osmd-extended/demo/index.js

import { OpenSheetMusicDisplay } from '../src/OpenSheetMusicDisplay/OpenSheetMusicDisplay';

/*jslint browser:true */
(function () {
    "use strict";
    var openSheetMusicDisplay;
    var sampleFolder = process.env.STATIC_FILES_SUBFOLDER ? process.env.STATIC_FILES_SUBFOLDER + "/" : "",
        samples = {
            "Beethoven, L.v. - An die ferne Geliebte": "Beethoven_AnDieFerneGeliebte.xml",
            "Clementi, M. - Sonatina Op.36 No.1 Pt.1": "MuzioClementi_SonatinaOpus36No1_Part1.xml",
            "Clementi, M. - Sonatina Op.36 No.1 Pt.2": "MuzioClementi_SonatinaOpus36No1_Part2.xml",
            "Clementi, M. - Sonatina Op.36 No.3 Pt.1": "MuzioClementi_SonatinaOpus36No3_Part1.xml",
            "Clementi, M. - Sonatina Op.36 No.3 Pt.2": "MuzioClementi_SonatinaOpus36No3_Part2.xml",
            "Bach, J.S. - Praeludium in C-Dur BWV846 1": "JohannSebastianBach_PraeludiumInCDur_BWV846_1.xml",
            "Bach, J.S. - Air": "JohannSebastianBach_Air.xml",
            "Gounod, C. - Méditation": "CharlesGounod_Meditation.xml",
            "Haydn, J. - Concertante Cello": "JosephHaydn_ConcertanteCello.xml",
            "Joplin, S. - Elite Syncopations": "ScottJoplin_EliteSyncopations.xml",
            "Joplin, S. - The Entertainer": "ScottJoplin_The_Entertainer.xml",
            "Mozart, W.A. - An Chloe": "Mozart_AnChloe.xml",
            "Mozart, W.A. - Das Veilchen": "Mozart_DasVeilchen.xml",
            "Mozart, W.A. - Clarinet Quintet (Excerpt)": "Mozart_Clarinet_Quintet_Excerpt.mxl",
            "Mozart, W.A. - String Quartet in G, K. 387, 1st Mvmt Excerpt": "Mozart_String_Quartet_in_G_K._387_1st_Mvmnt_excerpt.musicxml",
            "Mozart/Holzer - Land der Berge (national anthem of Austria)": "Land_der_Berge.musicxml",
            "OSMD Function Test - All": "OSMD_function_test_all.xml",
            "OSMD Function Test - Accidentals": "OSMD_function_test_accidentals.musicxml",
            "OSMD Function Test - Autobeam": "OSMD_function_test_autobeam.musicxml",
            "OSMD Function Test - Auto-/Custom-Coloring": "OSMD_function_test_auto-custom-coloring-entchen.musicxml",
            "OSMD Function Test - Bar lines": "OSMD_function_test_bar_lines.musicxml",
            "OSMD Function Test - Color (from XML)": "OSMD_function_test_color.musicxml",
            "OSMD Function Test - Drumset": "OSMD_function_test_drumset.musicxml",
            "OSMD Function Test - Expressions": "OSMD_function_test_expressions.musicxml",
            "OSMD Function Test - Expressions Overlap": "OSMD_function_test_expressions_overlap.musicxml",
            "OSMD Function Test - Grace Notes": "OSMD_function_test_GraceNotes.xml",
            "OSMD Function Test - Invisible Notes": "OSMD_function_test_invisible_notes.musicxml",
            "OSMD Function Test - Selecting Measures To Draw": "OSMD_function_test_measuresToDraw_Beethoven_AnDieFerneGeliebte.xml",
            "OSMD Function Test - Notehead Shapes": "OSMD_function_test_noteheadShapes.musicxml",
            "OSMD Function Test - Ornaments": "OSMD_function_test_Ornaments.xml",
            "OSMD Function Test - Tremolo": "OSMD_Function_Test_Tremolo_2bars.musicxml",
            "Schubert, F. - An Die Musik": "Schubert_An_die_Musik.xml",
            "Actor, L. - Prelude (Large Sample, loading time)": "ActorPreludeSample.xml",
            "Anonymous - Saltarello": "Saltarello.mxl",
            "Debussy, C. - Mandoline": "Debussy_Mandoline.xml",
            "Levasseur, F. - Parlez Mois": "Parlez-moi.mxl",
            "Schumann, R. - Dichterliebe": "Dichterliebe01.xml",
            "Telemann, G.P. - Sonate-Nr.1.1-Dolce": "TelemannWV40.102_Sonate-Nr.1.1-Dolce.xml",
            "Telemann, G.P. - Sonate-Nr.1.2-Allegro": "TelemannWV40.102_Sonate-Nr.1.2-Allegro-F-Dur.xml",
        },

