Ios 限制平移手势移动到90度
如果我为图中所示的ex.创建了一条线,通过Ios 限制平移手势移动到90度,ios,objective-c,line,uibezierpath,cashapelayer,Ios,Objective C,Line,Uibezierpath,Cashapelayer,如果我为图中所示的ex.创建了一条线,通过CAShapeLayer连接a和B,并且在该线的中心有一个集成了平移手势的UIView 如何使该UIView移动到与该线成90度角的特定方向,如图所示,红线表示UIView可以移动的方向 中点应从直线中心开始移动,移动方向如我更新的图所示 我想你可以处理这个锅,并且你可以得到接触点。您需要的是计算接触点到红线的投影,并将UIView放置在那里 红线垂直于AB,由AB的中点组成 // //when the pan gesture recognizer re
CAShapeLayer
连接a和B,并且在该线的中心有一个集成了平移手势的UIView
如何使该UIView
移动到与该线成90度角的特定方向,如图所示,红线表示UIView
可以移动的方向
中点应从直线中心开始移动,移动方向如我更新的图所示
我想你可以处理这个锅,并且你可以得到接触点。您需要的是计算接触点到红线的投影,并将UIView放置在那里 红线垂直于AB,由AB的中点组成
//
//when the pan gesture recognizer reports state change event
/*you have
CGPoint A;
CGPoint B;
CGPoint T; //touch point
*/
//midpoint
CGPoint M = {(A.x+B.x)/2, (A.y+B.y)/2};
//AB distance
CGFloat distAB = sqrtf(powf(B.x-A.x, 2) + powf(B.y-A.y, 2));
//direction of the red line with unit length
CGVector v = {(B.y-A.y)/distAB, -(B.x-A.x)/distAB};
// vector from midpoint to touch point
CGVector MT = {T.x-M.x, T.y-M.y};
// dot product of v and MT
// which is the signed distance of the projected point from M
CGFloat c = v.dx*MT.dx + v.dy*MT.dy;
// projected point is M + c*v
CGPoint projectedPoint = {M.x + c*v.dx, M.y + c*v.dy};
//TODO: set the center of the moving UIView to projectedPoint
更新:
您的评论表明,您对该解决方案的使用还不够清楚。因此,我将这个想法嵌入到一个工作示例中
@interface ViewController ()
@end
@implementation ViewController {
CGPoint A;
CGPoint B;
CGPoint M; //midpoint of AB
CGVector v; //direction of the red line with unit length
UIView* pointMover;
}
- (void)viewDidLoad {
[super viewDidLoad];
A = CGPointMake(50,50);
B = CGPointMake(300,200);
M = CGPointMake((A.x+B.x)/2, (A.y+B.y)/2);
CGFloat distAB = sqrtf(powf(B.x-A.x, 2) + powf(B.y-A.y, 2));
v = CGVectorMake((B.y-A.y)/distAB, -(B.x-A.x)/distAB);
pointMover = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 44, 44)];
pointMover.center = M;
pointMover.backgroundColor = [UIColor blueColor];
pointMover.layer.cornerRadius = 22.0f;
[self.view addSubview:pointMover];
UIPanGestureRecognizer* panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)];
[pointMover addGestureRecognizer:panRecognizer];
UIBezierPath* blackLinePath = [UIBezierPath bezierPath];
[blackLinePath moveToPoint:A];
[blackLinePath addLineToPoint:B];
CAShapeLayer *blackLineLayer = [CAShapeLayer layer];
blackLineLayer.path = [blackLinePath CGPath];
blackLineLayer.strokeColor = [[UIColor blackColor] CGColor];
blackLineLayer.lineWidth = 2.0;
[self.view.layer addSublayer:blackLineLayer];
}
- (void)handlePan:(UIPanGestureRecognizer*)recognizer {
//touch point
CGPoint T = [recognizer locationInView:self.view];
// vector from midpoint to touch point
CGVector MT = {T.x-M.x, T.y-M.y};
// dot product of v and MT
CGFloat c = v.dx*MT.dx + v.dy*MT.dy;
// projected point is M + c*v
CGPoint projectedPoint = {M.x + c*v.dx, M.y + c*v.dy};
pointMover.center = projectedPoint;
}
@end
可能您误解了我的担忧,该点应该从线的中间开始移动,您可以在更新的问题中看到。此外,当用户将中点放在某个点上并再次开始重新定位时,则仅从该点开始,而不是从中点的中心开始。