ios - 根据百分比用渐变颜色填充圆环。

Question

寻找我的问题的解决方案，我必须在环中填充颜色。我可以用我的代码在环中填充颜色，但我遇到了一些问题

1. 使用此代码我无法找到如何在圆圈中填充所需的颜色量，即 20%、40%、70% 等。

2. 当我赋予渐变色时，它与图像中显示的不一样。

我正在使用的代码:

 int radius = 130;

CAShapeLayer *arc = [CAShapeLayer layer];
arc.path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(100,0) radius:radius startAngle:39.8 endAngle:19.9 clockwise:YES].CGPath;

arc.position = CGPointMake(CGRectGetMidX(self.frame)-radius,
                           CGRectGetMidY(self.frame)-radius);

arc.fillColor = [UIColor clearColor].CGColor;
arc.strokeColor = [UIColor redColor].CGColor;
arc.lineWidth = 25;
CABasicAnimation *drawAnimation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];
drawAnimation.duration            = 5.0; // "animate over 10 seconds or so.."
drawAnimation.repeatCount         = 1.0;  // Animate only once..
drawAnimation.removedOnCompletion = NO;   // Remain stroked after the animation..
drawAnimation.fromValue = [NSNumber numberWithFloat:0.0f];
drawAnimation.toValue   = [NSNumber numberWithFloat:100.0f];
drawAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
[arc addAnimation:drawAnimation forKey:@"drawCircleAnimation"];

CAGradientLayer *gradientLayer = [CAGradientLayer layer];
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
UIColor *gradientColor = [UIColor colorWithRed:0.51 green:0.0 blue:0.49 alpha:1.0];

NSArray *gradientColors = [NSArray arrayWithObjects:
                           (id)[UIColor blueColor].CGColor,
                           (id)gradientColor.CGColor,
                           (id)[UIColor redColor].CGColor, nil];
CGFloat gradientLocations[] = {0, 0.5, 1};
CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (CFArrayRef)gradientColors, gradientLocations);

gradientLayer.colors = (__bridge NSArray *)(gradient);

gradientLayer.startPoint = CGPointMake(0.0,0.7);
gradientLayer.endPoint = CGPointMake(1,-0.1);
[self.layer addSublayer:gradientLayer];
gradientLayer.mask = arc;

重要:颜色必须如图所示

我正在为这个问题寻找非常特殊的答案。

在此先感谢所有有时间调查此事的人。

Answer 1

要用颜色填充一定量的圆圈，您必须在填充层的顶部绘制轮廓并仅剪裁填充层。

为了使渐变跟随圆，你必须将它分成多个分段线性的渐变。由于您提供的图形已经有一些带有轮廓的部分，我们可以使用这些轮廓来隐藏连接不同渐变的任何缺陷。

我举了一个例子，如果你想更好地控制颜色，你可以在 CircleGradientLayer 中为每个段设置它们。通过设置 CircleProgressView 的 progress 属性来控制绘制进度。

如果您在此处看到我的回答:https://stackoverflow.com/a/24580817/3659846，使用两个圆圈和一些线条可以更轻松地绘制轮廓。但是在编写这段代码时，复制和粘贴速度更快；)

.h 文件中没有什么特别的，只是插入编译器想要的内容，我在这里只发布 .m:

CircleProgressView

@implementation CircleProgressView{
    CircleGradientLayer *_gradientLayer;
    CircleOutlineLayer *_outlineLayer;
}

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.backgroundColor = [UIColor clearColor];

        int numSegments = 7;
        CGFloat circleRadius = 130;
        CGFloat circleWidth = 30;

        NSDictionary *circleData = @{
                                    @"numberOfSegments":@(numSegments),
                                    @"circleRadius":@(circleRadius),
                                    @"circleWidth":@(circleWidth)
                                    };

        _gradientLayer = [CircleGradientLayer layer];
        _gradientLayer.contentsScale = 2;
        _gradientLayer.frame = self.bounds;
        [_gradientLayer setCircleData:circleData];
        [_gradientLayer setNeedsDisplay];
        [self.layer addSublayer:_gradientLayer];

        _outlineLayer = [CircleOutlineLayer layer];
        _outlineLayer.frame = self.bounds;
        _outlineLayer.contentsScale = 2;
        [_outlineLayer setCircleData:circleData];
        [_outlineLayer setNeedsDisplay];
        [self.layer addSublayer:_outlineLayer];

        self.progress = 1;
    }
    return self;
}

- (void)setProgress:(CGFloat)progress{
    _progress = MAX(0, MIN(1, progress));
    _gradientLayer.progress = progress;
}

@end

圆形渐变图层

@implementation CircleGradientLayer{
    int _numSegments;
    CGFloat _circleRadius;
    CGFloat _circleWidth;

    CAShapeLayer *_maskLayer;
}

+(id)layer{
    CircleGradientLayer *layer = [[CircleGradientLayer alloc] init];
    return layer;
}

-(void)setCircleData:(NSDictionary*)data{
    _numSegments = [data[@"numberOfSegments"] intValue];
    _circleRadius = [data[@"circleRadius"] doubleValue];
    _circleWidth = [data[@"circleWidth"] doubleValue];

