV_LIBS} KF5::ConfigCore KF5::GlobalAccel KF5::WindowSystem)
 endif()
+
+add_executable(x11shadowreader x11shadowreader.cpp)
+target_link_libraries(x11shadowreader XCB::XCB Qt5::Widgets Qt5::X11Extras KF5::ConfigCore KF5::WindowSystem)

tests/x11shadowreader.cpp

@@ -0,0 +1,129 @@
+/*
+ * Copyright 2016  Martin Gräßlin <mgraesslin@kde.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License or (at your option) version 3 or any later version
+ * accepted by the membership of KDE e.V. (or its successor approved
+ * by the membership of KDE e.V.), which shall act as a proxy
+ * defined in Section 14 of version 3 of the license.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#include "../xcbutils.h"
+#include <QApplication>
+#include <QCommandLineParser>
+#include <QLabel>
+#include <QFormLayout>
+#include <QVBoxLayout>
+#include <QWidget>
+#include <QX11Info>
+
+static QVector<uint32_t> readShadow(quint32 windowId)
+{
+    KWin::Xcb::Atom atom(QByteArrayLiteral("_KDE_NET_WM_SHADOW"), false, QX11Info::connection());
+    QVector<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 QVector<QPixmap> getPixmaps(const QVector<uint32_t> &data)
+{
+    QVector<QPixmap> ret;
+    static const int ShadowElementsCount = 8;
+    QVector<KWin::Xcb::WindowGeometry> pixmapGeometries(ShadowElementsCount);
+    QVector<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 QVector<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 QVector<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().first().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;
+    }
+
+    QScopedPointer<QWidget> widget(new QWidget());
+    QFormLayout *layout = new QFormLayout(widget.data());
+    for (const auto &pix : pixmaps) {
+        QLabel *l = new QLabel(widget.data());
+        l->setPixmap(pix);
+        layout->addRow(QStringLiteral("%1x%2:").arg(pix.width()).arg(pix.height()), l);
+    }
+    widget->setLayout(layout);
+    widget->show();
+    return app.exec();
+}