scratch-paint/src/helper/bounding-box/bounding-box-tool.js

import paper from 'paper';
import keyMirror from 'keymirror';

import {clearSelection, getSelectedItems} from '../selection';
import {getGuideColor, removeHelperItems} from '../guides';
import {getGuideLayer} from '../layer';

import ScaleTool from './scale-tool';
import RotateTool from './rotate-tool';
import MoveTool from './move-tool';

/** SVG for the rotation icon on the bounding box */
const ARROW_PATH = 'M19.28,1.09C19.28.28,19,0,18.2,0c-1.67,0-3.34,0-5,0-.34,0-.88.24-1,.47a1.4,1.4,0,0,0,.36,1.08,15.27,15.27,0,0,0,1.46,1.36A6.4,6.4,0,0,1,6.52,4,5.85,5.85,0,0,1,5.24,3,15.27,15.27,0,0,0,6.7,1.61,1.4,1.4,0,0,0,7.06.54C7,.3,6.44.07,6.1.06c-1.67,0-3.34,0-5,0C.28,0,0,.31,0,1.12c0,1.67,0,3.34,0,5a1.23,1.23,0,0,0,.49,1,1.22,1.22,0,0,0,1-.31A14.38,14.38,0,0,0,2.84,5.26l.73.62a9.45,9.45,0,0,0,7.34,2,9.45,9.45,0,0,0,4.82-2.05l.73-.62a14.38,14.38,0,0,0,1.29,1.51,1.22,1.22,0,0,0,1,.31,1.23,1.23,0,0,0,.49-1C19.31,4.43,19.29,2.76,19.28,1.09Z';
/** Modes of the bounding box tool, which can do many things depending on how it's used. */
const Modes = keyMirror({
    SCALE: null,
    ROTATE: null,
    MOVE: null
});

/**
 * A paper.Tool that handles transforming the selection and drawing a bounding box with handles.
 * On mouse down, the type of function (move, scale, rotate) is determined based on what is clicked
 * (scale handle, rotate handle, the object itself). This determines the mode of the tool, which then
 * delegates actions to the MoveTool, RotateTool or ScaleTool accordingly.
 */
class BoundingBoxTool {
    constructor () {
        this.mode = null;
        this.boundsPath = null;
        this.boundsScaleHandles = [];
        this.boundsRotHandles = [];
        this._modeMap = {};
        this._modeMap[Modes.SCALE] = new ScaleTool();
        this._modeMap[Modes.ROTATE] = new RotateTool();
        this._modeMap[Modes.MOVE] = new MoveTool();
    }

    /**
     * @param {!MouseEvent} event The mouse event
     * @param {boolean} clone Whether to clone on mouse down (e.g. alt key held)
     * @param {boolean} multiselect Whether to multiselect on mouse down (e.g. shift key held)
     * @param {boolean} preselectedOnly If true, only get hit results on items that are already selected
     * @return {boolean} True if there was a hit, false otherwise
     */
    onMouseDown (event, clone, multiselect, preselectedOnly) {
        const hitResults = paper.project.hitTestAll(event.point, this.getHitOptions(preselectedOnly));
        if (!hitResults || hitResults.length === 0) {
            if (!multiselect) {
                this.removeBoundsPath();
                clearSelection();
            }
            return null;
        }

        // Prefer scale to trigger over rotate, and scale and rotate to trigger over other hits
        let hitResult = hitResults[0];
        for (let i = 0; i < hitResults.length; i++) {
            if (hitResults[i].item.data && hitResults[i].item.data.isScaleHandle) {
                hitResult = hitResults[i];
                this.mode = Modes.SCALE;
                this._modeMap[this.mode].onMouseDown(hitResult, this.boundsPath, getSelectedItems());
                break;
            } else if (hitResults[i].item.data && hitResults[i].item.data.isRotHandle) {
                hitResult = hitResults[i];
                this.mode = Modes.ROTATE;
                this._modeMap[this.mode].onMouseDown(hitResult, this.boundsPath, getSelectedItems());
            } else {
                this.mode = Modes.MOVE;
                this._modeMap[this.mode].onMouseDown(hitResult, clone, multiselect);
            }
        }

        // while transforming object, never show the bounds stuff
        this.removeBoundsPath();
    }
    onMouseDrag (event) {
        if (event.event.button > 0) return; // only first mouse button
        this._modeMap[this.mode].onMouseDrag(event);
    }
    onMouseUp (event) {
        if (event.event.button > 0) return; // only first mouse button
        this._modeMap[this.mode].onMouseUp(event);

        this.mode = null;
        
        if (getSelectedItems().length <= 0) {
            this.removeBoundsPath();
        } else {
            this.setSelectionBounds();
        }
    }
    setSelectionBounds () {
        this.removeBoundsPath();
        
        const items = getSelectedItems();
        if (items.length <= 0) return;
        
        let rect = null;
        for (const item of items) {
            if (rect) {
                rect = rect.unite(item.bounds);
            } else {
                rect = item.bounds;
            }
        }
        
        if (!this.boundsPath) {
            this.boundsPath = new paper.Path.Rectangle(rect);
            this.boundsPath.curves[0].divideAtTime(0.5);
            this.boundsPath.curves[2].divideAtTime(0.5);
            this.boundsPath.curves[4].divideAtTime(0.5);
            this.boundsPath.curves[6].divideAtTime(0.5);
        }
        this.boundsPath.guide = true;
        this.boundsPath.data.isSelectionBound = true;
        this.boundsPath.data.isHelperItem = true;
        this.boundsPath.fillColor = null;
        this.boundsPath.strokeScaling = false;
        this.boundsPath.fullySelected = true;
        this.boundsPath.parent = getGuideLayer();
        
        for (let index = 0; index < this.boundsPath.segments; index++) {
            const segment = this.boundsPath.segments[index];
            let size = 4;
            
            if (index % 2 === 0) {
                size = 6;
            }
            
            if (index === 7) {
                const offset = new paper.Point(0, 20);
                
                const arrows = new paper.Path(ARROW_PATH);
                arrows.translate(segment.point + offset + [-10.5, -5]);
                
                const line = new paper.Path.Rectangle(
                    segment.point + offset - [1, 0],
                    segment.point + [1, 0]);

                const rotHandle = arrows.unite(line);
                line.remove();
                arrows.remove();
                rotHandle.scale(1 / paper.view.zoom, segment.point);
                rotHandle.data = {
                    offset: offset,
                    isRotHandle: true,
                    isHelperItem: true,
                    noSelect: true,
                    noHover: true
                };
                rotHandle.fillColor = getGuideColor('blue');
                rotHandle.parent = getGuideLayer();
                this.boundsRotHandles[index] = rotHandle;
            }
            
            this.boundsScaleHandles[index] =
                new paper.Path.Rectangle({
                    center: segment.point,
                    data: {
                        index: index,
                        isScaleHandle: true,
                        isHelperItem: true,
                        noSelect: true,
                        noHover: true
                    },
                    size: [size / paper.view.zoom, size / paper.view.zoom],
                    fillColor: getGuideColor('blue'),
                    parent: getGuideLayer()
                });
        }
    }
    removeBoundsPath () {
        removeHelperItems();
        this.boundsPath = null;
        this.boundsScaleHandles.length = 0;
        this.boundsRotHandles.length = 0;
    }
}

export default BoundingBoxTool;