Otherwise you can't print out window objects with it.

Change-Id: I2a177bd71215cfcb3f5fc47c9171eaba9a12ac0f
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

While the parent class (QWindow) has that property, QDoc does not
allow documenting properties from base classes. The documentation
for QQuickWindow::transientParent includes QML-specific information,
so use QDOC_PROPERTY macro in the header file to make the property
documentation visible.

Pick-to: 6.0
Change-Id: Ib281c776717e09e6929420c6173a520613356d91
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>

[ChangeLog][QQuickWindow] Removed the obsolete QQuickWindow::sendEvent
function. Use QCoreApplication::sendEvent instead.

Change-Id: I583ea8f87b870b136315efa4e1105de484e5f1ab
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Maximilian Goldstein <max.goldstein@qt.io>
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

Following the pattern from QtGui.

Task-number: QTBUG-85239
Change-Id: I07b4456028d0f45223ad10e55ce65f423bab6a9b
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

Change-Id: I2bf50a46ea18fe06068192ad695652830c3a3861
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

...and fix up the docs.

The string-based setSceneGraphBackend() stays of course (the docs have
been enhanced, however). The GraphicsApi enum-based overload is now
renamed to setGraphicsApi().

Using the same name for both functions is a historical artifact, reflecting
the evolution (5.0 - 5.8 - 5.14). In 6.0 we can give it a more appropriate
name, since it does not have much to do with "backends" from the user's
perspective.

Change-Id: Id75dbf81f50a148797e5b5de9be4000153737473
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

All the classes are implicitly shared, as is the Qt standard, so just
return them as is by value. This is useful when applications split up
their logic and so certain settings are set from different places. (we
see this a lot in practice with QSurfaceFormat for instance) In this case
it is helpful if they can query what they previously stored via the setter.

Change-Id: Id133df8a48d22b896754e6e47a4047ba374597ef
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

Follow the pattern of QQuickRenderTarget and QQuickGraphicsDevice.

This makes it possible to integrate with real world frameworks, such as
OpenXR, that, especially with Vulkan, expect this level of
configurability. (i.e. one pulls the list of extensions to be enabled on
the device, that then needs to be taken into account by Quick, otherwise
it will end up with a VkDevice that is not usable by OpenXR)

Same goes when integrating native Vulkan rendering into an application:
if certain extensions need to be enabled on the VkDevice, today that can
only be done with an environment variable which is not entirely ideal.

These issues are now solved by a new simple (and extensible) container
QQuickGraphicsConfiguration, which is associated with the QQuickWindow.
When applicable, the scene graph will then pick up the relevant settings.

Expand the related docs everywhere. Also rename the vulkanInstance() to
defaultVulkanInstance() to emphasize that it is the instance that is
used for normal QQuickWindows, and is not provided when redirecting
via QQuickRenderControl.

While we are at it, include another obvious candidate: the use-depth-buffer
flag. It turns out that Quick3D's Overlay render mode can be pretty
problematic if Quick writes to the depth buffer. In order to avoid
relying on environment variables (QSG_NO_DEPTH_BUFFER), we now provide
a proper API for controlling that as well.

Change-Id: Iefdb62c1f53de8bd34e3f0d393b00c5020d6188a
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

Accelerated graphics is now possible without OpenGL support. With
this change, a Qt build with -no-opengl can still run Qt Quick with
a Vulkan, Metal, or Direct3D backend.

Fixes: QTBUG-84027
Change-Id: Ib63c733d28cfdf7de16b138df136fa7628e1747b
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

The doc update reveals that this setting has been ignored with the RHI
always, and there is no plans (or ways) to support this.

As the beforeRenderPassRecording() signal documents, connecting to that
signal is effectively an alternative to disabling clearing the color
buffer. (because it allows the application to execute custom GL or other
calls after the clear but before the rest of Qt Quick's rendering)

Therefore, remove the clearBeforeRendering flag from Qt 6.

[ChangeLog][Qt Quick][QQuickWindow] setClearBeforeRendering() and
clearBeforeRendering() are removed.

Change-Id: I6a0a6f56552331923f2e07390e2f33f58c6c31e0
Reviewed-by: Andy Nichols <andy.nichols@qt.io>