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Unified Diff: client/dom/templates/html/frog/impl_Window.darttemplate

Issue 9403004: Wrapperless dart:html generator (Closed) Base URL: https://dart.googlecode.com/svn/branches/bleeding_edge/dart
Patch Set: Final version to check in. changes generator script but doesn't check in an active version of the … Created 8 years, 10 months ago
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Index: client/dom/templates/html/frog/impl_Window.darttemplate
diff --git a/client/dom/templates/html/frog/impl_Window.darttemplate b/client/dom/templates/html/frog/impl_Window.darttemplate
new file mode 100644
index 0000000000000000000000000000000000000000..668475b313ae23be2165c55abd715891242949b9
--- /dev/null
+++ b/client/dom/templates/html/frog/impl_Window.darttemplate
@@ -0,0 +1,131 @@
+// 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.
+
+typedef Object ComputeValue();
+
+class _MeasurementRequest<T> {
+ final ComputeValue computeValue;
+ final Completer<T> completer;
+ Object value;
+ bool exception = false;
+ _MeasurementRequest(this.computeValue, this.completer);
+}
+
+final _MEASUREMENT_MESSAGE = "DART-MEASURE";
+List<_MeasurementRequest> _pendingRequests;
+List<TimeoutHandler> _pendingMeasurementFrameCallbacks;
+bool _nextMeasurementFrameScheduled = false;
+bool _firstMeasurementRequest = true;
+
+void _maybeScheduleMeasurementFrame() {
+ if (_nextMeasurementFrameScheduled) return;
+
+ _nextMeasurementFrameScheduled = true;
+ // postMessage gives us a way to receive a callback after the current
+ // event listener has unwound but before the browser has repainted.
+ if (_firstMeasurementRequest) {
+ // Messages from other windows do not cause a security risk as
+ // all we care about is that _onCompleteMeasurementRequests 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((e) => _completeMeasurementFutures());
+ _firstMeasurementRequest = false;
+ }
+
+ // TODO(jacobr): other mechanisms such as setImmediate and
+ // requestAnimationFrame may work better of platforms that support them.
+ // The key is we need a way to execute code immediately after the current
+ // event listener queue unwinds.
+ window.postMessage(_MEASUREMENT_MESSAGE, "*");
+}
+
+/**
+ * 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() {
+ if (_nextMeasurementFrameScheduled == false) {
+ // Ignore spurious call to this function.
+ return;
+ }
+
+ _nextMeasurementFrameScheduled = false;
+ // 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(var 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();
+ }
+ }
+}
+
+class $CLASSNAME$EXTENDS$IMPLEMENTS native "@*DOMWindow" {
+
+ _DocumentJs get document() native "return this.document.documentElement;";
+
+ void requestLayoutFrame(TimeoutHandler callback) {
+ _addMeasurementFrameCallback(callback);
+ }
+
+$!MEMBERS
+}

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