iOS:用手指画一条线 [英] IOS: draw a line with your finger
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问题描述
我想知道在白色视图中用手指画一条线的方法。我想做一个画板,我想开始理解如何用手指画一条简单的线或轨迹。我该怎么办?
I want to know what's the approach to draw a line with a finger in a white view. I want to do an artboard, and I want begin to understand how draw a simple line or a track done with a finger. How can I do it?
推荐答案
我已经了解您的问题。
请参见下面的代码,它将完全为您使用。
I have understood your problem. Please see the bellow code.It will use full for you.
-(void)intializeDrawImage
{
drawImage = [[UIImageView alloc]initWithFrame:CGRectMake(0, 100, 320, 320)];
[drawImage setBackgroundColor:[UIColor purpleColor]];
[drawImage setUserInteractionEnabled:YES];
[self.view addSubview:drawImage];
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
NSLog(@"touchesBegan");
UITouch *touch = [touches anyObject];
CGPoint p = [touch locationInView:drawImage];
startPoint = p;
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
NSLog(@"touchesMoved");
UITouch *touch = [touches anyObject];
CGPoint p = [touch locationInView:drawImage];
[self drawLineFrom:startPoint endPoint:p];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
[self touchesMoved:touches withEvent:event];
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
[self touchesEnded:touches withEvent:event];
}
-(void)drawLineFrom:(CGPoint)from endPoint:(CGPoint)to
{
drawImage.image = [UIImage imageNamed:@""];
UIGraphicsBeginImageContext(drawImage.frame.size);
[drawImage.image drawInRect:CGRectMake(0, 0, drawImage.frame.size.width, drawImage.frame.size.height)];
[[UIColor greenColor] set];
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0f);
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), from.x, from.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), to.x , to.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
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