/*
 * Copyright (c) 2009-2011 Madhav Vaidyanathan
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2.
 *
 *  This program 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 General Public License for more details.
 */

package com.jinmingyunle.midiplaylib.midifile;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

import java.util.ArrayList;


/** @class Piano
 *
 * The Piano Control is the panel at the top that displays the
 * piano, and highlights the piano notes during playback.
 * The main methods are:
 *
 * SetMidiFile() - Set the Midi file to use for shading.  The Midi file
 *                 is needed to determine which notes to shade.
 *
 * ShadeNotes() - Shade notes on the piano that occur at a given pulse time.
 * 自定义钢琴界面
 */
public class Piano extends SurfaceView implements SurfaceHolder.Callback {
    public static final int KeysPerOctave = 7;  //八度音阶
    public static final int MaxOctave = 6;

    private static int WhiteKeyWidth;  /** 单个白键的宽度 */
    private static int WhiteKeyHeight; /** Height of a single white key */
    private static int BlackKeyWidth;  /** Width of a single black key */
    private static int BlackKeyHeight; /** Height of a single black key */
    private static int margin;         /** The top/left margin to the piano (0) */
    private static int BlackBorder;    /** The width of the black border around the keys */

    private static int[] blackKeyOffsets;   /** The x pixles of the black keys  黑键的X轴像素*/

    /* The colors for drawing black/gray lines */
    private int gray1, gray2, gray3, shade1, shade2;

    private boolean useTwoColors;         /** 如果正确，使用两种颜色来突出 */
    private ArrayList<MidiNote> notes;    /** The Midi notes 音符 for shading 阴影 */
    private int maxShadeDuration;         /** 我们给音符着色的最长时间 */
    private int showNoteLetters;          /** Display the letter for each piano note 显示每个钢琴的音符信息 */
    private Paint paint;                  /** The paint options for drawing */
    private boolean surfaceReady;         /** True if we can draw on the surface */
    private Bitmap  bufferBitmap;         /** The bitmap for double-buffering */
    private Canvas  bufferCanvas;         /** The canvas for double-buffering */
    private MidiPlayer player;            /** Used to pause the player */

    /** Create a new Piano. */
    public Piano(Context context) {
        super(context);
        WhiteKeyWidth = 0;
        blackKeyOffsets = null;
        paint = new Paint();
        //抗锯齿
        paint.setAntiAlias(false);
        paint.setTextSize(9.0f);
        gray1 = Color.rgb(16, 16, 16);
        gray2 = Color.rgb(90, 90, 90);
        gray3 = Color.rgb(200, 200, 200);
        shade1 = Color.rgb(210, 205, 220);
        shade2 = Color.rgb(150, 200, 220);
        showNoteLetters = MidiOptions.NoteNameNone;
        SurfaceHolder holder = getHolder();
        holder.addCallback(this);
    }
    
    public Piano(Context context, AttributeSet attrs) {
        super(context, attrs);
        WhiteKeyWidth = 0;
        blackKeyOffsets = null;
        paint = new Paint();
        paint.setTextSize(10.0f);
        paint.setAntiAlias(false);
        gray1 = Color.rgb(16, 16, 16);
        gray2 = Color.rgb(90, 90, 90);
        gray3 = Color.rgb(200, 200, 200);
        shade1 = Color.rgb(210, 205, 220);
        shade2 = Color.rgb(150, 200, 220);
        showNoteLetters = MidiOptions.NoteNameNone;

        SurfaceHolder holder = getHolder();
        holder.addCallback(this);
    }

    /** Get the preferreed width/height, given the screen width/height */
    public static Point getPreferredSize(int screenwidth, int screenheight) {
        int keywidth = (int)(screenwidth / (2.0 + KeysPerOctave * MaxOctave));
        if (keywidth % 2 != 0) {
            keywidth--;
        }
        //int margin = keywidth/2;
        int margin = 0;
        int border = keywidth/2;

        Point result = new Point();
        result.x = margin*2 + border*2 + keywidth * KeysPerOctave * MaxOctave;
        result.y = margin*2 + border*3 + WhiteKeyHeight;
        return result;
    }

