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Unified Diff: sdk/lib/html/src/Measurement.dart

Issue 11691009: Moved most of html lib generating scripts into tools. (Closed) Base URL: https://dart.googlecode.com/svn/branches/bleeding_edge/dart
Patch Set: Created 8 years ago
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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();
- }
- }
-}
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