        zoom = 1.0,
        // HTML Elements in the page
        divControls,
        zoomControls,
        header,
        err,
        error_tr,
        canvas,
        selectSample,
        selectBounding,
        skylineDebug,
        bottomlineDebug,
        zoomIn,
        zoomOut,
        zoomDiv,
        custom,
        nextCursorBtn,
        resetCursorBtn,
        followCursorCheckbox,
        showCursorBtn,
        hideCursorBtn,
        backendSelect,
        backendSelectDiv,
        debugReRenderBtn,
        debugClearBtn,
        selectPageSize,
        printPdfBtn;
    
    // manage option setting and resetting for specific samples, e.g. in the autobeam sample autobeam is set to true, otherwise reset to previous state
    // TODO design a more elegant option state saving & restoring system, though that requires saving the options state in OSMD
    var minMeasureToDrawStashed = 1;
    var maxMeasureToDrawStashed = Number.MAX_SAFE_INTEGER;
    var measureToDrawRangeNeedsReset = false;
    var autobeamOptionNeedsReset = false;
    var autobeamOptionStashedValue = false;
    var autoCustomColoringOptionNeedsReset = false;
    var autoCustomColoringOptionStashedValue = false;
    var drawPartNamesOptionStashedValue = true;
    var drawPartAbbreviationsStashedValue = true;
    var drawPartNamesOptionNeedsReset = false;

    var showControls = true;
    var showZoomControl = true;
    var showHeader = true;
    var showDebugControls = false;

    if (process.env.OSMD_DEMO_TITLE) {
        document.title = process.env.OSMD_DEMO_TITLE;
    }

    // Initialization code
    function init() {
        var name, option;

        // Handle window parameter
        var paramEmbedded = findGetParameter('embedded');
        var paramShowControls = findGetParameter('showControls');
        var paramShowZoomControl = findGetParameter('showZoomControl');
        var paramShowHeader = findGetParameter('showHeader');
        var paramZoom = findGetParameter('zoom');
        var paramOverflow = findGetParameter('overflow');
        var paramOpenUrl = findGetParameter('openUrl');
        var paramDebugControls = findGetParameter('debugControls');

        var paramCompactMode = findGetParameter('compactMode');
        var paramMeasureRangeStart = findGetParameter('measureRangeStart');
        var paramMeasureRangeEnd = findGetParameter('measureRangeEnd');
        var paramPageFormat = findGetParameter('pageFormat');

        showHeader = (paramShowHeader !== '0');
        if (paramEmbedded !== undefined) {
            showControls = (paramShowControls !== '0');
            showZoomControl = (paramShowZoomControl !== '0');
        }

        if (paramZoom !== undefined) {
            if (paramZoom > 0.1 && paramZoom < 5.0) {
                zoom = paramZoom;
                console.log('Set zoom to ' + zoom);
            }
        }
        if (paramOverflow !== undefined && typeof paramOverflow === 'string') {
            if (paramOverflow === 'hidden' || paramOverflow === 'auto' || paramOverflow === 'scroll' || paramOverflow === 'visible') {
                document.body.style.overflow = paramOverflow;
            }
        }
        
