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// Copyright (c) 2014-2017 Khronos Group. This work is licensed under a
// Creative Commons Attribution 4.0 International License; see
// http://creativecommons.org/licenses/by/4.0/

[[wsi]]
= Window System Integration (WSI)

This chapter discusses the window system integration (WSI) between the
Vulkan API and the various forms of displaying the results of rendering to a
user.
Since the Vulkan API can: be used without displaying results, WSI is
provided through the use of optional Vulkan extensions.
This chapter provides an overview of WSI.
See the appendix for additional details of each WSI extension, including
which extensions must: be enabled in order to use each of the functions
described in this chapter.


== WSI Platform

A platform is an abstraction for a window system, OS, etc.
Some examples include MS Windows, Android, and Wayland.
The Vulkan API may: be integrated in a unique manner for each platform.

The Vulkan API does not define any type of platform object.
Platform-specific WSI extensions are defined, which contain
platform-specific functions for using WSI.
Use of these extensions is guarded by preprocessor symbols as defined in the
<<boilerplate-wsi-header,Window System-Specific Header Control>> appendix.

In order for an application to be compiled to use WSI with a given platform,
it must: #define the appropriate preprocessor symbol prior to including the
"vulkan.h" header file.
Each platform-specific extension is an instance extension.
The application must: enable instance extensions with fname:vkCreateInstance
before using them.


== WSI Surface

[open,refpage='VkSurfaceKHR',desc='Opaque handle to a surface object',type='handles']
--

Native platform surface or window objects are abstracted by surface objects,
which are represented by sname:VkSurfaceKHR handles:

include::../../api/handles/VkSurfaceKHR.txt[]

The +VK_KHR_surface+ extension declares the sname:VkSurfaceKHR object, and
provides a function for destroying sname:VkSurfaceKHR objects.
Separate platform-specific extensions each provide a function for creating a
sname:VkSurfaceKHR object for the respective platform.
From the application's perspective this is an opaque handle, just like the
handles of other Vulkan objects.

ifdef::implementation-guide[]
[NOTE]
.Note
====
On certain platforms, the Vulkan loader and ICDs may: have conventions that
treat the handle as a pointer to a struct that contains the
platform-specific information about the surface.
This will be described in the documentation for the loader-ICD interface,
and in the "vk_icd.h" header file of the LoaderAndTools source-code
repository.
This does not affect the loader-layer interface; layers may: wrap
sname:VkSurfaceKHR objects.
====
endif::implementation-guide[]

--

ifdef::editing-notes[]
[NOTE]
.editing-note
====
TODO: Consider replacing the above note editing note with a pointer to the
loader spec when it exists.
However, the information is not relevant to users of the API nor does it
affect conformance of a Vulkan implementation to this spec.
====
endif::editing-notes[]

ifdef::VK_KHR_android_surface[]
include::../VK_KHR_android_surface/platformCreateSurface_android.txt[]
endif::VK_KHR_android_surface[]

ifdef::VK_KHR_mir_surface[]
include::../VK_KHR_mir_surface/platformCreateSurface_mir.txt[]
endif::VK_KHR_mir_surface[]

ifdef::VK_KHR_wayland_surface[]
include::../VK_KHR_wayland_surface/platformCreateSurface_wayland.txt[]
endif::VK_KHR_wayland_surface[]

ifdef::VK_KHR_win32_surface[]
include::../VK_KHR_win32_surface/platformCreateSurface_win32.txt[]
endif::VK_KHR_win32_surface[]

ifdef::VK_KHR_xcb_surface[]
include::../VK_KHR_xcb_surface/platformCreateSurface_xcb.txt[]
endif::VK_KHR_xcb_surface[]

ifdef::VK_KHR_xlib_surface[]
include::../VK_KHR_xlib_surface/platformCreateSurface_xlib.txt[]
endif::VK_KHR_xlib_surface[]

ifdef::VK_MVK_ios_surface[]
include::../VK_MVK_ios_surface/platformCreateSurface_ios.txt[]
endif::VK_MVK_ios_surface[]

ifdef::VK_MVK_macos_surface[]
include::../VK_MVK_macos_surface/platformCreateSurface_macos.txt[]
endif::VK_MVK_macos_surface[]

ifdef::VK_NN_vi_surface[]
include::../VK_NN_vi_surface/platformCreateSurface_vi.txt[]
endif::VK_NN_vi_surface[]


=== Platform-Independent Information

Once created, sname:VkSurfaceKHR objects can: be used in this and other
extensions, in particular the +VK_KHR_swapchain+ extension.

Several WSI functions return ename:VK_ERROR_SURFACE_LOST_KHR if the surface
becomes no longer available.
After such an error, the surface (and any child swapchain, if one exists)
should: be destroyed, as there is no way to restore them to a not-lost
state.
Applications may: attempt to create a new sname:VkSurfaceKHR using the same
native platform window object, but whether such re-creation will succeed is
platform-dependent and may: depend on the reason the surface became
unavailable.
A lost surface does not otherwise cause devices to be
<<devsandqueues-lost-device,lost>>.

[open,refpage='vkDestroySurfaceKHR',desc='Destroy a VkSurfaceKHR object',type='protos']
--

To destroy a sname:VkSurfaceKHR object, call:

include::../../api/protos/vkDestroySurfaceKHR.txt[]

  * pname:instance is the instance used to create the surface.
  * pname:surface is the surface to destroy.
  * pname:pAllocator is the allocator used for host memory allocated for the
    surface object when there is no more specific allocator available (see
    <<memory-allocation,Memory Allocation>>).

Destroying a sname:VkSurfaceKHR merely severs the connection between Vulkan
and the native surface, and does not imply destroying the native surface,
closing a window, or similar behavior.

.Valid Usage
****
  * [[VUID-vkDestroySurfaceKHR-surface-01266]]
    All sname:VkSwapchainKHR objects created for pname:surface must: have
    been destroyed prior to destroying pname:surface
  * [[VUID-vkDestroySurfaceKHR-surface-01267]]
    If sname:VkAllocationCallbacks were provided when pname:surface was
    created, a compatible set of callbacks must: be provided here
  * [[VUID-vkDestroySurfaceKHR-surface-01268]]
    If no sname:VkAllocationCallbacks were provided when pname:surface was
    created, pname:pAllocator must: be `NULL`
****

include::../../validity/protos/vkDestroySurfaceKHR.txt[]
--

ifdef::VK_KHR_display[]
include::../VK_KHR_display/display.txt[]
endif::VK_KHR_display[]


== Querying for WSI Support

Not all physical devices will include WSI support.
Within a physical device, not all queue families will support presentation.
WSI support and compatibility can: be determined in a platform-neutral
manner (which determines support for presentation to a particular surface
object) and additionally may: be determined in platform-specific manners
(which determine support for presentation on the specified physical device
but do not guarantee support for presentation to a particular surface
object).

