iOS 绘图

1.Quart2D绘图 绘图（CGcontext）

绘制简单的直线
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    CGContextMoveToPoint(ctx, 14, 19);
    CGContextAddLineToPoint(ctx, 45, 65);
    CGContextStrokePath(ctx);

2.贝塞尔曲线

绘制简单的直线
    UIBezierPath *linePath = [UIBezierPath bezierPath];
    [linePath moveToPoint:(CGPoint){20,20}];
    [linePath addLineToPoint:(CGPoint){160,160}];
    [linePath addLineToPoint:(CGPoint){200,20}];

3. 贝塞尔曲线 与 CGcontext 结合

   //使用贝塞尔曲线和图形上下文画图
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    UIBezierPath *path = [UIBezierPath bezierPath];
    [path moveToPoint:CGPointZero];
    [path addLineToPoint:CGPointMake(233, 69)];
   //这个是C语言的写法，必须使用path.CGPath，否则无效
    CGContextAddPath(ctx, path.CGPath);
    CGContextStrokePath(ctx);

4.贝塞尔曲线放在layer上

    UIBezierPath *linePath = [UIBezierPath bezierPath];
    [linePath moveToPoint:(CGPoint){20,20}];
    [linePath addLineToPoint:(CGPoint){160,160}];
    [linePath addLineToPoint:(CGPoint){200,20}];
    
    CAShapeLayer *layer = [CAShapeLayer layer];
    layer.frame = CGRectMake(0, 0, 200, 200);
    layer.position = (CGPoint){ScreenWidth/2,ScreenWidth/2};
    layer.lineWidth = 5;
    layer.strokeColor = [UIColor orangeColor].CGColor;
    layer.path = linePath.CGPath;
    layer.fillColor = nil; // 默认是黑色
    layer.lineCap = kCALineCapRound;
    
    [_disPlayView.layer addSublayer:layer];

5.将 （CGcontext） 绘制在image上面

    UIGraphicsBeginImageContextWithOptions(self.frame.size, NO, 0);
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    CGContextMoveToPoint(ctx, 14, 19);
    CGContextAddLineToPoint(ctx, 45, 65);
    CGContextStrokePath(ctx);
    image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

CGcontext API
UIGraphicsBeginImage 对图片的处理

Quart2D绘图之UIGraphicsGetCurrentContext基础