scratch-blocks/core/events_abstract.js
2018-05-09 15:34:36 -07:00

113 lines
2.9 KiB
JavaScript

/**
* @license
* Visual Blocks Editor
*
* Copyright 2018 Google Inc.
* https://developers.google.com/blockly/
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* @fileoverview Abstract class for events fired as a result of actions in
* Blockly's editor.
* @author fraser@google.com (Neil Fraser)
*/
'use strict';
goog.provide('Blockly.Events.Abstract');
goog.require('Blockly.Events');
goog.require('goog.array');
goog.require('goog.math.Coordinate');
/**
* Abstract class for an event.
* @constructor
*/
Blockly.Events.Abstract = function() {
/**
* The workspace identifier for this event.
* @type {string|undefined}
*/
this.workspaceId = undefined;
/**
* The event group id for the group this event belongs to. Groups define
* events that should be treated as an single action from the user's
* perspective, and should be undone together.
* @type {string}
*/
this.group = Blockly.Events.group_;
/**
* Sets whether the event should be added to the undo stack.
* @type {boolean}
*/
this.recordUndo = Blockly.Events.recordUndo;
};
/**
* Encode the event as JSON.
* @return {!Object} JSON representation.
*/
Blockly.Events.Abstract.prototype.toJson = function() {
var json = {
'type': this.type
};
if (this.group) {
json['group'] = this.group;
}
return json;
};
/**
* Decode the JSON event.
* @param {!Object} json JSON representation.
*/
Blockly.Events.Abstract.prototype.fromJson = function(json) {
this.group = json['group'];
};
/**
* Does this event record any change of state?
* By default we assume events are non-null. Subclasses may override to
* indicate that they do not change state.
* @return {boolean} False if something changed.
*/
Blockly.Events.Abstract.prototype.isNull = function() {
return false;
};
/**
* Run an event.
* @param {boolean} _forward True if run forward, false if run backward (undo).
*/
Blockly.Events.Abstract.prototype.run = function(_forward) {
// Defined by subclasses.
};
/**
* Get workspace the event belongs to.
* @return {Blockly.Workspace} The workspace the event belongs to.
* @throws {Error} if workspace is null.
* @protected
*/
Blockly.Events.Abstract.prototype.getEventWorkspace_ = function() {
var workspace = Blockly.Workspace.getById(this.workspaceId);
if (!workspace) {
throw Error('Workspace is null. Event must have been generated from real' +
' Blockly events.');
}
return workspace;
};