    [self createMask];
}

- (void)createMask{
    _maskLayer = [CAShapeLayer layer];
    _maskLayer.frame = self.bounds;

    CGFloat angleStep = 2*M_PI/(_numSegments+1);
    CGFloat startAngle = angleStep/2 + M_PI_2;
    CGFloat endAngle = startAngle+_numSegments*angleStep+0.005; //add a bit that the outline is not clipped

    _maskLayer.path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(CGRectGetMidX(self.bounds), CGRectGetMidY(self.bounds)) radius:_circleRadius startAngle:startAngle endAngle:endAngle clockwise:YES].CGPath;
    _maskLayer.fillColor = [UIColor clearColor].CGColor;
    _maskLayer.strokeColor = [UIColor redColor].CGColor;
    _maskLayer.lineWidth = 2*_circleWidth+2; //stroke is centered -> *2 to cover all

    self.mask = _maskLayer;
}

- (void)setProgress:(CGFloat)progress{
    _progress = MAX(0, MIN(1, progress));
    _maskLayer.strokeEnd = _progress;
}

-(void)drawInContext:(CGContextRef)ctx{
   // would get better gradient joints by not using antialias, but since they are hidden, it is not needed to adjust it     
   // CGContextSetAllowsAntialiasing(ctx, NO);

    UIGraphicsPushContext(ctx);

    //some values to adjust the circle
    UIColor *startColor = [UIColor colorWithRed:1 green:0 blue:21/255. alpha:1];
    UIColor *endColor = [UIColor colorWithRed:0 green:180/255. blue:35/255. alpha:1];

    CGPoint centerPoint = CGPointMake(CGRectGetMidX(self.bounds), CGRectGetMidY(self.bounds));

    //calculate startAngle and the increment between segements
    CGFloat angleStep = 2*M_PI/(_numSegments+1);
    CGFloat startAngle = angleStep/2 + M_PI_2;

    //convert colors to hsv
    CGFloat startHue,startSat,startBrightness,startAlpha;
    CGFloat endHue,endSat,endBrightness,endAlpha;
    [startColor getHue:&startHue saturation:&startSat brightness:&startBrightness alpha:&startAlpha];
    [endColor getHue:&endHue saturation:&endSat brightness:&endBrightness alpha:&endAlpha];
    if(endHue<startHue)
        endHue+=1;


    //draw the segments
    for(int i=0;i<_numSegments;i++){
        //calcualte segment startColor
        CGFloat hue = startHue+((endHue-startHue)*i)/_numSegments;
        if(hue>1)
            hue-=1;

        CGFloat brightness = startBrightness+((endBrightness-startBrightness)*i)/(_numSegments);
        if(_numSegments==7){
            //just increasing the brighness a bit to get more yellow like on your picture ;)
            brightness = i>3?startBrightness+((endBrightness-startBrightness)*(i-4))/(_numSegments-4):startBrightness;
        }
        UIColor *fromColor = [UIColor colorWithHue:hue saturation:startSat+((endSat-startSat)*i)/_numSegments brightness:brightness alpha:startAlpha+((endAlpha-startAlpha)*i)/_numSegments];

        //calculate segement endColor
        hue = startHue+((endHue-startHue)*(i+1))/_numSegments;
        if(hue>1)
            hue-=1;
        brightness = startBrightness+((endBrightness-startBrightness)*i)/(_numSegments);
        if(_numSegments==7){
            brightness = i>3?startBrightness+((endBrightness-startBrightness)*(i-3))/(_numSegments-4):startBrightness;
        }

        UIColor *toColor = [UIColor colorWithHue:hue saturation:startSat+((endSat-startSat)*(i+1))/_numSegments brightness:brightness alpha:startAlpha+((endAlpha-startAlpha)*(i+1))/_numSegments];

        //actually draw the segment
        [self drawSegmentAtCenter:centerPoint from:startAngle to:startAngle+angleStep radius:_circleRadius width:_circleWidth startColor:fromColor endColor:toColor];

        startAngle+=angleStep;
    }

    //start clearing the inside
    CGContextSetBlendMode(UIGraphicsGetCurrentContext(), kCGBlendModeClear);

    UIBezierPath* innerPath = [UIBezierPath bezierPath];
    [innerPath moveToPoint:centerPoint];
    [innerPath addArcWithCenter:centerPoint radius:_circleRadius-_circleWidth-0.5 startAngle:0 endAngle:2*M_PI clockwise:YES];
    [innerPath fill];
}

- (void)drawSegmentAtCenter:(CGPoint)center from:(CGFloat)startAngle to:(CGFloat)endAngle radius:(CGFloat)radius width:(CGFloat)width startColor:(UIColor *)startColor endColor:(UIColor*)endColor{

    CGContextSaveGState(UIGraphicsGetCurrentContext());

    //apply a clip arc for the gradient
    UIBezierPath *path = [UIBezierPath bezierPath];
    [path moveToPoint:center];
    [path addArcWithCenter:center radius:radius startAngle:startAngle endAngle:endAngle clockwise:YES];
    [path addClip];


