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  • ¶

    Tetragon factory

    A factory for generating various straight-line tetragonal shape-based entitys

    Path-defined entitys represent a diverse range of shapes rendered onto a DOM <canvas> element using the Canvas API’s Path2D interface. They use the shapeBasic and shapePathCalculation (some also use shapeCurve) mixins to define much of their functionality.

    All path-defined entitys can be positioned, cloned, filtered etc:

    • Positioning functionality for the entity is supplied by the position mixin, while rendering functionality comes from the entity mixin.
    • Dimensions, however, have little meaning for path-defined entitys - their width and height are determined by their SVG path data Strings; use scale instead.
    • Path-defined entitys can use CSS color Strings for their fillStyle and strokeStyle values, alongside Gradient, RadialGradient, Color and Pattern objects.
    • They will also accept Filter objects.
    • They can use Anchor objects for user navigation.
    • They can be rendered to the canvas by including them in a Cell object’s Group.
    • They can be animated directly, or using delta animation, or act as the target for Tween animations.
    • Path-defined entitys can be cloned, and killed.
  • ¶

    Using path-defined entitys as Scrawl-canvas paths

    A path is a track - straight, or curved, or as complex as required - placed across a container which artefacts can use as a source of their positioning data. We can animate an artifact to move along the path:

    • To enable a path-defined entity to be used as a path by other artefacts, set its useAsPath flag to true.
    • The artefact can then set its path attribute to the path-defined entity’s name-String (or the entity itself), and set its lockTo Array values to "path".
    • We position the artefact by setting its pathPosition attribute to a float Number value between 0.0 - 1.0, with 0 being the start of the path, and 1 being its end.
    • Path-defined entitys can use other path-defined entitys as a path.
    • Phrase entitys can use a path to position their text block; they can also use a path to position each letter individually along the path.
    • Artefacts (and letters) can be rotated so that they match the rotation at that point along the path - tangential rotation by setting their addPathRotation flag to true.
    • Animate an artefact along the path by either using the artefact’s delta object, or triggering a Tween to perform the movement.
  • ¶

    Demos:

    • Canvas-011 - Shape entity (make, clone, method); drag and drop shape entitys
    • Canvas-012 - Shape entity position; shape entity as a path for other artefacts to follow
    • Canvas-013 - Path-defined entitys: oval, rectangle, line, quadratic, bezier, tetragon, polygon, star, spiral
    • Canvas-014 - Line, quadratic and bezier entitys - control lock alternatives
    • Canvas-018 - Phrase entity - text along a path
    • Canvas-024 - Loom entity functionality
    • Canvas-030 - Polyline entity functionality
    • Canvas-038 - Responsive Shape-based entitys
    • DOM-015 - Use stacked DOM artefact corners as pivot points
    • Component-004 - Scrawl-canvas packets - save and load a range of different entitys
  • ¶

    Imports

    import { constructors } from '../core/library.js';
    import { mergeOver } from '../core/utilities.js';
    
    import baseMix from '../mixin/base.js';
    import shapeMix from '../mixin/shapeBasic.js';
  • ¶

    Tetragon constructor

    const Tetragon = function (items = {}) {
    
        this.shapeInit(items);
        return this;
    };
  • ¶

    Tetragon prototype

    let P = Tetragon.prototype = Object.create(Object.prototype);
    P.type = 'Tetragon';
    P.lib = 'entity';
    P.isArtefact = true;
    P.isAsset = false;
  • ¶