[open,refpage='vkGetPhysicalDeviceSurfaceSupportKHR',desc='Query if presentation is supported',type='protos']
--

To determine whether a queue family of a physical device supports
presentation to a given surface, call:

include::../../api/protos/vkGetPhysicalDeviceSurfaceSupportKHR.txt[]

  * pname:physicalDevice is the physical device.
  * pname:queueFamilyIndex is the queue family.
  * pname:surface is the surface.
  * pname:pSupported is a pointer to a basetype:VkBool32, which is set to
    ename:VK_TRUE to indicate support, and ename:VK_FALSE otherwise.

.Valid Usage
****
  * [[VUID-vkGetPhysicalDeviceSurfaceSupportKHR-queueFamilyIndex-01269]]
    pname:queueFamilyIndex must: be less than
    pname:pQueueFamilyPropertyCount returned by
    fname:vkGetPhysicalDeviceQueueFamilyProperties for the given
    pname:physicalDevice
****

include::../../validity/protos/vkGetPhysicalDeviceSurfaceSupportKHR.txt[]
--

ifdef::VK_KHR_android_surface[]
include::../VK_KHR_android_surface/platformQuerySupport_android.txt[]
endif::VK_KHR_android_surface[]

ifdef::VK_KHR_mir_surface[]
include::../VK_KHR_mir_surface/platformQuerySupport_mir.txt[]
endif::VK_KHR_mir_surface[]

ifdef::VK_KHR_wayland_surface[]
include::../VK_KHR_wayland_surface/platformQuerySupport_wayland.txt[]
endif::VK_KHR_wayland_surface[]

ifdef::VK_KHR_win32_surface[]
include::../VK_KHR_win32_surface/platformQuerySupport_win32.txt[]
endif::VK_KHR_win32_surface[]

ifdef::VK_KHR_xcb_surface[]
include::../VK_KHR_xcb_surface/platformQuerySupport_xcb.txt[]
endif::VK_KHR_xcb_surface[]

ifdef::VK_KHR_xlib_surface[]
include::../VK_KHR_xlib_surface/platformQuerySupport_xlib.txt[]
endif::VK_KHR_xlib_surface[]

ifdef::VK_MVK_ios_surface[]
include::../VK_MVK_ios_surface/platformQuerySupport_ios.txt[]
endif::VK_MVK_ios_surface[]

ifdef::VK_MVK_macos_surface[]
include::../VK_MVK_macos_surface/platformQuerySupport_macos.txt[]
endif::VK_MVK_macos_surface[]

ifdef::VK_NN_vi_surface[]
include::../VK_NN_vi_surface/platformQuerySupport_vi.txt[]
endif::VK_NN_vi_surface[]


== Surface Queries

[open,refpage='vkGetPhysicalDeviceSurfaceCapabilitiesKHR',desc='Query surface capabilities',type='protos']
--

To query the basic capabilities of a surface, needed in order to create a
swapchain, call:

include::../../api/protos/vkGetPhysicalDeviceSurfaceCapabilitiesKHR.txt[]

  * pname:physicalDevice is the physical device that will be associated with
    the swapchain to be created, as described for
    flink:vkCreateSwapchainKHR.
  * pname:surface is the surface that will be associated with the swapchain.
  * pname:pSurfaceCapabilities is a pointer to an instance of the
    slink:VkSurfaceCapabilitiesKHR structure in which the capabilities are
    returned.

include::../../validity/protos/vkGetPhysicalDeviceSurfaceCapabilitiesKHR.txt[]
--

[open,refpage='VkSurfaceCapabilitiesKHR',desc='Structure describing capabilities of a surface',type='structs']
--

The sname:VkSurfaceCapabilitiesKHR structure is defined as:

include::../../api/structs/VkSurfaceCapabilitiesKHR.txt[]

  * pname:minImageCount is the minimum number of images the specified device
    supports for a swapchain created for the surface, and will be at least
    one.
  * pname:maxImageCount is the maximum number of images the specified device
    supports for a swapchain created for the surface, and will be either 0,
    or greater than or equal to pname:minImageCount.
    A value of 0 means that there is no limit on the number of images,
    though there may: be limits related to the total amount of memory used
    by presentable images.
  * pname:currentExtent is the current width and height of the surface, or
    the special value [eq]#(0xFFFFFFFF, 0xFFFFFFFF)# indicating that the
    surface size will be determined by the extent of a swapchain targeting
    the surface.
  * pname:minImageExtent contains the smallest valid swapchain extent for
    the surface on the specified device.
  * pname:maxImageExtent contains the largest valid swapchain extent for the
    surface on the specified device.
    The pname:width and pname:height of the extent will each be greater than
    or equal to the corresponding pname:width and pname:height of
    pname:minImageExtent.
    The pname:width and pname:height of the extent will each be greater than
    or equal to the corresponding pname:width and pname:height of
    pname:currentExtent, unless pname:currentExtent has the special value
    described above.
  * pname:maxImageArrayLayers is the maximum number of layers presentable
    images can: have for a swapchain created for this device and surface,
    and will be at least one.
  * pname:supportedTransforms is a bitmask of
    elink:VkSurfaceTransformFlagBitsKHR indicating the presentation
    transforms supported for the surface on the specified device.
    At least one bit will be set.
  * pname:currentTransform is elink:VkSurfaceTransformFlagBitsKHR value
    indicating the surface's current transform relative to the presentation
    engine's natural orientation.
  * pname:supportedCompositeAlpha is a bitmask of
    elink:VkCompositeAlphaFlagBitsKHR, representing the alpha compositing
    modes supported by the presentation engine for the surface on the
    specified device, and at least one bit will be set.
    Opaque composition can: be achieved in any alpha compositing mode by
    either using an image format that has no alpha component, or by ensuring
    that all pixels in the presentable images have an alpha value of 1.0.
  * pname:supportedUsageFlags is a bitmask of elink:VkImageUsageFlagBits
    representing the ways the application can: use the presentable images of
    a swapchain created
ifdef::VK_KHR_shared_presentable_image[]
    with elink:VkPresentModeKHR set to ename:VK_PRESENT_MODE_IMMEDIATE_KHR,
    ename:VK_PRESENT_MODE_MAILBOX_KHR, ename:VK_PRESENT_MODE_FIFO_KHR or
    ename:VK_PRESENT_MODE_FIFO_RELAXED_KHR
endif::VK_KHR_shared_presentable_image[]
    for the surface on the specified device.
    ename:VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT must: be included in the set
    but implementations may: support additional usages.

