VexFlow - Copyright (c) Mohit Muthanna 2010.
This class by Raffaele Viglianti, 2012 http://itisnotsound.wordpress.com/
This class implements hairpins between notes. Hairpins can be either Crescendo or Descrescendo.
import { Vex } from './vex';
import { Element } from './element';
import { Modifier } from './modifier';
export class StaveHairpin extends Element {
static get type() {
return {
CRESC: 1,
DECRESC: 2,
};
}
/* Helper function to convert ticks into pixels.
* Requires a Formatter with voices joined and formatted (to
* get pixels per tick)
*
* options is struct that has:
*
* {
* height: px,
* y_shift: px, //vertical offset
* left_shift_ticks: 0, //left horizontal offset expressed in ticks
* right_shift_ticks: 0 // right horizontal offset expressed in ticks
* }
*
**/
static FormatByTicksAndDraw(ctx, formatter, notes, type, position, options) {
const ppt = formatter.pixelsPerTick;
if (ppt == null) {
throw new Vex.RuntimeError('BadArguments',
'A valid Formatter must be provide to draw offsets by ticks.'); }
const l_shift_px = ppt * options.left_shift_ticks;
const r_shift_px = ppt * options.right_shift_ticks;
const hairpin_options = {
height: options.height,
y_shift: options.y_shift,
left_shift_px: l_shift_px,
right_shift_px: r_shift_px };
new StaveHairpin({
first_note: notes.first_note,
last_note: notes.last_note,
}, type)
.setContext(ctx)
.setRenderOptions(hairpin_options)
.setPosition(position)
.draw();
}
/**
* Create a new hairpin from the specified notes.
*
* @constructor
* @param {!Object} notes The notes to tie up.
* @param {!Object} type The type of hairpin
*/
constructor(notes, type) {
/**
* Notes is a struct that has:
*
* {
* first_note: Note,
* last_note: Note,
* }
*
**/
super();
this.attrs.type = 'StaveHairpin';
this.notes = notes;
this.hairpin = type;
this.position = Modifier.Position.BELOW;
this.render_options = {
height: 10,
y_shift: 0, // vertical offset
left_shift_px: 0, // left horizontal offset
right_shift_px: 0, // right horizontal offset
};
this.setNotes(notes);
}
setPosition(position) {
if (position === Modifier.Position.ABOVE || position === Modifier.Position.BELOW) {
this.position = position;
}
return this;
}
setRenderOptions(options) {
if (
options.height != null &&
options.y_shift != null &&
options.left_shift_px != null &&
options.right_shift_px != null
) {
this.render_options = options;
}
return this;
}
/**
* Set the notes to attach this hairpin to.
*
* @param {!Object} notes The start and end notes.
*/
setNotes(notes) {
if (!notes.first_note && !notes.last_note) {
throw new Vex.RuntimeError(
'BadArguments',
'Hairpin needs to have either first_note or last_note set.'
);
}Success. Lets grab ‘em notes.
this.first_note = notes.first_note;
this.last_note = notes.last_note;
return this;
}
renderHairpin(params) {
const ctx = this.checkContext();
let dis = this.render_options.y_shift + 20;
let y_shift = params.first_y;
if (this.position === Modifier.Position.ABOVE) {
dis = -dis + 30;
y_shift = params.first_y - params.staff_height;
}
const l_shift = this.render_options.left_shift_px;
const r_shift = this.render_options.right_shift_px;
ctx.beginPath();
switch (this.hairpin) {
case StaveHairpin.type.CRESC:
ctx.moveTo(params.last_x + r_shift, y_shift + dis);
ctx.lineTo(params.first_x + l_shift, y_shift + (this.render_options.height / 2) + dis);
ctx.lineTo(params.last_x + r_shift, y_shift + this.render_options.height + dis);
break;
case StaveHairpin.type.DECRESC:
ctx.moveTo(params.first_x + l_shift, y_shift + dis);
ctx.lineTo(params.last_x + r_shift, y_shift + (this.render_options.height / 2) + dis);
ctx.lineTo(params.first_x + l_shift, y_shift + this.render_options.height + dis);
break;
default:Default is NONE, so nothing to draw
break;
}
ctx.stroke();
ctx.closePath();
}
draw() {
this.checkContext();
const firstNote = this.first_note;
const lastNote = this.last_note;
const start = firstNote.getModifierStartXY(this.position, 0);
const end = lastNote.getModifierStartXY(this.position, 0);
this.renderHairpin({
first_x: start.x,
last_x: end.x,
first_y: firstNote.getStave().y + firstNote.getStave().height,
last_y: lastNote.getStave().y + lastNote.getStave().height,
staff_height: firstNote.getStave().height,
});
return true;
}
}