Moved most of html lib generating scripts into tools.

sdk/lib/html/src/Measurement.dart

-// 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();
-    }
-  }
-}