29.5. Surface Queries

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

 

VkResult vkGetPhysicalDeviceSurfaceCapabilitiesKHR(
    VkPhysicalDevice                            physicalDevice,
    VkSurfaceKHR                                surface,
    VkSurfaceCapabilitiesKHR*                   pSurfaceCapabilities);

The VkSurfaceCapabilitiesKHR structure is defined as:

 

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;

The supportedTransforms and currentTransform members are of type VkSurfaceTransformFlagBitsKHR, which contains the following values:

 

typedef enum VkSurfaceTransformFlagBitsKHR {
    VK_SURFACE_TRANSFORM_IDENTITY_BIT_KHR = 0x00000001,
    VK_SURFACE_TRANSFORM_ROTATE_90_BIT_KHR = 0x00000002,
    VK_SURFACE_TRANSFORM_ROTATE_180_BIT_KHR = 0x00000004,
    VK_SURFACE_TRANSFORM_ROTATE_270_BIT_KHR = 0x00000008,
    VK_SURFACE_TRANSFORM_HORIZONTAL_MIRROR_BIT_KHR = 0x00000010,
    VK_SURFACE_TRANSFORM_HORIZONTAL_MIRROR_ROTATE_90_BIT_KHR = 0x00000020,
    VK_SURFACE_TRANSFORM_HORIZONTAL_MIRROR_ROTATE_180_BIT_KHR = 0x00000040,
    VK_SURFACE_TRANSFORM_HORIZONTAL_MIRROR_ROTATE_270_BIT_KHR = 0x00000080,
    VK_SURFACE_TRANSFORM_INHERIT_BIT_KHR = 0x00000100,
} VkSurfaceTransformFlagBitsKHR;

These values are described as follows:

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

 

typedef enum VkCompositeAlphaFlagBitsKHR {
    VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR = 0x00000001,
    VK_COMPOSITE_ALPHA_PRE_MULTIPLIED_BIT_KHR = 0x00000002,
    VK_COMPOSITE_ALPHA_POST_MULTIPLIED_BIT_KHR = 0x00000004,
    VK_COMPOSITE_ALPHA_INHERIT_BIT_KHR = 0x00000008,
} VkCompositeAlphaFlagBitsKHR;

These values are described as follows:

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

 

VkResult vkGetPhysicalDeviceSurfaceFormatsKHR(
    VkPhysicalDevice                            physicalDevice,
    VkSurfaceKHR                                surface,
    uint32_t*                                   pSurfaceFormatCount,
    VkSurfaceFormatKHR*                         pSurfaceFormats);

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

The VkSurfaceFormatKHR structure is defined as:

 

typedef struct VkSurfaceFormatKHR {
    VkFormat           format;
    VkColorSpaceKHR    colorSpace;
} VkSurfaceFormatKHR;

While the format of a presentable image refers to the encoding of each pixel, the colorspace determines how the the presentation engine interprets the pixel values. A colorspace in this document refers to a specific combination of color model (i.e. RGB, YUV, HSL etc.), the actual colorspace (defined by the chromaticities of its primaries and a whitepoint in CIE Lab), and a transfer function that is applied before storing or transmitting color data in the given colorspace.

The VkColorSpaceKHR is defined as follows:

 

typedef enum VkColorSpaceKHR {
    VK_COLOR_SPACE_SRGB_NONLINEAR_KHR = 0,
} VkColorSpaceKHR;

[Note]Note

If pSurfaceFormats includes just one entry, whose value for format is VK_FORMAT_UNDEFINED, surface has no preferred format. In this case, the application can use any valid VkFormat value.

[Note]Note

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

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

 

VkResult vkGetPhysicalDeviceSurfacePresentModesKHR(
    VkPhysicalDevice                            physicalDevice,
    VkSurfaceKHR                                surface,
    uint32_t*                                   pPresentModeCount,
    VkPresentModeKHR*                           pPresentModes);

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

The definition of VkPresentModeKHR is:

 

typedef enum VkPresentModeKHR {
    VK_PRESENT_MODE_IMMEDIATE_KHR = 0,
    VK_PRESENT_MODE_MAILBOX_KHR = 1,
    VK_PRESENT_MODE_FIFO_KHR = 2,
    VK_PRESENT_MODE_FIFO_RELAXED_KHR = 3,
} VkPresentModeKHR;

[Note]Note

For reference, the mode indicated by 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 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).