Add deprecated support for wl_scaler

[ChangeLog][Compositor] Add deprecated support for the deprecated wl_scaler.

Some clients are stuck on the unofficial Weston protocol wl_scaler instead of
the standardized and stable wp_viewporter. This implements optional support for
wl_scaler.

This patch has been written to be easily removable in Qt 6, and touches a
minimal amount of other code.

The implementation can be tested using the new manual test compositor:
tests/manual/wlscaler.

Weston 1.11.1 has a demo client named weston-resizor, which can be used to
test. Note that although newer versions of Weston also have weston-resizor,
those versions use wp_viewporter instead of wl_scaler, so you really need
1.11.1 or earlier to test.

Fixes: QTBUG-69635
Change-Id: Id572e28044cd764eaf63b1259a92bc589711c39d
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

4 files changed, 438 insertions, 0 deletions

diff --git a/src/compositor/extensions/extensions.pri b/src/compositor/extensions/extensions.pri
index 38fe79a2f..361f93984 100644
--- a/src/compositor/extensions/extensions.pri
+++ b/src/compositor/extensions/extensions.pri
@@ -10,6 +10,7 @@ WAYLANDSERVERSOURCES += \
     ../extensions/qt-windowmanager.xml \
     ../3rdparty/protocol/text-input-unstable-v2.xml \
     ../3rdparty/protocol/viewporter.xml \
+    ../3rdparty/protocol/scaler.xml \
     ../3rdparty/protocol/xdg-shell-unstable-v6.xml \
     ../3rdparty/protocol/xdg-shell.xml \
     ../3rdparty/protocol/xdg-decoration-unstable-v1.xml \
@@ -30,6 +31,8 @@ HEADERS += \
     extensions/qwaylandqtwindowmanager_p.h \
     extensions/qwaylandviewporter.h \
     extensions/qwaylandviewporter_p.h \
+    extensions/qwaylandwlscaler.h \
+    extensions/qwaylandwlscaler_p.h \
     extensions/qwaylandxdgshellv5.h \
     extensions/qwaylandxdgshellv5_p.h \
     extensions/qwaylandxdgshellv6.h \
@@ -53,6 +56,7 @@ SOURCES += \
     extensions/qwaylandtextinputmanager.cpp \
     extensions/qwaylandqtwindowmanager.cpp \
     extensions/qwaylandviewporter.cpp \
+    extensions/qwaylandwlscaler.cpp \
     extensions/qwaylandxdgshellv5.cpp \
     extensions/qwaylandxdgshellv6.cpp \
     extensions/qwaylandxdgshell.cpp \
diff --git a/src/compositor/extensions/qwaylandwlscaler.cpp b/src/compositor/extensions/qwaylandwlscaler.cpp
new file mode 100644
index 000000000..e097ea3c5
--- /dev/null
+++ b/src/compositor/extensions/qwaylandwlscaler.cpp
@@ -0,0 +1,274 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the QtWaylandCompositor module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL3$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPLv3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or later as published by the Free
+** Software Foundation and appearing in the file LICENSE.GPL included in
+** the packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 2.0 requirements will be
+** met: http://www.gnu.org/licenses/gpl-2.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qwaylandwlscaler_p.h"
+
+#include <QtWaylandCompositor/QWaylandSurface>
+#include <QtWaylandCompositor/QWaylandCompositor>
+
+#include <QtWaylandCompositor/private/qwaylandsurface_p.h>
+
+QT_BEGIN_NAMESPACE
+
+#if QT_DEPRECATED_SINCE(5, 13)
+/*!
+    \qmltype WlScaler
+    \inqmlmodule QtWayland.Compositor
+    \since 5.13
+    \brief Provides an extension for surface resizing and cropping.
+
+    The WlScaler extension provides a way for clients to resize and crop surface contents.
+
+    WlScaler corresponds to the Wayland interface, \c wl_scaler.
+
+    \c wl_scaler is a non-standard and deprecated protocol that has largely been replaced by
+    \c wp_viewporter. I.e. This extensions is only useful for supporting legacy clients.
+    \c wp_viewporter support is enabled automatically for all Qml compositors.
+
