abcjs/src/write/layout/layout.js

Renderer for abc music notation

var layoutVoice = require('./voice');
var setUpperAndLowerElements = require('./set-upper-and-lower-elements');
var layoutStaffGroup = require('./staff-group');
var getLeftEdgeOfStaff = require('./get-left-edge-of-staff');
var layoutInGrid = require('./layout-in-grid');
var toTimeAndStaffBased = require("./to-time-and-staff-based");

// This sets the "x" attribute on all the children in abctune.lines
// It also sets the "w" and "startx" attributes on "voices"
// It also sets the "w" and "startx" attributes on "voices.children"
var layout = function (renderer, abctune, width, space, expandToWidest, timeBasedLayout) {
	var i;
	var abcLine;
	// Adjust the x-coordinates to their absolute positions
	var maxWidth = width;
	for (i = 0; i < abctune.lines.length; i++) {
		abcLine = abctune.lines[i];
		if (abcLine.staff) {
			// console.log("=== line", i)
			var thisWidth;
			if (timeBasedLayout !== undefined)
				thisWidth = layoutInGrid(renderer, abcLine.staffGroup, timeBasedLayout);
			else
				thisWidth = setXSpacing(renderer, maxWidth, space, abcLine.staffGroup, abctune.formatting, i === abctune.lines.length - 1, false);
			// console.log(thisWidth, maxWidth)
			if (Math.round(thisWidth) > Math.round(maxWidth)) { // to take care of floating point weirdness
				maxWidth = thisWidth
				if (expandToWidest)
					i = -1 // do the calculations over with the new width
			}
		}
	}

	// Layout the beams and add the stems to the beamed notes.
	for (i = 0; i < abctune.lines.length; i++) {
		abcLine = abctune.lines[i];
		if (abcLine.staffGroup && abcLine.staffGroup.voices) {
			for (var j = 0; j < abcLine.staffGroup.voices.length; j++)
				layoutVoice(abcLine.staffGroup.voices[j]);
			setUpperAndLowerElements(renderer, abcLine.staffGroup);
		}
	}

	// See if there are collisions between voices that need to be tweaked
	var timeBased = toTimeAndStaffBased(abctune.lines)
	for (i = 0; i < abctune.lines.length; i++) {
		abcLine = abctune.lines[i];
		if (abcLine.staffGroup) {
			fixVoiceCollisions(timeBased[i])
			//setUpperAndLowerElements(renderer, abcLine.staffGroup);
		}
	}

	// Set the staff spacing
	// TODO-PER: we should have been able to do this by the time we called setUpperAndLowerElements, but for some reason the "bottom" element seems to be set as a side effect of setting the X spacing.
	for (i = 0; i < abctune.lines.length; i++) {
		abcLine = abctune.lines[i];
		if (abcLine.staffGroup) {
			abcLine.staffGroup.setHeight();
		}
	}
	return maxWidth;
}
// Do the x-axis positioning for a single line (a group of related staffs)
var setXSpacing = function (renderer, width, space, staffGroup, formatting, isLastLine, debug) {
	var leftEdge = getLeftEdgeOfStaff(renderer, staffGroup.getTextSize, staffGroup.voices, staffGroup.brace, staffGroup.bracket);
	var newspace = space;
	//dumpGroup("before", staffGroup)
	for (var it = 0; it < 8; it++) { // TODO-PER: shouldn't need multiple passes, but each pass gets it closer to the right spacing. (Only affects long lines: normal lines break out of this loop quickly.)
		// console.log("iteration", it)
		var ret = layoutStaffGroup(newspace, renderer.minPadding, debug, staffGroup, leftEdge);
		newspace = calcHorizontalSpacing(isLastLine, formatting.stretchlast, width + renderer.padding.left, staffGroup.w, newspace, ret.spacingUnits, ret.minSpace, renderer.padding.left + renderer.padding.right);
		if (debug)
			console.log("setXSpace", it, staffGroup.w, newspace, staffGroup.minspace);
		if (newspace === null) break;
	}
	//dumpGroup("after",staffGroup)
	centerWholeRests(staffGroup.voices);
	return staffGroup.w - leftEdge
};

function replacer(key, value) {
	// Filtering out properties
	if (key === 'parent') {
		return 'parent';
	}
	if (key === 'beam') {
		return 'beam';
	}
	return value;
}

function dumpGroup(label, staffGroup) {
	console.log("=================== " + label + " =========================")
	console.log(staffGroup)
	console.log(JSON.stringify(staffGroup, replacer, "\t"))
}

