Surface class Rendering

Manages the swapchain color textures a Scene composites onto the Flutter canvas, plus the pools of transient render-graph attachments.

Each Scene owns one Surface. A scene may render several views per frame (split-screen, picture-in-picture); each view gets its own swapchain ring and its own transient texture pool, so simultaneous views never share a render target within a frame. View 0 is the single-view default.

Every view, every frame, the renderer asks the surface for that view's next swapchain color texture via getNextSwapchainColorTexture; the surface rotates through a small ring per view so the GPU isn't asked to overwrite one the compositor is still reading. The tone-mapping pass renders the final image into this texture, which is then drawn to the canvas via Texture.asImage. A view keeps the ring and transient pool of its two most recent sizes, so a resolution that toggles (an adaptive render scale) reuses them instead of reallocating every target; a size left unused for a while is released.

Applications typically don't interact with Surface directly; it is driven internally by Scene.render / Scene.renderViews.