ifdef::VK_KHR_shared_presentable_image[]
[NOTE]
.Note
====
Supported usage flags of a presentable image when using
ename:VK_PRESENT_MODE_SHARED_DEMAND_REFRESH_KHR or
ename:VK_PRESENT_MODE_SHARED_CONTINUOUS_REFRESH_KHR presentation mode are
provided by
slink:VkSharedPresentSurfaceCapabilitiesKHR::pname:sharedPresentSupportedUsageFlags.
====
endif::VK_KHR_shared_presentable_image[]

[NOTE]
.Note
====
Formulas such as [eq]#min(N, pname:maxImageCount)# are not correct, since
pname:maxImageCount may: be zero.
====

include::../../validity/structs/VkSurfaceCapabilitiesKHR.txt[]
--

ifdef::VK_KHR_get_surface_capabilities2[]

[open,refpage='vkGetPhysicalDeviceSurfaceCapabilities2KHR',desc='Reports capabilities of a surface on a physical device',type='protos']
--

To query the basic capabilities of a surface defined by the core or
extensions, call:

include::../../api/protos/vkGetPhysicalDeviceSurfaceCapabilities2KHR.txt[]

  * pname:physicalDevice is the physical device that will be associated with
    the swapchain to be created, as described for
    flink:vkCreateSwapchainKHR.
  * pname:pSurfaceInfo points to an instance of the
    slink:VkPhysicalDeviceSurfaceInfo2KHR structure, describing the surface
    and other fixed parameters that would be consumed by
    flink:vkCreateSwapchainKHR.
  * pname:pSurfaceCapabilities points to an instance of the
    slink:VkSurfaceCapabilities2KHR structure in which the capabilities are
    returned.

fname:vkGetPhysicalDeviceSurfaceCapabilities2KHR behaves similarly to
flink:vkGetPhysicalDeviceSurfaceCapabilitiesKHR, with the ability to specify
extended inputs via chained input structures, and to return extended
information via chained output structures.

include::../../validity/protos/vkGetPhysicalDeviceSurfaceCapabilities2KHR.txt[]
--

[open,refpage='VkPhysicalDeviceSurfaceInfo2KHR',desc='Structure specifying a surface and related swapchain creation parameters',type='structs']
--

The sname:VkPhysicalDeviceSurfaceInfo2KHR structure is defined as:

include::../../api/structs/VkPhysicalDeviceSurfaceInfo2KHR.txt[]

  * pname:sType is the type of this structure.
  * pname:pNext is `NULL` or a pointer to an extension-specific structure.
  * pname:surface is the surface that will be associated with the swapchain.

The members of sname:VkPhysicalDeviceSurfaceInfo2KHR correspond to the
arguments to flink:vkGetPhysicalDeviceSurfaceCapabilities, with pname:sType
and pname:pNext added for extensibility.

include::../../validity/structs/VkPhysicalDeviceSurfaceInfo2KHR.txt[]
--

[open,refpage='VkSurfaceCapabilities2KHR',desc='Structure describing capabilities of a surface',type='structs']
--

The sname:VkSurfaceCapabilities2KHR structure is defined as:

include::../../api/structs/VkSurfaceCapabilities2KHR.txt[]

  * pname:sType is the type of this structure.
  * pname:pNext is `NULL` or a pointer to an extension-specific structure.
  * pname:surfaceCapabilities is a structure of type
    slink:VkSurfaceCapabilitiesKHR describing the capabilities of the
    specified surface.

include::../../validity/structs/VkSurfaceCapabilities2KHR.txt[]
--

ifdef::VK_KHR_shared_presentable_image[]
[open,refpage='VkSharedPresentSurfaceCapabilitiesKHR',desc='structure describing capabilities of a surface for shared presentation',type='structs']
--

The sname:VkSharedPresentSurfaceCapabilitiesKHR structure is defined as:

include::../../api/structs/VkSharedPresentSurfaceCapabilitiesKHR.txt[]

  * pname:sType is the type of this structure.
  * pname:pNext is `NULL` or a pointer to an extension-specific structure.
  * pname:sharedPresentSupportedUsageFlags is a bitmask of
    elink:VkImageUsageFlagBits representing the ways the application can:
    use the shared presentable image from a swapchain created with
    elink:VkPresentModeKHR set to
    ename:VK_PRESENT_MODE_SHARED_DEMAND_REFRESH_KHR or
    ename:VK_PRESENT_MODE_SHARED_CONTINUOUS_REFRESH_KHR for the surface on
    the specified device.
    ename:VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT must: be included in the set
    but implementations may: support additional usages.

include::../../validity/structs/VkSharedPresentSurfaceCapabilitiesKHR.txt[]

--
endif::VK_KHR_shared_presentable_image[]
endif::VK_KHR_get_surface_capabilities2[]

ifdef::VK_EXT_display_surface_counter[]
include::../VK_EXT_display_surface_counter/surface_capabilities.txt[]
endif::VK_EXT_display_surface_counter[]

[open,refpage='VkSurfaceTransformFlagBitsKHR',desc='presentation transforms supported on a device',type='enums']
--

Bits which may: be set in
slink:VkSurfaceCapabilitiesKHR::pname:supportedTransforms indicating the
presentation transforms supported for the surface on the specified device,
and possible values of
slink:VkSurfaceCapabilitiesKHR::pname:currentTransform is indicating the
surface's current transform relative to the presentation engine's natural
orientation, are:

include::../../api/enums/VkSurfaceTransformFlagBitsKHR.txt[]

  * ename:VK_SURFACE_TRANSFORM_IDENTITY_BIT_KHR indicates that image content
    is presented without being transformed.
  * ename:VK_SURFACE_TRANSFORM_ROTATE_90_BIT_KHR indicates that image
    content is rotated 90 degrees clockwise.
  * ename:VK_SURFACE_TRANSFORM_ROTATE_180_BIT_KHR indicates that image
    content is rotated 180 degrees clockwise.
  * ename:VK_SURFACE_TRANSFORM_ROTATE_270_BIT_KHR indicates that image
    content is rotated 270 degrees clockwise.
  * ename:VK_SURFACE_TRANSFORM_HORIZONTAL_MIRROR_BIT_KHR indicates that
    image content is mirrored horizontally.
  * ename:VK_SURFACE_TRANSFORM_HORIZONTAL_MIRROR_ROTATE_90_BIT_KHR indicates
    that image content is mirrored horizontally, then rotated 90 degrees
    clockwise.
  * ename:VK_SURFACE_TRANSFORM_HORIZONTAL_MIRROR_ROTATE_180_BIT_KHR
    indicates that image content is mirrored horizontally, then rotated 180
    degrees clockwise.
  * ename:VK_SURFACE_TRANSFORM_HORIZONTAL_MIRROR_ROTATE_270_BIT_KHR
    indicates that image content is mirrored horizontally, then rotated 270
    degrees clockwise.
  * ename:VK_SURFACE_TRANSFORM_INHERIT_BIT_KHR indicates that the
    presentation transform is not specified, and is instead determined by
    platform-specific considerations and mechanisms outside Vulkan.

