/*

     File: CircleView.m

 Abstract: NSView subclass showing the use of the text system for drawing glyphs.

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#import <Cocoa/Cocoa.h>

#import "CircleView.h"

@implementation CircleView

// Many of the methods here are similar to those in the simpler DotView example.

// See that example for detailed explanations; here we will discuss those

// features that are unique to CircleView. 

// CircleView draws text around a circle, using Cocoa's text system for

// glyph generation and layout, then calculating the positions of glyphs

// based on that layout, and using NSLayoutManager for drawing.

- (id)initWithFrame:(NSRect)frame {

    if(self = [super initWithFrame:frame])  {

        // First, we set default values for the various parameters.

        center.x = frame.size.width / 2;

        center.y = frame.size.height / 2;

        radius = 115.0;

        startingAngle = M_PI_2;

        angularVelocity = M_PI_2;

        // Next, we create and initialize instances of the three 

        // basic non-view components of the text system:

        // an NSTextStorage, an NSLayoutManager, and an NSTextContainer.

        textStorage = [[NSTextStorage alloc] initWithString:@"Here's to the crazy ones, the misfits, the rebels, the troublemakers, the round pegs in the square holes, the ones who see things differently."];

        layoutManager = [[NSLayoutManager alloc] init];

        textContainer = [[NSTextContainer alloc] init];

        [layoutManager addTextContainer:textContainer];

        [textContainer release];    // The layoutManager will retain the textContainer

        [textStorage addLayoutManager:layoutManager];

        [layoutManager release];    // The textStorage will retain the layoutManager

        // Screen fonts are not suitable for scaled or rotated drawing.

        // Views that use NSLayoutManager directly for text drawing should

        // set this parameter appropriately.

        [layoutManager setUsesScreenFonts:NO];

    }

    return self;

}

- (void)dealloc {

    [timer invalidate];

    [timer release];

    [textStorage release];

    [super dealloc];

}

- (void)drawRect:(NSRect)rect {

    NSUInteger glyphIndex;

    NSRange glyphRange;

    NSRect usedRect;

    [[NSColor whiteColor] set];

    NSRectFill([self bounds]);

    // Note that usedRectForTextContainer: does not force layout, so it must 

    // be called after glyphRangeForTextContainer:, which does force layout.

    glyphRange = [layoutManager glyphRangeForTextContainer:textContainer];

    usedRect = [layoutManager usedRectForTextContainer:textContainer];

    for (glyphIndex = glyphRange.location; glyphIndex < NSMaxRange(glyphRange); glyphIndex++) {

        NSGraphicsContext *context = [NSGraphicsContext currentContext];

    NSRect lineFragmentRect = [layoutManager lineFragmentRectForGlyphAtIndex:glyphIndex effectiveRange:NULL];

    NSPoint viewLocation, layoutLocation = [layoutManager locationForGlyphAtIndex:glyphIndex];

        CGFloat angle, distance;

        NSAffineTransform *transform = [NSAffineTransform transform];

        // Here layoutLocation is the location (in container coordinates) where the glyph was laid out. 

        layoutLocation.x += lineFragmentRect.origin.x;

        layoutLocation.y += lineFragmentRect.origin.y;

        // We then use the layoutLocation to calculate an appropriate position for the glyph 

        // around the circle (by angle and distance, or viewLocation in rectangular coordinates).

        distance = radius + usedRect.size.height - layoutLocation.y;

        angle = startingAngle + layoutLocation.x / distance;

        viewLocation.x = center.x + distance * sin(angle);

        viewLocation.y = center.y + distance * cos(angle);

        // We use a different affine transform for each glyph, to position and rotate it

        // based on its calculated position around the circle.  

        [transform translateXBy:viewLocation.x yBy:viewLocation.y];

        [transform rotateByRadians:-angle];

        // We save and restore the graphics state so that the transform applies only to this glyph.

        [context saveGraphicsState];

        [transform concat];

        // drawGlyphsForGlyphRange: draws the glyph at its laid-out location in container coordinates.

