UIImageView 触摸方向旋转动画

Question

我有一个带有箭头图像的 UIImageView。当用户点击 UIView 时，这个箭头应该指向点击的方向，保持它的位置，它应该只是改变变换。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。在此屏幕截图中，当我触摸左上角时，箭头方向应如图所示。但事实并非如此。

-(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来指向你触摸的地方，我试过了，这就是我能想到的。我放置了一个带有向上箭头的图像视图（没有尝试从任何其他位置开始，日志给出正确的角度）并且在触摸不同位置时它会旋转并指向触摸位置。希望它有所帮助（尝试了一些旧数学:-)）

-(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

鉴于你告诉我的，我认为问题在于你没有在touchesBegan 中重置你的转换。试着把它改成这样，看看效果是否更好：

-(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

您需要这条线来“消除不连续性”吗？似乎 atan2f() 返回 +π 到 -π 之间的值。这些不会直接与CATransform3DMakeRotation()一起工作吗？

Answer 4

您需要的是箭头指向最后点击的点。为了简化和测试，我使用了轻击手势（但它类似于 touchBegan:withEvent:)。

在 viewDidLoad 方法中，我注册了手势：

UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapped:)]; [self.view addGestureRecognizer:tapGesture]; [点击手势释放]；

每次点击时调用的方法：

- (void)tapped:(UITapGestureRecognizer *)gesture { CGPoint imageCenter = mFlecheImageView.center; CGPoint tapPoint = [手势 locationInView:self.view]; 双 deltaY = tapPoint.y - imageCenter.y; 双 deltaX = tapPoint.x - imageCenter.x; 双角弧度 = atan2(deltaY, deltaX) + M_PI_2; mFlecheImageView.transform = CGAffineTransformMakeRotation(angleInRadians); }

一个键是+ M_PI_2，因为 UIKit 坐标的原点位于左上角（而在三角函数中，我们使用左下角）。