我使用 CGAffineTransform
旋转我的视图
[view setTransform:newTransform];
应用变换后,框架的值保持不变,但我该如何找到这个框架的“旋转”或变换后的值?
(来源: informit.com)
我想要旋转框架边缘的精确坐标,也就是a、b、c、d点。
我使用 CGAffineTransform
旋转我的视图
[view setTransform:newTransform];
应用变换后,框架的值保持不变,但我该如何找到这个框架的“旋转”或变换后的值?
(来源: informit.com)
我想要旋转框架边缘的精确坐标,也就是a、b、c、d点。
需要记住的一件事是,变换会改变坐标系,因此您需要能够在父“视图”和子(经过变换的)视图之间进行转换。此外,变换会保留变换对象的中心,但不保留任何其他坐标。因此,您需要以中心为基础计算。您还需要使用几个辅助方法。(我大多数采用这个方法是从Erica Sadun的书《Core iOS Developer's Cookbook》中得来的。)
我通常将它们添加为UIView的一个类别。
为了将子视图的坐标转换为父视图的坐标,您需要类似以下代码:
// helper to get pre transform frame
-(CGRect)originalFrame {
CGAffineTransform currentTransform = self.transform;
self.transform = CGAffineTransformIdentity;
CGRect originalFrame = self.frame;
self.transform = currentTransform;
return originalFrame;
}
// helper to get point offset from center
-(CGPoint)centerOffset:(CGPoint)thePoint {
return CGPointMake(thePoint.x - self.center.x, thePoint.y - self.center.y);
}
// helper to get point back relative to center
-(CGPoint)pointRelativeToCenter:(CGPoint)thePoint {
return CGPointMake(thePoint.x + self.center.x, thePoint.y + self.center.y);
}
// helper to get point relative to transformed coords
-(CGPoint)newPointInView:(CGPoint)thePoint {
// get offset from center
CGPoint offset = [self centerOffset:thePoint];
// get transformed point
CGPoint transformedPoint = CGPointApplyAffineTransform(offset, self.transform);
// make relative to center
return [self pointRelativeToCenter:transformedPoint];
}
// now get your corners
-(CGPoint)newTopLeft {
CGRect frame = [self originalFrame];
return [self newPointInView:frame.origin];
}
-(CGPoint)newTopRight {
CGRect frame = [self originalFrame];
CGPoint point = frame.origin;
point.x += frame.size.width;
return [self newPointInView:point];
}
-(CGPoint)newBottomLeft {
CGRect frame = [self originalFrame];
CGPoint point = frame.origin;
point.y += frame.size.height;
return [self newPointInView:point];
}
-(CGPoint)newBottomRight {
CGRect frame = [self originalFrame];
CGPoint point = frame.origin;
point.x += frame.size.width;
point.y += frame.size.height;
return [self newPointInView:point];
}
Swift 4
extension UIView {
/// Helper to get pre transform frame
var originalFrame: CGRect {
let currentTransform = transform
transform = .identity
let originalFrame = frame
transform = currentTransform
return originalFrame
}
/// Helper to get point offset from center
func centerOffset(_ point: CGPoint) -> CGPoint {
return CGPoint(x: point.x - center.x, y: point.y - center.y)
}
/// Helper to get point back relative to center
func pointRelativeToCenter(_ point: CGPoint) -> CGPoint {
return CGPoint(x: point.x + center.x, y: point.y + center.y)
}
/// Helper to get point relative to transformed coords
func newPointInView(_ point: CGPoint) -> CGPoint {
// get offset from center
let offset = centerOffset(point)
// get transformed point
let transformedPoint = offset.applying(transform)
// make relative to center
return pointRelativeToCenter(transformedPoint)
}
var newTopLeft: CGPoint {
return newPointInView(originalFrame.origin)
}
var newTopRight: CGPoint {
var point = originalFrame.origin
point.x += originalFrame.width
return newPointInView(point)
}
var newBottomLeft: CGPoint {
var point = originalFrame.origin
point.y += originalFrame.height
return newPointInView(point)
}
var newBottomRight: CGPoint {
var point = originalFrame.origin
point.x += originalFrame.width
point.y += originalFrame.height
return newPointInView(point)
}
}
通过使用基本三角函数,可以找到旋转视图的坐标。以下是您可以执行此操作的步骤:
第一步是知道视图的宽度和高度。将它们除以2,即可得到三角形的相邻边和对边(分别为青色和绿色)。在上面的示例中,宽度=300,高度=300。因此相邻边=150,对边=150。
查找斜边长度(红色)。为此,使用公式:h^2 = a^2 + b^2
。应用此公式后,我们发现斜边长度=212.13。
查找角度θ。这是相邻边(青色)和斜边(红色)之间的夹角。为此,使用公式cos(theta) = (h^2 + a^2 - o^2)/2*h*o
。应用此公式后,我们发现theta = 0.785(弧度)。要将其转换为度数,应使用公式degrees = radians * 180 / PI