    /** Set the measured width and height */
    @Override
    protected void onMeasure(int widthspec, int heightspec) {
        int screenwidth = MeasureSpec.getSize(widthspec);
        int screenheight = MeasureSpec.getSize(heightspec);
        WhiteKeyWidth = (int)(screenwidth / (2.0 + KeysPerOctave * MaxOctave));
        if (WhiteKeyWidth % 2 != 0)
            WhiteKeyWidth--;

        // margin = WhiteKeyWidth/2;
        margin = 0;
        BlackBorder = WhiteKeyWidth/2;
        WhiteKeyHeight = WhiteKeyWidth * 5;
        BlackKeyWidth = WhiteKeyWidth / 2;
        BlackKeyHeight = WhiteKeyHeight * 5 / 9; 

        blackKeyOffsets = new int[] { 
            WhiteKeyWidth - BlackKeyWidth/2 - 1,
            WhiteKeyWidth + BlackKeyWidth/2 - 1,
            2*WhiteKeyWidth - BlackKeyWidth/2,
            2*WhiteKeyWidth + BlackKeyWidth/2,
            4*WhiteKeyWidth - BlackKeyWidth/2 - 1,
            4*WhiteKeyWidth + BlackKeyWidth/2 - 1,
            5*WhiteKeyWidth - BlackKeyWidth/2,
            5*WhiteKeyWidth + BlackKeyWidth/2,
            6*WhiteKeyWidth - BlackKeyWidth/2,
            6*WhiteKeyWidth + BlackKeyWidth/2
        };

        int width = margin*2 + BlackBorder*2 + WhiteKeyWidth * KeysPerOctave * MaxOctave;
        int height = margin*2 + BlackBorder*3 + WhiteKeyHeight;
        setMeasuredDimension(width, height);
        bufferBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        bufferCanvas = new Canvas(bufferBitmap);
        this.invalidate();
        draw();
    }


    @Override
    protected void onSizeChanged(int newwidth, int newheight, int oldwidth, int oldheight) {
        super.onSizeChanged(newwidth, newheight, oldwidth, oldheight);
    }

    /** Set the MidiFile to use.
     *  Save the list of midi notes. Each midi note includes the note Number
     *  and StartTime (in pulses), so we know which notes to shade given the
     *  current pulse time.
     */
    public void SetMidiFile(MidiFile midifile, MidiOptions options, 
                            MidiPlayer player) {
        if (midifile == null) {
            notes = null;
            useTwoColors = false;
            return;
        }
        this.player = player;
        ArrayList<MidiTrack> tracks = midifile.ChangeMidiNotes(options);
        MidiTrack track = MidiFile.CombineToSingleTrack(tracks);
        notes = track.getNotes();

        maxShadeDuration = midifile.getTime().getQuarter() * 2;

        /* We want to know which track the note came from.
         * Use the 'channel' field to store the track.
         */
        for (int tracknum = 0; tracknum < tracks.size(); tracknum++) {
            for (MidiNote note : tracks.get(tracknum).getNotes()) {
                note.setChannel(tracknum);
            }
        }

        /* When we have exactly two tracks, we assume this is a piano song,
         * and we use different colors for highlighting the left hand and
         * right hand notes.
         */
        useTwoColors = false;
        if (tracks.size() == 2) {
            useTwoColors = true;
        }

        showNoteLetters = options.showNoteLetters;
        this.invalidate();
    }

    /** Set the colors to use for shading */
    public void SetShadeColors(int c1, int c2) {
        shade1 = c1;
        shade2 = c2;
    }

    /** Draw the outline of a 12-note (7 white note) piano octave */
    private void DrawOctaveOutline(Canvas canvas) {
        int right = WhiteKeyWidth * KeysPerOctave;

        // Draw the bounding rectangle, from C to B
        paint.setColor(gray1);
        canvas.drawLine(0, 0, 0, WhiteKeyHeight, paint);
        canvas.drawLine(right, 0, right, WhiteKeyHeight, paint);
        // canvas.drawLine(0, 0, right, 0, paint);
        canvas.drawLine(0, WhiteKeyHeight, right, WhiteKeyHeight, paint);
        paint.setColor(gray3);
        canvas.drawLine(right-1, 0, right-1, WhiteKeyHeight, paint);
        canvas.drawLine(1, 0, 1, WhiteKeyHeight, paint);

