InterAppAudioSampler/InterAppAudioSampler/UI/CAUIKeyboardView.m

/*
     File: CAUIKeyboardView.m
 Abstract: 
  Version: 1.1.2
 
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#import "CAUIKeyboardView.h"
#import "AppDelegate.h"
 
#define kWhiteKeyWidthRatio     0.268f
#define kBlackKeyHeightRatio    0.634f
#define kBlackKeyWidthRatio     0.159f
#define kDbKeyOffsetRatio       0.201f
#define kEbKeyOffsetRatio       0.232f
#define kGbKeyOffsetRatio       0.146f
#define kAbKeyOffsetRatio       0.195f
#define kBbKeyOffsetRatio       0.234f
 
typedef enum NoteIdentifier {
    C = 0, Db= 1, D = 2, Eb= 3, E = 4, F = 5, Gb= 6, G = 7, Ab= 8, A = 9, Bb= 10, B = 11
} NoteIdentifier;
 
#pragma mark utility functions
BOOL IsWhiteKey(NSInteger note) {
    NSInteger value = note % 12;
    
    switch (value) {
        case 0: case 2: case 4: case 5: case 7: case 9: case 11:
            return YES;
        default:
            return NO;
    }
}
 
BOOL IsNoteSharp(NSInteger note) {
    NSInteger value = note % 12;
    
    switch (value) {
        case 0: case 2: case 4: case 5: case 7: case 9: case 11:
            return false;
        case 1: case 3: case 6: case 8: case 10:
            return true;
    }
    return false;
}
 
NoteIdentifier IdentifierForNote(NSInteger note) {
    NSInteger value = note % 12;
    return (NoteIdentifier)value;
}
 
NSInteger NumWhiteKeysBetweenNotes(NSInteger startNote, NSInteger endNote) {
    // figure out how many octaves between notes
    if (startNote == endNote)
        return 0;
    
    NSInteger keys = 0;
    NSInteger octaves = ((endNote - startNote) / 12);
    if (octaves > 0)
        keys = octaves * 7;
    
    if (IsWhiteKey(startNote))
        keys--;
    
    NSInteger extraNotes = (endNote - startNote) % 12;
    NSInteger indexKey = 0;
    for (indexKey = endNote - extraNotes; indexKey < endNote; indexKey++) {
        if (IsWhiteKey(indexKey))
            keys++;
    }
    
    return keys;
}
 
@implementation CAUIKeyboardView
{
    NSMutableSet    *notesDown;         // notes the user has pressed
    NSInteger       displayKeyStart;
    NSInteger       displayKeyEnd;
 
    UInt32          dbKeyOffset;
    UInt32          ebKeyOffset;
    UInt32          gbKeyOffset;
    UInt32          abKeyOffset;
    UInt32          bbKeyOffset;
 
    UIColor         *noteDownColor;
 
    NSDictionary    *labelAttributes;
    UIImage         *imageCache;
}
 
@synthesize whiteKeyWidth, whiteKeyHeight, blackKeyWidth, blackKeyHeight;
@synthesize noteDownColor;
@synthesize engine = _engine;
 
#pragma mark Initialization/Dealloc
- (id) initWithCoder:(NSCoder *)aDecoder {
    self = [super initWithCoder: aDecoder];
    if (self) {
        [self initialize];
    }
    return self;
}
 
- (void) initialize {
    _engine = NULL;
    whiteKeyHeight  = floorf(self.frame.size.height);
    whiteKeyWidth   = roundf(whiteKeyHeight * kWhiteKeyWidthRatio);
    blackKeyHeight  = roundf(whiteKeyHeight * kBlackKeyHeightRatio);
    blackKeyWidth   = roundf(whiteKeyHeight * kBlackKeyWidthRatio);
    
    dbKeyOffset     = roundf(whiteKeyHeight * kDbKeyOffsetRatio);
    ebKeyOffset     = roundf(whiteKeyHeight * kEbKeyOffsetRatio);
    gbKeyOffset     = roundf(whiteKeyHeight * kGbKeyOffsetRatio);
    abKeyOffset     = roundf(whiteKeyHeight * kAbKeyOffsetRatio);
    bbKeyOffset     = roundf(whiteKeyHeight * kBbKeyOffsetRatio);
            
    notesDown = [[NSMutableSet setWithCapacity: 0] retain];
    
    self.noteDownColor = [[UIColor redColor] colorWithAlphaComponent: .7];
            