= 45(度)。这是斜边的初始(偏移)角度。这非常重要。如果您的视图旋转为零,则斜边具有45(度)的偏移角度。我们马上需要θ。
现在,我们知道了斜边(红色),还需要旋转角度。在此示例中,我使用了UIRotationGestureRecognizer
类来旋转正方形视图。该类具有“rotation”属性,告诉我们视图旋转了多少。该值以弧度为单位。在上面的示例中,旋转角度为0.3597弧度。要将其转换为度数,应使用公式degrees = radians * PI / 180
。应用该公式后,我们发现旋转角度为20.61度。
最终,我们可以找到偏移宽度(橙色)和高度(紫色)。对于宽度,我们使用公式width = cos(rotationAngle - theta) * hypotenuse
,而对于高度,我们使用公式height = sen(rotationAngle - theta)
。我们必须从旋转角度(以弧度为单位)中减去theta(也是以弧度为单位),因为theta是初始偏移量。可以这样看:当旋转角度为零时,斜边的角度为45 (度)。应用公式后,我们发现宽度=193.20,高度=-87.60。
最后,我们可以将这些值(宽度和高度)添加到正方形的中心,以找到蓝色点的坐标。
-示例-
// Get the center point
CGPoint squareCenter = self.squareView.center;
// Get the blue point coordinates
CGPoint bluePointCoordinates = CGPointMake(squareCenter.x + width, squareCenter.y + height);
蓝色点的坐标为 (963.20, 272.40)
为了更好地理解公式,请查看以下链接:
此外,如果您想尝试玩弄我创建的测试项目(就是图片中的那个),请随意从以下链接下载。
更新
这里提供了一种简明的方法来计算您正在寻找的右上角偏移点(蓝色)。
/* Params:
/ viewCenter: The center point (in superView coordinates) of your view
/ width: The total width of your view
/ height: The total height of your view
/ angleOfRotation: The rotation angle of your view. Can be either DEGREES or RADIANS
/ degrees: A boolean flag indicating whether 'angleOfRotation' is degrees
/ or radians. E.g.: If 'angleOfRotation' is expressed in degrees
/ this parameter must be 'YES'
*/
-(CGPoint)calculateTopRightCoordinatesFromViewCenter:(CGPoint)viewCenter viewWidth:(CGFloat)viewWidth viewHeight:(CGFloat)viewHeight angleOfRotation:(CGFloat)angleOfRotation degrees:(BOOL)degrees {
CGFloat adjacent = viewWidth/2.0;
CGFloat opposite = viewHeight/2.0;
CGFloat hipotenuse = sqrtf(powf(adjacent, 2.0) + pow(opposite, 2.0));
CGFloat thetaRad = acosf((powf(hipotenuse, 2.0) + powf(adjacent, 2.0) - pow(opposite, 2.0)) / (2 * hipotenuse * adjacent));
CGFloat angleRad = 0.0;
if (degrees) {
angleRad = angleOfRotation*M_PI/180.0;
} else {
angleRad = angleOfRotation;
}
CGFloat widthOffset = cosf(angleRad - thetaRad) * hipotenuse;
CGFloat heightOffset = sinf(angleRad - thetaRad) * hipotenuse;
CGPoint offsetPoint = CGPointMake(viewCenter.x + widthOffset, viewCenter.y + heightOffset);
return offsetPoint;
}
希望这可以帮到您!atan2f
方法测试了一下,它可以正常工作。只需在计算“宽度”和“高度”时记得使用弧度制。不要将“theta”转换为弧度制,直接使用“atan2f”的结果,因为该函数返回弧度制。 - LuisCienCGPointApplyAffineTransform()
或 CGRectApplyAffineTransform()
。 - nielsbot所有这些答案都很疯狂,这很简单...
CGPoint topLeft = [rotatedView convertPoint:CGPointMake(0, 0) toView:rotatedView.superview];
CGPoint topRight = [rotatedView convertPoint:CGPointMake(rotatedView.bounds.size.width, 0) toView:rotatedView.superview];
CGPoint bottomLeft = [rotatedView convertPoint:CGPointMake(0, rotatedView.bounds.size.height) toView:rotatedView.superview];
CGPoint bottomRight = [rotatedView convertPoint:CGPointMake(rotatedView.bounds.size.width, rotatedView.bounds.size.height) toView:rotatedView.superview];
你应该使用:
CGPoint CGPointApplyAffineTransform (
CGPoint point,
CGAffineTransform t
);
为什么要弄得这么复杂?保持简单吗?在变换之前,点x与锚点的距离会增加q弧度/角度,就像围绕锚点的其他点一样。
本来想讲解所有内容,但是这篇文章中的人用更短的语境解释了:
CGFloat radians = atan2f(yourView.transform.b, yourView.transform.a);
CGFloat degrees = radians * (180 / M_PI);
CGPoint localBeforeTransform = CGPointMake( view.bounds.size.width/2.0f, view.bounds.size.height/2.0f ); // lower left corner
CGPoint localAfterTransform = CGPointApplyAffineTransform(localBeforeTransform, transform);
CGPoint globalAfterTransform = CGPointMake(localAfterTransform.x + view.center.x, localAfterTransform.y + view.center.y);
TransformedViewFrameCalculator.h
#import <Foundation/Foundation.h>
@interface TransformedViewFrameCalculator : NSObject
@property (nonatomic, strong) UIView *viewToProcess;
- (void)calculateTransformedCornersWithTranslation:(CGPoint)translation
scale:(CGFloat)scale
rotation:(CGFloat)rotation;
@property (nonatomic, readonly) CGPoint transformedTopLeftCorner;
@property (nonatomic, readonly) CGPoint transformedTopRightCorner;
