在iOS上的圆内绘制曲线矩形 [英] Draw a Curvilinear Rectangle inside a circle on iOS

问题描述

我正在尝试绘制一个分集轮（内部带有曲线矩形的圆），请参见：

I'm trying to draw a diversity wheel (a circle with curvilinear rectangles inside) see:

圆http://api.ning.com/files/oKZwndeqeam7%2aMiO7f4BDUT%2aAgw3WsK3kW- b-wXjR8gCrCqVAv3RpyBAdi％2adYSLaca0kAYCY0Wk13bSHDnEbOVR1NNUuYotV / diversity_wheel3.JPG？width = 500

我知道如何绘制圆，但是我不知道如何绘制圆基于圆坐标的曲线矩形。

I know how to draw a circle, but I don't know how to draw the curvilinear rectangle based on the circle coordinates.

我该怎么做？

推荐答案

因为您知道如何绘制圆，只需在其中心添加一些线，您将得到与发布的图像类似的图像：

Since you know how to draw circles, just add some lines to its center and you get something like the image you posted:

- (void)drawRect:(CGRect)rect
{
    CGPoint centerPoint = self.center;
    CGFloat circleWidth = 30;
    int numCircles = 4;

    [[UIColor colorWithHue:0.53 saturation:1 brightness:0.6 alpha:1] setStroke];

    CGContextRef ctx = UIGraphicsGetCurrentContext();
    for(int i=numCircles-1;i>=0;i--){
        //calculate some color
        CGFloat colorModifier = ((numCircles-i)/(float)numCircles);
        [[UIColor colorWithHue:0.53 saturation:colorModifier*0.8+0.2 brightness:1-colorModifier*0.4 alpha:1] setFill];

        CGFloat radius = circleWidth*(i+1);

        //draw the circle
        CGContextFillEllipseInRect(ctx, CGRectMake(centerPoint.x-radius, centerPoint.y-radius, 2*radius, 2*radius));
        CGContextStrokeEllipseInRect(ctx, CGRectMake(centerPoint.x-radius, centerPoint.y-radius, 2*radius, 2*radius));

        if(i>0){
            //just add a random number of dividers here
            int numDivider = 3+(arc4random()%5);
            float angleStep = 2*M_PI/numDivider;
            for(int j=0;j<numDivider;j++){
                CGFloat x = centerPoint.x + sinf(j*angleStep)*radius;
                CGFloat y = centerPoint.y + cosf(j*angleStep)*radius;
                CGContextMoveToPoint(ctx, centerPoint.x, centerPoint.y);
                CGContextAddLineToPoint(ctx, x, y);
                CGContextStrokePath(ctx);
            }
        }
    }
}

A仅绘制单个弯曲矩形的可能性是绘制圆弧并擦除内部圆。像这样：

A possibility to just draw a single curved rectangle would be to draw an arc and erase an inner circle. Like this:

    UIBezierPath *path = [UIBezierPath bezierPath];
    [path moveToPoint:self.center];
    [path addArcWithCenter:self.center radius:150 startAngle:-0.3 endAngle:0.3 clockwise:YES];
    [path fill];

    UIBezierPath *innerPath = [UIBezierPath bezierPath];
    [innerPath moveToPoint:self.center];
    [innerPath addArcWithCenter:self.center radius:120 startAngle:0 endAngle:2*M_PI clockwise:YES];
    CGContextSetBlendMode(UIGraphicsGetCurrentContext(), kCGBlendModeClear);
    [innerPath fill];

这篇关于在iOS上的圆内绘制曲线矩形的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！