UIImageView旋转动画在触摸方向

Question

我有一个UIImageView有一个箭头的图像。当用户点击UIView时，这个箭头应该指向水龙头保持其位置的方向，它应该改变变换。我已经实现了以下代码。但它没有按预期工作。我添加了一个截图。在这个屏幕截图中，当我触摸左上方的点时，箭头方向应该如图所示。但它不会发生。

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

UITouch *touch=[[event allTouches]anyObject]; 
touchedPoint= [touch locationInView:touch.view]; 
imageViews.transform = CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(rangle11)); 
previousTouchedPoint = touchedPoint ; 
} 

- (CGFloat) pointPairToBearingDegrees:(CGPoint)startingPoint secondPoint:(CGPoint) endingPoint 
{ 

CGPoint originPoint = CGPointMake(endingPoint.x - startingPoint.x, endingPoint.y - startingPoint.y); // get origin point to origin by subtracting end from start 
    float bearingRadians = atan2f(originPoint.y, originPoint.x); // get bearing in radians 
float bearingDegrees = bearingRadians * (180.0/M_PI); // convert to degrees 
bearingDegrees = (bearingDegrees > 0.0 ? bearingDegrees : (360.0 + bearingDegrees)); // correct discontinuity 
return bearingDegrees; 
} 

Answer 1

我假设你想要一个箭头图像指向你触摸的地方，我试过了，这是我能想出来的。我用一个向上的箭头（没有尝试从任何其他位置开始尝试，日志给出正确的角度）放置图像视图，并在它旋转的不同位置触摸并指向触摸位置。希望它可以帮助（尝试了一些旧的数学:-)）

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

    UITouch *touch=[[event allTouches]anyObject]; 
    touchedPoint= [touch locationInView:touch.view]; 
    CGFloat angle = [self getAngle:touchedPoint]; 
    imageView.transform = CGAffineTransformMakeRotation(angle); 

} 

-(CGFloat) getAngle: (CGPoint) touchedPoints 
{ 
    CGFloat x1 = imageView.center.x; 
    CGFloat y1 = imageView.center.y; 

    CGFloat x2 = touchedPoints.x; 
    CGFloat y2 = touchedPoints.y; 

    CGFloat x3 = x1; 
    CGFloat y3 = y2; 

    CGFloat oppSide = sqrtf(((x2-x3)*(x2-x3)) + ((y2-y3)*(y2-y3))); 
    CGFloat adjSide = sqrtf(((x1-x3)*(x1-x3)) + ((y1-y3)*(y1-y3))); 

    CGFloat angle = atanf(oppSide/adjSide); 
    // Quadrant Identifiaction 
    if(x2 < imageView.center.x) 
    { 
     angle = 0-angle; 
    } 


    if(y2 > imageView.center.y) 
    { 
     angle = M_PI/2 + (M_PI/2 -angle); 
    } 
    NSLog(@"Angle is %2f",angle*180/M_PI); 
    return angle; 

} 

-anoop4real

Answer 2

鉴于你告诉我，我认为这个问题是你是不是重置您在touchesBegan变换。尝试改变它到这样的事情，看看它是否更好地工作：

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

UITouch *touch=[[event allTouches]anyObject]; 
touchedPoint= [touch locationInView:touch.view]; 
imageViews.transform = CGAffineTransformIdentity; 
imageViews.transform = CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(rangle11)); 
previousTouchedPoint = touchedPoint ; 
} 

Answer 3

你是否需要行“去除不连续性”？似乎atan2f()返回+π到-π之间的值。那些不会直接使用CATransform3DMakeRotation()？

Answer 4

你需要的是箭头指向最后一个点击点。为了简化和测试，我使用了轻敲手势（但它与touchBegan类似：withEvent :)。

在viewDidLoad方法，我注册的手势：

 
- (void)tapped:(UITapGestureRecognizer *)gesture 
{ 
    CGPoint imageCenter = mFlecheImageView.center; 
    CGPoint tapPoint = [gesture locationInView:self.view]; 

    double deltaY = tapPoint.y - imageCenter.y; 
    double deltaX = tapPoint.x - imageCenter.x; 
    double angleInRadians = atan2(deltaY, deltaX) + M_PI_2; 

    mFlecheImageView.transform = CGAffineTransformMakeRotation(angleInRadians); 
} 

一个关键是+ M_PI_2因为UIKit的坐标具有在左上角的原点：

 
UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapped:)]; 
[self.view addGestureRecognizer:tapGesture]; 
[tapGesture release]; 

呼吁每个抽头的方法拐角（在三角函数中，我们使用左下角）。