        // Draw the line between E and F
        paint.setColor(gray1);
        canvas.drawLine(3*WhiteKeyWidth, 0, 3*WhiteKeyWidth, WhiteKeyHeight, paint);
        paint.setColor(gray3);
        canvas.drawLine(3*WhiteKeyWidth - 1, 0, 3*WhiteKeyWidth - 1, WhiteKeyHeight, paint);
        canvas.drawLine(3*WhiteKeyWidth + 1, 0, 3*WhiteKeyWidth + 1, WhiteKeyHeight, paint);

        // Draw the sides/bottom of the black keys
        for (int i =0; i < 10; i += 2) {
            int x1 = blackKeyOffsets[i];
            int x2 = blackKeyOffsets[i+1];

            paint.setColor(gray1);
            canvas.drawLine(x1, 0, x1, BlackKeyHeight, paint);
            canvas.drawLine(x2, 0, x2, BlackKeyHeight, paint);
            canvas.drawLine(x1, BlackKeyHeight, x2, BlackKeyHeight, paint);
            paint.setColor(gray2);
            canvas.drawLine(x1-1, 0, x1-1, BlackKeyHeight+1, paint);
            canvas.drawLine(x2+1, 0, x2+1, BlackKeyHeight+1, paint);
            canvas.drawLine(x1-1, BlackKeyHeight+1, x2+1, BlackKeyHeight+1, paint);
            paint.setColor(gray3);
            canvas.drawLine(x1-2, 0, x1-2, BlackKeyHeight+2, paint);
            canvas.drawLine(x2+2, 0, x2+2, BlackKeyHeight+2, paint);
            canvas.drawLine(x1-2, BlackKeyHeight+2, x2+2, BlackKeyHeight+2, paint);
        }

        // Draw the bottom-half of the white keys
        for (int i = 1; i < KeysPerOctave; i++) {
            if (i == 3) {
                continue;  // we draw the line between E and F above
            }
            paint.setColor(gray1);
            canvas.drawLine(i*WhiteKeyWidth, BlackKeyHeight, 
                            i*WhiteKeyWidth, WhiteKeyHeight, paint);
            paint.setColor(gray2);
            canvas.drawLine(i*WhiteKeyWidth - 1, BlackKeyHeight+1, 
                            i*WhiteKeyWidth - 1, WhiteKeyHeight, paint);
            paint.setColor(gray3);
            canvas.drawLine(i*WhiteKeyWidth + 1, BlackKeyHeight+1, 
                            i*WhiteKeyWidth + 1, WhiteKeyHeight, paint);
        }

    }

    /** Draw an outline of the piano for 6 octaves */
    private void DrawOutline(Canvas canvas) {
        for (int octave = 0; octave < MaxOctave; octave++) {
            canvas.translate(octave * WhiteKeyWidth * KeysPerOctave, 0);
            DrawOctaveOutline(canvas);
            canvas.translate(-(octave * WhiteKeyWidth * KeysPerOctave), 0);
        }
    }
 
    /* Draw the Black keys */
    private void DrawBlackKeys(Canvas canvas) {
        paint.setStyle(Paint.Style.FILL); 
        for (int octave = 0; octave < MaxOctave; octave++) {
            canvas.translate(octave * WhiteKeyWidth * KeysPerOctave, 0);
            for (int i = 0; i < 10; i += 2) {
                int x1 = blackKeyOffsets[i];
                int x2 = blackKeyOffsets[i+1];
                paint.setColor(gray1);
                canvas.drawRect(x1, 0, x1 + BlackKeyWidth, BlackKeyHeight, paint);
                paint.setColor(gray2);
                canvas.drawRect(x1+1, BlackKeyHeight - BlackKeyHeight/8, 
                                x1+1 + BlackKeyWidth-2, 
                                BlackKeyHeight - BlackKeyHeight/8 + BlackKeyHeight/8, 
                                paint);
            }
            canvas.translate(-(octave * WhiteKeyWidth * KeysPerOctave), 0);
        }
        paint.setStyle(Paint.Style.STROKE); 
    }

