Adjust present time calculation

Adjust the target present time when using
render_ahead to better fit in the gaps between
vsync pulses. This prevents small clock
drifts from causing jank.

Bug: 143540628
Test: manual, looked at systrace
Change-Id: I26ae6ebf16a3dea48dfd8e1c420d9e5e43e42bcb

parent d1ab7670

libs/hwui/renderthread/CanvasContext.cpp

+2 −1

Original line number	Diff line number	Diff line
		@@ -429,7 +429,8 @@ void CanvasContext::setPresentTime() {

		if (renderAhead) {
		presentTime = mCurrentFrameInfo->get(FrameInfoIndex::Vsync) +
		(frameIntervalNanos * (renderAhead + 1));
		(frameIntervalNanos * (renderAhead + 1)) - DeviceInfo::get()->getAppOffset() +
		(frameIntervalNanos / 2);
		}
		native_window_set_buffers_timestamp(mNativeSurface->getNativeWindow(), presentTime);
		}