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我是iPhone开发新手，

我正在制作一个应用程序，在该应用程序中我试图制作一条笔直的线，这样它就没有任何不规则的曲线，它必须是平滑的

我使用了核心图形，但它似乎不起作用。

屏幕截图 我只想用 UITouch 使这些以红色绘制的线条笔直。

我应该去openGl吗？

如果是，我该如何实施。

  drawImage = [[UIImageView alloc] initWithImage:nil];
drawImage.frame = viewField.frame;
[self.view addSubview:drawImage];
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

mouseSwiped = NO;
UITouch *touch = [touches anyObject];

if ([touch tapCount] == 2) {
    drawImage.image = nil;
    return;
}

lastPoint = [touch locationInView:viewField];
//lastPoint.y = 20;

}


- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
mouseSwiped = YES;
UITouch *touch = [touches anyObject];    
CGPoint currentPoint = [touch locationInView:viewField];
//currentPoint.y -= 20; // only for 'kCGLineCapRound'
UIGraphicsBeginImageContext(viewField.frame.size);
//Albert Renshaw - Apps4Life
[drawImage.image drawInRect:CGRectMake(0, 0, drawImage.frame.size.width, drawImage.frame.size.height)]; //originally self.frame.size.width, self.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound); //kCGLineCapSquare, kCGLineCapButt, kCGLineCapRound
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0); // for size
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0); //values for R, G, B, and Alpha
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

lastPoint = currentPoint;    
   }

 - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {

  UITouch *touch = [touches anyObject];

  if ([touch tapCount] == 2) {
    drawImage.image = nil;
    return;
  }
  if(!mouseSwiped) {
    //if color == green
    UIGraphicsBeginImageContext(viewField.frame.size);
    [drawImage.image drawInRect:CGRectMake(0, 0, drawImage.frame.size.width,   drawImage.frame.size.height)]; //originally self.frame.size.width, self.frame.size.height)];
    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);   //kCGLineCapSquare, kCGLineCapButt, kCGLineCapRound
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
    CGContextStrokePath(UIGraphicsGetCurrentContext());
    CGContextFlush(UIGraphicsGetCurrentContext());
    drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
   }
   }

提前致谢 ！

4

1 回答 1

0

从你发布的图片来看，我建议你改变你的方法。双击开始绘制。然后在多边形中的每个边缘点上点击（= touchesStarted 和 touchesEnded，而不是 touchesMoved）。在这些点之间画一条直线。双击结束多边形。如果终点距离起点足够近，您可以决定自动关闭路径。

于 2012-11-23T19:59:03.713 回答