/*

     File: GraphingView.m

 Abstract: Graphing View, the class responsible for drawing the graph, based on the formula

  Version: 1.2

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*/

#import "GraphingView.h"

#import "ViewController.h"

@implementation GraphingView

@synthesize formulaConstant;

- (void)dealloc

{

    [accessibilityChildren release];

    [super dealloc];

}

#pragma mark -

#pragma mark === Accessibility Container methods ===

// _accessibilityChildren returns the list of "sub-elements" that GraphingView contains

- (NSArray *)_accessibilityChildren

{

    if ( accessibilityChildren != nil )

    {

        return accessibilityChildren;

    }

    accessibilityChildren = [[NSMutableArray alloc] init];

    // create an accessibility element to represent the graph

    UIAccessibilityElement *graph = [[[UIAccessibilityElement alloc] initWithAccessibilityContainer:self] autorelease];

    graph.accessibilityLabel = @"Graph";

    graph.accessibilityTraits = UIAccessibilityTraitImage;

    [accessibilityChildren addObject:graph];

    // create accessibility elements for each "button"

    // assign labels and traits

    // add to the children array

    UIAccessibilityElement *button1 = [[[UIAccessibilityElement alloc] initWithAccessibilityContainer:self] autorelease];

    button1.accessibilityLabel = @"f of negative pi over 2";

    button1.accessibilityTraits = UIAccessibilityTraitButton;

    [accessibilityChildren addObject:button1];

    UIAccessibilityElement *button2 = [[[UIAccessibilityElement alloc] initWithAccessibilityContainer:self] autorelease];

    button2.accessibilityLabel = @"f of 0";

    button2.accessibilityTraits = UIAccessibilityTraitButton;

    [accessibilityChildren addObject:button2];

    UIAccessibilityElement *button3 = [[[UIAccessibilityElement alloc] initWithAccessibilityContainer:self] autorelease];

    button3.accessibilityLabel = @"f of pi over 2";

    button3.accessibilityTraits = UIAccessibilityTraitButton;

    [accessibilityChildren addObject:button3];

    // set the frame of each method. 

    // use this view's accessibilityFrame to base calculations off of

    CGRect frame = [self accessibilityFrame];

    CGFloat height = 40, width = 60;

    button1.accessibilityFrame = CGRectMake(frame.origin.x + 15, CGRectGetMaxY(frame) - height, width, height); 

    button2.accessibilityFrame = CGRectMake(frame.origin.x + 105, CGRectGetMaxY(frame) - height, width, height); 

    button3.accessibilityFrame = CGRectMake(frame.origin.x + 190, CGRectGetMaxY(frame) - height, width, height);     

    graph.accessibilityFrame = CGRectMake(frame.origin.x, frame.origin.y, frame.size.width, frame.size.height - height);   

    return accessibilityChildren;

}

// if a UIView implements the container protocol, it cannot be an accessible element

- (BOOL)isAccessibilityElement

{

    return NO;

}

// Accessibility Container protocol methods only need to reference _accessibilityChildren to be complete

- (NSInteger)accessibilityElementCount

{

    return [[self _accessibilityChildren] count];

}

- (id)accessibilityElementAtIndex:(NSInteger)index

{

    return [[self _accessibilityChildren] objectAtIndex:index];

}

- (NSInteger)indexOfAccessibilityElement:(id)element

{

    return [[self _accessibilityChildren] indexOfObject:element];    

}

#pragma mark -

#pragma mark === Drawing and layout methods ===

- (void)awakeFromNib

{

    // set up a rounded border

    CALayer *layer = [self layer];

    // clear the view's background color so that our background

    // fits within the rounded border

    CGColorRef backgroundColor = [self.backgroundColor CGColor];

    self.backgroundColor = [UIColor clearColor];

    layer.backgroundColor = backgroundColor;

    layer.borderColor = [[UIColor blackColor] CGColor];

    layer.borderWidth = 3.0f;

    layer.cornerRadius = 4.0f;

    shapeLayer = [CAShapeLayer layer];   

    [shapeLayer setFillColor:[[UIColor clearColor] CGColor]];

    [shapeLayer setStrokeColor:[[UIColor whiteColor] CGColor]];

    [shapeLayer setLineCap:kCALineCapRound];

    [shapeLayer setLineWidth:4.0f];

    [layer addSublayer:shapeLayer];   

    [self setNeedsDisplay];

}

- (void)drawRect:(CGRect)rect

{

    // draw the "buttons" which are really strings.

    [[UIColor whiteColor] set];

    [[NSString stringWithString:@"f(-∏/2)"] drawAtPoint:CGPointMake(CGRectGetMinX(rect) + 20, CGRectGetMaxY(rect) - 30) withFont:[UIFont boldSystemFontOfSize:16]];

    [[NSString stringWithFormat:@"f(0.00)"] drawAtPoint:CGPointMake(CGRectGetMinX(rect) + 110, CGRectGetMaxY(rect) - 30) withFont:[UIFont boldSystemFontOfSize:16]];

    [[NSString stringWithString:@"f(∏/2)"] drawAtPoint:CGPointMake(CGRectGetMinX(rect) + 200, CGRectGetMaxY(rect) - 30) withFont:[UIFont boldSystemFontOfSize:16]];    

}

- (void)updateGraph

{

    // draw the graph line

    CGRect bounds = self.bounds;

    CGMutablePathRef path = CGPathCreateMutable();

    CGFloat startX = CGRectGetMinX(bounds) + 10;

    CGFloat width = CGRectGetWidth(bounds) - 20;

    CGFloat startY = CGRectGetMidY(bounds);

    CGFloat height = CGRectGetHeight(bounds);

    CGPathMoveToPoint(path, NULL, startX, startY);

    CGFloat x;

    for ( x = -2*M_PI; x <= 2*M_PI; x += .15 )

    {

        // find the value that we will plot

        CGFloat fx = formulaConstant * x * sin(x);

        // convert the x value to a x coordinate

        CGFloat rectX = (((x + 2*M_PI)/(4*M_PI)) * width) + startX;

        // convert the f(x) value to a y coordinate

        CGFloat rectY = ((fx/3) * height) + startY;

        CGPathAddLineToPoint(path, NULL, rectX, rectY);        

    }

    [shapeLayer setPath:path];

    [shapeLayer setNeedsDisplay];

    CFRelease(path);    

}

- (void)setFormulaConstant:(CGFloat)constant

{

    // alpha as in the alpha of the equation (not opacity alpha)

    formulaConstant = constant;

    [self updateGraph];

}

@end