src/views/ITProgressIndicator.mm

//Copyright 2013-2015 Ilija Tovilo
//
//Licensed under the Apache License, Version 2.0 (the "License");
//you may not use this file except in compliance with the License.
//You may obtain a copy of the License at
//
//http://www.apache.org/licenses/LICENSE-2.0
//
//Unless required by applicable law or agreed to in writing, software
//distributed under the License is distributed on an "AS IS" BASIS,
//WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//See the License for the specific language governing permissions and
//limitations under the License.

#if !__has_feature(objc_arc)
#error ARC needs to be enabled!
#endif


#import "ITProgressIndicator.h"


#pragma mark - Consts
#define kITSpinAnimationKey @"spinAnimation"
#define kITProgressPropertyKey @"progress"


// ----------------------------------------------------------------------------------------
#pragma mark - NSBezierPath+IT_Geometry
// ----------------------------------------------------------------------------------------

@interface NSBezierPath (IT_Geometry)

- (NSBezierPath*)it_rotatedBezierPath:(float) angle;
- (NSBezierPath*)it_rotatedBezierPath:(float) angle aboutPoint:(NSPoint)point;

@end

@implementation NSBezierPath (IT_Geometry)

- (NSBezierPath *)it_rotatedBezierPath:(float)angle {
	return [self it_rotatedBezierPath:angle aboutPoint:NSMakePoint(NSMidX(self.bounds), NSMidY(self.bounds))];
}

- (NSBezierPath*)it_rotatedBezierPath:(float)angle aboutPoint:(NSPoint)point {
	if(angle == 0.0) return self;
	else
	{
		NSBezierPath* copy = [self copy];
		NSAffineTransform *xfm = [self it_rotationTransformWithAngle:angle aboutPoint:point];
		[copy transformUsingAffineTransform:xfm];

		return copy;
	}
}

- (NSAffineTransform *)it_rotationTransformWithAngle:(const float)angle aboutPoint:(const NSPoint)aboutPoint {
	NSAffineTransform *xfm = [NSAffineTransform transform];
	[xfm translateXBy:aboutPoint.x yBy:aboutPoint.y];
	[xfm rotateByRadians:angle];
	[xfm translateXBy:-aboutPoint.x yBy:-aboutPoint.y];

	return xfm;
}

@end




// ----------------------------------------------------------------------------------------
#pragma mark - ITProgressIndicator
// ----------------------------------------------------------------------------------------

#pragma mark - Private Interface

@interface ITProgressIndicator ()
@property (nonatomic, strong, readonly) CALayer *rootLayer;
@property (nonatomic, strong, readonly) CALayer *progressIndicatorLayer;
@end


#pragma mark - Implementation

@implementation ITProgressIndicator
@synthesize progressIndicatorLayer = _progressIndicatorLayer;


#pragma mark - Init

- (id)initWithCoder:(NSCoder *)coder
{
    self = [super initWithCoder:coder];
    if (self) {
        [self initLayers];
    }
    return self;
}

- (id)initWithFrame:(NSRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        [self initLayers];
    }
    return self;
}

- (void)initLayers {
    // Setting initial values
    self.color = [NSColor blackColor];
    self.innerMargin = 4;
	self.widthOfLine = 3;
    self.lengthOfLine = 6;
    self.numberOfLines = 8;
    self.animationDuration = 0.6;
    self.isIndeterminate = YES;
    self.steppedAnimation = YES;
    self.hideWhenStopped = YES;
    self.animates = YES;

    // Init layers
    _rootLayer = [CALayer layer];
    self.layer = _rootLayer;
    [self setWantsLayer:YES];
    self.progressIndicatorLayer.frame = _rootLayer.bounds;
    [_rootLayer addSublayer:self.progressIndicatorLayer];

    [self reloadIndicatorContent];
    [self reloadAnimation];
}

- (void)awakeFromNib {
    [self reloadAnimation];
}

- (void)reloadIndicatorContent {
    self.progressIndicatorLayer.contents = [self progressImage];
}

- (void)reloadAnimation {
    [self.progressIndicatorLayer removeAnimationForKey:kITSpinAnimationKey];

    if (self.animates) {
        [self.progressIndicatorLayer addAnimation:[self keyFrameAnimationForCurrentPreferences] forKey:kITSpinAnimationKey];
    }
}


#pragma mark - Drawing

- (NSImage *)progressImage {
    NSImage *progressImage = [[NSImage alloc] initWithSize:self.bounds.size];
    [progressImage lockFocus];
    {
        [NSGraphicsContext saveGraphicsState];
        {
            [self.color set];

            NSRect r = self.bounds;
            NSBezierPath *line = [NSBezierPath bezierPathWithRoundedRect:
                                  NSMakeRect((NSWidth(r) / 2) - (self.widthOfLine / 2),
                                             (NSHeight(r) / 2) - self.innerMargin - self.lengthOfLine,
                                             self.widthOfLine, self.lengthOfLine)
                                                                 xRadius:self.widthOfLine / 2
                                                                 yRadius:self.widthOfLine / 2];

            void (^lineDrawingBlock)(NSUInteger line) =
            ^(NSUInteger lineNumber) {
                NSBezierPath *lineInstance = [line copy];
                lineInstance = [lineInstance it_rotatedBezierPath:((2 * M_PI) / self.numberOfLines * lineNumber) + M_PI
                                                       aboutPoint:NSMakePoint(NSWidth(r) / 2, NSHeight(r) / 2)];

                if (_isIndeterminate) [[self.color colorWithAlphaComponent:1.0 - (1.0 / self.numberOfLines * lineNumber)] set];