        var compactMode = paramCompactMode && paramCompactMode !== '0';
        var measureRangeStart = paramMeasureRangeStart ? Number.parseInt(paramMeasureRangeStart) : 0;
        var measureRangeEnd = paramMeasureRangeEnd ? Number.parseInt(paramMeasureRangeEnd) : Number.MAX_SAFE_INTEGER;
        if (measureRangeStart && measureRangeEnd && measureRangeEnd < measureRangeStart) {
            console.log("[OSMD] warning: measure range end parameter should not be smaller than measure range start. We've set start measure = end measure now.")
            measureRangeStart = measureRangeEnd;
        }
        var pageFormat = paramPageFormat ? paramPageFormat : "Endless";

        divControls = document.getElementById('divControls');
        zoomControls = document.getElementById('zoomControls');
        header = document.getElementById('header');
        err = document.getElementById("error-td");
        error_tr = document.getElementById("error-tr");
        zoomDiv = document.getElementById("zoom-str");
        custom = document.createElement("option");
        selectSample = document.getElementById("selectSample");
        selectBounding = document.getElementById("selectBounding");
        skylineDebug = document.getElementById("skylineDebug");
        bottomlineDebug = document.getElementById("bottomlineDebug");
        zoomIn = document.getElementById("zoom-in-btn");
        zoomOut = document.getElementById("zoom-out-btn");
        canvas = document.createElement("div");
        //canvas.style.overflowX = 'auto'; // enable horizontal scrolling
        nextCursorBtn = document.getElementById("next-cursor-btn");
        resetCursorBtn = document.getElementById("reset-cursor-btn");
        followCursorCheckbox = document.getElementById("follow-cursor-checkbox");
        showCursorBtn = document.getElementById("show-cursor-btn");
        hideCursorBtn = document.getElementById("hide-cursor-btn");
        backendSelect = document.getElementById("backend-select");
        backendSelectDiv = document.getElementById("backend-select-div");
        debugReRenderBtn = document.getElementById("debug-re-render-btn");
        debugClearBtn = document.getElementById("debug-clear-btn");
        selectPageSize = document.getElementById("selectPageSize");
        printPdfBtn = document.getElementById("print-pdf-btn");

        //var defaultDisplayVisibleValue = "block"; // TODO in some browsers flow could be the better/default value
        var defaultVisibilityValue = "visible";
        var devDemoRunning = process.env.OSMD_DEBUG_CONTROLS;
        showDebugControls = paramDebugControls === '1' || (devDemoRunning && paramDebugControls !== '0')
        if (showDebugControls) {
            var elementsToEnable = [
                selectSample, selectBounding, selectPageSize, backendSelect, backendSelectDiv, divControls
            ];
            for (var i=0; i<elementsToEnable.length; i++) {
                if (elementsToEnable[i]) { // make sure this element is not null/exists in the index.html, e.g. github.io demo has different index.html
                    if (elementsToEnable[i].style) {
                        elementsToEnable[i].style.visibility = defaultVisibilityValue;
                    }
                }
            }
        } else {
            if (divControls) {
                divControls.style.display = "none";
            }
        }

        if (!showControls) {
            if (divControls) {
                divControls.style.display = 'none';
            }
        }
        if (!showHeader) {
            if (header) {
                header.style.display = 'none';
            }
        }
        // Hide error
        error();

        if (!showControls && showZoomControl) {
            const zoomControlsButtons = document.getElementById('zoomControlsButtons');
            const zoomControlsString = document.getElementById('zoom-str');
            const optionalControls = document.getElementById('optionalControls');
            if (optionalControls) {
                optionalControls.appendChild(zoomControlsButtons);
                optionalControls.appendChild(zoomControlsString);
                optionalControls.style.position = 'absolute';
                optionalControls.style.zIndex = '10';
                optionalControls.style.right = '10px';
                optionalControls.style.padding = '10px';
            }

            if (zoomControlsString) {
                zoomControlsString.style.display = 'inline';
                zoomControlsString.style.padding = '10px';
            }
        }

