// 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/

[open,refpage='VkPresentRegionsKHR',desc='Structure hint of rectangular regions changed by vkQueuePresentKHR',type='structs']
--

When the +VK_KHR_incremental_present+ extension is enabled, additional
fields can: be specified that allow an application to specify that only
certain rectangular regions of the presentable images of a swapchain are
changed.
This is an optimization hint that a presentation engine may: use to only
update the region of a surface that is actually changing.
The application still must: ensure that all pixels of a presented image
contain the desired values, in case the presentation engine ignores this
hint.
An application can: provide this hint by including the
sname:VkPresentRegionsKHR structure in the pname:pNext chain of the
sname:VkPresentInfoKHR structure.

The sname:VkPresentRegionsKHR structure is defined as:

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

  * pname:sType is the type of this structure.
  * pname:pNext is `NULL` or a pointer to an extension-specific structure.
  * pname:swapchainCount is the number of swapchains being presented to by
    this command.
  * pname:pRegions is `NULL` or a pointer to an array of
    sname:VkPresentRegionKHR elements with pname:swapchainCount entries.
    If not `NULL`, each element of pname:pRegions contains the region that
    has changed since the last present to the swapchain in the corresponding
    entry in the sname:VkPresentInfoKHR::pname:pSwapchains array.

.Valid Usage
****
  * [[VUID-VkPresentRegionsKHR-swapchainCount-01260]]
    pname:swapchainCount must: be the same value as
    sname:VkPresentInfoKHR::pname:swapchainCount, where
    sname:VkPresentInfoKHR is in the pNext-chain of this
    sname:VkPresentRegionsKHR structure.
****

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

[open,refpage='VkPresentRegionKHR',desc='Structure containing rectangular region changed by vkQueuePresentKHR for a given VkImage',type='structs']
--

For a given image and swapchain, the region to present is specified by the
sname:VkPresentRegionKHR structure, which is defined as:

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

  * pname:rectangleCount is the number of rectangles in pname:pRectangles,
    or zero if the entire image has changed and should be presented.
  * pname:pRectangles is either `NULL` or a pointer to an array of
    sname:VkRectLayerKHR structures.
    The sname:VkRectLayerKHR structure is the framebuffer coordinates, plus
    layer, of a portion of a presentable image that has changed and must: be
    presented.
    If non-`NULL`, each entry in pname:pRectangles is a rectangle of the
    given image that has changed since the last image was presented to the
    given swapchain.

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

[open,refpage='VkRectLayerKHR',desc='Structure containing a rectangle, including layer, changed by vkQueuePresentKHR for a given VkImage',type='structs']
--

The sname:VkRectLayerKHR structure is defined as:

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

    * pname:offset is the origin of the rectangle, in pixels.
    * pname:extent is the size of the rectangle, in pixels.
    * pname:layer is the layer of the image.
      For images with only one layer, the value of pname:layer must: be 0.

.Valid Usage
****
  * [[VUID-VkRectLayerKHR-offset-01261]]
    The sum of pname:offset and pname:extent must: be no greater than the
    pname:imageExtent member of the sname:VkSwapchainCreateInfoKHR structure
    given to flink:vkCreateSwapchainKHR.
  * [[VUID-VkRectLayerKHR-layer-01262]]
    pname:layer must: be less than pname:imageArrayLayers member of the
    sname:VkSwapchainCreateInfoKHR structure given to
    flink:vkCreateSwapchainKHR.
****

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

Some platforms allow the size of a surface to change, and then scale the
pixels of the image to fit the surface.
VkRectLayerKHR specifies pixels of the swapchain's image(s), which will be
constant for the life of the swapchain.

--