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>

1 files changed, 119 insertions, 0 deletions

diff --git a/src/gui/vulkan/qvulkandefaultinstance.cpp b/src/gui/vulkan/qvulkandefaultinstance.cpp
new file mode 100644
index 0000000000..c9ec6b6499
--- /dev/null
+++ b/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