add dither tojson

Author: strausr

__TESTS__/unit/toJson/effect.toJson.test.ts

@@ -1,5 +1,6 @@
 import {Transformation} from "../../../src";
 import {Effect} from "../../../src/actions/effect";
+import {halftone4x4Orthogonal} from "../../../src/qualifiers/dither";
 
 
 describe('Effect toJson()', () => {
@@ -194,4 +195,15 @@ describe('Effect toJson()', () => {
       }
     ]);
   });
+
+  it('effect.dither', () => {
+    const transformation = new Transformation()
+      .addAction(Effect.dither().type(halftone4x4Orthogonal()));
+    expect(transformation.toJson()).toStrictEqual( [
+      {
+        actionType: 'Dither',
+        type: 9,
+      }
+    ]);
+  });
 });

src/actions/effect/Dither.ts

@@ -1,4 +1,5 @@
 import {LeveledEffectAction} from "./EffectActions/LeveledEffectAction.js";
+import {IDitherModel} from "../../internal/models/IEffectActionModel.js";
 
 /**
  * @description Applies an ordered dither filter to the image.
@@ -7,13 +8,17 @@ import {LeveledEffectAction} from "./EffectActions/LeveledEffectAction.js";
  * @see Visit {@link Actions.Effect|Effect} for an example
  */
 class DitherEffectAction extends LeveledEffectAction {
+  protected _actionModel: IDitherModel = {actionType: 'Dither'};
   /**
    *
    * @param {Qualifiers.Dither} ditherType - The dither type applied to the image
    * @return {this}
    */
   type(ditherType:number): this {
-    return this.setLevel(ditherType);
+    this._actionModel.type = ditherType;
+    const qualifierEffect = this.createEffectQualifier(this.effectType, ditherType);
+    this.addQualifier(qualifierEffect);
+    return this;
   }
 }
 

src/internal/models/IEffectActionModel.ts

@@ -37,4 +37,16 @@ interface IMakeTransparentEffectModel extends IActionModel{
   tolerance?: number;
   color?: string;
 }
-export {IEffectActionWithLevelModel, ISimpleEffectActionModel, IShadowEffectActionModel, IColorizeModel, ICartoonifyEffectModel, IEffectOutlineModel, IMakeTransparentEffectModel};
+interface IDitherModel extends IActionModel {
+  type?: number;
+}
+export {
+  IEffectActionWithLevelModel,
+  ISimpleEffectActionModel,
+  IShadowEffectActionModel,
+  IColorizeModel,
+  ICartoonifyEffectModel,
+  IEffectOutlineModel,
+  IMakeTransparentEffectModel,
+  IDitherModel
+};