# Render Scope **Path:** Components/Advanced [Back to Documentation Index](http://rubicblazor.skyconis.com/docs.md) --- Render Scope RbRenderScope limits child rendering to explicit moments instead of allowing every parent StateHasChanged() call to flow through automatically. Use it when child content is expensive, visually noisy, or should refresh only on demand. The same behavior is also available through RbRenderScope as a compatibility alias. When To Use Wrap expensive fragments that should not rerender on every parent state change. Refresh a section only after a button click, filter apply, or explicit workflow step. Run a post-render callback with OnRenderCompleted when DOM-dependent work must happen after the gated render finishes. Parent Always Renders The parent can render freely while the scoped fragment stays frozen after its initial render. Show code Invoke StateHasChanged Normal content Parent render tick: 1 Scoped content This block renders only on first load because AllowRender was never opened. Scoped render tick: 1 Render On Request This is the common @bind-AllowRender flow: open the gate, render once, and let the component push the flag back to false . Show code The parent can rerender many times, but the child fragment updates only when AllowRender becomes true . Requested content Scoped render tick: 639227312464457456 After rendering, the component automatically pushes false back through AllowRenderChanged . AllowRender = true Parent StateHasChanged Sticky Parent Rule Advanced scenarios can handle AllowRenderChanged manually and keep the parent-side flag sticky. Show code Some flows want to keep the parent-side flag checked while still preventing duplicate renders inside the same cycle. This pattern shows custom AllowRenderChanged handling. Sticky content Scoped render tick: 639227312464458577 Keep AllowRender checked Render Completed Callback Use OnRenderCompleted for DOM-dependent work that must run only after the scoped content really rendered. Show code OnRenderCompleted runs after the scoped fragment really rendered, so it is the right place for measurement, focus, scrolling, or JS interop that depends on fresh DOM. Callback content Scoped render tick: 639227312464459099 Render Scoped Content Completed count: 0 Last firstRender: - API RbRenderScope A render gate component that hosts child content and allows that content to rerender only when explicitly enabled. AllowRender Opens the render gate for the next scoped render. When false, parent rerenders do not refresh the child fragment. Parameters bool AllowRender = false Set to true when you want the wrapped content to rerender on the next cycle. AllowRenderChanged Raised after a successful scoped render so the parent can sync its flag back to false or apply custom state rules. Parameters EventCallback AllowRenderChanged Usually used through @bind-AllowRender . Advanced flows can handle it manually for sticky or conditional parent state. OnRenderCompleted Callback executed after the scoped content actually rendered. Parameters Func OnRenderCompleted Receives firstRender so you can distinguish initial render from later requested renders. Return Task Complete the task when any post-render work, such as JS interop or focus logic, is done. ChildContent The fragment protected by the render gate. Parameters RenderFragment ChildContent Place the expensive or controlled UI subtree here. ✕ Contents