scratch-vm/src/blocks/scratch3_pen.js

const ArgumentType = require('../extension-support/argument-type');
const BlockType = require('../extension-support/block-type');
const Cast = require('../util/cast');
const Clone = require('../util/clone');
const Color = require('../util/color');
const MathUtil = require('../util/math-util');
const RenderedTarget = require('../sprites/rendered-target');


/**
 * Enum for pen color parameters.
 * @readonly
 * @enum {string}
 */
const ColorParam = {
    COLOR: 'color',
    SATURATION: 'saturation',
    BRIGHTNESS: 'brightness',
    TRANSPARENCY: 'transparency'
};

/**
 * @typedef {object} PenState - the pen state associated with a particular target.
 * @property {Boolean} penDown - tracks whether the pen should draw for this target.
 * @property {number} color - the current color (hue) of the pen.
 * @property {PenAttributes} penAttributes - cached pen attributes for the renderer. This is the authoritative value for
 *   diameter but not for pen color.
 */

/**
 * Host for the Pen-related blocks in Scratch 3.0
 * @param {Runtime} runtime - the runtime instantiating this block package.
 * @constructor
 */
class Scratch3PenBlocks {
    constructor (runtime) {
        /**
         * The runtime instantiating this block package.
         * @type {Runtime}
         */
        this.runtime = runtime;

        /**
         * The ID of the renderer Drawable corresponding to the pen layer.
         * @type {int}
         * @private
         */
        this._penDrawableId = -1;

        /**
         * The ID of the renderer Skin corresponding to the pen layer.
         * @type {int}
         * @private
         */
        this._penSkinId = -1;

        this._onTargetCreated = this._onTargetCreated.bind(this);
        this._onTargetMoved = this._onTargetMoved.bind(this);

        runtime.on('targetWasCreated', this._onTargetCreated);
    }

    /**
     * The default pen state, to be used when a target has no existing pen state.
     * @type {PenState}
     */
    static get DEFAULT_PEN_STATE () {
        return {
            penDown: false,
            color: 66.66,
            saturation: 100,
            brightness: 100,
            transparency: 0,
            penAttributes: {
                color4f: [0, 0, 1, 1],
                diameter: 1
            }
        };
    }

    /**
     * Place the pen layer in front of the backdrop but behind everything else.
     * We should probably handle this somewhere else... somewhere central that knows about pen, backdrop, video, etc.
     * Maybe it should be in the GUI?
     * @type {int}
     */
    static get PEN_ORDER () {
        return 1;
    }

    /**
     * The minimum and maximum allowed pen size.
     * @type {{min: number, max: number}}
     */
    static get PEN_SIZE_RANGE () {
        return {min: 1, max: 255};
    }

    /**
     * The key to load & store a target's pen-related state.
     * @type {string}
     */
    static get STATE_KEY () {
        return 'Scratch.pen';
    }

    /**
     * Clamp a pen size value to the range allowed by the pen.
     * @param {number} requestedSize - the requested pen size.
     * @returns {number} the clamped size.
     * @private
     */
    _clampPenSize (requestedSize) {
        return MathUtil.clamp(
            requestedSize,
            Scratch3PenBlocks.PEN_SIZE_RANGE.min,
            Scratch3PenBlocks.PEN_SIZE_RANGE.max
        );
    }

    /**
     * Retrieve the ID of the renderer "Skin" corresponding to the pen layer. If
     * the pen Skin doesn't yet exist, create it.
     * @returns {int} the Skin ID of the pen layer, or -1 on failure.
     * @private
     */
    _getPenLayerID () {
        if (this._penSkinId < 0 && this.runtime.renderer) {
            this._penSkinId = this.runtime.renderer.createPenSkin();
            this._penDrawableId = this.runtime.renderer.createDrawable();
            this.runtime.renderer.setDrawableOrder(this._penDrawableId, Scratch3PenBlocks.PEN_ORDER);
            this.runtime.renderer.updateDrawableProperties(this._penDrawableId, {skinId: this._penSkinId});
        }
        return this._penSkinId;
    }

    /**
     * @param {Target} target - collect pen state for this target. Probably, but not necessarily, a RenderedTarget.
     * @returns {PenState} the mutable pen state associated with that target. This will be created if necessary.
     * @private
     */
    _getPenState (target) {
        let penState = target.getCustomState(Scratch3PenBlocks.STATE_KEY);
        if (!penState) {
            penState = Clone.simple(Scratch3PenBlocks.DEFAULT_PEN_STATE);
            target.setCustomState(Scratch3PenBlocks.STATE_KEY, penState);
        }
        return penState;
    }

    /**
     * When a pen-using Target is cloned, clone the pen state.
     * @param {Target} newTarget - the newly created target.
     * @param {Target} [sourceTarget] - the target used as a source for the new clone, if any.
     * @listens Runtime#event:targetWasCreated
     * @private
     */
    _onTargetCreated (newTarget, sourceTarget) {
        if (sourceTarget) {
            const penState = sourceTarget.getCustomState(Scratch3PenBlocks.STATE_KEY);
            if (penState) {
                newTarget.setCustomState(Scratch3PenBlocks.STATE_KEY, Clone.simple(penState));
                if (penState.penDown) {
                    newTarget.addListener(RenderedTarget.EVENT_TARGET_MOVED, this._onTargetMoved);
                }
            }
        }
    }

