VkSwapchainKHR

VkSwapchainKHR is a Vulkan handle type that represents a swapchain, a collection of presentable images used to render and present frames to a window system surface. A swapchain is created for a specific presentation surface (VkSurfaceKHR) and is tied to a queue family capable of presenting. The swapchain contains one or more images that the application renders into and then presents to the screen.

Creation and management of a swapchain are performed with vkCreateSwapchainKHR and vkDestroySwapchainKHR, using a VkSwapchainCreateInfoKHR structure. This structure specifies the target surface, image format and color space (for example, VK_FORMAT_B8G8R8A8_SRGB and VK_COLOR_SPACE_SRGB_NONLINEAR_KHR), the image extent (width and height), usage flags, the number of images (minImageCount), and presentation parameters such as presentMode and preTransform. If an existing swapchain must be replaced, the oldSwapchain field allows passing the previous handle to enable a smooth transition.

Images in the swapchain are retrieved with vkGetSwapchainImagesKHR, and image views are typically created for each swapchain image to attach them as color attachments in framebuffers. Rendering is performed to one of the acquired images, synchronized with semaphores or fences, and presented with vkQueuePresentKHR through a VkPresentInfoKHR describing the swapchain and the image index.

Lifecycle considerations include handling window resizes and surface changes, which may require recreating the swapchain. If the swapchain becomes out of date or suboptimal, Vulkan returns VK_ERROR_OUT_OF_DATE_KHR or VK_SUBOPTIMAL_KHR, indicating that recreation is necessary. VkSwapchainKHR, through the VK_KHR_swapchain extension, is central to presenting rendered frames in almost all Vulkan applications.