    /* Draw the black border area surrounding the piano keys.
     * Also, draw gray outlines at the bottom of the white keys.
     */
    private void DrawBlackBorder(Canvas canvas) {
        int PianoWidth = WhiteKeyWidth * KeysPerOctave * MaxOctave;
        paint.setStyle(Paint.Style.FILL);
        paint.setColor(gray1);
        canvas.drawRect(margin, margin, margin + PianoWidth + BlackBorder*2, 
                        margin + BlackBorder-2, paint);
        canvas.drawRect(margin, margin, margin + BlackBorder, 
                        margin + WhiteKeyHeight + BlackBorder * 3, paint);
        canvas.drawRect(margin, margin + BlackBorder + WhiteKeyHeight, 
                        margin + BlackBorder*2 + PianoWidth, 
                        margin + BlackBorder + WhiteKeyHeight + BlackBorder*2, paint);
        canvas.drawRect(margin + BlackBorder + PianoWidth, margin, 
                        margin + BlackBorder + PianoWidth + BlackBorder, 
                        margin + WhiteKeyHeight + BlackBorder*3, paint);

        paint.setColor(gray2);
        canvas.drawLine(margin + BlackBorder, margin + BlackBorder -1, 
                        margin + BlackBorder +  PianoWidth, 
                        margin + BlackBorder -1, paint);
        
        canvas.translate(margin + BlackBorder, margin + BlackBorder);

        // Draw the gray bottoms of the white keys  
        for (int i = 0; i < KeysPerOctave * MaxOctave; i++) {
            canvas.drawRect(i*WhiteKeyWidth+1, WhiteKeyHeight+2, 
                            i*WhiteKeyWidth+1 + WhiteKeyWidth-2, 
                            WhiteKeyHeight+2 + BlackBorder/2, paint);
        }
        canvas.translate(-(margin + BlackBorder), -(margin + BlackBorder));
    }

    /** Draw the note letters (A, A#, Bb, etc) underneath each white note */
    private void DrawNoteLetters(Canvas canvas) {
        String[] letters = { "C", "D", "E", "F", "G", "A", "B" };
        String[] numbers = { "1", "3", "5", "6", "8", "10", "12" };
        String[] names;
        if (showNoteLetters == MidiOptions.NoteNameLetter) {
            names = letters;
        }
        else if (showNoteLetters == MidiOptions.NoteNameFixedNumber) {
            names = numbers;
        }
        else {
            return;
        }
        canvas.translate(margin + BlackBorder, margin + BlackBorder);
        paint.setColor(Color.WHITE);
        for (int octave = 0; octave < MaxOctave; octave++) {
            for (int i = 0; i < KeysPerOctave; i++) {
                canvas.drawText(names[i], 
                                (octave*KeysPerOctave + i) * WhiteKeyWidth + WhiteKeyWidth/3,
                                WhiteKeyHeight + BlackBorder + 4, paint);
            }
        }
        canvas.translate(-(margin + BlackBorder), -(margin + BlackBorder));
        paint.setColor(Color.BLACK);
    }


    /** Obtain the drawing canvas and call onDraw() */
    void draw() {
        if (!surfaceReady) {
            return;
        }
        SurfaceHolder holder = getHolder();
        Canvas canvas = holder.lockCanvas();
        if (canvas == null) {
            return;
        }
        onDraw(canvas);
        holder.unlockCanvasAndPost(canvas);
    }

    /** Draw the Piano. */
    @Override
    protected void onDraw(Canvas canvas) {
        if (!surfaceReady || bufferBitmap == null) {
            return;
        }
        if (WhiteKeyWidth == 0) {
            return;
        }

        paint.setAntiAlias(false);
        bufferCanvas.translate(margin + BlackBorder, margin + BlackBorder);
        paint.setStyle(Paint.Style.FILL);
        paint.setColor(Color.WHITE);
        bufferCanvas.drawRect(0, 0, 0 + WhiteKeyWidth * KeysPerOctave * MaxOctave, 
                        WhiteKeyHeight, paint);
        paint.setStyle(Paint.Style.STROKE);
        paint.setColor(gray1);
        DrawBlackKeys(bufferCanvas);
        DrawOutline(bufferCanvas);
        bufferCanvas.translate(-(margin + BlackBorder), -(margin + BlackBorder));
        DrawBlackBorder(bufferCanvas);
        canvas.drawBitmap(bufferBitmap, 0, 0, paint);
        if (showNoteLetters != MidiOptions.NoteNameNone) {
            DrawNoteLetters(canvas);
        }
    }