    Mixins

    • base
    • shapeBasic
    P = baseMix(P);
    P = shapeMix(P);
  • ¶

    Tetragon attributes

    • Attributes defined in the base mixin: name.
    • Attributes defined in the position mixin: group, visibility, order, start, startX, startY, handle, handleX, handleY, offset, offsetX, offsetY, dimensions, width, height, pivoted, mimicked, lockTo, lockXTo, lockYTo, scale, roll, noUserInteraction, noPositionDependencies, noCanvasEngineUpdates, noFilters, noPathUpdates, purge, bringToFrontOnDrag.
    • Attributes defined in the delta mixin: delta, noDeltaUpdates.
    • Attributes defined in the pivot mixin: pivot, pivotCorner, addPivotHandle, addPivotOffset, addPivotRotation.
    • Attributes defined in the mimic mixin: mimic, useMimicDimensions, useMimicScale, useMimicStart, useMimicHandle, useMimicOffset, useMimicRotation, useMimicFlip, addOwnDimensionsToMimic, addOwnScaleToMimic, addOwnStartToMimic, addOwnHandleToMimic, addOwnOffsetToMimic, addOwnRotationToMimic.
    • Attributes defined in the path mixin: path, pathPosition, addPathHandle, addPathOffset, addPathRotation, constantPathSpeed.
    • Attributes defined in the entity mixin: method, pathObject, winding, flipReverse, flipUpend, scaleOutline, lockFillStyleToEntity, lockStrokeStyleToEntity, onEnter, onLeave, onDown, onUp, fillStyle, strokeStyle, globalAlpha, globalCompositeOperation, lineWidth, lineCap, lineJoin, lineDash, lineDashOffset, miterLimit, shadowOffsetX, shadowOffsetY, shadowBlur, shadowColor, filter.
    • Attributes defined in the anchor mixin: anchor.
    • Attributes defined in the filter mixin: filters, isStencil.
    • Attributes defined in the shapeBasic mixin: species, useAsPath, precision, pathDefinition, showBoundingBox, boundingBoxColor, minimumBoundingBoxDimensions, constantPathSpeed.
    let defaultAttributes = {
    
        radiusX: 5,
        radiusY: 5,
        intersectX: 0.5,
        intersectY: 0.5,
    };
    P.defs = mergeOver(P.defs, defaultAttributes);
  • ¶

    Packet management

    No additional packet functionality required

  • ¶

    Clone management

    No additional clone functionality required

  • ¶

    Kill management

    No additional kill functionality required

  • ¶

    Get, Set, deltaSet

    let S = P.setters,
        D = P.deltaSetters;
    
    S.radius = function (item) {
    
        this.setRectHelper(item, ['radiusX', 'radiusY']);
    };
    S.radiusX = function (item) {
    
        this.setRectHelper(item, ['radiusX']);
    };
    S.radiusY = function (item) {
    
        this.setRectHelper(item, ['radiusY']);
    };
    D.radius = function (item) {
    
        this.deltaRectHelper(item, ['radiusX', 'radiusY']);
    };
    D.radiusX = function (item) {
    
        this.deltaRectHelper(item, ['radiusX']);
    };
    D.radiusY = function (item) {
    
        this.deltaRectHelper(item, ['radiusY']);
    };
    
    S.intersectA = function (item) {
    
        this.intersectA = item;
        this.updateDirty();
    };
    S.intersectB = function (item) {
    
        this.intersectB = item;
        this.updateDirty();
    };
    D.intersectA = function (item) {
    
        if (item.toFixed) {
    
            this.intersectA += item;
            this.updateDirty();
        }
    };
    D.intersectB = function (item) {
    
        if (item.toFixed) {
    
            this.intersectB += item;
            this.updateDirty();
        }
    };
  • ¶

    Prototype functions

  • ¶

    setRectHelper - internal setter helper function

    P.setRectHelper = function (item, corners) {
    
        this.updateDirty();
    
        corners.forEach(corner => {
    
            this[corner] = item;
        }, this);
    };
  • ¶

    deltaRectHelper - internal setter helper function

    P.deltaRectHelper = function (item, corners) {
    
        this.updateDirty();
    
        corners.forEach(corner => {
    
            this[corner] = addStrings(this[corner], item);
        }, this);
    };
  • ¶

    cleanSpecies - internal helper function - called by prepareStamp

    P.cleanSpecies = function () {
    
        this.dirtySpecies = false;
    