+    To provide the functionality of the extension in a compositor, create an instance of the
+    WlScaler component and add it to the list of extensions supported by the compositor:
+
+    \code
+    import QtWayland.Compositor 1.13
+
+    WaylandCompositor {
+        // ...
+        WlScaler {}
+    }
+    \endcode
+
+    \deprecated
+*/
+
+/*!
+    \class QWaylandWlScaler
+    \inmodule QtWaylandCompositor
+    \since 5.13
+    \brief Provides an extension for surface resizing and croping.
+
+    The QWaylandWlScaler extension provides a way for clients to resize and crop surface
+    contents.
+
+    QWaylandWlScaler corresponds to the Wayland interface, \c wl_scaler.
+
+    \c wl_scaler is a non-standard and deprecated protocol that has largely been replaced by
+    \c wp_viewporter. I.e. This extensions is only useful for supporting legacy clients.
+
+    \sa QWaylandViewporter
+
+    \deprecated
+*/
+
+/*!
+    Constructs a QWaylandWlScaler object.
+*/
+QWaylandWlScaler::QWaylandWlScaler()
+    : QWaylandCompositorExtensionTemplate<QWaylandWlScaler>(*new QWaylandWlScalerPrivate)
+{
+}
+
+/*!
+ * Constructs a QWaylandWlScaler object for the provided \a compositor.
+ */
+QWaylandWlScaler::QWaylandWlScaler(QWaylandCompositor *compositor)
+    : QWaylandCompositorExtensionTemplate<QWaylandWlScaler>(compositor, *new QWaylandWlScalerPrivate())
+{
+}
+
+/*!
+    Initializes the extension.
+*/
+void QWaylandWlScaler::initialize()
+{
+    Q_D(QWaylandWlScaler);
+
+    QWaylandCompositorExtensionTemplate::initialize();
+    auto *compositor = static_cast<QWaylandCompositor *>(extensionContainer());
+    if (!compositor) {
+        qWarning() << "Failed to find QWaylandCompositor when initializing QWaylandWlScaler";
+        return;
+    }
+    d->init(compositor->display(), 2);
+}
+
+/*!
+    Returns the Wayland interface for the QWaylandWlScaler.
+*/
+const wl_interface *QWaylandWlScaler::interface()
+{
+    return QWaylandWlScalerPrivate::interface();
+}
+
+void QWaylandWlScalerPrivate::scaler_destroy(Resource *resource)
+{
+    // Viewport objects are allowed ot outlive the scaler
+    wl_resource_destroy(resource->handle);
+}
+
+void QWaylandWlScalerPrivate::scaler_get_viewport(Resource *resource, uint id, wl_resource *surfaceResource)
+{
+    auto *surface = QWaylandSurface::fromResource(surfaceResource);
+    if (!surface) {
+        qWarning() << "Couldn't find surface for viewporter";
+        return;
+    }
+
+    // Note: This will only protect us not creating scalers for surfaces with wp_viewport objects
+    auto *surfacePrivate = QWaylandSurfacePrivate::get(surface);
+    if (surfacePrivate->viewport) {
+        wl_resource_post_error(resource->handle, WL_SCALER_ERROR_VIEWPORT_EXISTS,
+                               "viewport already exists for surface");
+        return;
+    }
+
+    // We can't set viewport here, since it's of the new type for wp_viewporter
+//    surfacePrivate->viewport = new Viewport(surface, resource->client(), id, resource->version());
+    new Viewport(surface, resource->client(), id, resource->version());
+}
+
+QWaylandWlScalerPrivate::Viewport::Viewport(QWaylandSurface *surface, wl_client *client, int id, int version)
+    : QtWaylandServer::wl_viewport(client, id, version)
+    , m_surface(surface)
+{
+    Q_ASSERT(surface);
+}
+
+//TODO: This isn't currently called
+// This function has to be called immediately after a surface is committed, before no
+// other client events have been dispatched, or we may incorrectly error out on an
+// incomplete pending state. See comment below.
+void QWaylandWlScalerPrivate::Viewport::checkCommittedState()
+{
+    auto *surfacePrivate = QWaylandSurfacePrivate::get(m_surface);
+
+    // We can't use the current state for destination/source when checking,
+    // as that has fallbacks to the buffer size so we can't distinguish
