lib/ui/hooks.dart

// Copyright 2015 The Chromium Authors. 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 dart.ui;

String _decodeUTF8(ByteData message) {
  return message != null ? UTF8.decoder.convert(message.buffer.asUint8List()) : null;
}

dynamic _decodeJSON(String message) {
  return message != null ? JSON.decode(message) : null;
}

void _updateWindowMetrics(double devicePixelRatio,
                          double width,
                          double height,
                          double top,
                          double right,
                          double bottom,
                          double left) {
  window
    .._devicePixelRatio = devicePixelRatio
    .._physicalSize = new Size(width, height)
    .._padding = new WindowPadding._(
      top: top, right: right, bottom: bottom, left: left);
  _invoke(window.onMetricsChanged, window._onMetricsChangedZone);
}

void _updateLocale(String languageCode, String countryCode) {
  window._locale = new Locale(languageCode, countryCode);
  _invoke(window.onLocaleChanged, window._onLocaleChangedZone);
}

void _updateTextScaleFactor(double textScaleFactor) {
  window._textScaleFactor = textScaleFactor;
  _invoke(window.onTextScaleFactorChanged, window._onTextScaleFactorChangedZone);
}

void _updateSemanticsEnabled(bool enabled) {
  window._semanticsEnabled = enabled;
  _invoke(window.onSemanticsEnabledChanged, window._onSemanticsEnabledChangedZone);
}

void _dispatchPlatformMessage(String name, ByteData data, int responseId) {
  if (window.onPlatformMessage != null) {
    _invoke3<String, ByteData, PlatformMessageResponseCallback>(
      window.onPlatformMessage,
      window._onPlatformMessageZone,
      name,
      data,
      (ByteData responseData) {
        window._respondToPlatformMessage(responseId, responseData);
      },
    );
  } else {
    window._respondToPlatformMessage(responseId, null);
  }
}

void _dispatchPointerDataPacket(ByteData packet) {
  if (window.onPointerDataPacket != null)
    _invoke1<PointerDataPacket>(window.onPointerDataPacket, window._onPointerDataPacketZone, _unpackPointerDataPacket(packet));
}

void _dispatchSemanticsAction(int id, int action) {
  _invoke2<int, SemanticsAction>(
    window.onSemanticsAction,
    window._onSemanticsActionZone,
    id,
    SemanticsAction.values[action],
  );
}

void _beginFrame(int microseconds) {
  _invoke1<Duration>(window.onBeginFrame, window._onBeginFrameZone, new Duration(microseconds: microseconds));
}

void _drawFrame() {
  _invoke(window.onDrawFrame, window._onDrawFrameZone);
}

/// Invokes [callback] inside the given [zone].
void _invoke(void callback(), Zone zone) {
  if (callback == null)
    return;

  assert(zone != null);

  if (identical(zone, Zone.current)) {
    callback();
  } else {
    zone.runGuarded(callback);
  }
}

/// Invokes [callback] inside the given [zone] passing it [arg].
void _invoke1<A>(void callback(A a), Zone zone, A arg) {
  if (callback == null)
    return;

  assert(zone != null);

  if (identical(zone, Zone.current)) {
    callback(arg);
  } else {
    zone.runUnaryGuarded<Null, A>(callback, arg);
  }
}

/// Invokes [callback] inside the given [zone] passing it [arg1] and [arg2].
void _invoke2<A1, A2>(void callback(A1 a1, A2 a2), Zone zone, A1 arg1, A2 arg2) {
  if (callback == null)
    return;

  assert(zone != null);

  if (identical(zone, Zone.current)) {
    callback(arg1, arg2);
  } else {
    zone.runBinaryGuarded<Null, A1, A2>(callback, arg1, arg2);
  }
}

/// Invokes [callback] inside the given [zone] passing it [arg1], [arg2] and [arg3].
void _invoke3<A1, A2, A3>(void callback(A1 a1, A2 a2, A3 a3), Zone zone, A1 arg1, A2 arg2, A3 arg3) {
  if (callback == null)
    return;

  assert(zone != null);

  if (identical(zone, Zone.current)) {
    callback(arg1, arg2, arg3);
  } else {
    zone.runGuarded(() {
      callback(arg1, arg2, arg3);
    });
  }
}

// If this value changes, update the encoding code in the following files:
//
//  * pointer_data.cc
//  * FlutterView.java
const int _kPointerDataFieldCount = 19;

PointerDataPacket _unpackPointerDataPacket(ByteData packet) {
  const int kStride = Int64List.BYTES_PER_ELEMENT;
  const int kBytesPerPointerData = _kPointerDataFieldCount * kStride;
  final int length = packet.lengthInBytes ~/ kBytesPerPointerData;
  assert(length * kBytesPerPointerData == packet.lengthInBytes);
  List<PointerData> data = new List<PointerData>(length);
  for (int i = 0; i < length; ++i) {
    int offset = i * _kPointerDataFieldCount;
    data[i] = new PointerData(
      timeStamp: new Duration(microseconds: packet.getInt64(kStride * offset++, _kFakeHostEndian)),
      change: PointerChange.values[packet.getInt64(kStride * offset++, _kFakeHostEndian)],
      kind: PointerDeviceKind.values[packet.getInt64(kStride * offset++, _kFakeHostEndian)],
      device: packet.getInt64(kStride * offset++, _kFakeHostEndian),
      physicalX: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
      physicalY: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
      buttons: packet.getInt64(kStride * offset++, _kFakeHostEndian),
      obscured: packet.getInt64(kStride * offset++, _kFakeHostEndian) != 0,
      pressure: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
      pressureMin: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
      pressureMax: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
      distance: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
      distanceMax: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
      radiusMajor: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
      radiusMinor: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
      radiusMin: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
      radiusMax: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
      orientation: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
      tilt: packet.getFloat64(kStride * offset++, _kFakeHostEndian)
    );
    assert(offset == (i + 1) * _kPointerDataFieldCount);
  }
  return new PointerDataPacket(data: data);
}