                [lineInstance fill];
            };

            if (!self.isIndeterminate) {
                for (NSUInteger i = self.numberOfLines;
                     i > round(self.numberOfLines - (self.numberOfLines * self.progress));
                     i--)
                {
                    lineDrawingBlock(i);
                }
            } else {
                for (NSUInteger i = 0; i < self.numberOfLines; i++) {
                    lineDrawingBlock(i);
                }
            }
        }
        [NSGraphicsContext restoreGraphicsState];
    }
    [progressImage unlockFocus];

    return progressImage;
}


#pragma mark - Helpers

- (CAKeyframeAnimation *)keyFrameAnimationForCurrentPreferences {
    NSMutableArray* keyFrameValues = [NSMutableArray array];
    NSMutableArray* keyTimeValues;

    if (self.steppedAnimation) {
        {
            [keyFrameValues addObject:[NSNumber numberWithFloat:0.0]];
            for (NSUInteger i = 0; i < self.numberOfLines; i++) {
                [keyFrameValues addObject:[NSNumber numberWithFloat:-M_PI * (2.0 / self.numberOfLines * i)]];
                [keyFrameValues addObject:[NSNumber numberWithFloat:-M_PI * (2.0 / self.numberOfLines * i)]];
            }
            [keyFrameValues addObject:[NSNumber numberWithFloat:-M_PI*2.0]];
        }

        keyTimeValues = [NSMutableArray array];
        {
            [keyTimeValues addObject:[NSNumber numberWithFloat:0.0]];
            for (NSUInteger i = 0; i < (self.numberOfLines - 1); i++) {
                [keyTimeValues addObject:[NSNumber numberWithFloat:1.0 / self.numberOfLines * i]];
                [keyTimeValues addObject:[NSNumber numberWithFloat:1.0 / self.numberOfLines * (i + 1)]];
            }
            [keyTimeValues addObject:[NSNumber numberWithFloat:1.0 / self.numberOfLines * (self.numberOfLines - 1)]];
        }
    } else {
        {
            [keyFrameValues addObject:[NSNumber numberWithFloat:-M_PI*0.0]];
            [keyFrameValues addObject:[NSNumber numberWithFloat:-M_PI*0.5]];
            [keyFrameValues addObject:[NSNumber numberWithFloat:-M_PI*1.0]];
            [keyFrameValues addObject:[NSNumber numberWithFloat:-M_PI*1.5]];
            [keyFrameValues addObject:[NSNumber numberWithFloat:-M_PI*2.0]];
        }
    }


    CAKeyframeAnimation* animation = [CAKeyframeAnimation animationWithKeyPath:@"transform"];

    [animation setRepeatCount:HUGE_VALF];
    [animation setValues:keyFrameValues];
    [animation setKeyTimes:keyTimeValues];
    [animation setValueFunction:[CAValueFunction functionWithName: kCAValueFunctionRotateZ]];
    [animation setDuration:self.animationDuration];

    return animation;
}

- (void)reloadVisibility {
    if (_hideWhenStopped && !_animates && _isIndeterminate) {
        [self setHidden:YES];
    } else {
        [self setHidden:NO];
    }
}


#pragma mark - NSView methods

// Animatible proxy
+ (id)defaultAnimationForKey:(NSString *)key
{
    if ([key isEqualToString:kITProgressPropertyKey]) {
        return [CABasicAnimation animation];
    } else {
        return [super defaultAnimationForKey:key];
    }
}


#pragma mark - Setters & Getters

- (void)setIndeterminate:(BOOL)isIndeterminate {
    _isIndeterminate = isIndeterminate;

    if (!_isIndeterminate) {
        self.animates = NO;
    }
}

- (void)setProgress:(CGFloat)progress {
    if (progress < 0 || progress > 1) {
        @throw [NSException exceptionWithName:@"Invalid `progress` property value"
                                       reason:@"`progress` property needs to be between 0 and 1"
                                     userInfo:nil];
    }

    _progress = progress;

    if (!self.isIndeterminate) {
        [self reloadIndicatorContent];
    }
}

- (void)setAnimates:(BOOL)animates {
    _animates = animates;
    [self reloadIndicatorContent];
    [self reloadAnimation];
    [self reloadVisibility];
}

- (void)setHideWhenStopped:(BOOL)hideWhenStopped {
    _hideWhenStopped = hideWhenStopped;
    [self reloadVisibility];
}

- (CALayer *)progressIndicatorLayer {
    if (!_progressIndicatorLayer) {
        _progressIndicatorLayer = [CALayer layer];
    }

    return _progressIndicatorLayer;
}

- (void)setLengthOfLine:(CGFloat)lengthOfLine {
    _lengthOfLine = lengthOfLine;
    [self reloadIndicatorContent];
}

- (void)setWidthOfLine:(CGFloat)widthOfLine {
    _widthOfLine = widthOfLine;
    [self reloadIndicatorContent];
}

- (void)setInnerMargin:(CGFloat)innerMargin {
    _innerMargin = innerMargin;
    [self reloadIndicatorContent];
}

- (void)setAnimationDuration:(CGFloat)animationDuration {
    _animationDuration = animationDuration;
    [self reloadAnimation];
}

- (void)setNumberOfLines:(NSUInteger)numberOfLines {
    _numberOfLines = numberOfLines;
    [self reloadIndicatorContent];
    [self reloadAnimation];
}

- (void)setSteppedAnimation:(BOOL)steppedAnimation {
    _steppedAnimation = steppedAnimation;
    [self reloadAnimation];
}

- (void)setColor:(NSColor *)color {
    _color = color;
    [self reloadIndicatorContent];
}

@end