Index: sdk/lib/html/src/Measurement.dart |
diff --git a/sdk/lib/html/src/Measurement.dart b/sdk/lib/html/src/Measurement.dart |
deleted file mode 100644 |
index 7d34e7b2db819ea7a865dcc9ef2a3f633e01f8d0..0000000000000000000000000000000000000000 |
--- a/sdk/lib/html/src/Measurement.dart |
+++ /dev/null |
@@ -1,200 +0,0 @@ |
-// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
-// for details. All rights reserved. Use of this source code is governed by a |
-// BSD-style license that can be found in the LICENSE file. |
- |
-part of html; |
- |
-typedef Object ComputeValue(); |
- |
-class _MeasurementRequest<T> { |
- final ComputeValue computeValue; |
- final Completer<T> completer; |
- Object value; |
- bool exception = false; |
- _MeasurementRequest(this.computeValue, this.completer); |
-} |
- |
-typedef void _MeasurementCallback(); |
- |
-/** |
- * This class attempts to invoke a callback as soon as the current event stack |
- * unwinds, but before the browser repaints. |
- */ |
-abstract class _MeasurementScheduler { |
- bool _nextMeasurementFrameScheduled = false; |
- _MeasurementCallback _callback; |
- |
- _MeasurementScheduler(this._callback); |
- |
- /** |
- * Creates the best possible measurement scheduler for the current platform. |
- */ |
- factory _MeasurementScheduler.best(_MeasurementCallback callback) { |
- if (MutationObserver.supported) { |
- return new _MutationObserverScheduler(callback); |
- } |
- return new _PostMessageScheduler(callback); |
- } |
- |
- /** |
- * Schedules a measurement callback if one has not been scheduled already. |
- */ |
- void maybeSchedule() { |
- if (this._nextMeasurementFrameScheduled) { |
- return; |
- } |
- this._nextMeasurementFrameScheduled = true; |
- this._schedule(); |
- } |
- |
- /** |
- * Does the actual scheduling of the callback. |
- */ |
- void _schedule(); |
- |
- /** |
- * Handles the measurement callback and forwards it if necessary. |
- */ |
- void _onCallback() { |
- // Ignore spurious messages. |
- if (!_nextMeasurementFrameScheduled) { |
- return; |
- } |
- _nextMeasurementFrameScheduled = false; |
- this._callback(); |
- } |
-} |
- |
-/** |
- * Scheduler which uses window.postMessage to schedule events. |
- */ |
-class _PostMessageScheduler extends _MeasurementScheduler { |
- const _MEASUREMENT_MESSAGE = "DART-MEASURE"; |
- |
- _PostMessageScheduler(_MeasurementCallback callback): super(callback) { |
- // Messages from other windows do not cause a security risk as |
- // all we care about is that _handleMessage is called |
- // after the current event loop is unwound and calling the function is |
- // a noop when zero requests are pending. |
- window.on.message.add(this._handleMessage); |
- } |
- |
- void _schedule() { |
- window.postMessage(_MEASUREMENT_MESSAGE, "*"); |
- } |
- |
- _handleMessage(e) { |
- this._onCallback(); |
- } |
-} |
- |
-/** |
- * Scheduler which uses a MutationObserver to schedule events. |
- */ |
-class _MutationObserverScheduler extends _MeasurementScheduler { |
- MutationObserver _observer; |
- Element _dummy; |
- |
- _MutationObserverScheduler(_MeasurementCallback callback): super(callback) { |
- // Mutation events get fired as soon as the current event stack is unwound |
- // so we just make a dummy event and listen for that. |
- _observer = new MutationObserver(this._handleMutation); |
- _dummy = new DivElement(); |
- _observer.observe(_dummy, attributes: true); |
- } |
- |
- void _schedule() { |
- // Toggle it to trigger the mutation event. |
- _dummy.hidden = !_dummy.hidden; |
- } |
- |
- _handleMutation(List<MutationRecord> mutations, MutationObserver observer) { |
- this._onCallback(); |
- } |
-} |
- |
- |
-List<_MeasurementRequest> _pendingRequests; |
-List<TimeoutHandler> _pendingMeasurementFrameCallbacks; |
-_MeasurementScheduler _measurementScheduler = null; |
- |
-void _maybeScheduleMeasurementFrame() { |
- if (_measurementScheduler == null) { |
- _measurementScheduler = |
- new _MeasurementScheduler.best(_completeMeasurementFutures); |
- } |
- _measurementScheduler.maybeSchedule(); |
-} |
- |
-/** |
- * Registers a [callback] which is called after the next batch of measurements |
- * completes. Even if no measurements completed, the callback is triggered |
- * when they would have completed to avoid confusing bugs if it happened that |
- * no measurements were actually requested. |
- */ |
-void _addMeasurementFrameCallback(TimeoutHandler callback) { |
- if (_pendingMeasurementFrameCallbacks == null) { |
- _pendingMeasurementFrameCallbacks = <TimeoutHandler>[]; |
- _maybeScheduleMeasurementFrame(); |
- } |
- _pendingMeasurementFrameCallbacks.add(callback); |
-} |
- |
-/** |
- * Returns a [Future] whose value will be the result of evaluating |
- * [computeValue] during the next safe measurement interval. |
- * The next safe measurement interval is after the current event loop has |
- * unwound but before the browser has rendered the page. |
- * It is important that the [computeValue] function only queries the html |
- * layout and html in any way. |
- */ |
-Future _createMeasurementFuture(ComputeValue computeValue, |
- Completer completer) { |
- if (_pendingRequests == null) { |
- _pendingRequests = <_MeasurementRequest>[]; |
- _maybeScheduleMeasurementFrame(); |
- } |
- _pendingRequests.add(new _MeasurementRequest(computeValue, completer)); |
- return completer.future; |
-} |
- |
-/** |
- * Complete all pending measurement futures evaluating them in a single batch |
- * so that the the browser is guaranteed to avoid multiple layouts. |
- */ |
-void _completeMeasurementFutures() { |
- // We must compute all new values before fulfilling the futures as |
- // the onComplete callbacks for the futures could modify the DOM making |
- // subsequent measurement calculations expensive to compute. |
- if (_pendingRequests != null) { |
- for (_MeasurementRequest request in _pendingRequests) { |
- try { |
- request.value = request.computeValue(); |
- } catch (e) { |
- request.value = e; |
- request.exception = true; |
- } |
- } |
- } |
- |
- final completedRequests = _pendingRequests; |
- final readyMeasurementFrameCallbacks = _pendingMeasurementFrameCallbacks; |
- _pendingRequests = null; |
- _pendingMeasurementFrameCallbacks = null; |
- if (completedRequests != null) { |
- for (_MeasurementRequest request in completedRequests) { |
- if (request.exception) { |
- request.completer.completeException(request.value); |
- } else { |
- request.completer.complete(request.value); |
- } |
- } |
- } |
- |
- if (readyMeasurementFrameCallbacks != null) { |
- for (TimeoutHandler handler in readyMeasurementFrameCallbacks) { |
- // TODO(jacobr): wrap each call to a handler in a try-catch block. |
- handler(); |
- } |
- } |
-} |