## C Specification

The VkSurfaceCapabilitiesKHR structure is defined as:

// Provided by VK_KHR_surface
typedef struct VkSurfaceCapabilitiesKHR {
uint32_t                         minImageCount;
uint32_t                         maxImageCount;
VkExtent2D                       currentExtent;
VkExtent2D                       minImageExtent;
VkExtent2D                       maxImageExtent;
uint32_t                         maxImageArrayLayers;
VkSurfaceTransformFlagsKHR       supportedTransforms;
VkSurfaceTransformFlagBitsKHR    currentTransform;
VkCompositeAlphaFlagsKHR         supportedCompositeAlpha;
VkImageUsageFlags                supportedUsageFlags;
} VkSurfaceCapabilitiesKHR;

## Description

• minImageCount is the minimum number of images the specified device supports for a swapchain created for the surface, and will be at least one.

• 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 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.

• currentExtent is the current width and height of the surface, or the special value (0xFFFFFFFF, 0xFFFFFFFF) indicating that the surface size will be determined by the extent of a swapchain targeting the surface.

• minImageExtent contains the smallest valid swapchain extent for the surface on the specified device. The width and height of the extent will each be less than or equal to the corresponding width and height of currentExtent, unless currentExtent has the special value described above.

• maxImageExtent contains the largest valid swapchain extent for the surface on the specified device. The width and height of the extent will each be greater than or equal to the corresponding width and height of minImageExtent. The width and height of the extent will each be greater than or equal to the corresponding width and height of currentExtent, unless currentExtent has the special value described above.

• 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.

• supportedTransforms is a bitmask of VkSurfaceTransformFlagBitsKHR indicating the presentation transforms supported for the surface on the specified device. At least one bit will be set.

• currentTransform is VkSurfaceTransformFlagBitsKHR value indicating the surface’s current transform relative to the presentation engine’s natural orientation.

• supportedCompositeAlpha is a bitmask of 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.

• supportedUsageFlags is a bitmask of VkImageUsageFlagBits representing the ways the application can use the presentable images of a swapchain created with VkPresentModeKHR set to VK_PRESENT_MODE_IMMEDIATE_KHR, VK_PRESENT_MODE_MAILBOX_KHR, VK_PRESENT_MODE_FIFO_KHR or VK_PRESENT_MODE_FIFO_RELAXED_KHR for the surface on the specified device. VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT must be included in the set. Implementations may support additional usages.

 Note Supported usage flags of a presentable image when using VK_PRESENT_MODE_SHARED_DEMAND_REFRESH_KHR or VK_PRESENT_MODE_SHARED_CONTINUOUS_REFRESH_KHR presentation mode are provided by VkSharedPresentSurfaceCapabilitiesKHR::sharedPresentSupportedUsageFlags.
 Note Formulas such as min(N, maxImageCount) are not correct, since maxImageCount may be zero.