        // Create select
        for (name in samples) {
            if (samples.hasOwnProperty(name)) {
                option = document.createElement("option");
                option.value = samples[name];
                option.textContent = name;
            }
            if (selectSample) {
                selectSample.appendChild(option);
            }
        }
        if (selectSample) {
            selectSample.onchange = selectSampleOnChange;
        }
        if (selectBounding) {
            selectBounding.onchange = selectBoundingOnChange;
        }

        if (selectPageSize) {
            selectPageSize.onchange = function (evt) {
                var value = evt.target.value;
                openSheetMusicDisplay.setPageFormat(value);
                openSheetMusicDisplay.render();
            };
        }

        if (printPdfBtn) {
            printPdfBtn.onclick = function () {
                openSheetMusicDisplay.createPdf();
            }
        }

        // Pre-select default music piece

        custom.appendChild(document.createTextNode("Custom"));

        // Create zoom controls
        if (zoomIn) {
            zoomIn.onclick = function () {
                zoom *= 1.2;
                scale();
            };
        }
        if (zoomOut) {
            zoomOut.onclick = function () {
                zoom /= 1.2;
                scale();
            };
        }

        if (skylineDebug) {
            skylineDebug.onclick = function () {
                openSheetMusicDisplay.DrawSkyLine = !openSheetMusicDisplay.DrawSkyLine;
            }
        }

        if (bottomlineDebug) {
            bottomlineDebug.onclick = function () {
                openSheetMusicDisplay.DrawBottomLine = !openSheetMusicDisplay.DrawBottomLine;
            }
        }

        if (debugReRenderBtn) {
            debugReRenderBtn.onclick = function () {
                rerender();
            }
        }

        if (debugClearBtn) {
            debugClearBtn.onclick = function () {
                openSheetMusicDisplay.clear();
            }
        }

        // Create OSMD object and canvas
        openSheetMusicDisplay = new OpenSheetMusicDisplay(canvas, {
            autoResize: true,
            backend: backendSelect.value,
            //backend: "canvas",
            disableCursor: false,
            drawingParameters: compactMode ? "compact" : "default", // try compact (instead of default)
            drawPartNames: true, // try false
            // drawTitle: false,
            // drawSubtitle: false,
            drawFingerings: true,
            fingeringPosition: "left", // left is default. try right. experimental: auto, above, below.
            // fingeringInsideStafflines: "true", // default: false. true draws fingerings directly above/below notes
            setWantedStemDirectionByXml: true, // try false, which was previously the default behavior
            // drawUpToMeasureNumber: 3, // draws only up to measure 3, meaning it draws measure 1 to 3 of the piece.
            drawFromMeasureNumber : measureRangeStart,
            drawUpToMeasureNumber : measureRangeEnd,

            //drawMeasureNumbers: false, // disable drawing measure numbers
            //measureNumberInterval: 4, // draw measure numbers only every 4 bars (and at the beginning of a new system)

            // coloring options
            coloringEnabled: true,
            // defaultColorNotehead: "#CC0055", // try setting a default color. default is black (undefined)
            // defaultColorStem: "#BB0099",

            autoBeam: false, // try true, OSMD Function Test AutoBeam sample
            autoBeamOptions: {
                beam_rests: false,
                beam_middle_rests_only: false,
                //groups: [[3,4], [1,1]],
                maintain_stem_directions: false
            },

            pageFormat: pageFormat

            // tupletsBracketed: true, // creates brackets for all tuplets except triplets, even when not set by xml
            // tripletsBracketed: true,
            // tupletsRatioed: true, // unconventional; renders ratios for tuplets (3:2 instead of 3 for triplets)
        });
        openSheetMusicDisplay.setLogLevel('info'); // set this to 'debug' if you want to see more detailed control flow information in console
        document.body.appendChild(canvas);

