Convert Vulkan instance setup from Qt Quick into a Gui helper

Make it possible to reuse what's in QSGRhiSupport from other modules as
well. Both Gui (texture-based widget/backingstore composition) and
Multimedia are potential users of this in the future.

Change-Id: I1b50cc5efd6811e9bc95f6287b9576931d4bcc44
Reviewed-by: Christian Strømme <christian.stromme@qt.io>

src/gui/CMakeLists.txt

@@ -860,6 +860,7 @@ qt_internal_extend_target(Gui CONDITION QT_FEATURE_vulkan
         rhi/qrhivulkan_p_p.h
         vulkan/qbasicvulkanplatforminstance.cpp vulkan/qbasicvulkanplatforminstance_p.h
         vulkan/qplatformvulkaninstance.cpp vulkan/qplatformvulkaninstance.h
+        vulkan/qvulkandefaultinstance.cpp vulkan/qvulkandefaultinstance_p.h
         vulkan/qvulkanfunctions.cpp
         vulkan/qvulkaninstance.cpp vulkan/qvulkaninstance.h
         vulkan/qvulkanwindow.cpp vulkan/qvulkanwindow.h vulkan/qvulkanwindow_p.h

src/gui/kernel/qguiapplication.cpp

@@ -123,6 +123,10 @@
 #include <emscripten.h>
 #endif
 
+#if QT_CONFIG(vulkan)
+#include <private/qvulkandefaultinstance_p.h>
+#endif
+
 #include <qtgui_tracepoints_p.h>
 
 #include <ctype.h>
@@ -1713,6 +1717,10 @@ QGuiApplicationPrivate::~QGuiApplicationPrivate()
     }
 #endif
 
+#if QT_CONFIG(vulkan)
+    QVulkanDefaultInstance::cleanup();
+#endif
+
     platform_integration->destroy();
 
     delete platform_theme;

src/gui/vulkan/qvulkandefaultinstance.cpp

@@ -0,0 +1,119 @@
+/****************************************************************************
+**
+** Copyright (C) 2022 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://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.LGPL3 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-3.0.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 (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qvulkandefaultinstance_p.h"
+#include <private/qrhivulkan_p.h>
+#include <QLoggingCategory>
+
+QT_BEGIN_NAMESPACE
+
+Q_LOGGING_CATEGORY(lcGuiVk, "qt.vulkan")
+
+static QVulkanInstance *s_vulkanInstance;
+static QVulkanDefaultInstance::Flags s_vulkanInstanceFlags;
+
+QVulkanDefaultInstance::Flags QVulkanDefaultInstance::flags()
+{
+    return s_vulkanInstanceFlags;
+}
+
+// As always, calling this when hasInstance() is already true has no effect. (unless cleanup() is called)
+void QVulkanDefaultInstance::setFlag(Flag flag, bool on)
+{
+    s_vulkanInstanceFlags.setFlag(flag, on);
+}
+
+bool QVulkanDefaultInstance::hasInstance()
+{
+    return s_vulkanInstance != nullptr;
+}
+
+QVulkanInstance *QVulkanDefaultInstance::instance()
+{
+    if (s_vulkanInstance)
+        return s_vulkanInstance;
+
+    s_vulkanInstance = new QVulkanInstance;
+
+    // With a Vulkan implementation >= 1.1 we can check what
+    // vkEnumerateInstanceVersion() says and request 1.2 or 1.1 based on the
+    // result. To prevent future surprises, be conservative and ignore any > 1.2
+    // versions for now. For 1.0 implementations nothing will be requested, the
+    // default 0 in VkApplicationInfo means 1.0.
+    //
+    // Vulkan 1.0 is actually sufficient for 99% of Qt Quick (3D)'s
+    // functionality. In addition, Vulkan implementations tend to enable 1.1 and 1.2
+    // functionality regardless of the VkInstance API request. However, the
+    // validation layer seems to take this fairly seriously, so we should be
+    // prepared for using 1.1 and 1.2 features in a fully correct manner. This also
+    // helps custom Vulkan code in applications, which is not under out control; it
+    // is ideal if Vulkan 1.1 and 1.2 are usable without requiring such applications
+    // to create their own QVulkanInstance just to be able to make an appropriate
+    // setApiVersion() call on it.
+
+    const QVersionNumber supportedVersion = s_vulkanInstance->supportedApiVersion();
+    if (supportedVersion >= QVersionNumber(1, 2))
+        s_vulkanInstance->setApiVersion(QVersionNumber(1, 2));
+    else if (supportedVersion >= QVersionNumber(1, 1))
+        s_vulkanInstance->setApiVersion(QVersionNumber(1, 2));
+    qCDebug(lcGuiVk) << "QVulkanDefaultInstance: Creating Vulkan instance"
+                     << "Requesting Vulkan API" << s_vulkanInstance->apiVersion()
+                     << "Instance-level version was reported as" << supportedVersion;
+
+    if (s_vulkanInstanceFlags.testFlag(EnableValidation))
+        s_vulkanInstance->setLayers({ "VK_LAYER_KHRONOS_validation" });
+
+    s_vulkanInstance->setExtensions(QRhiVulkanInitParams::preferredInstanceExtensions());
+
+    if (!s_vulkanInstance->create()) {
+        qWarning("QVulkanDefaultInstance: Failed to create Vulkan instance");
+        delete s_vulkanInstance;
+        s_vulkanInstance = nullptr;
+    }
+
+    return s_vulkanInstance;
+}
+
+void QVulkanDefaultInstance::cleanup()
+{
+    delete s_vulkanInstance;
+    s_vulkanInstance = nullptr;
+}
+
+QT_END_NAMESPACE

src/gui/vulkan/qvulkandefaultinstance_p.h

@@ -0,0 +1,82 @@
+/****************************************************************************
+**
+** Copyright (C) 2022 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://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.LGPL3 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-3.0.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 (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QVULKANDEFAULTINSTANCE_P_H
+#define QVULKANDEFAULTINSTANCE_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists for the convenience
+// of a number of Qt sources files.  This header file may change from
+// version to version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtGui/private/qtguiglobal_p.h>
+
+#if QT_CONFIG(vulkan)
+
+#include <QtGui/qvulkaninstance.h>
+
+QT_BEGIN_NAMESPACE
+
+struct Q_GUI_EXPORT QVulkanDefaultInstance
+{
+    enum Flag {
+        EnableValidation = 0x01
+    };
+    Q_DECLARE_FLAGS(Flags, Flag)
+
+    static Flags flags();
+    static void setFlag(Flag flag, bool on = true);
+    static bool hasInstance();
+    static QVulkanInstance *instance();
+    static void cleanup();
+};
+
+Q_DECLARE_OPERATORS_FOR_FLAGS(QVulkanDefaultInstance::Flags)
+
+QT_END_NAMESPACE
+
+#endif // QT_CONFIG(vulkan)
+
+#endif

src/gui/vulkan/qvulkanwindow.cpp

@@ -47,7 +47,7 @@
 
 QT_BEGIN_NAMESPACE
 
-Q_LOGGING_CATEGORY(lcGuiVk, "qt.vulkan")
+Q_DECLARE_LOGGING_CATEGORY(lcGuiVk)
 
 /*!
   \class QVulkanWindow