--

[open,refpage='VkCompositeAlphaFlagBitsKHR',desc='alpha compositing modes supported on a device',type='enums']
--

The pname:supportedCompositeAlpha member is of type
elink:VkCompositeAlphaFlagBitsKHR, which contains the following values:

include::../../api/enums/VkCompositeAlphaFlagBitsKHR.txt[]

These values are described as follows:

  * ename:VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR: The alpha channel, if it
    exists, of the images is ignored in the compositing process.
    Instead, the image is treated as if it has a constant alpha of 1.0.
  * ename:VK_COMPOSITE_ALPHA_PRE_MULTIPLIED_BIT_KHR: The alpha channel, if
    it exists, of the images is respected in the compositing process.
    The non-alpha channels of the image are expected to already be
    multiplied by the alpha channel by the application.
  * ename:VK_COMPOSITE_ALPHA_POST_MULTIPLIED_BIT_KHR: The alpha channel, if
    it exists, of the images is respected in the compositing process.
    The non-alpha channels of the image are not expected to already be
    multiplied by the alpha channel by the application; instead, the
    compositor will multiply the non-alpha channels of the image by the
    alpha channel during compositing.
  * ename:VK_COMPOSITE_ALPHA_INHERIT_BIT_KHR: The way in which the
    presentation engine treats the alpha channel in the images is unknown to
    the Vulkan API.
    Instead, the application is responsible for setting the composite alpha
    blending mode using native window system commands.
    If the application does not set the blending mode using native window
    system commands, then a platform-specific default will be used.

--

[open,refpage='vkGetPhysicalDeviceSurfaceFormatsKHR',desc='Query color formats supported by surface',type='protos']
--

To query the supported swapchain format-color space pairs for a surface,
call:

include::../../api/protos/vkGetPhysicalDeviceSurfaceFormatsKHR.txt[]

  * pname:physicalDevice is the physical device that will be associated with
    the swapchain to be created, as described for
    flink:vkCreateSwapchainKHR.
  * pname:surface is the surface that will be associated with the swapchain.
  * pname:pSurfaceFormatCount is a pointer to an integer related to the
    number of format pairs available or queried, as described below.
  * pname:pSurfaceFormats is either `NULL` or a pointer to an array of
    sname:VkSurfaceFormatKHR structures.

If pname:pSurfaceFormats is `NULL`, then the number of format pairs
supported for the given pname:surface is returned in
pname:pSurfaceFormatCount.
The number of format pairs supported will be greater than or equal to 1.
Otherwise, pname:pSurfaceFormatCount must: point to a variable set by the
user to the number of elements in the pname:pSurfaceFormats array, and on
return the variable is overwritten with the number of structures actually
written to pname:pSurfaceFormats.
If the value of pname:pSurfaceFormatCount is less than the number of format
pairs supported, at most pname:pSurfaceFormatCount structures will be
written.
If pname:pSurfaceFormatCount is smaller than the number of format pairs
supported for the given pname:surface, ename:VK_INCOMPLETE will be returned
instead of ename:VK_SUCCESS to indicate that not all the available values
were returned.

include::../../validity/protos/vkGetPhysicalDeviceSurfaceFormatsKHR.txt[]
--

[open,refpage='VkSurfaceFormatKHR',desc='Structure describing a supported swapchain format-color space pair',type='structs']
--

The sname:VkSurfaceFormatKHR structure is defined as:

include::../../api/structs/VkSurfaceFormatKHR.txt[]

  * pname:format is a elink:VkFormat that is compatible with the specified
    surface.
  * pname:colorSpace is a presentation elink:VkColorSpaceKHR that is
    compatible with the surface.

include::../../validity/structs/VkSurfaceFormatKHR.txt[]
--

ifdef::VK_KHR_get_surface_capabilities2[]

[open,refpage='vkGetPhysicalDeviceSurfaceFormats2KHR',desc='Query color formats supported by surface',type='protos']
--

To query the supported swapchain format tuples for a surface, call:

include::../../api/protos/vkGetPhysicalDeviceSurfaceFormats2KHR.txt[]

  * pname:physicalDevice is the physical device that will be associated with
    the swapchain to be created, as described for
    flink:vkCreateSwapchainKHR.
  * pname:pSurfaceInfo points to an instance of the
    slink:VkPhysicalDeviceSurfaceInfo2KHR structure, describing the surface
    and other fixed parameters that would be consumed by
    flink:vkCreateSwapchainKHR.
  * pname:pSurfaceFormatCount is a pointer to an integer related to the
    number of format tuples available or queried, as described below.
  * pname:pSurfaceFormats is either `NULL` or a pointer to an array of
    slink:VkSurfaceFormat2KHR structures.

If pname:pSurfaceFormats is `NULL`, then the number of format tuples
supported for the given pname:surface is returned in
pname:pSurfaceFormatCount.
The number of format tuples supported will be greater than or equal to 1.
Otherwise, pname:pSurfaceFormatCount must: point to a variable set by the
user to the number of elements in the pname:pSurfaceFormats array, and on
return the variable is overwritten with the number of structures actually
written to pname:pSurfaceFormats.
If the value of pname:pSurfaceFormatCount is less than the number of format
tuples supported, at most pname:pSurfaceFormatCount structures will be
written.
If pname:pSurfaceFormatCount is smaller than the number of format tuples
supported for the surface parameters described in pname:pSurfaceInfo,
ename:VK_INCOMPLETE will be returned instead of ename:VK_SUCCESS to indicate
that not all the available values were returned.

include::../../validity/protos/vkGetPhysicalDeviceSurfaceFormats2KHR.txt[]
--

[open,refpage='VkSurfaceFormat2KHR',desc='Structure describing a supported swapchain format tuple',type='structs']
--

The sname:VkSurfaceFormat2KHR structure is defined as:

include::../../api/structs/VkSurfaceFormat2KHR.txt[]

  * pname:sType is the type of this structure.
  * pname:pNext is `NULL` or a pointer to an extension-specific structure.
  * pname:surfaceFormat is an instance of slink:VkSurfaceFormatKHR
    describing a format-color space pair that is compatible with the
    specified surface.

include::../../validity/structs/VkSurfaceFormat2KHR.txt[]
--

endif::VK_KHR_get_surface_capabilities2[]

While the pname:format of a presentable image refers to the encoding of each
pixel, the pname:colorSpace determines how the presentation engine
interprets the pixel values.
A color space in this document refers to a specific color space (defined by
the chromaticities of its primaries and a white point in CIE Lab), and a
transfer function that is applied before storing or transmitting color data
in the given color space.