        window.addEventListener("keydown", function (e) {
            var event = window.event ? window.event : e;
            if (event.keyCode === 39) {
                openSheetMusicDisplay.cursor.next();
            }
        });
        nextCursorBtn.addEventListener("click", function () {
            openSheetMusicDisplay.cursor.next();
        });
        resetCursorBtn.addEventListener("click", function () {
            openSheetMusicDisplay.cursor.reset();
        });
        if (followCursorCheckbox) {
            followCursorCheckbox.onclick = function () {
                openSheetMusicDisplay.FollowCursor = !openSheetMusicDisplay.FollowCursor;
            }
        }
        hideCursorBtn.addEventListener("click", function () {
            if (openSheetMusicDisplay.cursor) {
                openSheetMusicDisplay.cursor.hide();
            } else {
                console.info("Can't hide cursor, as it was disabled (e.g. by drawingParameters).");
            }
        });
        showCursorBtn.addEventListener("click", function () {
            if (openSheetMusicDisplay.cursor) {
                openSheetMusicDisplay.cursor.show();
            } else {
                console.info("Can't show cursor, as it was disabled (e.g. by drawingParameters).");
            }
        });

        backendSelect.addEventListener("change", function (e) {
            var value = e.target.value;
            var createNewOsmd = true;

            if (createNewOsmd) {
                // clears the canvas element
                canvas.innerHTML = "";
                openSheetMusicDisplay = new OpenSheetMusicDisplay(canvas, { backend: value });
                openSheetMusicDisplay.setLogLevel('info'); // set this to 'debug' if you want to get more detailed control flow information
            } else {
                // alternative, doesn't work yet, see setOptions():
                openSheetMusicDisplay.setOptions({ backend: value });
            }
            console.log("[OSMD] selectSampleOnChange addEventListener change");
            // selectSampleOnChange();
        });

        if (paramOpenUrl !== undefined) {
            if (openSheetMusicDisplay.getLogLevel() < 2) { // debug or trace
                console.log("[OSMD] selectSampleOnChange with " + paramOpenUrl);
            }
            selectSampleOnChange(paramOpenUrl);
        } else {
            if (openSheetMusicDisplay.getLogLevel() < 2) { // debug or trace
                console.log("[OSMD] selectSampleOnChange without param");
            }
            selectSampleOnChange();
        }
    }

    function findGetParameter(parameterName) {
        let result = undefined;
        let tmp = [];
        location.search
            .substr(1)
            .split('&')
            .forEach(function (item) {
                tmp = item.split('=');
                if (tmp[0] === parameterName) {
                    result = decodeURIComponent(tmp[1]);
                    //console.log('Found param:' + parameterName + ' = ' + result);
                }
            });
        return result;
    }

    function selectBoundingOnChange(evt) {
        var value = evt.target.value;
        openSheetMusicDisplay.DrawBoundingBox = value;
    }

    function selectSampleOnChange(str) {
        error();
        disable();
        var isCustom = typeof str === "string";
        if (!isCustom) {
            if (selectSample) {
                str = sampleFolder + selectSample.value;
            } else {
                if (samples && samples.length > 0) {
                    str = sampleFolder + samples[0];
                } else {
                    return; // no sample to load right now
                }
            }
        }
        // zoom = 1.0;

        setSampleSpecificOptions(str, isCustom);

        openSheetMusicDisplay.load(str).then(
            function () {
                // This gives you access to the osmd object in the console. Do not use in productive code
                window.osmd = openSheetMusicDisplay;
                openSheetMusicDisplay.zoom = zoom;
                return openSheetMusicDisplay.render();
            },
            function (e) {
                errorLoadingOrRenderingSheet(e, "rendering");
            }
        ).then(
            function () {
                return onLoadingEnd(isCustom);
            }, function (e) {
                errorLoadingOrRenderingSheet(e, "loading");
                onLoadingEnd(isCustom);
            }
        );
    }

    function setSampleSpecificOptions(str, isCustom) {
        if (!isCustom && str.includes("measuresToDraw")) { // set options for measuresToDraw sample
            // stash previously set range of measures to draw
            if (!measureToDrawRangeNeedsReset) { // only stash once, when measuresToDraw called multiple times in a row
                minMeasureToDrawStashed = openSheetMusicDisplay.EngravingRules.MinMeasureToDrawIndex + 1;
                maxMeasureToDrawStashed = openSheetMusicDisplay.EngravingRules.MaxMeasureToDrawIndex + 1;
            }
            measureToDrawRangeNeedsReset = true;