    /* Shade the given note with the given brush.
     * We only draw notes from notenumber 24 to 96.
     * (Middle-C is 60).
     */
    private void ShadeOneNote(Canvas canvas, int notenumber, int color) {
        int octave = notenumber / 12;
        int notescale = notenumber % 12;

        octave -= 2;
        if (octave < 0 || octave >= MaxOctave)
            return;

        paint.setColor(color);
        paint.setStyle(Paint.Style.FILL);
        canvas.translate(octave * WhiteKeyWidth * KeysPerOctave, 0);
        int x1, x2, x3;

        int bottomHalfHeight = WhiteKeyHeight - (BlackKeyHeight+3);

        /* notescale goes from 0 to 11, from C to B. */
        switch (notescale) {
        case 0: /* C */
            x1 = 2;
            x2 = blackKeyOffsets[0] - 2;
            canvas.drawRect(x1, 0, x1 + x2 - x1, 0 + BlackKeyHeight+3, paint);
            canvas.drawRect(x1, BlackKeyHeight+3, x1 + WhiteKeyWidth-3, 
                            BlackKeyHeight+3 + bottomHalfHeight, paint);
            break;
        case 1: /* C# */
            x1 = blackKeyOffsets[0]; 
            x2 = blackKeyOffsets[1];
            canvas.drawRect(x1, 0, x1 + x2 - x1, 0 + BlackKeyHeight, paint);
            if (color == gray1) {
                paint.setColor(gray2);
                canvas.drawRect(x1+1, BlackKeyHeight - BlackKeyHeight/8, 
                                x1+1 + BlackKeyWidth-2, 
                                BlackKeyHeight - BlackKeyHeight/8 + BlackKeyHeight/8, 
                                paint);
            }
            break;
        case 2: /* D */
            x1 = WhiteKeyWidth + 2;
            x2 = blackKeyOffsets[1] + 3;
            x3 = blackKeyOffsets[2] - 2; 
            canvas.drawRect(x2, 0, x2 + x3 - x2, 0 + BlackKeyHeight+3, paint);
            canvas.drawRect(x1, BlackKeyHeight+3, x1 + WhiteKeyWidth-3, 
                            BlackKeyHeight+3 + bottomHalfHeight, paint);
            break;
        case 3: /* D# */
            x1 = blackKeyOffsets[2]; 
            x2 = blackKeyOffsets[3];
            canvas.drawRect(x1, 0, x1 + BlackKeyWidth, 0 + BlackKeyHeight, paint);
            if (color == gray1) {
                paint.setColor(gray2);
                canvas.drawRect(x1+1, BlackKeyHeight - BlackKeyHeight/8, 
                                x1+1 + BlackKeyWidth-2, 
                                BlackKeyHeight - BlackKeyHeight/8 + BlackKeyHeight/8, 
                                paint);
            }
            break;
        case 4: /* E */
            x1 = WhiteKeyWidth * 2 + 2;
            x2 = blackKeyOffsets[3] + 3; 
            x3 = WhiteKeyWidth * 3 - 1;
            canvas.drawRect(x2, 0, x2 + x3 - x2, 0 + BlackKeyHeight+3, paint);
            canvas.drawRect(x1, BlackKeyHeight+3, x1 + WhiteKeyWidth-3, 
                            BlackKeyHeight+3 + bottomHalfHeight, paint);
            break;
        case 5: /* F */
            x1 = WhiteKeyWidth * 3 + 2;
            x2 = blackKeyOffsets[4] - 2; 
            x3 = WhiteKeyWidth * 4 - 2;
            canvas.drawRect(x1, 0, x1 + x2 - x1, 0 + BlackKeyHeight+3, paint);