[open,refpage='VkColorSpaceKHR',desc='supported color space of the presentation engine',type='enums']
--

Possible values of slink:VkSurfaceFormatKHR::pname:colorSpace, specifying
supported color spaces of a presentation engine, are:

include::../../api/enums/VkColorSpaceKHR.txt[]

  * ename:VK_COLOR_SPACE_SRGB_NONLINEAR_KHR indicates support for the sRGB
    color space.
ifdef::VK_EXT_swapchain_colorspace[]
  * ename:VK_COLOR_SPACE_DISPLAY_P3_NONLINEAR_EXT indicates support for the
    Display-P3 color space and applies an sRGB-like transfer function
    (defined below).
  * ename:VK_COLOR_SPACE_EXTENDED_SRGB_LINEAR_EXT indicates support for the
    extended sRGB color space and applies a linear transfer function.
  * ename:VK_COLOR_SPACE_EXTENDED_SRGB_NONLINEAR_EXT indicates support for
    the extended sRGB color space and applies an sRGB transfer function.
  * ename:VK_COLOR_SPACE_DCI_P3_LINEAR_EXT indicates support for the DCI-P3
    color space and applies a linear OETF.
  * ename:VK_COLOR_SPACE_DCI_P3_NONLINEAR_EXT indicates support for the
    DCI-P3 color space and applies the Gamma 2.6 OETF.
  * ename:VK_COLOR_SPACE_BT709_LINEAR_EXT indicates support for the BT709
    color space and applies a linear OETF.
  * ename:VK_COLOR_SPACE_BT709_NONLINEAR_EXT indicates support for the BT709
    color space and applies the SMPTE 170M OETF.
  * ename:VK_COLOR_SPACE_BT2020_LINEAR_EXT indicates support for the BT2020
    color space and applies a linear OETF.
  * ename:VK_COLOR_SPACE_HDR10_ST2084_EXT indicates support for the HDR10
    (BT2020 color) space and applies the SMPTE ST2084 Perceptual Quantizer
    (PQ) OETF.
  * ename:VK_COLOR_SPACE_DOLBYVISION_EXT indicates support for the Dolby
    Vision (BT2020 color space), proprietary encoding, and applies the SMPTE
    ST2084 OETF.
  * ename:VK_COLOR_SPACE_HDR10_HLG_EXT indicates support for the HDR10
    (BT2020 color space) and applies the Hybrid Log Gamma (HLG) OETF.
  * ename:VK_COLOR_SPACE_ADOBERGB_LINEAR_EXT indicates support for the
    AdobeRGB color space and applies a linear OETF.
  * ename:VK_COLOR_SPACE_ADOBERGB_NONLINEAR_EXT indicates support for the
    AdobeRGB color space and applies the Gamma 2.2 OETF.
  * ename:VK_COLOR_SPACE_PASS_THROUGH_EXT indicates that color components
    are used "`as is`".
    This is intended to allow applications to supply data for color spaces
    not described here.

The color components of Non-linear color space swap chain images have had
the appropriate transfer function applied.
Vulkan requires that all implementations support the sRGB transfer function
when using an SRGB pixel format.
Other transfer functions, such as SMPTE 170M or SMPTE2084, must: not be
performed by the implementation, but can: be performed by the application
shader.
This extension defines enums for elink:VkColorSpaceKHR that correspond to
the following color spaces::

[[VK_EXT_swapchain_colorspace-table]]
.Color Spaces and Attributes
[options="header"]
|====
| Name           | Red Primary  | Green Primary | Blue Primary | White-point | Transfer function
| DCI-P3         | 0.680, 0.320 | 0.265, 0.690  | 0.150, 0.060 | 0.3127, 0.3290 (D65) | Gamma 2.6
| Display-P3     | 0.680, 0.320 | 0.265, 0.690  | 0.150, 0.060 | 0.3127, 0.3290 (D65) | Display-P3
| BT709          | 0.640, 0.330 | 0.300, 0.600  | 0.150, 0.060 | 0.3127, 0.3290 (D65) | SMPTE 170M
| sRGB           | 0.640, 0.330 | 0.300, 0.600  | 0.150, 0.060 | 0.3127, 0.3290 (D65) | sRGB
| extended sRGB  | 0.640, 0.330 | 0.300, 0.600  | 0.150, 0.060 | 0.3127, 0.3290 (D65) | extended sRGB
| HDR10_ST2084   | 0.708, 0.292 | 0.170, 0.797  | 0.131, 0.046 | 0.3127, 0.3290 (D65) | ST2084
| DOLBYVISION    | 0.708, 0.292 | 0.170, 0.797  | 0.131, 0.046 | 0.3127, 0.3290 (D65) | ST2084
| HDR10_HLG      | 0.708, 0.292 | 0.170, 0.797  | 0.131, 0.046 | 0.3127, 0.3290 (D65) | HLG
| AdobeRGB       | 0.640, 0.330 | 0.210, 0.710  | 0.150, 0.060 | 0.3127, 0.3290 (D65) | AdobeRGB
|====

For Opto-Electrical Transfer Function (OETF), unless otherwise specified,
the values of [eq]#L# and [eq]#E# are defined as:

[eq]#L# - linear luminance of image latexmath:[0 \leq L \leq 1] for
conventional colorimetry

[eq]#E# - corresponding electrical signal (value stored in memory)

// @@@ The ref page is ended earlier than in the original markup due to
// asciidoctor issues described in internal MR 2201.
endif::VK_EXT_swapchain_colorspace[]

--

ifdef::VK_EXT_swapchain_colorspace[]