    [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(prepareBackground)
                                                name:@"UIDeviceOrientationDidChangeNotification"
                                              object:nil];
}
 
- (void) dealloc {
    [[NSNotificationCenter defaultCenter]removeObserver:self];
    
    [labelAttributes release];
    [imageCache release];
    [notesDown release];
    [super dealloc];
}
 
#pragma mark Utility methods
- (NSInteger) offsetForBlackKey:(NSInteger) note {
    NoteIdentifier identifier = IdentifierForNote(note);
    switch (identifier) {
        case Db:
            return dbKeyOffset;
        case Eb:
            return ebKeyOffset;
        case Gb:
            return gbKeyOffset;
        case Ab:
            return abKeyOffset;
        case Bb:
            return bbKeyOffset;
        default:
            return 0;
    }
}
 
- (CGRect) noteRectForNote:(NSInteger) note inRect:(CGRect) rect {
    // starting with the starting note, calculate the rect that the note to be drawn is in
    // if the starting note is a sharp, we need to get the previous white key
    // if the starting note is a white key, we can calculate the location of the new note
    
    CGRect firstNoteRect = CGRectZero;
    CGRect firstWhiteNoteRect = CGRectZero;
    
    BOOL startingNoteSharp = IsNoteSharp(displayKeyStart);
    firstWhiteNoteRect = CGRectMake(rect.origin.x, rect.origin.y, self.whiteKeyWidth, self.whiteKeyHeight);
    
    if (startingNoteSharp) {
        firstNoteRect = CGRectMake(rect.origin.x, rect.origin.y, self.blackKeyWidth, self.blackKeyHeight);
        
        // we need to calculate the starting location of the previous white key
        NSInteger offset = [self offsetForBlackKey: note];
        firstWhiteNoteRect.origin.x -= offset;
    }
    else
        firstNoteRect = firstWhiteNoteRect;
    
    if (displayKeyStart == note)
        return firstNoteRect;
    
    // calculate distance in white keys between note and displayKeyStart
    NSInteger whiteInterval = NumWhiteKeysBetweenNotes(displayKeyStart, note) * self.whiteKeyWidth;
    NSInteger lastWhiteStart = firstWhiteNoteRect.origin.x + whiteInterval;
    
    BOOL endingNoteSharp = IsNoteSharp(note);
    if (!endingNoteSharp) {
        return CGRectMake(lastWhiteStart+self.whiteKeyWidth, rect.origin.y, self.whiteKeyWidth, self.whiteKeyHeight);
    }
    else
        return CGRectMake(lastWhiteStart+ [self offsetForBlackKey:note], rect.origin.y, self.blackKeyWidth, self.blackKeyHeight);
}
 
- (CGFloat) leftEdgeOfNote:(NSInteger) note {
    CGRect rect = [self noteRectForNote: note inRect: self.bounds];
    return rect.origin.x;
}
 
- (CGFloat) rightEdgeOfNote:(NSInteger) note {
    CGRect rect = [self noteRectForNote: note inRect: self.bounds];
    return rect.origin.x + rect.size.width;
}
 
- (UIBezierPath *) bezierPathForNote:(NSInteger) note {
    if (note < 0 || note > 127)
        return nil;
    
    if (!IsWhiteKey(note))
        return [UIBezierPath bezierPathWithRect: [self noteRectForNote: note inRect: self.bounds]];
    else {
        UIBezierPath *path = [UIBezierPath bezierPath];
        CGFloat edge;
        if (note == 0 || IsWhiteKey(note-1)) { // special case the very first note
            edge = [self leftEdgeOfNote: note] + 1;
            
