二维绘图引擎：圆半圆弧线绘制

Posted 2020-09-30 mfmdaoyou

二维画图引擎-画圆、半圆、弧线

//
//  QHCircle.m
//  绘图
//

#import "QHCircle.h"

@implementation QHCircle


// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
/**
 *  当View第一次显示的时候调用
 *
 *  @param rect
 */

- (void)drawRect:(CGRect)rect {
    // Drawing code
    
    //仅仅会调一次
    
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    
    //2.画1/4圆

    CGContextMoveToPoint(ctx, 100, 100);
    
    CGContextAddLineToPoint(ctx, 100, 150);
    
    CGContextAddArc(ctx, 100, 100, 50, -M_PI_2, M_PI, 1);
    
    CGContextClosePath(ctx);
    
    [[UIColor redColor]set];
    
    CGContextFillPath(ctx);
    
    drawArc();
    drawCircle();
    
}


void drawArc()
{
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    // 2.画圆弧
    // x\y : 圆心
    // radius : 半径
    // startAngle : 開始角度
    // endAngle : 结束角度
    // clockwise : 圆弧的伸展方向(0:顺时针, 1:逆时针)
    CGContextAddArc(ctx, 100, 100, 50, M_PI_2, M_PI, 0);
    
    CGContextFillPath(ctx);
}

void drawCircle()
{
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    
    //画圆
    CGContextAddEllipseInRect(ctx, CGRectMake(50, 10, 100, 100));
    
    CGContextSetLineWidth(ctx, 10);
    
    CGContextStrokePath(ctx);
}
@end