=== sRGB transfer function

[latexmath]
+++++++++++++++++++
\begin{aligned}
E & =
  \begin{cases}
    1.055 \times L^{1 \over 2.4} - 0.055 & \text{for}\  0.0031308 \leq L \leq 1 \\
    12.92 \times L                       & \text{for}\  0 \leq L < 0.0031308
  \end{cases}
\end{aligned}
+++++++++++++++++++


=== Display-P3 EOTF

[latexmath]
+++++++++++++++++++
\begin{aligned}
E & =
  \begin{cases}
    (a \times L + b)^{2.4} & \text{for}\  0.039 \leq L \leq 1 \\
    b \times L                    & \text{for}\  0 \leq L < 0.039
  \end{cases}
\end{aligned}
+++++++++++++++++++

latexmath:[a = 0.948] +
latexmath:[b = 0.052] +
latexmath:[c = 0.077] +


=== Display-P3 OETF

[latexmath]
+++++++++++++++++++
\begin{aligned}
E & =
  \begin{cases}
    1.055 \times L^{1 \over 2.4} - 0.055 & \text{for}\  0.0030186 \leq L \leq 1 \\
    12.92 \times L                       & \text{for}\  0 \leq L < 0.0030186
  \end{cases}
\end{aligned}
+++++++++++++++++++

[NOTE]
.Note
====
For most uses, the sRGB OETF is equivalent.
====


=== Extended sRGB OETF

[latexmath]
+++++++++++++++++++
\begin{aligned}
E & =
  \begin{cases}
    1.055 \times L^{1 \over 2.4} - 0.055 & \text{for}\  0.0031308 \leq L \leq 7.5913 \\
    12.92 \times L                       & \text{for}\  0 \leq L < 0.0031308 \\
    -f(-L)                               & \text{for}\  L < 0
  \end{cases}
\end{aligned}
+++++++++++++++++++

[eq]#L# - luminance of image is within [eq]#[-0.6038, 7.5913]#.

[eq]#E# can be negative and/or > 1.
That is how extended sRGB specifies colors outside the standard sRGB gamut.
This means extended sRGB needs a floating point pixel format to cover the
intended color range.


=== SMPTE 170M OETF

[latexmath]
+++++++++++++++++++
\begin{aligned}
E & =
  \begin{cases}
    \alpha \times L^{0.45} - (1 - \alpha) & \text{for}\  \beta \leq L \leq 1 \\
    4.5 \times L                            & \text{for}\  0 \leq L < \beta
  \end{cases}
\end{aligned}
+++++++++++++++++++

latexmath:[\alpha = 1.099 \text{ and } \beta = 0.018 \text{ for 10-bits and
less per sample system (the values given in Rec.
709)}] +
latexmath:[\alpha = 1.0993 \text{ and } \beta = 0.0181 \text{ for 12-bits
per sample system}]


=== SMPTE ST2084 OETF (Inverse-EOTF)

[latexmath]
+++++++++++++++++++
\[
E = (\frac{c_1 + c_2 \times L^{m_1}}{1 + c_3 \times L^{m_1}})^{m_2}
\]
+++++++++++++++++++

where:

latexmath:[m_1 = 2610 / 4096 \times \frac{1}{4} = 0.1593017578125] +
latexmath:[m_2 = 2523 / 4096 \times 128 = 78.84375] +
latexmath:[c_1 = 3424 / 4096 = 0.8359375 = c3 - c2 + 1] +
latexmath:[c_2 = 2413 / 4096 \times 32 = 18.8515625] +
latexmath:[c_3 = 2392 / 4096 \times 32 = 18.6875] +


=== Hybrid Log Gamma (HLG)

[latexmath]
+++++++++++++++++++
\begin{aligned}
E & =
  \begin{cases}
    r \sqrt{L}                & \text{for}\  0 \leq L \leq 1 \\
    a \times \ln(L - b) + c    & \text{for}\  1 < L
  \end{cases}
\end{aligned}
+++++++++++++++++++

[eq]#_L_# -- is the signal normalized by the reference white level +
[eq]#_r_# -- is the reference white level and has a signal value of 0.5 +
[eq]#_a_ = 0.17883277# and [eq]#_b_ = 0.28466892# and [eq]#_c_ = 0.55991073#


=== Adobe RGB (1998) OETF

latexmath:[E = L^\frac{1}{2.19921875}]


=== Gamma 2.6 OETF

latexmath:[E = L^\frac{1}{2.6}]

An implementation supporting this extension indicates support for these
color spaces via slink:VkSurfaceFormatKHR structures returned from
flink:vkGetPhysicalDeviceSurfaceFormatsKHR.

Specifying the supported surface color space when calling
flink:vkCreateSwapchainKHR will create a swapchain using that color space.

Vulkan requires that all implementations support the sRGB Opto-Electrical
Transfer Function (OETF) and Electro-optical transfer function (EOTF) when
using an SRGB pixel format.
Other transfer functions, such as SMPTE 170M, must: not be performed by the
implementation, but can: be performed by the application shader.

endif::VK_EXT_swapchain_colorspace[]

If pname:pSurfaceFormats includes an entry whose value for pname:colorSpace
is ename:VK_COLOR_SPACE_SRGB_NONLINEAR_KHR and whose value for pname:format
is a UNORM (or SRGB) format and the corresponding SRGB (or UNORM) format is
a color renderable format for ename:VK_IMAGE_TILING_OPTIMAL, then
pname:pSurfaceFormats must: also contain an entry with the same value for
pname:colorSpace and pname:format equal to the corresponding SRGB (or UNORM)
format.

[NOTE]
.Note
====
If pname:pSurfaceFormats includes just one entry, whose value for
pname:format is ename:VK_FORMAT_UNDEFINED, pname:surface has no preferred
format.
In this case, the application can: use any valid elink:VkFormat value.
====

[NOTE]
.Note
====
In the initial release of the +VK_KHR_surface+ and +VK_KHR_swapchain+
extensions, the token ename:VK_COLORSPACE_SRGB_NONLINEAR_KHR was used.
Starting in the 2016-05-13 updates to the extension branches, matching
release 1.0.13 of the core API specification,
ename:VK_COLOR_SPACE_SRGB_NONLINEAR_KHR is used instead for consistency with
Vulkan naming rules.
The older enum is still available for backwards compatibility.
====

// @@@ originally, the VkColorSpaceKHR ref page ended here
// --

[open,refpage='vkGetPhysicalDeviceSurfacePresentModesKHR',desc='Query supported presentation modes',type='protos']
--

To query the supported presentation modes for a surface, call:

include::../../api/protos/vkGetPhysicalDeviceSurfacePresentModesKHR.txt[]

  * pname:physicalDevice is the physical device that will be associated with
    the swapchain to be created, as described for
    flink:vkCreateSwapchainKHR.
  * pname:surface is the surface that will be associated with the swapchain.
  * pname:pPresentModeCount is a pointer to an integer related to the number
    of presentation modes available or queried, as described below.
  * pname:pPresentModes is either `NULL` or a pointer to an array of
    elink:VkPresentModeKHR values, indicating the supported presentation
    modes.