            // for debugging: draw from a random range of measures
            let minMeasureToDraw = Math.ceil(Math.random() * 15); // measures start at 1 (measureIndex = measure number - 1 elsewhere)
            let maxMeasureToDraw = Math.ceil(Math.random() * 15);
            if (minMeasureToDraw > maxMeasureToDraw) {
                minMeasureToDraw = maxMeasureToDraw;
                let a = minMeasureToDraw;
                maxMeasureToDraw = a;
            }
            //minMeasureToDraw = 1; // set your custom indexes here. Drawing only one measure can be a special case
            //maxMeasureToDraw = 1;
            console.log("drawing measures in the range: [" + minMeasureToDraw + "," + maxMeasureToDraw + "]");
            openSheetMusicDisplay.setOptions({
                drawFromMeasureNumber: minMeasureToDraw,
                drawUpToMeasureNumber: maxMeasureToDraw
            });
        } else if (measureToDrawRangeNeedsReset) { // reset for other samples
            openSheetMusicDisplay.setOptions({
                drawFromMeasureNumber: minMeasureToDrawStashed,
                drawUpToMeasureNumber: maxMeasureToDrawStashed
            });
            measureToDrawRangeNeedsReset = false;
        }

        // Enable Boomwhacker-like coloring for OSMD Function Test - Auto-Coloring (Boomwhacker-like, custom color set)
        if (!isCustom && str.includes("auto-custom-coloring")) { // set options for auto coloring sample
            autoCustomColoringOptionNeedsReset = true;
            //openSheetMusicDisplay.setOptions({coloringMode: 1}); // Auto-Coloring with pre-defined colors
            openSheetMusicDisplay.setOptions({
                coloringMode: 2, // custom coloring set. 0 would be XML, 1 autocoloring
                coloringSetCustom: ["#d82c6b", "#F89D15", "#FFE21A", "#4dbd5c", "#009D96", "#43469d", "#76429c", "#ff0000"],
                // last color value of coloringSetCustom is for rest notes

                colorStemsLikeNoteheads: true
            });
        } else if (autoCustomColoringOptionNeedsReset) {
            openSheetMusicDisplay.setOptions({ // set default values. better would be to restore to stashed values, but unnecessarily complex for demo
                coloringMode: 0,
                colorStemsLikeNoteheads: false,
                coloringSetCustom: null
            });
            autoCustomColoringOptionNeedsReset = false;
        }
        if (!isCustom && str.includes("autobeam")) {
            autobeamOptionStashedValue = openSheetMusicDisplay.EngravingRules.AutoBeamNotes; // stash previously set value, to restore later
            autobeamOptionNeedsReset = true;
            openSheetMusicDisplay.setOptions({ autoBeam: true });
        } else if (autobeamOptionNeedsReset) {
            openSheetMusicDisplay.setOptions({ autoBeam: autobeamOptionStashedValue });
            autobeamOptionNeedsReset = false;
        }
        if (!isCustom && str.includes("Schubert_An_die_Musik")) { // TODO weird layout bug here with part names. but shouldn't be in score anyways
            drawPartNamesOptionStashedValue = openSheetMusicDisplay.EngravingRules.RenderPartNames;
            drawPartAbbreviationsStashedValue = openSheetMusicDisplay.EngravingRules.RenderPartAbbreviations;
            openSheetMusicDisplay.setOptions({ drawPartNames: false, drawPartAbbreviations: false }); // TODO sets osmd.drawingParameters.DrawPartNames! also check EngravingRules.RenderPartAbbreviations, was false
            drawPartNamesOptionNeedsReset = true;
        } else if (drawPartNamesOptionNeedsReset) {
            openSheetMusicDisplay.setOptions({ drawPartNames: drawPartNamesOptionStashedValue, drawPartAbbreviations: drawPartAbbreviationsStashedValue });
            drawPartNamesOptionNeedsReset = false;
        }
    }

