How does Flutter's rendering pipeline work (Build, Layout, Paint)?

Updated Apr 28, 2026

Short answer

Flutter's pipeline consists of 4 phases: Animate, Build, Layout, and Paint, ending with compositing.

Build: The framework calls build() to construct the Widget/Element trees. 2. Layout: The Render tree walks down to pass constraints and walks up to pass sizes. 3. Paint: RenderObjects record drawing commands. 4. Compositing: Painted layers are composited into scenes and sent to the GPU via the Skia/Impeller engine.

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