If pname:pPresentModes is `NULL`, then the number of presentation modes
supported for the given pname:surface is returned in
pname:pPresentModeCount.
Otherwise, pname:pPresentModeCount must: point to a variable set by the user
to the number of elements in the pname:pPresentModes array, and on return
the variable is overwritten with the number of values actually written to
pname:pPresentModes.
If the value of pname:pPresentModeCount is less than the number of
presentation modes supported, at most pname:pPresentModeCount values will be
written.
If pname:pPresentModeCount is smaller than the number of presentation modes
supported for the given pname:surface, ename:VK_INCOMPLETE will be returned
instead of ename:VK_SUCCESS to indicate that not all the available values
were returned.

include::../../validity/protos/vkGetPhysicalDeviceSurfacePresentModesKHR.txt[]
--

[open,refpage='VkPresentModeKHR',desc='presentation mode supported for a surface',type='enums']
--

Possible values of elements of the
flink:vkGetPhysicalDeviceSurfacePresentModesKHR::pname:pPresentModes array,
indicating the supported presentation modes for a surface, are:

include::../../api/enums/VkPresentModeKHR.txt[]

  * ename:VK_PRESENT_MODE_IMMEDIATE_KHR indicates that the presentation
    engine does not wait for a vertical blanking period to update the
    current image, meaning this mode may: result in visible tearing.
    No internal queuing of presentation requests is needed, as the requests
    are applied immediately.
  * ename:VK_PRESENT_MODE_MAILBOX_KHR indicates that the presentation engine
    waits for the next vertical blanking period to update the current image.
    Tearing cannot: be observed.
    An internal single-entry queue is used to hold pending presentation
    requests.
    If the queue is full when a new presentation request is received, the
    new request replaces the existing entry, and any images associated with
    the prior entry become available for re-use by the application.
    One request is removed from the queue and processed during each vertical
    blanking period in which the queue is non-empty.
  * ename:VK_PRESENT_MODE_FIFO_KHR indicates that the presentation engine
    waits for the next vertical blanking period to update the current image.
    Tearing cannot: be observed.
    An internal queue is used to hold pending presentation requests.
    New requests are appended to the end of the queue, and one request is
    removed from the beginning of the queue and processed during each
    vertical blanking period in which the queue is non-empty.
    This is the only value of pname:presentMode that is required: to be
    supported.
  * ename:VK_PRESENT_MODE_FIFO_RELAXED_KHR indicates that the presentation
    engine generally waits for the next vertical blanking period to update
    the current image.
    If a vertical blanking period has already passed since the last update
    of the current image then the presentation engine does not wait for
    another vertical blanking period for the update, meaning this mode may:
    result in visible tearing in this case.
    This mode is useful for reducing visual stutter with an application that
    will mostly present a new image before the next vertical blanking
    period, but may occasionally be late, and present a new image just after
    the next vertical blanking period.
    An internal queue is used to hold pending presentation requests.
    New requests are appended to the end of the queue, and one request is
    removed from the beginning of the queue and processed during or after
    each vertical blanking period in which the queue is non-empty.
ifdef::VK_KHR_shared_presentable_image[]
  * ename:VK_PRESENT_MODE_SHARED_DEMAND_REFRESH_KHR indicates that the
    presentation engine and application have concurrent access to a single
    image, which is referred to as a _shared presentable image_.
    The presentation engine is only required to update the current image
    after a new presentation request is received.
    Therefore the application must: make a presentation request whenever an
    update is required.
    However, the presentation engine may: update the current image at any
    point, meaning this mode may: result in visible tearing.
  * ename:VK_PRESENT_MODE_SHARED_CONTINUOUS_REFRESH_KHR indicates that the
    presentation engine and application have concurrent access to a single
    image, which is referred to as a _shared presentable image_.
    The presentation engine periodically updates the current image on its
    regular refresh cycle.
    The application is only required to make one initial presentation
    request, after which the presentation engine must: update the current
    image without any need for further presentation requests.
    The application can: indicate the image contents have been updated by
    making a presentation request, but this does not guarantee the timing of
    when it will be updated.
    This mode may: result in visible tearing if rendering to the image is
    not timed correctly.

The supported elink:VkImageUsageFlagBits of the presentable images of a
swapchain created for a surface may: differ depending on the presentation
mode, and can be determined as per the table below:

.Presentable image usage queries
[width="100%",cols="<50%,<50%",options="header"]
|====
| Presentation mode                                   | Image usage flags
| ename:VK_PRESENT_MODE_IMMEDIATE_KHR                 | slink:VkSurfaceCapabilitiesKHR::pname:supportedUsageFlags
| ename:VK_PRESENT_MODE_MAILBOX_KHR                   | slink:VkSurfaceCapabilitiesKHR::pname:supportedUsageFlags
| ename:VK_PRESENT_MODE_FIFO_KHR                      | slink:VkSurfaceCapabilitiesKHR::pname:supportedUsageFlags
| ename:VK_PRESENT_MODE_FIFO_RELAXED_KHR              | slink:VkSurfaceCapabilitiesKHR::pname:supportedUsageFlags
| ename:VK_PRESENT_MODE_SHARED_DEMAND_REFRESH_KHR     | slink:VkSharedPresentSurfaceCapabilitiesKHR::pname:sharedPresentSupportedUsageFlags
| ename:VK_PRESENT_MODE_SHARED_CONTINUOUS_REFRESH_KHR | slink:VkSharedPresentSurfaceCapabilitiesKHR::pname:sharedPresentSupportedUsageFlags
|====
endif::VK_KHR_shared_presentable_image[]

[NOTE]
.Note
====
For reference, the mode indicated by ename:VK_PRESENT_MODE_FIFO_KHR is
equivalent to the behavior of {wgl|glX|egl}SwapBuffers with a swap interval
of 1, while the mode indicated by ename:VK_PRESENT_MODE_FIFO_RELAXED_KHR is
equivalent to the behavior of {wgl|glX}SwapBuffers with a swap interval of
-1 (from the {WGL|GLX}_EXT_swap_control_tear extensions).
====

--

ifdef::VK_KHR_swapchain[]
ifdef::VK_KHX_device_group[]


== Device Group Queries

[open,refpage='vkGetDeviceGroupPresentCapabilitiesKHX',desc='Query present capabilities from other physical devices',type='protos']
--

A logical device that represents multiple physical devices may: support
presenting from images on more than one physical device, or combining images
from multiple physical devices.