        let p = 'M0,0';
        p = this.makeTetragonPath();
    
        this.pathDefinition = p;
    };
  • ¶

    makeTetragonPath - internal helper function - called by cleanSpecies

    P.makeTetragonPath = function () {
    
        let radiusX = this.radiusX,
            radiusY = this.radiusY,
            width, height;
    
        if (radiusX.substring || radiusY.substring) {
  • ¶

    let here = this.getHere(), rx = (radiusX.substring) ? (parseFloat(radiusX) / 100) * here.w : radiusX, ry = (radiusY.substring) ? (parseFloat(radiusY) / 100) * here.h : radiusY;

  • ¶

    width = rx * 2; height = ry * 2;

            let host = this.getHost();
    
            if (host) {
    
                let [hW, hH] = host.currentDimensions;
    
                let rx = (radiusX.substring) ? (parseFloat(radiusX) / 100) * hW : radiusX,
                    ry = (radiusY.substring) ? (parseFloat(radiusY) / 100) * hH : radiusY;
    
                width = rx * 2;
                height = ry * 2;
            } 
        }
        else {
    
            width = radiusX * 2;
            height = radiusY * 2;
        }
    
        let port = parseFloat((width * this.intersectX).toFixed(2)),
            starboard = parseFloat((width - port).toFixed(2)),
            fore = parseFloat((height * this.intersectY).toFixed(2)),
            aft = parseFloat((height - fore).toFixed(2));
    
        let myData = 'm0,0';
    
        myData += `l${starboard},${fore} ${-starboard},${aft} ${-port},${-aft} ${port},${-fore}z`;
    
        return myData;
    };
    
    P.calculateLocalPathAdditionalActions = function () {
    
        let [x, y, w, h] = this.localBox;
    
        this.pathDefinition = this.pathDefinition.replace('m0,0', `m${-x},${-y}`);
    
        this.pathCalculatedOnce = false;
  • ¶

    ALWAYS, when invoking calculateLocalPath from calculateLocalPathAdditionalActions, include the second argument, set to true! Failure to do this leads to an infinite loop which will make your machine weep.

    • We need to recalculate the local path to take into account the offset required to put the Tetragon entity’s start coordinates at the top-left of the local box, and to recalculate the data used by other artefacts to place themselves on, or move along, its path.
        this.calculateLocalPath(this.pathDefinition, true);
    };
  • ¶

    Factories

  • ¶
    makeTetragon

    Scrawl-canvas uses lines internally to create the Shape path.

    • The main shape of the tetragon is determined by differing radius lengths in the x and y directions, as set by the attributes radiusX and radiusY; to set both radiuses to the same value, use radius instead.
    • The radius values can be: absolute (using Number values); or relative using %-String values - with the y radius representing a portion of the Cell container’s height and the x radius the Cell’s width.
    • The radiuses (as diameter lines) cross in the middle of the tetragon shape. We can move the position of where the intersection happens by setting a float Number value between 0.0 - 1.0 (or beyond those limits) for the intersectX and intersectY attributes.
    • intersectX (default: 0.5) represents the point at which the y diameter crosses the x diameter, with 0 being the left end and 1 being the right end.
    • intersectY (default: 0.5) represents the point at which the x diameter crosses the y diameter, with 0 being the top end and 1 being the bottom end.
    scrawl.makeTetragon({
    
        name: 'diamond',
    
        fillStyle: 'lightGreen',
        method: 'fillAndDraw',
    
        startX: 20,
        startY: 750,
    
        radiusX: 40,
        radiusY: 60,
    });
    const makeTetragon = function (items = {}) {
    
        items.species = 'tetragon';
        return new Tetragon(items);
    };
    
    constructors.Tetragon = Tetragon;
  • ¶

    Exports

    export {
        makeTetragon,
    };