    /**
     * Handle a target which has moved. This only fires when the pen is down.
     * @param {RenderedTarget} target - the target which has moved.
     * @param {number} oldX - the previous X position.
     * @param {number} oldY - the previous Y position.
     * @private
     */
    _onTargetMoved (target, oldX, oldY) {
        const penSkinId = this._getPenLayerID();
        if (penSkinId >= 0) {
            const penState = this._getPenState(target);
            this.runtime.renderer.penLine(penSkinId, penState.penAttributes, oldX, oldY, target.x, target.y);
            this.runtime.requestRedraw();
        }
    }

    _wrapColor (value) {
        return MathUtil.wrapClamp(value, 0, 100);
    }

    /**
     * Clamp a pen color parameter to the range (0,100).
     * @param {number} value - the value to be clamped.
     * @returns {number} the clamped value.
     * @private
     */
    _clampColorParam (value) {
        return MathUtil.clamp(value, 0, 100);
    }

    /**
     * Convert an alpha value to a pen transparency value.
     * Alpha ranges from 0 to 1, where 0 is transparent and 1 is opaque.
     * Transparency ranges from 0 to 100, where 0 is opaque and 100 is transparent.
     * @param {number} alpha - the input alpha value.
     * @returns {number} the transparency value.
     * @private
     */
    _alphaToTransparency (alpha) {
        return (1.0 - alpha) * 100.0;
    }

    /**
     * Convert a pen transparency value to an alpha value.
     * Alpha ranges from 0 to 1, where 0 is transparent and 1 is opaque.
     * Transparency ranges from 0 to 100, where 0 is opaque and 100 is transparent.
     * @param {number} transparency - the input transparency value.
     * @returns {number} the alpha value.
     * @private
     */
    _transparencyToAlpha (transparency) {
        return 1.0 - (transparency / 100.0);
    }

    /**
     * @returns {object} metadata for this extension and its blocks.
     */
    getInfo () {
        return {
            id: 'pen',
            name: 'Pen',
            blocks: [
                {
                    opcode: 'clear',
                    blockType: BlockType.COMMAND
                },
                {
                    opcode: 'stamp',
                    blockType: BlockType.COMMAND
                },
                {
                    opcode: 'penDown',
                    blockType: BlockType.COMMAND,
                    text: 'pen down'
                },
                {
                    opcode: 'penUp',
                    blockType: BlockType.COMMAND,
                    text: 'pen up'
                },
                {
                    opcode: 'setPenColorToColor',
                    blockType: BlockType.COMMAND,
                    text: 'set pen color to [COLOR]',
                    arguments: {
                        COLOR: {
                            type: ArgumentType.COLOR
                        }
                    }
                },
                {
                    opcode: 'changePenColorParamBy',
                    blockType: BlockType.COMMAND,
                    text: 'change pen [COLOR_PARAM] by [VALUE]',
                    arguments: {
                        COLOR_PARAM: {
                            type: ArgumentType.STRING,
                            menu: 'colorParam',
                            defaultValue: ColorParam.COLOR
                        },
                        VALUE: {
                            type: ArgumentType.NUMBER,
                            defaultValue: 10
                        }
                    }
                },
                {
                    opcode: 'setPenColorParamTo',
                    blockType: BlockType.COMMAND,
                    text: 'set pen [COLOR_PARAM] to [VALUE]',
                    arguments: {
                        COLOR_PARAM: {
                            type: ArgumentType.STRING,
                            menu: 'colorParam',
                            defaultValue: ColorParam.COLOR
                        },
                        VALUE: {
                            type: ArgumentType.NUMBER,
                            defaultValue: 50
                        }
                    }
                },
                {
                    opcode: 'changePenSizeBy',
                    blockType: BlockType.COMMAND,
                    text: 'change pen size by [SIZE]',
                    arguments: {
                        SIZE: {
                            type: ArgumentType.NUMBER,
                            defaultValue: 1
                        }
                    }
                },
                {
                    opcode: 'setPenSizeTo',
                    blockType: BlockType.COMMAND,
                    text: 'set pen size to [SIZE]',
                    arguments: {
                        SIZE: {
                            type: ArgumentType.NUMBER,
                            defaultValue: 1
                        }
                    }
                }
            ],
            menus: {
                colorParam:
                    [ColorParam.COLOR, ColorParam.SATURATION,
                    ColorParam.BRIGHTNESS, ColorParam.TRANSPARENCY]
            }
        };
    }

    /**
     * The pen "clear" block clears the pen layer's contents.
     */
    clear () {
        const penSkinId = this._getPenLayerID();
        if (penSkinId >= 0) {
            this.runtime.renderer.penClear(penSkinId);
            this.runtime.requestRedraw();
        }
    }