+    // between the set/unset case. We use the pending state because no other
+    // requests has modified it yet.
+    QSize destination = surfacePrivate->pending.destinationSize;
+    QRectF source = surfacePrivate->pending.sourceGeometry;
+
+    if (!destination.isValid() && source.size() != source.size().toSize()) {
+        //TODO: Do rounding to nearest integer
+    }
+
+    QRectF max = QRectF(QPointF(), m_surface->bufferSize() / m_surface->bufferScale());
+    // We can't use QRectF.contains, because that would return false for values on the border
+    if (max.united(source) != max) {
+        //TODO: surface contents are no undefined, surface size is still valid though
+        qCDebug(qLcWaylandCompositor) << "Source set outside buffer bounds (client error)";
+    }
+}
+
+
+void QWaylandWlScalerPrivate::Viewport::viewport_destroy_resource(Resource *resource)
+{
+    Q_UNUSED(resource);
+    delete this;
+}
+
+void QWaylandWlScalerPrivate::Viewport::viewport_destroy(Resource *resource)
+{
+    if (m_surface) {
+        auto *surfacePrivate = QWaylandSurfacePrivate::get(m_surface);
+        surfacePrivate->pending.destinationSize = QSize();
+        surfacePrivate->pending.sourceGeometry = QRectF();
+    }
+    wl_resource_destroy(resource->handle);
+}
+
+void QWaylandWlScalerPrivate::Viewport::viewport_set(QtWaylandServer::wl_viewport::Resource *resource, wl_fixed_t src_x, wl_fixed_t src_y, wl_fixed_t src_width, wl_fixed_t src_height, int32_t dst_width, int32_t dst_height)
+{
+    viewport_set_source(resource, src_x, src_y, src_width, src_height);
+    viewport_set_destination(resource, dst_width, dst_height);
+}
+
+void QWaylandWlScalerPrivate::Viewport::viewport_set_source(QtWaylandServer::wl_viewport::Resource *resource, wl_fixed_t x, wl_fixed_t y, wl_fixed_t width, wl_fixed_t height)
+{
+    Q_UNUSED(resource);
+
+    if (!m_surface) {
+        qCDebug(qLcWaylandCompositor) << "set_source requested for destroyed surface";
+        return;
+    }
+
+    QPointF position(wl_fixed_to_double(x), wl_fixed_to_double(y));
+    QSizeF size(wl_fixed_to_double(width), wl_fixed_to_double(height));
+    QRectF sourceGeometry(position, size);
+
+    if (sourceGeometry == QRectF(-1, -1, -1, -1)) {
+        auto *surfacePrivate = QWaylandSurfacePrivate::get(m_surface);
+        surfacePrivate->pending.sourceGeometry = QRectF();
+        return;
+    }
+
+    if (position.x() < 0 || position.y() < 0) {
+        wl_resource_post_error(resource->handle, error_bad_value,
+                               "negative position in set_source");
+        return;
+    }
+
+    if (!size.isValid()) {
+        wl_resource_post_error(resource->handle, error_bad_value,
+                               "negative size in set_source");
+        return;
+    }
+
+    auto *surfacePrivate = QWaylandSurfacePrivate::get(m_surface);
+    surfacePrivate->pending.sourceGeometry = sourceGeometry;
+}
+
+void QWaylandWlScalerPrivate::Viewport::viewport_set_destination(QtWaylandServer::wl_viewport::Resource *resource, int32_t width, int32_t height)
+{
+    Q_UNUSED(resource);
+
+    if (!m_surface) {
+        qCDebug(qLcWaylandCompositor) << "set_destination requested for destroyed surface";
+        return;
+    }
+
+    QSize destinationSize(width, height);
+    if (!destinationSize.isValid() && destinationSize != QSize(-1, -1)) {
+        wl_resource_post_error(resource->handle, error_bad_value,
+                               "negative size in set_destination");
+        return;
+    }
+    auto *surfacePrivate = QWaylandSurfacePrivate::get(m_surface);
+    surfacePrivate->pending.destinationSize = destinationSize;
+}
+#endif // QT_DEPRECATED_SINCE
+
+QT_END_NAMESPACE
diff --git a/src/compositor/extensions/qwaylandwlscaler.h b/src/compositor/extensions/qwaylandwlscaler.h
new file mode 100644
index 000000000..4ecdf3968
