QVulkanWindow: Allow to change queues to create

This allows users to request queues beyond the default graphics queue without having
to completely reimplement Vulkan device initialization or giving up the convenience
of QVulkanWindow.

[ChangeLog][QtGui] Extended QVulkanWindow to allow user to specify additional queues
to be created.

Change-Id: I96d8d4bcc4da3ffedca3d25c87547669f5b18e40
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

src/gui/vulkan/qvulkanwindow.cpp

@@ -647,18 +647,40 @@ void QVulkanWindowPrivate::init()
 #endif
     qCDebug(lcGuiVk, "Using queue families: graphics = %u present = %u", gfxQueueFamilyIdx, presQueueFamilyIdx);
 
-    VkDeviceQueueCreateInfo queueInfo[2];
+    QVector<VkDeviceQueueCreateInfo> queueInfo;
+    queueInfo.reserve(2);
     const float prio[] = { 0 };
-    memset(queueInfo, 0, sizeof(queueInfo));
-    queueInfo[0].sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
-    queueInfo[0].queueFamilyIndex = gfxQueueFamilyIdx;
-    queueInfo[0].queueCount = 1;
-    queueInfo[0].pQueuePriorities = prio;
+    VkDeviceQueueCreateInfo addQueueInfo;
+    memset(&addQueueInfo, 0, sizeof(addQueueInfo));
+    addQueueInfo.sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
+    addQueueInfo.queueFamilyIndex = gfxQueueFamilyIdx;
+    addQueueInfo.queueCount = 1;
+    addQueueInfo.pQueuePriorities = prio;
+    queueInfo.append(addQueueInfo);
     if (gfxQueueFamilyIdx != presQueueFamilyIdx) {
-        queueInfo[1].sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
-        queueInfo[1].queueFamilyIndex = presQueueFamilyIdx;
-        queueInfo[1].queueCount = 1;
-        queueInfo[1].pQueuePriorities = prio;
+        addQueueInfo.queueFamilyIndex = presQueueFamilyIdx;
+        addQueueInfo.queueCount = 1;
+        addQueueInfo.pQueuePriorities = prio;
+        queueInfo.append(addQueueInfo);
+    }
+    if (queueCreateInfoModifier) {
+        queueCreateInfoModifier(queueFamilyProps.constData(), queueCount, queueInfo);
+        bool foundGfxQueue = false;
+        bool foundPresQueue = false;
+        for (const VkDeviceQueueCreateInfo& createInfo : qAsConst(queueInfo)) {
+            foundGfxQueue |= createInfo.queueFamilyIndex == gfxQueueFamilyIdx;
+            foundPresQueue |= createInfo.queueFamilyIndex == presQueueFamilyIdx;
+        }
+        if (!foundGfxQueue) {
+            qWarning("QVulkanWindow: Graphics queue missing after call to queueCreateInfoModifier");
+            status = StatusFail;
+            return;
+        }
+        if (!foundPresQueue) {
+            qWarning("QVulkanWindow: Present queue missing after call to queueCreateInfoModifier");
+            status = StatusFail;
+            return;
+        }
     }
 
     // Filter out unsupported extensions in order to keep symmetry
@@ -676,8 +698,8 @@ void QVulkanWindowPrivate::init()
     VkDeviceCreateInfo devInfo;
     memset(&devInfo, 0, sizeof(devInfo));
     devInfo.sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO;
-    devInfo.queueCreateInfoCount = gfxQueueFamilyIdx == presQueueFamilyIdx ? 1 : 2;
-    devInfo.pQueueCreateInfos = queueInfo;
+    devInfo.queueCreateInfoCount = queueInfo.size();
+    devInfo.pQueueCreateInfos = queueInfo.constData();
     devInfo.enabledExtensionCount = devExts.count();
     devInfo.ppEnabledExtensionNames = devExts.constData();
 
@@ -1545,6 +1567,52 @@ bool QVulkanWindow::event(QEvent *e)
     return QWindow::event(e);
 }
 
+/*!
+    \typedef QVulkanWindow::QueueCreateInfoModifier
+
+    A function function that is called during graphics initialization to add
+    additAional queues that should be created.
+
+    Set if the renderer needs additional queues besides the default graphics
+    queue (e.g. a transfer queue).
+    The provided queue family properties can be used to select the indices for
+    the additional queues.
+    The renderer can subsequently request the actual queue in initResources().
+
+    Note when requesting additional graphics queues: Qt itself always requests
+    a graphics queue, you'll need to search queueCreateInfo for the appropriate
+    entry and manipulate it to obtain the additional queue.
+
+    \sa setQueueCreateInfoModifier()
+ */
+
+/*!
+    Return a previously set queue create info modification function.
+
+    \sa setQueueCreateInfoModifier()
+
+    \since 5.15
+ */
+QVulkanWindow::QueueCreateInfoModifier QVulkanWindow::queueCreateInfoModifier() const
+{
+    Q_D(const QVulkanWindow);
+    return d->queueCreateInfoModifier;
+}
+
+/*!
+    Set a queue create info modification function.
+
+    \sa queueCreateInfoModifier()
+
+    \since 5.15
+ */
+void QVulkanWindow::setQueueCreateInfoModifier(QueueCreateInfoModifier modifier)
+{
+    Q_D(QVulkanWindow);
+    d->queueCreateInfoModifier = modifier;
+}
+
+
 /*!
     Returns true if this window has successfully initialized all Vulkan
     resources, including the swapchain.

src/gui/vulkan/qvulkanwindow.h

@@ -103,6 +103,12 @@ public:
     QVector<int> supportedSampleCounts();
     void setSampleCount(int sampleCount);
 
+    typedef std::function<void(const VkQueueFamilyProperties *,
+                               uint32_t,
+                               QVector<VkDeviceQueueCreateInfo> &)> QueueCreateInfoModifier;
+    QueueCreateInfoModifier queueCreateInfoModifier() const;
+    void setQueueCreateInfoModifier(QueueCreateInfoModifier modifier);
+
     bool isValid() const;
 
     virtual QVulkanWindowRenderer *createRenderer();

src/gui/vulkan/qvulkanwindow_p.h

@@ -102,6 +102,7 @@ public:
     QHash<VkPhysicalDevice, QVulkanInfoVector<QVulkanExtension> > supportedDevExtensions;
     QVector<VkFormat> requestedColorFormats;
     VkSampleCountFlagBits sampleCount = VK_SAMPLE_COUNT_1_BIT;
+    QVulkanWindow::QueueCreateInfoModifier queueCreateInfoModifier;
 
     VkDevice dev = VK_NULL_HANDLE;
     QVulkanDeviceFunctions *devFuncs;