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  ./source/core/animation-loop.js ./source/core/display-cycle.js ./source/core/document-root-elements.js ./source/core/document.js ./source/core/events.js ./source/core/init.js ./source/core/library.js ./source/core/random-seed.js ./source/core/shared-vars.js ./source/core/snippets.js ./source/core/system-flags.js ./source/core/user-interaction.js ./source/core/utilities.js ./source/factory/action.js ./source/factory/anchor.js ./source/factory/animation.js ./source/factory/array-pool.js ./source/factory/bezier.js ./source/factory/block.js ./source/factory/canvas.js ./source/factory/cell-fragment.js ./source/factory/cell.js ./source/factory/cog.js ./source/factory/color.js ./source/factory/conic-gradient.js ./source/factory/coordinate.js ./source/factory/crescent.js ./source/factory/drag-zone.js ./source/factory/element.js ./source/factory/emitter.js ./source/factory/filter-engine-bluenoise-data.js ./source/factory/filter-engine.js ./source/factory/filter.js ./source/factory/font-attributes.js ./source/factory/gradient.js ./source/factory/grid.js ./source/factory/group.js ./source/factory/image-asset.js ./source/factory/keyboard-zone.js ./source/factory/line-spiral.js ./source/factory/line.js ./source/factory/loom.js ./source/factory/mesh.js ./source/factory/net.js ./source/factory/noise-asset.js ./source/factory/observe-update.js ./source/factory/oval.js ./source/factory/palette.js ./source/factory/particle-force.js ./source/factory/particle-history.js ./source/factory/particle-spring.js ./source/factory/particle-world.js ./source/factory/particle.js ./source/factory/pattern.js ./source/factory/phrase.js ./source/factory/picture.js ./source/factory/polygon.js ./source/factory/polyline.js ./source/factory/quadratic.js ./source/factory/quaternion.js ./source/factory/radial-gradient.js ./source/factory/raw-asset.js ./source/factory/reaction-diffusion-asset.js ./source/factory/rectangle.js ./source/factory/render-animation.js ./source/factory/shape.js ./source/factory/spiral.js ./source/factory/sprite-asset.js ./source/factory/stack.js ./source/factory/star.js ./source/factory/state.js ./source/factory/tetragon.js ./source/factory/ticker.js ./source/factory/tracer.js ./source/factory/tween.js ./source/factory/unstacked-element.js ./source/factory/vector.js ./source/factory/video-asset.js ./source/factory/wheel.js ./source/mixin/anchor.js ./source/mixin/asset-advanced-functionality.js ./source/mixin/asset-consumer.js ./source/mixin/asset.js ./source/mixin/base.js ./source/mixin/cascade.js ./source/mixin/cell-key-functions.js ./source/mixin/delta.js ./source/mixin/display-shape.js ./source/mixin/dom.js ./source/mixin/entity.js ./source/mixin/filter.js ./source/mixin/mimic.js ./source/mixin/path.js ./source/mixin/pattern.js ./source/mixin/pivot.js ./source/mixin/position.js ./source/mixin/shape-basic.js ./source/mixin/shape-curve.js ./source/mixin/shape-path-calculation.js ./source/mixin/styles.js ./source/mixin/tween.js

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  # Gradient factory

  Scrawl-canvas Gradient objects implement the Canvas API’s createLinearGradient method. The resulting CanvasGradient object can be used by any Scrawl-canvas entity as its `fillStyle` or `strokeStyle`.

  - Most gradient-related functionality has been coded up in the styles mixin, and is documented there.
  - Gradients fully participate in the Scrawl-canvas packet system, thus can be saved, restored, cloned, killed, etc.
  - Gradients can be animated in a variety of ways; the can act as target objects for Scrawl-canvas Tweens.

  Gradients can be applied to an entity in two different ways, depending on the entity’s `lockFillStyleToEntity` and `lockStrokeStyleToEntity` attribute flags:

  - Cell-locked Gradients will cover the entire Cell; an entity moved from one part of the display to another will show different parts of the gradient
  - Entity-locked Gradients display their entire color range on the entity, move with the entity and even rotate with the entity.
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  #### Demos:

  - Canvas-003 - Linear gradients
  - Canvas-005 - Cell-locked, and Entity-locked, gradients; animating gradients by delta, and by tween
  - Canvas-022 - Grid entity - basic functionality (color, gradients)
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  #### Imports

      import { constructors } from '../core/library.js';

      import { doCreate, pushUnique, Ωempty } from '../core/utilities.js';

      import baseMix from '../mixin/base.js';
      import stylesMix from '../mixin/styles.js';

      import { BLANK, STYLES, T_GRADIENT } from '../core/shared-vars.js';

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  #### Gradient constructor

      const Gradient = function (items = Ωempty) {

          this.stylesInit(items);
          return this;
      };

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  #### Gradient prototype

      const P = Gradient.prototype = doCreate();

      P.type = T_GRADIENT;
      P.lib = STYLES;
      P.isArtefact = false;
      P.isAsset = false;

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  #### Mixins

      baseMix(P);
      stylesMix(P);

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  #### Gradient attributes

  - Attributes defined in the base mixin: name.
  - Attributes defined in the styles mixin: start, end, palette, paletteStart, paletteEnd, cyclePalette.
  - Attributes defined in the Palette factory: colors, cyclic.

  No additional attributes are defined in this file.

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  #### Packet management

      P.packetObjects = pushUnique(P.packetObjects, ['palette']);

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  #### Clone management

  No additional clone functionality required

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  #### Kill management

  No additional kill functionality required

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  #### Get, Set, deltaSet

  No additional functionality required

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  #### Prototype functions

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  `buildStyle` - internal function: creates the linear gradient on the Cell’s CanvasRenderingContext2D engine, and then adds the color stops to it.

      P.buildStyle = function (cell) {

          if (cell) {

              const engine = cell.engine;

              if (engine) {

                  const gradient = engine.createLinearGradient(...this.gradientArgs);

                  return this.addStopsToGradient(gradient, this.paletteStart, this.paletteEnd, this.cyclePalette);
              }
          }
          return BLANK;
      };

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  `updateGradientArgs` - internal function

      P.updateGradientArgs = function (x, y) {

          const gradientArgs = this.gradientArgs,
              currentStart = this.currentStart,
              currentEnd = this.currentEnd;

          const sx = currentStart[0] + x,
              sy = currentStart[1] + y,
              ey = currentEnd[1] + y;

          let ex = currentEnd[0] + x;

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  check to correct situation where coordinates represent a ‘0 x 0’ box - which will cause errors in some browsers

          if (sx == ex && sy == ey) ex++;

          gradientArgs.length = 0;
          gradientArgs.push(sx, sy, ex, ey);
      };

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  #### Factory

      scrawl.makeGradient({
          name: 'colored-pipes',
          endX: '100%',
          cyclePalette: true,
          colors: [
              [0, 'black'],
              [99, 'red'],
              [199, 'black'],
              [299, 'blue'],
              [399, 'black'],
              [499, 'gold'],
              [599, 'black'],
              [699, 'green'],
              [799, 'black'],
              [899, 'lavender'],
              [999, 'black']
          ],
      })

      scrawl.makeBlock({

          name: 'animated-block',

          width: 150,
          height: 150,

          startX: 180,
          startY: 120,

          handleX: 'center',
          handleY: 'center',

          strokeStyle: 'coral',
          fillStyle: 'colored-pipes',
          lineWidth: 2,

          method: 'fillAndDraw',
      });

      export const makeGradient = function (items) {

          if (!items) return false;
          return new Gradient(items);
      };

      constructors.Gradient = Gradient;