            // if the previous key is a white key, then the left edge is the same as the edge of the note
            [path moveToPoint: CGPointMake(edge, whiteKeyHeight-1)];
            [path addLineToPoint: CGPointMake(edge + whiteKeyWidth-1, whiteKeyHeight-1)];
            [path addLineToPoint: CGPointMake(edge + whiteKeyWidth-1, blackKeyHeight)];
            
            edge = [self leftEdgeOfNote: note+1];
            [path addLineToPoint: CGPointMake(edge, blackKeyHeight)];
            [path addLineToPoint: CGPointMake(edge, 1)];
            edge = [self leftEdgeOfNote: note] + 1;
        } else {
            edge = [self rightEdgeOfNote: note-1];
            [path moveToPoint: CGPointMake(edge, 1)];
            [path addLineToPoint: CGPointMake(edge, blackKeyHeight)];
            
            edge = [self leftEdgeOfNote: note];
            [path addLineToPoint: CGPointMake(edge, blackKeyHeight)];
            [path addLineToPoint: CGPointMake(edge, whiteKeyHeight-1)];
            [path addLineToPoint: CGPointMake(edge + whiteKeyWidth-1, whiteKeyHeight-1)];
            
            // if the next key is a white key, then the right edge is the same as the edge of the note
            if (note == 127 || IsWhiteKey(note+1)) {
                edge = [self rightEdgeOfNote: note]-1;
                [path addLineToPoint: CGPointMake(edge, 1)];
            } else {
                [path addLineToPoint: CGPointMake(edge+ whiteKeyWidth-1, blackKeyHeight)];
                
                edge = [self leftEdgeOfNote: note+1];
                [path addLineToPoint: CGPointMake(edge, blackKeyHeight)];
            }
        }
        [path addLineToPoint: CGPointMake(edge, 1)];
        [path closePath];
        
        return path;
    }
    
    return nil;
}
 
- (void) drawRect:(CGRect) rect {
    CGRect myFrame = self.bounds;
    
    if (!imageCache)
        [self prepareBackground];
    
    // draw the cached image instead of above code
    [imageCache drawInRect: myFrame];
    
    [noteDownColor set];
    for (NSNumber *noteDown in notesDown) {
        NSInteger note = [noteDown integerValue];
        if (IsNoteSharp(note))
            UIRectFill([self noteRectForNote: note inRect: self.bounds]);
        else {
            UIBezierPath *path = [self bezierPathForNote: note];
            if (path)
                [path fill];
        }
    }
}
 
-(NSInteger) displayKeyStart {
    return displayKeyStart;
}
 
- (void) setDisplayKeyStart:(NSInteger) note {
    if (note >= 0 && note < 128 && note != displayKeyStart) {
        displayKeyStart = note;
        
        [self prepareBackground];
        [self setNeedsDisplay];
    }
}
 
- (void) prepareBackground {
    UIGraphicsBeginImageContext(self.bounds.size);
    
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    
    displayKeyEnd = 127;    
    CGContextSetFillColorWithColor(ctx, [UIColor whiteColor].CGColor);
    CGContextFillRect(ctx, self.bounds);
    
    CGContextSetFillColorWithColor(ctx, [UIColor blackColor].CGColor);
    CGContextStrokeRect(ctx, self.bounds);
    
    CGRect noteRect = CGRectZero;
    NSInteger keyIndex, startKey = displayKeyStart;
    if (startKey > 0 == !IsWhiteKey(startKey-1))
        startKey--;
    
    for (keyIndex = startKey; keyIndex < 128; keyIndex++) {
        if ([notesDown containsObject: @(keyIndex)])
            continue;
        
        noteRect = [self noteRectForNote: keyIndex inRect: self.bounds];
        
        if (noteRect.origin.x > self.frame.origin.x + self.frame.size.width) {
            displayKeyEnd = keyIndex-1;
            break;
        }
        if (IsNoteSharp(keyIndex))
            CGContextFillRect(ctx, noteRect);
        else {
            CGContextStrokeRect(ctx, noteRect);
            
            // draw the note label if this is a C
            NoteIdentifier identifier = IdentifierForNote(keyIndex);
            if (identifier == C) {
                if (!labelAttributes) {
                    UIFont *font = [UIFont systemFontOfSize: 12];
                    NSMutableParagraphStyle *paraStyle = [NSMutableParagraphStyle new];
                    paraStyle.alignment = NSTextAlignmentCenter;
                    
                    labelAttributes = [[NSDictionary alloc] initWithObjectsAndKeys: font, NSFontAttributeName,
                                       paraStyle, NSParagraphStyleAttributeName,
                                       [UIColor grayColor], NSForegroundColorAttributeName, nil];
                    [paraStyle release];
                }
                NSAttributedString *label = [[NSAttributedString alloc]initWithString:[NSString stringWithFormat: @"C%d", (int)(keyIndex / 12) - 1] attributes: labelAttributes];
                [label drawInRect: CGRectMake(noteRect.origin.x + 1, noteRect.origin.y + self.whiteKeyHeight - 16, noteRect.size.width -2, 12)];
                
