//Matthew Shotton, R&D User Experience,© BBC 2015
import EffectNode from "./effectnode";
class TransitionNode extends EffectNode{
/**
* Initialise an instance of a TransitionNode. You should not instantiate this directly, but use VideoContest.createTransitonNode().
*/
constructor(gl, renderGraph, definition){
super(gl, renderGraph, definition);
this._transitions = {};
//save a version of the original property values
this._initialPropertyValues = {};
for (let propertyName in this._properties){
this._initialPropertyValues[propertyName] = this._properties[propertyName].value;
}
this._displayName = "TransitionNode";
}
_doesTransitionFitOnTimeline(testTransition){
if (this._transitions[testTransition.property] === undefined) return true;
for (let transition of this._transitions[testTransition.property]) {
if (testTransition.start > transition.start && testTransition.start < transition.end)return false;
if (testTransition.end > transition.start && testTransition.end < transition.end)return false;
if(transition.start > testTransition.start && transition.start < testTransition.end) return false;
if(transition.end > testTransition.start && transition.end < testTransition.end) return false;
}
return true;
}
_insertTransitionInTimeline(transition){
if (this._transitions[transition.property] === undefined) this._transitions[transition.property] = [];
this._transitions[transition.property].push(transition);
this._transitions[transition.property].sort(function(a,b){
return a.start - b.start;
});
}
/**
* Create a transition on the timeline.
*
* @param {number} startTime - The time at which the transition should start (relative to currentTime of video context).
* @param {number} endTime - The time at which the transition should be completed by (relative to currentTime of video context).
* @param {number} currentValue - The value to start the transition at.
* @param {number} targetValue - The value to transition to by endTime.
* @param {String} propertyName - The name of the property to clear transitions on, if undefined default to "mix".
*
* @return {Boolean} returns True if a transition is successfully added, false otherwise.
*/
transition(startTime, endTime, currentValue, targetValue, propertyName="mix"){
let transition = {start:startTime + this._currentTime, end:endTime + this._currentTime, current:currentValue, target:targetValue, property:propertyName};
if (!this._doesTransitionFitOnTimeline(transition))return false;
this._insertTransitionInTimeline(transition);
return true;
}
/**
* Create a transition on the timeline at an absolute time.
*
* @param {number} startTime - The time at which the transition should start (relative to time 0).
* @param {number} endTime - The time at which the transition should be completed by (relative to time 0).
* @param {number} currentValue - The value to start the transition at.
* @param {number} targetValue - The value to transition to by endTime.
* @param {String} propertyName - The name of the property to clear transitions on, if undefined default to "mix".
*
* @return {Boolean} returns True if a transition is successfully added, false otherwise.
*/
transitionAt(startTime, endTime, currentValue, targetValue, propertyName="mix"){
let transition = {start:startTime, end:endTime, current:currentValue, target:targetValue, property:propertyName};
if (!this._doesTransitionFitOnTimeline(transition))return false;
this._insertTransitionInTimeline(transition);
return true;
}
/**
* Clear all transistions on the passed property. If no property is defined clear all transitions on the node.
*
* @param {String} propertyName - The name of the property to clear transitions on, if undefined clear all transitions on the node.
*/
clearTransitions(propertyName){
if (propertyName === undefined){
this._transitions = {};
}else{
this._transitions[propertyName] = [];
}
}
/**
* Clear a transistion on the passed property that the specified time lies within.
*
* @param {String} propertyName - The name of the property to clear a transition on.
* @param {number} time - A time which lies within the property you're trying to clear.
*
* @return {Boolean} returns True if a transition is removed, false otherwise.
*/
clearTransition(propertyName, time){
let transitionIndex = undefined;
for (var i = 0; i < this._transitions[propertyName].length; i++) {
let transition = this._transitions[propertyName][i];
if (time > transition.start && time < transition.end){
transitionIndex = i;
}
}
if(transitionIndex !== undefined){
this._transitions[propertyName].splice(transitionIndex, 1);
return true;
}
return false;
}
_update(currentTime){
super._update(currentTime);
for (let propertyName in this._transitions){
let value = this[propertyName];
if (this._transitions[propertyName].length > 0){
value = this._transitions[propertyName][0].current;
}
let transitionActive = false;
for (var i = 0; i < this._transitions[propertyName].length; i++) {
let transition = this._transitions[propertyName][i];
if (currentTime > transition.end){
value = transition.target;
continue;
}
if (currentTime > transition.start && currentTime < transition.end){
let difference = transition.target - transition.current;
let progress = (this._currentTime - transition.start)/(transition.end - transition.start);
transitionActive = true;
this[propertyName] = transition.current + (difference * progress);
break;
}
}
if(!transitionActive)this[propertyName] = value;
}
}
}
export default TransitionNode;