js-draw
Version:
Draw pictures using a pen, touchscreen, or mouse! JS-draw is a drawing library for JavaScript and TypeScript.
94 lines (93 loc) • 3.38 kB
JavaScript
import { Path, PathCommandType } from '@js-draw/math';
import Stroke from '../Stroke.mjs';
import makeSnapToGridAutocorrect from './autocorrect/makeSnapToGridAutocorrect.mjs';
/**
* Creates a stroke builder that generates arrows.
*
* Example:
* [[include:doc-pages/inline-examples/changing-pen-types.md]]
*/
export const makeArrowBuilder = makeSnapToGridAutocorrect((initialPoint, viewport) => {
return new ArrowBuilder(initialPoint, viewport);
});
export default class ArrowBuilder {
constructor(startPoint, viewport) {
this.startPoint = startPoint;
this.viewport = viewport;
this.endPoint = startPoint;
}
getLineWidth() {
return Math.max(this.endPoint.width, this.startPoint.width);
}
getBBox() {
const preview = this.buildPreview();
return preview.getBBox();
}
buildPreview() {
const lineStartPoint = this.startPoint.pos;
const endPoint = this.endPoint.pos;
const toEnd = endPoint.minus(lineStartPoint).normalized();
const arrowLength = endPoint.distanceTo(lineStartPoint);
// Ensure that the arrow tip is smaller than the arrow.
const arrowTipSize = Math.min(this.getLineWidth(), arrowLength / 2);
const startSize = this.startPoint.width / 2;
const endSize = this.endPoint.width / 2;
const arrowTipBase = endPoint.minus(toEnd.times(arrowTipSize));
// Scaled normal vectors.
const lineNormal = toEnd.orthog();
const scaledStartNormal = lineNormal.times(startSize);
const scaledBaseNormal = lineNormal.times(endSize);
const path = new Path(arrowTipBase.minus(scaledBaseNormal), [
// Stem
{
kind: PathCommandType.LineTo,
point: lineStartPoint.minus(scaledStartNormal),
},
{
kind: PathCommandType.LineTo,
point: lineStartPoint.plus(scaledStartNormal),
},
{
kind: PathCommandType.LineTo,
point: arrowTipBase.plus(scaledBaseNormal),
},
// Head
{
kind: PathCommandType.LineTo,
point: arrowTipBase.plus(lineNormal.times(arrowTipSize).plus(scaledBaseNormal)),
},
{
kind: PathCommandType.LineTo,
point: endPoint.plus(toEnd.times(endSize)),
},
{
kind: PathCommandType.LineTo,
point: arrowTipBase.plus(lineNormal.times(-arrowTipSize).minus(scaledBaseNormal)),
},
{
kind: PathCommandType.LineTo,
point: arrowTipBase.minus(scaledBaseNormal),
},
// Round all points in the arrow (to remove unnecessary decimal places)
]).mapPoints((point) => this.viewport.roundPoint(point));
const preview = new Stroke([
{
startPoint: path.startPoint,
commands: path.parts,
style: {
fill: this.startPoint.color,
},
},
]);
return preview;
}
build() {
return this.buildPreview();
}
preview(renderer) {
this.buildPreview().render(renderer);
}
addPoint(point) {
this.endPoint = point;
}
}