satie/src/implLine_centerPostprocessor.ts

A sheet music renderer for the web

/**
 * This file is part of Satie music engraver <https://github.com/jnetterf/satie>.
 * Copyright (C) Joshua Netterfield <joshua.ca> 2015 - present.
 * 
 * Satie is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * 
 * Satie is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with Satie.  If not, see <http://www.gnu.org/licenses/>.
 */

import {forEach, max, map, times, findIndex, last} from "lodash";
import * as invariant from "invariant";

import {Type} from "./document";

import {IMeasureLayout} from "./private_measureLayout";
import {ILayoutOptions} from "./private_layoutOptions";
import {ILineBounds} from "./private_lineBounds";

/** 
 * Centers elements marked as such
 * 
 * @returns new end of line
 */
function center(options: ILayoutOptions, bounds: ILineBounds,
        measures: IMeasureLayout[]): IMeasureLayout[] {

    forEach(measures, function(measure, measureIdx) {
        let maxIdx = max(map(measure.elements, el => el.length));
        times(maxIdx, function(j) {
            for (let i = 0; i < measure.elements.length; ++i) {
                if (measure.elements[i][j].expandPolicy === "centered") {
                    let intrinsicWidth = measure.elements[i][j].renderedWidth;
                    invariant(isFinite(intrinsicWidth),
                        "Intrinsic width must be set on centered items");
                    let measureSpaceRemaining: number;
                    let attribIdx = findIndex(measure.elements[0],
                        el => el.renderClass === Type.Attributes && el.renderedWidth > 0);
                    let base = 0;
                    if (attribIdx !== -1 && attribIdx < j) {
                        base = measure.elements[0][attribIdx].overrideX +
                            measure.elements[0][attribIdx].renderedWidth;
                        measureSpaceRemaining = last(measure.elements[i]).overrideX - base;
                    } else if (measures[measureIdx - 1]) {
                        measureSpaceRemaining = last(measure.elements[i]).overrideX -
                            (measures[measureIdx - 1].width -
                            last(measures[measureIdx - 1].elements[0]).overrideX);
                    } else {
                        measureSpaceRemaining = last(measure.elements[i]).overrideX;
                    }
                    if (measures[measureIdx + 1] && measures[measureIdx + 1].width === 0) {
                        measureSpaceRemaining += 16.6;
                    }
                    measure.elements[i][j].x =
                        base + measureSpaceRemaining / 2 -
                        intrinsicWidth / 2;
                }
            }
        });
    });

    return measures;
}

export default center;