            canvas.drawRect(x1, BlackKeyHeight+3, x1 + WhiteKeyWidth-3, 
                            BlackKeyHeight+3 + bottomHalfHeight, paint);
            break;
        case 6: /* F# */
            x1 = blackKeyOffsets[4]; 
            x2 = blackKeyOffsets[5];
            canvas.drawRect(x1, 0, x1 + BlackKeyWidth, 0 + BlackKeyHeight, paint);
            if (color == gray1) {
                paint.setColor(gray2);
                canvas.drawRect(x1+1, BlackKeyHeight - BlackKeyHeight/8, 
                                x1+1 + BlackKeyWidth-2, 
                                BlackKeyHeight - BlackKeyHeight/8 + BlackKeyHeight/8, 
                                paint);
            }
            break;
        case 7: /* G */
            x1 = WhiteKeyWidth * 4 + 2;
            x2 = blackKeyOffsets[5] + 3; 
            x3 = blackKeyOffsets[6] - 2; 
            canvas.drawRect(x2, 0, x2 + x3 - x2, 0 + BlackKeyHeight+3, paint);
            canvas.drawRect(x1, BlackKeyHeight+3, x1 + WhiteKeyWidth-3, 
                            BlackKeyHeight+3 + bottomHalfHeight, paint);
            break;
        case 8: /* G# */
            x1 = blackKeyOffsets[6]; 
            x2 = blackKeyOffsets[7];
            canvas.drawRect(x1, 0, x1 + BlackKeyWidth, 0 + BlackKeyHeight, paint);
            if (color == gray1) {
                paint.setColor(gray2);
                canvas.drawRect(x1+1, BlackKeyHeight - BlackKeyHeight/8, 
                                x1+1 + BlackKeyWidth-2, 
                                BlackKeyHeight - BlackKeyHeight/8 + BlackKeyHeight/8, 
                                paint);
            }
            break;
        case 9: /* A */
            x1 = WhiteKeyWidth * 5 + 2;
            x2 = blackKeyOffsets[7] + 3; 
            x3 = blackKeyOffsets[8] - 2; 
            canvas.drawRect(x2, 0, x2 + x3 - x2, 0 + BlackKeyHeight+3, paint);
            canvas.drawRect(x1, BlackKeyHeight+3, x1 + WhiteKeyWidth-3, 
                            BlackKeyHeight+3 + bottomHalfHeight, paint);
            break;
        case 10: /* A# */
            x1 = blackKeyOffsets[8]; 
            x2 = blackKeyOffsets[9];
            canvas.drawRect(x1, 0, x1 + BlackKeyWidth, 0 + BlackKeyHeight, paint);
            if (color == gray1) {
                paint.setColor(gray2);
                canvas.drawRect(x1+1, BlackKeyHeight - BlackKeyHeight/8, 
                                x1+1 + BlackKeyWidth-2, 
                                BlackKeyHeight - BlackKeyHeight/8 + BlackKeyHeight/8, 
                                paint);
            }
            break;
        case 11: /* B */
            x1 = WhiteKeyWidth * 6 + 2;
            x2 = blackKeyOffsets[9] + 3; 
            x3 = WhiteKeyWidth * KeysPerOctave - 1;
            canvas.drawRect(x2, 0, x2 + x3 - x2, 0 + BlackKeyHeight+3, paint);
            canvas.drawRect(x1, BlackKeyHeight+3, x1 + WhiteKeyWidth-3, 
                            BlackKeyHeight+3 + bottomHalfHeight, paint);
            break;
        default:
            break;
        }
        canvas.translate(-(octave * WhiteKeyWidth * KeysPerOctave), 0);
    }