To query these capabilities, call:

include::../../api/protos/vkGetDeviceGroupPresentCapabilitiesKHX.txt[]

  * pname:device is the logical device.
  * pname:pDeviceGroupPresentCapabilities is a pointer to a structure of
    type slink:VkDeviceGroupPresentCapabilitiesKHX that is filled with the
    logical device's capabilities.

include::../../validity/protos/vkGetDeviceGroupPresentCapabilitiesKHX.txt[]
--

[open,refpage='VkDeviceGroupPresentCapabilitiesKHX',desc='Present capabilities from other physical devices',type='structs']
--

The sname:VkDeviceGroupPresentCapabilitiesKHX structure is defined as:

include::../../api/structs/VkDeviceGroupPresentCapabilitiesKHX.txt[]

  * pname:sType is the type of this structure.
  * pname:pNext is `NULL` or a pointer to an extension-specific structure.
  * pname:presentMask is an array of masks, where the mask at element
    [eq]#i# is non-zero if physical device [eq]#i# has a presentation
    engine, and where bit [eq]#j# is set in element [eq]#i# if physical
    device [eq]#i# can: present swapchain images from physical device
    [eq]#j#.
    If element [eq]#i# is non-zero, then bit [eq]#i# must: be set.
  * pname:modes is a bitmask of elink:VkDeviceGroupPresentModeFlagBitsKHX
    indicating which device group presentation modes are supported.

pname:modes always has ename:VK_DEVICE_GROUP_PRESENT_MODE_LOCAL_BIT_KHX set.

The present mode flags are also used when presenting an image, in
slink:VkDeviceGroupPresentInfoKHX::pname:mode.

If a device group only includes a single physical device, then pname:modes
must: equal ename:VK_DEVICE_GROUP_PRESENT_MODE_LOCAL_BIT_KHX.

include::../../validity/structs/VkDeviceGroupPresentCapabilitiesKHX.txt[]
--


[open,refpage='VkDeviceGroupPresentModeFlagBitsKHX',desc='Bitmask specifying supported device group present modes',type='enums']
--

Bits which may: be set in
slink:VkDeviceGroupPresentCapabilitiesKHX::pname:modes to indicate which
device group presentation modes are supported are:

include::../../api/enums/VkDeviceGroupPresentModeFlagBitsKHX.txt[]

  * ename:VK_DEVICE_GROUP_PRESENT_MODE_LOCAL_BIT_KHX indicates that any
    physical device with a presentation engine can: present its own
    swapchain images.
  * ename:VK_DEVICE_GROUP_PRESENT_MODE_REMOTE_BIT_KHX indicates that any
    physical device with a presentation engine can: present swapchain images
    from any physical device in its pname:presentMask.
  * ename:VK_DEVICE_GROUP_PRESENT_MODE_SUM_BIT_KHX indicates that any
    physical device with a presentation engine can: present the sum of
    swapchain images from any physical devices in its pname:presentMask.
  * ename:VK_DEVICE_GROUP_PRESENT_MODE_LOCAL_MULTI_DEVICE_BIT_KHX indicates
    that multiple physical devices with a presentation engine can: each
    present their own swapchain images.

--

[open,refpage='vkGetDeviceGroupSurfacePresentModesKHX',desc='Query present capabilities for a surface',type='protos']
--

Some surfaces may: not be capable of using all the device group present
modes.

To query the supported device group present modes for a particular surface,
call:

include::../../api/protos/vkGetDeviceGroupSurfacePresentModesKHX.txt[]

  * pname:device is the logical device.
  * pname:surface is the surface.
  * pname:pModes is a pointer to a value of type
    sname:VkDeviceGroupPresentModeFlagsKHX that is filled with the supported
    device group present modes for the surface.

The modes returned by this command are not invariant, and may: change in
response to the surface being moved, resized, or occluded.
These modes must: be a subset of the modes returned by
flink:vkGetDeviceGroupPresentCapabilitiesKHX.

include::../../validity/protos/vkGetDeviceGroupSurfacePresentModesKHX.txt[]

--

[open,refpage='vkGetPhysicalDevicePresentRectanglesKHX',desc='Query present rectangles for a surface on a physical device',type='protos']
--

When using ename:VK_DEVICE_GROUP_PRESENT_MODE_LOCAL_MULTI_DEVICE_BIT_KHX,
the application may: need to know which regions of the surface are used when
presenting locally on each physical device.
Presentation of swapchain images to this surface need only have valid
contents in the regions returned by this command.

To query a set of rectangles used in presentation on the physical device,
call:

include::../../api/protos/vkGetPhysicalDevicePresentRectanglesKHX.txt[]

  * pname:physicalDevice is the physical device.
  * pname:surface is the surface.
  * pname:pRectCount is a pointer to an integer related to the number of
    rectangles available or queried, as described below.
  * pname:pRects is either `NULL` or a pointer to an array of sname:VkRect2D
    structures.

If pname:pRects is `NULL`, then the number of rectangles used when
presenting the given pname:surface is returned in pname:pRectCount.
Otherwise, pname:pRectCount must: point to a variable set by the user to the
number of elements in the pname:pRects array, and on return the variable is
overwritten with the number of structures actually written to pname:pRects.
If the value of pname:pRectCount is less than the number of rectangles, at
most pname:pRectCount structures will be written.
If pname:pRectCount is smaller than the number of rectangles used for the
given pname:surface, ename:VK_INCOMPLETE will be returned instead of
ename:VK_SUCCESS to indicate that not all the available values were
returned.

The values returned by this command are not invariant, and may: change in
response to the surface being moved, resized, or occluded.

The rectangles returned by this command must: not overlap.

include::../../validity/protos/vkGetPhysicalDevicePresentRectanglesKHX.txt[]

--

endif::VK_KHX_device_group[]

ifdef::VK_GOOGLE_display_timing[]
include::../VK_GOOGLE_display_timing/queries.txt[]
endif::VK_GOOGLE_display_timing[]

include::../VK_KHR_swapchain/wsi.txt[]
endif::VK_KHR_swapchain[]