在饼图中计算旋转角度 [英] Calculate angle for rotation in Pie Chart

问题描述

我想围绕它的中心点旋转图像。我面临的问题是我需要获得角度来计算触摸移动事件（我不想使用多点触控）。我目前使用下面的代码

I want to rotate the image around its center point.The problem i am facing is i need to get the angle to calculate in touch moved event (i dont want to use multi touch).I am current using the below code

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

NSArray *allTouches = [touches allObjects]; 
gestureStartPoint = gestureMovedPoint;//i am getting the gestureStartPoint on touch began event

gestureMovedPoint = [[allTouches objectAtIndex:0] locationInView:[self superview]];

NSLog(@"gestureMovedPoint = %@",NSStringFromCGPoint(gestureMovedPoint));

}

CGFloat previousAngle = [self angleBetweenPoints:gestureStartPoint second11:gestureMovedPoint]; // atan2(gestureMovedPoint.y - gestureStartPoint.y, gestureMovedPoint.x - gestureStartPoint.x) * 180 / M_PI;
CGFloat currentAngle =atan2(self.transform.b, self.transform.a);//atan2(gestureMovedPoint.y - gestureStartPoint.y,gestureMovedPoint.x - gestureStartPoint.x) * 180 / M_PI;



CGFloat angleToRotate = currentAngle - previousAngle;



float xpoint = (((atan2((gestureMovedPoint.x - gestureStartPoint.x) , (gestureMovedPoint.y - gestureStartPoint.y)))*180)/M_PI);

    CGAffineTransform transform = CGAffineTransformMakeRotation(angleToRotate-100);



self.transform = transform;

请帮助我找到解决方案因为我被困在这里需要很快完成这个应用程序是一条死路线。
提前致谢

Kindly help me find the solution as i am stuck here and need to complete this application very soon as there is a dead line. Thanks in advance

推荐答案

很高兴我记得三角法

-(void)degreesToRotateObjectWithPosition:(CGPoint)objPos andTouchPoint:(CGPoint)touchPoint{

   float dX = touchPoint.x-objPos.x;        // distance along X
   float dY = touchPoint.y-objPos.y;        // distance along Y
   float radians = atan2(dY, dX);          // tan = opp / adj

   //Now we have to convert radians to degrees:
   float degrees = radians*M_PI/360;

   return degrees;
}

一旦你有了不错的方法，只需在触摸事件方法中执行此操作。 （我忘了它的名字......）

Once you have your nice method, just do this in the touch event method. (I forgot what it's called...)

CGAffineTransform current = view.transform;

[view setTransform:CGAffineTransformRotate(current,
                 [self degreesTorotateObjectWithPosition:view.frame.origin 
                                  andTouchPoint:[touch locationInView:parentView]]

//Note: parentView = The view that your object to rotate is sitting in.

这几乎是你需要的所有代码。数学是正确的，但我不确定setTransform的东西。我在学校用浏览器写这个。你应该能够想到祝你好运。

This is pretty much all the code that you'll need.The math is right, but I'm not sure about the setTransform stuff. I'm at school writing this in a browser. You should be able to figure it out from here.

祝你好运，

Aurum Aquila

Aurum Aquila

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