    /** Find the MidiNote with the startTime closest to the given time.
     *  Return the index of the note.  Use a binary search method.
     */
    private int FindClosestStartTime(int pulseTime) {
        int left = 0;
        int right = notes.size()-1;

        while (right - left > 1) {
            int i = (right + left)/2;
            if (notes.get(left).getStartTime() == pulseTime)
                break;
            else if (notes.get(i).getStartTime() <= pulseTime)
                left = i;
            else
                right = i;
        }
        while (left >= 1 && 
               (notes.get(left-1).getStartTime() == notes.get(left).getStartTime())) {
            left--;
        }
        return left;
    }

    /** Return the next StartTime that occurs after the MidiNote
     *  at offset i, that is also in the same track/channel.
     */
    private int NextStartTimeSameTrack(int i) {
        int start = notes.get(i).getStartTime();
        int end = notes.get(i).getEndTime();
        int track = notes.get(i).getChannel();

        while (i < notes.size()) {
            if (notes.get(i).getChannel() != track) {
                i++;
                continue;
            }
            if (notes.get(i).getStartTime() > start) {
                return notes.get(i).getStartTime();
            }
            end = Math.max(end, notes.get(i).getEndTime());
            i++;
        }
        return end;
    }


    /** Return the next StartTime that occurs after the MidiNote
     *  at offset i.  If all the subsequent notes have the same
     *  StartTime, then return the largest EndTime.
     */
    private int NextStartTime(int i) {
        int start = notes.get(i).getStartTime();
        int end = notes.get(i).getEndTime();

        while (i < notes.size()) {
            if (notes.get(i).getStartTime() > start) {
                return notes.get(i).getStartTime();
            }
            end = Math.max(end, notes.get(i).getEndTime());
            i++;
        }
        return end;
    }


    /** Find the Midi notes that occur in the current time.
     *  Shade those notes on the piano displayed.
     *  Un-shade the those notes played in the previous time.
     */
    public void ShadeNotes(int currentPulseTime, int prevPulseTime) {
        if (notes == null || notes.size() == 0 || !surfaceReady || bufferBitmap == null) {
            return;
        }
        SurfaceHolder holder = getHolder();
        Canvas canvas = holder.lockCanvas();
        if (canvas == null) {
            return;
        }

        bufferCanvas.translate(margin + BlackBorder, margin + BlackBorder);

        /* Loop through the Midi notes.
         * Unshade notes where StartTime <= prevPulseTime < next StartTime
         * Shade notes where StartTime <= currentPulseTime < next StartTime
         */
        int lastShadedIndex = FindClosestStartTime(prevPulseTime - maxShadeDuration * 2);
        for (int i = lastShadedIndex; i < notes.size(); i++) {
            int start = notes.get(i).getStartTime();
            int end = notes.get(i).getEndTime();
            int notenumber = notes.get(i).getNumber();
            int nextStart = NextStartTime(i);
            int nextStartTrack = NextStartTimeSameTrack(i);
            end = Math.max(end, nextStartTrack);
            end = Math.min(end, start + maxShadeDuration-1);
                
            /* If we've past the previous and current times, we're done. */
            if ((start > prevPulseTime) && (start > currentPulseTime)) {
                break;
            }

            /* If shaded notes are the same, we're done */
            if ((start <= currentPulseTime) && (currentPulseTime < nextStart) &&
                (currentPulseTime < end) && 
                (start <= prevPulseTime) && (prevPulseTime < nextStart) &&
                (prevPulseTime < end)) {
                break;
            }

            /* If the note is in the current time, shade it */
            if ((start <= currentPulseTime) && (currentPulseTime < end)) {
                if (useTwoColors) {
                    if (notes.get(i).getChannel() == 1) {
                        ShadeOneNote(bufferCanvas, notenumber, shade2);
                    }
                    else {
                        ShadeOneNote(bufferCanvas, notenumber, shade1);
                    }
                }
                else {
                    ShadeOneNote(bufferCanvas, notenumber, shade1);
                }
            }

            /* If the note is in the previous time, un-shade it, draw it white. */
            else if ((start <= prevPulseTime) && (prevPulseTime < end)) {
                int num = notenumber % 12;
                if (num == 1 || num == 3 || num == 6 || num == 8 || num == 10) {
                    ShadeOneNote(bufferCanvas, notenumber, gray1);
                }
                else {
                    ShadeOneNote(bufferCanvas, notenumber, Color.WHITE);
                }
            }
        }
        bufferCanvas.translate(-(margin + BlackBorder), -(margin + BlackBorder));
        canvas.drawBitmap(bufferBitmap, 0, 0, paint);
        holder.unlockCanvasAndPost(canvas);
    }


    /** TODO ?? */
    public void 
    surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        draw();
    }

    /** Surface is ready for shading the notes */
    public void surfaceCreated(SurfaceHolder holder) {
        surfaceReady = true;
        // setWillNotDraw(false);
        draw();         
    }

    /** Surface has been destroyed */
    public void surfaceDestroyed(SurfaceHolder holder) {
        surfaceReady = false;
    }

    /** When the Piano is touched, pause the midi player */
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (event.getActionMasked() == MotionEvent.ACTION_DOWN) {
            if (player != null) {
                player.Pause();
            }
        }
        return super.onTouchEvent(event);
    }
}