                [label autorelease];
            }
            [[UIColor blackColor] set];
        }
    }
    if (noteRect.origin.x + noteRect.size.width < self.bounds.size.width) {
        CGContextSetFillColorWithColor(ctx, [UIColor darkGrayColor].CGColor);
        CGFloat rightEdge = noteRect.origin.x + noteRect.size.width;
        CGContextFillRect(ctx, CGRectMake(rightEdge, 0, self.bounds.size.width - rightEdge, self.bounds.size.height));
    }
        
    [imageCache release];
    imageCache = UIGraphicsGetImageFromCurrentImageContext();
    [imageCache retain];
    
    UIGraphicsEndImageContext();
    [self setNeedsDisplay];
}
 
BOOL CGPointInRect(CGPoint aPoint, CGRect aRect) {
    return aPoint.x >= aRect.origin.x &&
    aPoint.x < (aRect.origin.x + aRect.size.width) &&
    aPoint.y >= aRect.origin.y &&
    aPoint.y < (aRect.origin.y + aRect.size.height);
}
 
- (NSInteger) noteAtPoint:(CGPoint) point {
    // check to see which white key we are in
    CGRect firstWhiteNoteRect = CGRectZero;
    
    BOOL startingNoteSharp = IsNoteSharp(displayKeyStart);
    firstWhiteNoteRect = CGRectMake(self.bounds.origin.x, self.bounds.origin.y, whiteKeyWidth, whiteKeyHeight);
    
    if (startingNoteSharp) {
        // we need to calculate the starting location of the previous white key
        NSInteger offset = [self offsetForBlackKey: displayKeyStart];
        firstWhiteNoteRect.origin.x -= offset;
    }
    
    NSInteger whiteNoteNumber = (point.x - firstWhiteNoteRect.origin.x)/whiteKeyWidth;
    NSInteger noteNumber = displayKeyStart + (((float)whiteNoteNumber/7) * 12);
    if (IsNoteSharp(noteNumber))
        noteNumber++;
    
    if (point.y <= blackKeyHeight) {    // we could be on a black key, so we need to check the black keys surrounding the white key
        // if we are not on a c or and f, check the previous flat
        BOOL foundFlat = NO;
        NoteIdentifier identifier = IdentifierForNote(noteNumber);
        if (identifier != C && identifier != F) {
            if (CGPointInRect(point, [self noteRectForNote:noteNumber-1 inRect:self.bounds])) {
                noteNumber--;
                foundFlat = YES;
            }
        }
        // check the next flat
        if (!foundFlat && CGPointInRect(point, [self noteRectForNote:noteNumber+1 inRect:self.bounds]))
            noteNumber++;
    }
    
    return noteNumber;
}
 
#pragma mark Note handling
//Midi related constants
enum {
    kMidiMessage_NoteOn             = 0x9,
    kMidiMessage_NoteOff            = 0x8,
    kMidiController_AllNotesOff     = 123
};
 
- (OSStatus) playNote:(UInt32) note velocity:(UInt32) velocity {
    const UInt32 noteOnCommand = kMidiMessage_NoteOn << 4 | 0;
    OSStatus result =  -1;
    if (self.engine){
        AudioUnit au = [self.engine getAudioUnitInstrument];
        result = MusicDeviceMIDIEvent(au, noteOnCommand, note, 100, 0);
    }
    return result;
}
 
