用一只手指触摸屏幕以中心为轴旋转图像

Question

用一只手指触摸屏幕以中心为轴旋转图像

iphoneimagerotation

11

我想用一根手指触摸来围绕中心点旋转下面的图像...

并且我想在旋转图像时用标签显示图像的值。

我已经完成了图像旋转，但问题是如何根据旋转设置图像的值。

旋转角度不断增加，因此我无法设置该值。

有人能帮忙吗？

以下是代码：

float fromAngle = atan2(firstLoc.y-imageView.center.y, 
                            firstLoc.x-imageView.center.x);

    NSLog(@"From angle:%f",fromAngle);
    float toAngle = atan2( currentLoc.y-imageView.center.y, 
                          currentLoc.x-imageView.center.x);

    NSLog(@"to Angle:%f",toAngle);
    // So the angle to rotate to is relative to our current angle and the
    // angle through which our finger moved (to-from)
    float newAngle =angle+(toAngle-fromAngle);


    NSLog(@"new angle:%.2f",newAngle);


 CGAffineTransform cgaRotate = CGAffineTransformMakeRotation(newAngle);

 imageView.transform=cgaRotate;


angle = newAngle;

有人能帮我吗？

- darshan

“value of the image” 是什么意思？ - Wex

我有一张图片，其中显示了从0到50的值。因此，当我旋转图像时，标签中应该显示特定的值。 - darshan

1个回答

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- Wex · Accepted Answer

我不是完全确定你所需要的内容；但是可以试试这段代码。

如果你创建一个名为“Rotation”的基于View的应用程序项目，并替换RotationViewController.h和.m中的代码，使用以下代码，你将获得一个绿色方块，可以使用你的计算进行旋转。你可以将绿色方块UIView替换为UIImageView，或者任何其他想要旋转的东西。

RotationViewController.h

#import <UIKit/UIKit.h>

@interface RotationViewController : UIViewController
{
    UIView* m_block;
    UILabel* m_label;
    CGPoint m_locationBegan;
    float m_currentAngle;
}

- (float) updateRotation:(CGPoint)_location;

@end

RotationViewController.m

#import "RotationViewController.h"

double wrapd(double _val, double _min, double _max)
{
    if(_val < _min) return _max - (_min - _val);
    if(_val > _max) return _min - (_max - _val);
    return _val;
}

@implementation RotationViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    CGRect blockFrame = CGRectMake(0, 0, 200, 200);
    m_block = [[UIView alloc] initWithFrame:blockFrame];
    m_block.backgroundColor = [UIColor greenColor];
    m_block.center = self.view.center;
    [self.view addSubview:m_block];
    [m_block release];
    
    CGRect labelFrame = CGRectMake(0, 0, 320, 30);
    m_label = [[UILabel alloc] initWithFrame:labelFrame];
    m_label.text = @"Loaded";
    [self.view addSubview:m_label];
}

- (void) touchesBegan:(NSSet *)_touches withEvent:(UIEvent *)_event
{
    UITouch* touch = [_touches anyObject];
    CGPoint location = [touch locationInView:self.view];
    m_locationBegan = location;
}

- (void) touchesMoved:(NSSet *)_touches withEvent:(UIEvent *)_event
{
    UITouch* touch = [_touches anyObject];
    CGPoint location = [touch locationInView:self.view];
    [self updateRotation:location];
}

- (void) touchesEnded:(NSSet *)_touches withEvent:(UIEvent *)_event
{
    UITouch* touch = [_touches anyObject];
    CGPoint location = [touch locationInView:self.view];
    m_currentAngle = [self updateRotation:location];
}

- (float) updateRotation:(CGPoint)_location
{
    float fromAngle = atan2(m_locationBegan.y-m_block.center.y, m_locationBegan.x-m_block.center.x);
    float toAngle = atan2(_location.y-m_block.center.y, _location.x-m_block.center.x);
    float newAngle = wrapd(m_currentAngle + (toAngle - fromAngle), 0, 2*3.14);

    CGAffineTransform cgaRotate = CGAffineTransformMakeRotation(newAngle);
    m_block.transform = cgaRotate;
    
    int oneInFifty = (newAngle*50)/(2*3.14);
    
    m_label.text = [NSString stringWithFormat:@"Angle: %f 1in50: %i", newAngle, oneInFifty];

    return newAngle;
}

@end