    /**
     * The pen "stamp" block stamps the current drawable's image onto the pen layer.
     * @param {object} args - the block arguments.
     * @param {object} util - utility object provided by the runtime.
     */
    stamp (args, util) {
        const penSkinId = this._getPenLayerID();
        if (penSkinId >= 0) {
            const target = util.target;
            this.runtime.renderer.penStamp(penSkinId, target.drawableID);
            this.runtime.requestRedraw();
        }
    }

    /**
     * The pen "pen down" block causes the target to leave pen trails on future motion.
     * @param {object} args - the block arguments.
     * @param {object} util - utility object provided by the runtime.
     */
    penDown (args, util) {
        const target = util.target;
        const penState = this._getPenState(target);

        if (!penState.penDown) {
            penState.penDown = true;
            target.addListener(RenderedTarget.EVENT_TARGET_MOVED, this._onTargetMoved);
        }

        const penSkinId = this._getPenLayerID();
        if (penSkinId >= 0) {
            this.runtime.renderer.penPoint(penSkinId, penState.penAttributes, target.x, target.y);
            this.runtime.requestRedraw();
        }
    }

    /**
     * The pen "pen up" block stops the target from leaving pen trails.
     * @param {object} args - the block arguments.
     * @param {object} util - utility object provided by the runtime.
     */
    penUp (args, util) {
        const target = util.target;
        const penState = this._getPenState(target);

        if (penState.penDown) {
            penState.penDown = false;
            target.removeListener(RenderedTarget.EVENT_TARGET_MOVED, this._onTargetMoved);
        }
    }

    /**
     * The pen "set pen color to {color}" block sets the pen to a particular RGB color.
     * @param {object} args - the block arguments.
     *  @property {int} COLOR - the color to set, expressed as a 24-bit RGB value (0xRRGGBB).
     * @param {object} util - utility object provided by the runtime.
     */
    setPenColorToColor (args, util) {
        const penState = this._getPenState(util.target);
        const rgb = Cast.toRgbColorObject(args.COLOR);
        const hsv = Color.rgbToHsv(rgb);
        penState.color = (hsv.h / 360) * 100;
        penState.saturation = hsv.s * 100;
        penState.brightness = hsv.v * 100;
        this._updatePenColor(penState);
    }

    /**
     * Update the cached color from the color, saturation, brightness and transparency values
     * in the provided PenState object.
     * @param {PenState} penState - the pen state to update.
     * @private
     */
    _updatePenColor (penState) {
        let rgb = Color.hsvToRgb({
            h: penState.color * 360 / 100,
            s: penState.saturation / 100,
            v: penState.brightness / 100
        });
        penState.penAttributes.color4f[0] = rgb.r / 255.0;
        penState.penAttributes.color4f[1] = rgb.g / 255.0;
        penState.penAttributes.color4f[2] = rgb.b / 255.0;
        penState.penAttributes.color4f[3] = this._transparencyToAlpha(penState.transparency);
    }

    _setOrChangeColorParam (param, value, penState, change) {
        switch (param) {
            case ColorParam.COLOR:
                penState.color = this._wrapColor(value + (change ? penState.color : 0));
                break;
            case ColorParam.SATURATION:
                penState.saturation = this._clampColorParam(value + (change ? penState.saturation : 0));
                break;
            case ColorParam.BRIGHTNESS:
                penState.brightness = this._clampColorParam(value + (change ? penState.brightness : 0));
                break;
            case ColorParam.TRANSPARENCY:
                penState.transparency = this._clampColorParam(value + (change ? penState.transparency : 0));
                break;
        }
        this._updatePenColor(penState);
    }

    changePenColorParamBy (args, util) {
        const penState = this._getPenState(util.target);
        this._setOrChangeColorParam(args.COLOR_PARAM, Cast.toNumber(args.VALUE), penState, true);
    }

    setPenColorParamTo (args, util) {
        const penState = this._getPenState(util.target);
        this._setOrChangeColorParam(args.COLOR_PARAM, Cast.toNumber(args.VALUE), penState, false);
    }

    /**
     * The pen "change pen size by {number}" block changes the pen size by the given amount.
     * @param {object} args - the block arguments.
     *  @property {number} SIZE - the amount of desired size change.
     * @param {object} util - utility object provided by the runtime.
     */
    changePenSizeBy (args, util) {
        const penAttributes = this._getPenState(util.target).penAttributes;
        penAttributes.diameter = this._clampPenSize(penAttributes.diameter + Cast.toNumber(args.SIZE));
    }

    /**
     * The pen "set pen size to {number}" block sets the pen size to the given amount.
     * @param {object} args - the block arguments.
     *  @property {number} SIZE - the amount of desired size change.
     * @param {object} util - utility object provided by the runtime.
     */
    setPenSizeTo (args, util) {
        const penAttributes = this._getPenState(util.target).penAttributes;
        penAttributes.diameter = this._clampPenSize(Cast.toNumber(args.SIZE));
    }
}

module.exports = Scratch3PenBlocks;