ios - 旋转图像后更改设备方向时，UIImageView 变得非常拉伸(stretch)

Question

我已经子类化了 UIImageView 以允许我旋转图像，或者用用户的手指拖动图像，或者使用 slider 来设置图像旋转。

这在最初使用时一切正常，但是如果用户旋转图像然后重新定位设备，则图像大小会变得非常糟糕 - 看起来如果用户顺时针旋转图像然后图像会变大，逆时针方向图像变小。

如果我将 UIImageView 的 autoresizingMask 设置为 none 那么问题就会消失，但是如果我这样做，我将需要在设备旋转时手动移动/重新调整 View 大小，我不想这样做。

下面的代码完成了大部分工作:

- (void) touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event{
    self.spinInProgress = NO;
    if (!self.spinnable || [[event allTouches] count]>1) {
        [super touchesBegan:touches withEvent:event];
        return;
    }
    UITouch *touch = (UITouch*)[touches anyObject];

    //check that touch is within radius of the circle
    float radius = MIN(self.frame.size.height, self.frame.size.width);
    radius = radius / 2;
    CGPoint centre = CGPointMake(self.frame.size.width/2, self.frame.size.height/2);

    CGPoint posInView = [touch locationInView:self];

    float x = posInView.x;
    float y = posInView.y;
    float centre_x = centre.x;
    float centre_y = centre.y;


    if ((powf(x - centre_x, 2) + powf(y - centre_y, 2)) > powf(radius, 2))
        return; //not within the circle..

    //so now doing the work
    self.spinInProgress = YES;

    //stop the spinning if it is doing so
    if (spinTimer!=nil && [spinTimer isValid]){
        [spinTimer invalidate];
        spinTimer = nil;
    }

    //store the current touch as the previous touch position for now for future calculation when touch moves
    CGPoint previousPosition = [touch locationInView:self.superview];

    CGPoint lowerLeft = self.frame.origin;
    CGSize size = self.frame.size;

    //find the centre of the image (really should cache this!)

    centreX = (size.width/2) + lowerLeft.x;
    centreY = (size.height/2) + lowerLeft.y;

    startX = previousPosition.x;
    startY = previousPosition.y;

    //work out the angle of the current touch
    float startdx = previousPosition.x - centreX;
    float startdy = previousPosition.y - centreY;
    startAngle = atan2(startdx, startdy) *180/M_PI;

    startAngle += self.currentAngle;

    [super touchesBegan:touches withEvent:event];


}

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

    if (!self.spinInProgress) {
        [super touchesMoved:touches withEvent:event];
        return;
    }

    UITouch *touch = (UITouch*)[touches anyObject];
    //work out the current position of the touch
    CGPoint currentPosition = [touch locationInView:self.superview];

    //calculate the angle
    float dx = currentPosition.x - centreX;
    float dy = currentPosition.y - centreY;

    float newangle = atan2(dx,dy) * 180/ M_PI;

    float rotateangle = startAngle - newangle;

    //float movedAngle = rotateangle - currentAngle;

    if (rotateangle > self.currentAngle){
        clockSpin = YES;
    } else {
        clockSpin = NO;
    }

    if (rotateangle>360)
        rotateangle = rotateangle-360;

    if (rotateangle<0)
        rotateangle = fabs(rotateangle);

    self.currentAngle = rotateangle;

    lastMove = [event timestamp]; 

    [super touchesMoved:touches withEvent:event];
}

-(void) touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event {
    [self stop:self];
    self.spinInProgress = NO;
    [super touchesEnded:touches withEvent:event];

}

-(void)setCurrentAngle:(float)currentAngle
{

    [self willChangeValueForKey:@"currentAngle"];
    __currentAngle = currentAngle;
    [self didChangeValueForKey:@"currentAngle"];

    CGAffineTransform trans = CGAffineTransformMakeRotation(self.currentAngle*DEGREES_TO_RADIANS);

    self.transform = trans;

}

我认为最重要的部分是 setCurrentAngle，因为它起作用了，但我认为我应该发布其余部分以提供一些背景信息。

如果您能提供任何帮助，我们将不胜感激!

谢谢

理查德

Answer 1

好的，所以终于解决了 - 事实证明自动布局和变换不能很好地协同工作(有关详细解释，请参阅 How do I adjust the anchor point of a CALayer, when Auto Layout is being used?)

由于旋转，解决方案有点复杂，涉及两个步骤..

1/将有问题的 UIImageView 保存在另一个 View 中(我在界面生成器中使用了“编辑器>嵌入> View ”)2/将所需的自动调整大小设置为 封闭 View (而不是 imageView 本身)3/为 UIImageView 设置任何 autorisizing mask 标志(这些将被忽略但需要存在以便在检测到旋转时调用 layoutSubviews)

重写子类 UIImageView 的 layoutSubviews 方法如下:

- (void)layoutSubviews
{
    [super layoutSubviews];
    self.bounds = self.superview.bounds;

}

上面的代码只是将 UIImageView 的边界设置为封闭 View 的边界——这有点麻烦，但它似乎可以工作!!

希望对大家有帮助!

理查德