@property (nonatomic, readonly) CGPoint transformedBottomLeftCorner;
@property (nonatomic, readonly) CGPoint transformedBottomRightCorner;
@end
TransformedViewFrameCalculator.m:
#import "TransformedViewFrameCalculator.h"
@interface TransformedViewFrameCalculator ()
@property (nonatomic, assign) CGRect viewToProcessNotTransformedFrame;
@property (nonatomic, assign) CGPoint viewToProcessNotTransformedCenter;
@end
@implementation TransformedViewFrameCalculator
- (void)setViewToProcess:(UIView *)viewToProcess {
_viewToProcess = viewToProcess;
CGAffineTransform t = _viewToProcess.transform;
_viewToProcess.transform = CGAffineTransformIdentity;
_viewToProcessNotTransformedFrame = _viewToProcess.frame;
_viewToProcessNotTransformedCenter = _viewToProcess.center;
_viewToProcess.transform = t;
}
- (void)calculateTransformedCornersWithTranslation:(CGPoint)translation
scale:(CGFloat)scale
rotation:(CGFloat)rotation {
double viewWidth = _viewToProcessNotTransformedFrame.size.width * scale;
double viewHeight = _viewToProcessNotTransformedFrame.size.height * scale;
CGPoint viewCenter = CGPointMake(_viewToProcessNotTransformedCenter.x + translation.x,
_viewToProcessNotTransformedCenter.y + translation.y);
_transformedTopLeftCorner = [self calculateCoordinatesForViewPoint:CGPointMake(0, 0)
fromViewCenter:viewCenter
viewWidth:viewWidth
viewHeight:viewHeight
angleOfRotation:rotation];
_transformedTopRightCorner = [self calculateCoordinatesForViewPoint:CGPointMake(0, viewHeight)
fromViewCenter:viewCenter
viewWidth:viewWidth
viewHeight:viewHeight
angleOfRotation:rotation];
_transformedBottomLeftCorner = [self calculateCoordinatesForViewPoint:CGPointMake(viewWidth, 0)
fromViewCenter:viewCenter
viewWidth:viewWidth
viewHeight:viewHeight
angleOfRotation:rotation];
_transformedBottomRightCorner = [self calculateCoordinatesForViewPoint:CGPointMake(viewWidth, viewHeight)
fromViewCenter:viewCenter
viewWidth:viewWidth
viewHeight:viewHeight
angleOfRotation:rotation];
}
- (CGPoint)calculateCoordinatesForViewPoint:(CGPoint)viewPoint
fromViewCenter:(CGPoint)viewCenter
viewWidth:(CGFloat)viewWidth
viewHeight:(CGFloat)viewHeight
angleOfRotation:(CGFloat)angleOfRotation {
CGPoint centeredViewPoint = CGPointMake(viewPoint.x - viewWidth/2.0, viewPoint.y - viewHeight/2.0);
CGPoint rotatedCenteredViewPoint = CGPointApplyAffineTransform(centeredViewPoint, CGAffineTransformMakeRotation(angleOfRotation));
CGPoint rotatedViewPoint = CGPointMake(rotatedCenteredViewPoint.x + viewCenter.x, rotatedCenteredViewPoint.y + viewCenter.y);
return rotatedViewPoint;
}
@property (nonatomic, strong) TransformedViewFrameCalculator *transformedFrameCalculator;
...
self.transformedFrameCalculator = [TransformedViewFrameCalculator new];
self.transformedFrameCalculator.viewToProcess = someView;
...
- (BOOL)transformedView:(UIView *)view
withTranslation:(CGPoint)translation
scale:(double)scale
rotation:(double)rotation
isFullyInsideValidFrame:(CGRect)validFrame {
[self.transformedFrameCalculator calculateTransformedCornersWithTranslation:translation
scale:scale
BOOL topRightIsInsideValidFrame = CGRectContainsPoint(validFrame, self.transformedFrameCalculator.transformedTopRightCorner);
BOOL topLeftIsInsideValidFrame = CGRectContainsPoint(validFrame, self.transformedFrameCalculator.transformedTopLeftCorner);
BOOL bottomRightIsInsideValidFrame = CGRectContainsPoint(validFrame, self.transformedFrameCalculator.transformedBottomRightCorner);
BOOL bottomLeftIsInsideValidFrame = CGRectContainsPoint(validFrame, self.transformedFrameCalculator.transformedBottomLeftCorner);
return topRightIsInsideValidFrame && topLeftIsInsideValidFrame && bottomRightIsInsideValidFrame && bottomLeftIsInsideValidFrame;
}
CGPointApplyAffineTransform()
或CGRectApplyAffineTransform()
,正如 @LeoNatan @Bladebunny 等人所建议的那样。 - nielsbot