--- /dev/null
+++ b/src/compositor/extensions/qwaylandwlscaler.h
@@ -0,0 +1,67 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the QtWaylandCompositor module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL3$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPLv3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or later as published by the Free
+** Software Foundation and appearing in the file LICENSE.GPL included in
+** the packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 2.0 requirements will be
+** met: http://www.gnu.org/licenses/gpl-2.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QWAYLANDWLSCALER_H
+#define QWAYLANDWLSCALER_H
+
+#include <QtWaylandCompositor/QWaylandCompositorExtension>
+
+QT_BEGIN_NAMESPACE
+
+#if QT_DEPRECATED_SINCE(5, 13)
+class QWaylandWlScalerPrivate;
+
+// TODO: We should have used the QT_DEPRECATED macro here, but for some reason
+// header file generation stops working when that's added.
+class Q_WAYLAND_COMPOSITOR_EXPORT QWaylandWlScaler
+        : public QWaylandCompositorExtensionTemplate<QWaylandWlScaler>
+{
+    Q_OBJECT
+    Q_DECLARE_PRIVATE(QWaylandWlScaler)
+
+public:
+    explicit QWaylandWlScaler();
+    explicit QWaylandWlScaler(QWaylandCompositor *compositor);
+
+    void initialize() override;
+
+    static const struct wl_interface *interface();
+};
+#endif
+
+QT_END_NAMESPACE
+
+#endif // QWAYLANDWLSCALER_H
diff --git a/src/compositor/extensions/qwaylandwlscaler_p.h b/src/compositor/extensions/qwaylandwlscaler_p.h
new file mode 100644
index 000000000..d3c2edd76
--- /dev/null
+++ b/src/compositor/extensions/qwaylandwlscaler_p.h
@@ -0,0 +1,93 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the QtWaylandCompositor module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL3$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPLv3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or later as published by the Free
+** Software Foundation and appearing in the file LICENSE.GPL included in
+** the packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 2.0 requirements will be
+** met: http://www.gnu.org/licenses/gpl-2.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QWAYLANDWLSCALER_P_H
+#define QWAYLANDWLSCALER_P_H
+
+#include "qwaylandwlscaler.h"
+
+#include <QtWaylandCompositor/private/qwaylandcompositorextension_p.h>
+#include <QtWaylandCompositor/private/qwayland-server-scaler.h>
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+QT_BEGIN_NAMESPACE
+
+class QWaylandSurface;
+
+class Q_WAYLAND_COMPOSITOR_EXPORT QWaylandWlScalerPrivate
+        : public QWaylandCompositorExtensionPrivate
+        , public QtWaylandServer::wl_scaler
+{
+    Q_DECLARE_PUBLIC(QWaylandWlScaler)
+public:
+    explicit QWaylandWlScalerPrivate() = default;
+
+protected:
+    void scaler_destroy(Resource *resource) override;
+    void scaler_get_viewport(Resource *resource, uint32_t id, wl_resource *surface) override;
+
+private:
+    class Viewport : public QtWaylandServer::wl_viewport
+    {
+    public:
+        explicit Viewport(QWaylandSurface *surface, wl_client *client, int id, int version);
+        void checkCommittedState();
+
+    protected:
+        void viewport_destroy_resource(Resource *resource) override;
+        void viewport_destroy(Resource *resource) override;
+        void viewport_set(Resource *resource, wl_fixed_t src_x, wl_fixed_t src_y, wl_fixed_t src_width, wl_fixed_t src_height, int32_t dst_width, int32_t dst_height) override;
+        void viewport_set_source(Resource *resource, wl_fixed_t x, wl_fixed_t y, wl_fixed_t width, wl_fixed_t height) override;
+        void viewport_set_destination(Resource *resource, int32_t width, int32_t height) override;
+
+    private:
+        QPointer<QWaylandSurface> m_surface = nullptr;
+    };
+};
+
+QT_END_NAMESPACE
+
+#endif // QWAYLANDWLSCALER_P_H