GetImageBuffer needs to access a snapshot of the canvas without retaining it, we could easily avoid calling EnsureTarget in most case by doing something like: if (mTarget) { snapshot = mTargetSnapshot() } else if (mBufferProvider) { snapshot = mBufferProvider->BorrowSnapshot(); } else { //fallback to EnsureTarget, should rarely happen though. } // .. do things with the snapshot if (!mTarget && mBufferProvider) { mBufferProvider->ReturnSnapsht(snapshot.forget()); } This way we can avoid triggering a copy of the canvas if the first command issued to the canvas in a frame is a snapshot.

I'll work on this too.

Try to avoid calling EnsureTarget in GetImageBuffer.

try server: https://treeherder.mozilla.org/#/jobs?repo=try&revision=e49512f5c066

Pushed by ryanvm@gmail.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/6a868ef45569 Avoid calling EnsureTarget in CanvasRenderingContext2D::GetImageBuffer. r=nical