    //draw the gradient
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGFloat locations[] = { 0.0, 1.0 };
    NSArray *colors = @[(__bridge id) startColor.CGColor, (__bridge id) endColor.CGColor];
    CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (__bridge CFArrayRef) colors, locations);

    CGPoint startPoint = CGPointMake(center.x-sinf(startAngle-M_PI_2)*radius, center.y+cosf(startAngle-M_PI_2)*radius);
    CGPoint endPoint = CGPointMake(center.x-sinf(endAngle-M_PI_2)*radius, center.y+cosf(endAngle-M_PI_2)*radius);
    CGContextDrawLinearGradient(UIGraphicsGetCurrentContext(), gradient, startPoint, endPoint, kCGGradientDrawsAfterEndLocation|kCGGradientDrawsBeforeStartLocation);

    CGGradientRelease(gradient);
    CGColorSpaceRelease(colorSpace);

    CGContextRestoreGState(UIGraphicsGetCurrentContext());
}

@end

圆形轮廓图层

@implementation CircleOutlineLayer{
    int _numSegments;
    CGFloat _circleradius;
    CGFloat _circlewidth;    
}

+(id)layer{
    CircleOutlineLayer *layer = [[CircleOutlineLayer alloc] init];
    return layer;
}

-(void)setCircleData:(NSDictionary*)data{
    _numSegments = [data[@"numberOfSegments"] intValue];
    _circleradius = [data[@"circleRadius"] doubleValue];
    _circlewidth = [data[@"circleWidth"] doubleValue];
}

-(void)drawInContext:(CGContextRef)ctx{
    UIGraphicsPushContext(ctx);

    //some values to adjust the circle
    [[UIColor colorWithWhite:130/255. alpha:1] setStroke]; //the outline color

    CGPoint centerPoint = CGPointMake(CGRectGetMidX(self.bounds), CGRectGetMidY(self.bounds));

    //calculate startAngle and the increment between segements
    CGFloat angleStep = 2*M_PI/(_numSegments+1);
    CGFloat startAngle = angleStep/2 + M_PI_2;

    //draw the segments
    for(int i=0;i<_numSegments;i++){
         //actually draw the segment
        [self drawSegmentAtCenter:centerPoint from:startAngle to:startAngle+angleStep radius:_circleradius width:_circlewidth doFill:NO];

        startAngle+=angleStep;
    }

    //draw an inner outline
    UIBezierPath *innerPath = [UIBezierPath bezierPath];
    [innerPath moveToPoint:centerPoint];
    [innerPath addArcWithCenter:centerPoint radius:_circleradius-_circlewidth startAngle:0 endAngle:2*M_PI clockwise:YES];
    [innerPath stroke];


    //start clearing the inside
    CGContextSetBlendMode(UIGraphicsGetCurrentContext(), kCGBlendModeClear);

    innerPath = [UIBezierPath bezierPath];
    [innerPath moveToPoint:centerPoint];
    [innerPath addArcWithCenter:centerPoint radius:_circleradius-_circlewidth-0.5 startAngle:0 endAngle:2*M_PI clockwise:YES];
    [innerPath fill];

    //also clear a whole segment at the bottom to get rid of the inner outline
    [self drawSegmentAtCenter:centerPoint from:-angleStep/2 + M_PI_2 to:angleStep/2+M_PI_2 radius:_circleradius width:_circlewidth doFill:YES];


    //redraw the outlines at begin and end of circle since beginning was just cleared and end-outline hasn't been drawed
    CGContextSetBlendMode(UIGraphicsGetCurrentContext(), kCGBlendModeNormal);

    CGPoint startPoint = CGPointMake(centerPoint.x+sinf(-angleStep/2)*(_circleradius), centerPoint.y+cosf(-angleStep/2)*(_circleradius));
    CGPoint endPoint = CGPointMake(centerPoint.x+sinf(-angleStep/2)*(_circleradius-_circlewidth), centerPoint.y+cosf(-angleStep/2)*(_circleradius-_circlewidth));
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 1);
    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), startPoint.x, startPoint.y);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), endPoint.x,endPoint.y);
    CGContextStrokePath(UIGraphicsGetCurrentContext());

    startPoint = CGPointMake(centerPoint.x+sinf(angleStep/2)*(_circleradius), centerPoint.y+cosf(angleStep/2)*(_circleradius));
    endPoint = CGPointMake(centerPoint.x+sinf(angleStep/2)*(_circleradius-_circlewidth), centerPoint.y+cosf(angleStep/2)*(_circleradius-_circlewidth));
    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), startPoint.x, startPoint.y);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), endPoint.x, endPoint.y);
    CGContextStrokePath(UIGraphicsGetCurrentContext());
}

- (void)drawSegmentAtCenter:(CGPoint)center from:(CGFloat)startAngle to:(CGFloat)endAngle radius:(CGFloat)radius width:(CGFloat)width doFill:(BOOL)fill{

    UIBezierPath *path = [UIBezierPath bezierPath];
    [path moveToPoint:center];
    [path addArcWithCenter:center radius:radius startAngle:startAngle endAngle:endAngle clockwise:YES];
    if(fill)
        [path fill];
    [path stroke];

}

@end