        // Since we are using the transform to place the glyph, we subtract the laid-out location here.

        [layoutManager drawGlyphsForGlyphRange:NSMakeRange(glyphIndex, 1) atPoint:NSMakePoint(-layoutLocation.x, -layoutLocation.y)];

        [context restoreGraphicsState];

    }

}

- (BOOL)isOpaque {

    return YES;

}

// DotView changes location on mouse up, but here we choose to do so

// on mouse down and mouse drags, so the text will follow the mouse.

- (void)mouseDown:(NSEvent *)event {

    NSPoint eventLocation = [event locationInWindow];

    center = [self convertPoint:eventLocation fromView:nil];

    [self setNeedsDisplay:YES];

}

- (void)mouseDragged:(NSEvent *)event {

    NSPoint eventLocation = [event locationInWindow];

    center = [self convertPoint:eventLocation fromView:nil];

    [self setNeedsDisplay:YES];

}

// DotView uses action methods to set its parameters.  Here we have

// factored each of those into a method to set each parameter directly

// and a separate action method.

- (void)setColor:(NSColor *)color {

    // Text drawing uses the attributes set on the text storage rather

    // than drawing context attributes like the current color.

    [textStorage addAttribute:NSForegroundColorAttributeName value:color range:NSMakeRange(0, [textStorage length])];

    [self setNeedsDisplay:YES];

}

- (void)setRadius:(CGFloat)distance {

    radius = distance;

    [self setNeedsDisplay:YES];

}

- (void)setStartingAngle:(CGFloat)angle {

    startingAngle = angle;

    [self setNeedsDisplay:YES];

}

- (void)setAngularVelocity:(CGFloat)velocity {

    angularVelocity = velocity;

    [self setNeedsDisplay:YES];

}

- (void)setString:(NSString *)string {

    [textStorage replaceCharactersInRange:NSMakeRange(0, [textStorage length]) withString:string];

    [self setNeedsDisplay:YES];

}

- (IBAction)takeColorFrom:(id)sender {

    [self setColor:[sender color]];

}

- (IBAction)takeRadiusFrom:(id)sender {

    [self setRadius:[sender doubleValue]];

}

- (IBAction)takeStartingAngleFrom:(id)sender {

    [self setStartingAngle:[sender doubleValue]];

}

- (IBAction)takeAngularVelocityFrom:(id)sender {

    [self setAngularVelocity:[sender doubleValue]];

}

- (IBAction)takeStringFrom:(id)sender {

    [self setString:[sender stringValue]];

}

- (IBAction)startAnimation:(id)sender {

    [self stopAnimation:sender];

    // We schedule a timer for a desired 30fps animation rate.

    // In performAnimation: we determine exactly

    // how much time has elapsed and animate accordingly.

    timer = [[NSTimer scheduledTimerWithTimeInterval:(1.0/30.0) target:self selector:@selector(performAnimation:) userInfo:nil repeats:YES] retain];

    // The next two lines make sure that animation will continue to occur

    // while modal panels are displayed and while event tracking is taking

    // place (for example, while a slider is being dragged).

    [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSModalPanelRunLoopMode];

    [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSEventTrackingRunLoopMode];

    lastTime = [NSDate timeIntervalSinceReferenceDate];

}

- (IBAction)stopAnimation:(id)sender {

    [timer invalidate];

    [timer release];

    timer = nil;

}

- (IBAction)toggleAnimation:(id)sender {

    if (timer != nil) {

        [self stopAnimation:sender];

    } else {

        [self startAnimation:sender];

    }

}

- (void)performAnimation:(NSTimer *)aTimer {

    // We determine how much time has elapsed since the last animation,

    // and we advance the angle accordingly.

    NSTimeInterval thisTime = [NSDate timeIntervalSinceReferenceDate];

    [self setStartingAngle:startingAngle + angularVelocity * (thisTime - lastTime)];

    lastTime = thisTime;

}

@end