- (OSStatus) stopNote:(UInt32) note {
    const UInt32 noteOffCommand = kMidiMessage_NoteOff << 4 | 0;
    OSStatus result =  -1;
    if (self.engine)
        result = MusicDeviceMIDIEvent([self.engine getAudioUnitInstrument], noteOffCommand, note, 100, 0);
 
    return result;
}
 
- (OSStatus) stopAllNotes {
    const UInt32 allNotesOffCommand = kMidiController_AllNotesOff << 4 | 0;
    OSStatus result =  -1;
    if (self.engine)
        result = MusicDeviceMIDIEvent([self.engine getAudioUnitInstrument], allNotesOffCommand, 0, 0, 0);
    
    return result;
}
 
#pragma mark Event handling
- (void) touchesBegan:(NSSet *) touches withEvent:(UIEvent *) event {
    
    for (UITouch *touch in touches) {
        CGPoint loc = [touch locationInView: self];
        NSNumber * note = @([self noteAtPoint: loc]);
                
        if (![notesDown containsObject: note])
            [notesDown addObject: note];
        
        CGRect noteRect = [self noteRectForNote:[note intValue] inRect:self.bounds];
        
        // generate a 1 to 127 value based on the vertical position of the tap
        NSInteger margin = 6;
        Float32 velocity = 127;
        
        CGFloat adjustedPoint = loc.y - noteRect.origin.y;
        if (adjustedPoint > noteRect.size.height - margin)
            velocity = 127;
        else if (adjustedPoint > margin) {
            velocity = (adjustedPoint - margin) / (noteRect.size.height - margin * 2);
            velocity = velocity * 127;
        }
        [self playNote: [note unsignedIntValue] velocity: velocity];
    }
    [self setNeedsDisplay];
}
 
- (void) touchesMoved:(NSSet *) touches withEvent:(UIEvent *) event {
    
    for (UITouch *touch in touches) {
        CGPoint previousLoc = [touch previousLocationInView: self];
        CGPoint currentLoc  = [touch locationInView: self];
        
        BOOL previousInView = CGPointInRect(previousLoc, self.bounds);
        BOOL currentInView  = CGPointInRect(currentLoc, self.bounds);
        
        NSInteger previousNote, currentNote;
        
        previousNote = previousInView ? [self noteAtPoint: previousLoc] : -1;
        currentNote  = currentInView  ? [self noteAtPoint: currentLoc]  : -1;
                
        // if the previous and current note match, don't do anything
        // otherwise, if the note has changed, end previous note, and start new note
        if (previousNote != currentNote) {
            if (previousNote > -1) {
                
                [notesDown removeObject: @(previousNote)];
                // end the note
                OSStatus result = [self stopNote: (UInt32)previousNote];
                if (result != noErr)
                    NSLog(@"Error stopping note %ld: %d", (long)previousNote, (int)result);
            }
            
            if (currentNote >= -1) {
                if (![notesDown containsObject: @(currentNote)])
                    [notesDown addObject: @(currentNote)];
                
                // start the new note
                OSStatus result = [self playNote: (UInt32)currentNote velocity: 100];
                if (result != noErr)
                    NSLog(@"Error playing note %ld: %d", (long)currentNote, (int)result);
            }
        }
    }
    [self setNeedsDisplay];
}
 
- (void) touchesEnded:(NSSet *) touches withEvent:(UIEvent *) event {
    for (UITouch *touch in touches) {
        CGPoint currentLoc  = [touch locationInView: self];
        CGPoint previousLoc = [touch previousLocationInView:self];
        
        NSNumber *note = @([self noteAtPoint: currentLoc]);
        NSNumber *prevNote = @([self noteAtPoint: previousLoc]);
                
        if ([notesDown containsObject: note]) {
            [notesDown removeObject: note];
        } else  if ([notesDown containsObject: prevNote]){
            [notesDown removeObject: prevNote];
            note = prevNote;
        }
        
        // end the note
        OSStatus result = [self stopNote: [note unsignedIntValue]];
        if (result != noErr)
            NSLog(@"Error stopping note %lu: %d", [note unsignedLongValue], (int)result);
    }
    [self setNeedsDisplay];
}
 
-(void) touchesCancelled:(NSSet *) touches withEvent:(UIEvent *) event {
    [notesDown removeAllObjects];
    [self setNeedsDisplay];
    
    // end all playing notes
    OSStatus result = [self stopAllNotes];
    if (result != noErr)
        NSLog(@"Error stopping all notes: %d", (int)result);
}
 
@end