80 lines
2.3 KiB
JavaScript
80 lines
2.3 KiB
JavaScript
define([
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'../Core/defaultValue',
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'../Core/defined',
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'../Core/defineProperties',
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'../Core/DeveloperError',
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'../Core/Event',
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'../ThirdParty/knockout'
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], function(
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defaultValue,
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defined,
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defineProperties,
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DeveloperError,
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Event,
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knockout) {
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'use strict';
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/**
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* Create a Command from a given function, for use with ViewModels.
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*
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* A Command is a function with an extra <code>canExecute</code> observable property to determine
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* whether the command can be executed. When executed, a Command function will check the
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* value of <code>canExecute</code> and throw if false. It also provides events for when
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* a command has been or is about to be executed.
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*
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* @exports createCommand
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*
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* @param {Function} func The function to execute.
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* @param {Boolean} [canExecute=true] A boolean indicating whether the function can currently be executed.
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*/
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function createCommand(func, canExecute) {
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//>>includeStart('debug', pragmas.debug);
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if (!defined(func)) {
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throw new DeveloperError('func is required.');
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}
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//>>includeEnd('debug');
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canExecute = defaultValue(canExecute, true);
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var beforeExecute = new Event();
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var afterExecute = new Event();
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function command() {
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//>>includeStart('debug', pragmas.debug);
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if (!command.canExecute) {
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throw new DeveloperError('Cannot execute command, canExecute is false.');
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}
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//>>includeEnd('debug');
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var commandInfo = {
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args : arguments,
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cancel : false
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};
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var result;
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beforeExecute.raiseEvent(commandInfo);
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if (!commandInfo.cancel) {
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result = func.apply(null, arguments);
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afterExecute.raiseEvent(result);
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}
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return result;
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}
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command.canExecute = canExecute;
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knockout.track(command, ['canExecute']);
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defineProperties(command, {
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beforeExecute : {
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value : beforeExecute
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},
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afterExecute : {
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value : afterExecute
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}
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});
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return command;
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}
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return createCommand;
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});
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