只绘制直线不平滑

Question

 -(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
mouseSwiped = YES;

UITouch *touch = [touches anyObject];   
CGPoint currentPoint = [touch locationInView:scrollView];

//[self drawLine:lastPoint.x :lastPoint.y :currentPoint.x :currentPoint.y]; 
tempShapeLayer = nil;
CGMutablePathRef linePath = nil;
linePath = CGPathCreateMutable();
tempShapeLayer = [CAShapeLayer layer];

tempShapeLayer.lineWidth = 4.0f;
tempShapeLayer.lineCap = kCALineJoinMiter;
tempShapeLayer.strokeColor = [[UIColor redColor] CGColor];


CGPathMoveToPoint(linePath, NULL, lastPoint.x, lastPoint.y);
CGPathAddLineToPoint(linePath, NULL, currentPoint.x, currentPoint.y);


tempShapeLayer.path = linePath;
CGPathRelease(linePath);

[scrollView.layer addSublayer:tempShapeLayer];

lastPoint = currentPoint;

}

我正在通过此代码绘制线条。但我希望这条线保持平直。意思是当我移动触摸时，线条不应变得平滑。线条将保持笔直。

我想我必须做一些像

这样的事情

  if (currentPoint.x > lastPoint.x){        
    currentPoint.y = lastPoint.y;
} 
else if (currentPoint.x < lastPoint.x) {
    currentPoint.x = lastPoint.x;
}

Answer 1

如果您要移动子像素，您将获得不需要的抗锯齿。我建议地板/ ceil到非浮动。当使用视网膜与非视网膜时，这显然变得更加复杂。