function calcHorizontalSpacing(isLastLine, stretchLast, targetWidth, lineWidth, spacing, spacingUnits, minSpace, padding) {
	if (isLastLine) {
		if (stretchLast === undefined) {
			if (lineWidth / targetWidth < 0.66) return null; // keep this for backward compatibility. The break isn't quite the same for some reason.
		} else {
			// "Stretch the last music line of a tune when it lacks less than the float fraction of the page width."
			var lack = 1 - (lineWidth + padding) / targetWidth;
			var stretch = lack < stretchLast;
			if (!stretch) return null; // don't stretch last line too much
		}
	}
	if (Math.abs(targetWidth - lineWidth) < 2) return null; // if we are already near the target width, we're done.
	var relSpace = spacingUnits * spacing;
	var constSpace = lineWidth - relSpace;
	if (spacingUnits > 0) {
		spacing = (targetWidth - constSpace) / spacingUnits;
		if (spacing * minSpace > 50) {
			spacing = 50 / minSpace;
		}
		return spacing;
	}
	return null;
}

function centerWholeRests(voices) {
	// whole rests are a special case: if they are by themselves in a measure, then they should be centered.
	// (If they are not by themselves, that is probably a user error, but we'll just center it between the two items to either side of it.)
	for (var i = 0; i < voices.length; i++) {
		var voice = voices[i];
		// Look through all of the elements except for the first and last. If the whole note appears there then there isn't anything to center it between anyway.
		for (var j = 1; j < voice.children.length - 1; j++) {
			var absElem = voice.children[j];
			if (absElem.abcelem.rest && (absElem.abcelem.rest.type === 'whole' || absElem.abcelem.rest.type === 'multimeasure')) {
				var before = voice.children[j - 1];
				var after = voice.children[j + 1];
				absElem.center(before, after);
			}
		}
	}
}

function fixVoiceCollisions(timeBasedLine) {
	for (var s = 0; s < timeBasedLine.length; s++) {
		var timeSlot = timeBasedLine[s]
		// If there is more than one thing happening at the same time,
		// and one of those things is a rest, then:
		// If the rest is in the first element, check to see if the bottom bumps into the top of any of the rest of the elements
		// If the rest is in the last element, check to see if the top bumps into the bottom of any of the rest of the elements.
		// Note: if there are more than two voices the staff will get sloppy, so there is a limit to how much that can be improved, but this should be fine when there are two voices.
		// If there is a collision, move the rest up or down to fix that.
		var keys = Object.keys(timeSlot)
		for (var z = 0; z < keys.length; z++) {
			var slot = timeSlot[keys[z]] // slot is an array of all the things happening at a particular time
			var lastIndex = slot.length - 1
			if (slot.length > 1) {
				var isRealRest = slot[0].abcelem.rest && slot[0].abcelem.rest.type === 'rest' // weed out invisible rests
				var isRealRest2 = slot[lastIndex].abcelem.rest && slot[lastIndex].abcelem.rest.type === 'rest' // weed out invisible rests
				if (isRealRest && !slot[lastIndex].abcelem.rest) {
					// the first voice has a rest and the second doesn't
					var restTop = slot[0].children.find(function (ch) { return ch.name.includes('rest') })
					var otherTop = closeTop(slot[lastIndex])
					if (restTop) {
						var distance1 = restTop.bottom - otherTop
						distance1 -= 2 // give some room between the rest and the note
						if (distance1 < 0 && slot[0].children.length > 0) {
							slot[0].bottom -= distance1
							slot[0].top -= distance1
							slot[0].children[0].bottom -= distance1
							slot[0].children[0].top -= distance1
							slot[0].children[0].pitch -= distance1
						}
					}
				} else if (isRealRest2 && !slot[0].abcelem.rest) {
					// the last voice has a rest and the first doesn't
					var restBottom = slot[lastIndex].children.find(function (ch) { return ch.name.includes('rest') })
					if (restBottom) {
						var distance2 = restBottom.top - closeBottom(slot[0])
						distance2 += 2 // give some room between the rest and the note
						if (distance2 > 0 && slot[lastIndex].children.length > 0) {
							slot[lastIndex].bottom -= distance2
							slot[lastIndex].top -= distance2
							slot[lastIndex].children[0].bottom -= distance2
							slot[lastIndex].children[0].top -= distance2
							slot[lastIndex].children[0].pitch -= distance2
						}
					}
				}
			}
		}
	}
}

function closeTop(absElem) {
	if (absElem.children) {
		var max = -90 // This is clearly way lower than the max calculated below
		for (var i = 0; i < absElem.children.length; i++) {
			var child = absElem.children[i]
			if (child.type !== 'chord')
				max = Math.max(max, child.top)
		}
		if (max > -90)
			return max
	}
	return absElem.top
}

function closeBottom(absElem) {
	if (absElem.children) {
		var min = 90 // This is clearly way higher than the min calculated below
		for (var i = 0; i < absElem.children.length; i++) {
			var child = absElem.children[i]
			if (child.type !== 'lyric')
				min = Math.min(min, child.bottom)
		}
		if (min < 90)
			return min
	}
	return absElem.bottom
}

module.exports = layout;