    function errorLoadingOrRenderingSheet(e, loadingOrRenderingString) {
        var errorString = "Error " + loadingOrRenderingString + " sheet: " + e;
        // if (process.env.DEBUG) { // people may not set a debug environment variable for the demo.
        // Always giving a StackTrace might give us more and better error reports.
        // TODO for a release, StackTrace control could be reenabled
        errorString += "\n" + "StackTrace: \n" + e.stack;
        // }
        console.warn(errorString);
    }

    function onLoadingEnd(isCustom) {
        // Remove option from select
        if (!isCustom && custom.parentElement === selectSample) {
            selectSample.removeChild(custom);
        }
        // Enable controls again
        enable();
    }

    function logCanvasSize() {
        zoomDiv.innerHTML = Math.floor(zoom * 100.0) + "%";
    }

    function scale() {
        disable();
        window.setTimeout(function () {
            openSheetMusicDisplay.zoom = zoom;
            openSheetMusicDisplay.render();
            enable();
        }, 0);
    }

    function rerender() {
        disable();
        window.setTimeout(function () {
            if (openSheetMusicDisplay.IsReadyToRender()) {
                openSheetMusicDisplay.render();
            } else {
                console.log("[OSMD demo] Looses context!"); // TODO not sure that this message is reasonable, renders fine anyways. maybe vexflow context lost?
                selectSampleOnChange(); // reload sample e.g. after osmd.clear()
            }
            enable();
        }, 0);
    }

    function error(errString) {
        if (!errString) {
            error_tr.style.display = "none";
        } else {
            err.textContent = errString;
            error_tr.style.display = "";
            canvas.width = canvas.height = 0;
            enable();
        }
    }

    // Enable/Disable Controls
    function disable() {
        document.body.style.opacity = 0.3;
        setDisabledForControls("disabled");
    }

    function enable() {
        document.body.style.opacity = 1;
        setDisabledForControls("");
        logCanvasSize();
    }

    function setDisabledForControls(disabledValue) {
        if (selectSample) {
            selectSample.disabled = disabledValue;
        }
        if (zoomIn) {
            zoomIn.disabled = disabledValue;
        }
        if (zoomOut) {
            zoomOut.disabled = disabledValue;
        }
    }

    // Register events: load, drag&drop
    window.addEventListener("load", function () {
        init();
    });
    window.addEventListener("dragenter", function (event) {
        event.preventDefault();
        disable();
    });
    window.addEventListener("dragover", function (event) {
        event.preventDefault();
    });
    window.addEventListener("dragleave", function (event) {
        enable();
    });
    window.addEventListener("drop", function (event) {
        event.preventDefault();
        if (!event.dataTransfer || !event.dataTransfer.files || event.dataTransfer.files.length === 0) {
            return;
        }
        // Add "Custom..." score
        selectSample.appendChild(custom);
        custom.selected = "selected";
        // Read dragged file
        var reader = new FileReader();
        reader.onload = function (res) {
            selectSampleOnChange(res.target.result);
        };
        var filename = event.dataTransfer.files[0].name;
        if (filename.toLowerCase().indexOf(".xml") > 0
            || filename.toLowerCase().indexOf(".musicxml") > 0) {
            reader.readAsText(event.dataTransfer.files[0]);
        } else if (event.dataTransfer.files[0].name.toLowerCase().indexOf(".mxl") > 0) {
            reader.readAsBinaryString(event.dataTransfer.files[0]);
        }
        else {
            alert("No vaild .xml/.mxl/.musicxml file!");
        }
    });
}());