Add duration to effect.fadeIn() (#306)

* Add duration to effect.fadeIn()

Author: patrick-tolosa

__TESTS__/unit/actions/Effect.test.ts

@@ -24,7 +24,7 @@ describe('Tests for Transformation Action -- Effect', () => {
       .effect(Effect.blackwhite(10))
       .effect(Effect.blackwhite().threshold(20))
       .effect(Effect.fadeIn(100))
-      .effect(Effect.fadeIn().length(5))
+      .effect(Effect.fadeIn().duration(5))
       .effect(Effect.fadeOut(100))
       .effect(Effect.fadeOut().duration(5))
       .effect(Effect.grayscale())

src/actions/effect.ts

@@ -21,6 +21,7 @@ import {Pixelate} from "./effect/pixelate/pixelate";
 import {ImageSource} from "../values/source/sourceTypes/ImageSource";
 import {EffectActionWithStrength} from "./effect/EffectActions/EffectActionWithStrength";
 import {BlackwhiteEffectAction} from "./effect/leveled/blackwhite";
+import {FadeInEffectAction} from "./effect/leveled/fadeIn";
 
 
 /**
@@ -214,10 +215,10 @@ function accelerate(speedIncreasePercent?: number): AccelerationEffectAction {
  * For details and examples, see 'Fade in and out' in the Video Transformations guide.
  * @memberOf Actions.Effect
  * @param {number} fadeLength The time in ms for the fade to occur. (Server default: 2000)
- * @return {EffectActionWithLength}
+ * @return {FadeInEffectAction}
  */
-function fadeIn(fadeLength?: number):EffectActionWithLength {
-  return new EffectActionWithLength('fade', fadeLength);
+function fadeIn(fadeLength?: number):FadeInEffectAction {
+  return new FadeInEffectAction('fade', fadeLength);
 }