如何实现单指旋转手势识别器？

Question

我知道 UIRotateGestureRecognizer 已经是 iOS 的一部分。但这个手势需要两根手指。如何实现只需要一根手指的类似手势识别器？ AppStore 中有一款游戏 - Gyrotate 很好地实现了这一点。任何线索表示赞赏。谢谢。

Answer 1

Kirby Turner 拥有完整的单指旋转手势识别器here。

Answer 2

这是代码 - 它适用于我的模拟器。如果那是您要找的，马克回答了。

    // On new touch, start a new array of points
- (void) touchesBegan:(NSSet *) touches withEvent:(UIEvent *) event
{
    self.points = [NSMutableArray array];
    CGPoint pt = [[touches anyObject] locationInView:self];
    [self.points addObject:[NSValue valueWithCGPoint:pt]];
}

// Add each point to the array
- (void) touchesMoved:(NSSet *) touches withEvent:(UIEvent *) event
{
    CGPoint pt = [[touches anyObject] locationInView:self];
    [self.points addObject:[NSValue valueWithCGPoint:pt]];
    [self setNeedsDisplay];
}

// At the end of touches, determine whether a circle was drawn
- (void) touchesEnded:(NSSet *) touches withEvent:(UIEvent *) event
{
    if (!self.points) return;
    if (self.points.count < 3) return;

    // Test 1: The start and end points must be between 60 pixels of each other
    CGRect tcircle;
    if (distance(POINT(0), POINT(self.points.count - 1)) < 60.0f)
        tcircle = [self centeredRectangle];

    // Test 2: Count the distance traveled in degrees. Must fall within 45 degrees of 2 PI
    CGPoint center = CGPointMake(CGRectGetMidX(tcircle), CGRectGetMidY(tcircle));
    float distance = ABS(acos(dotproduct(centerPoint(POINT(0), center), centerPoint(POINT(1), center))));
    for (int i = 1; i < (self.points.count - 1); i++)
        distance += ABS(acos(dotproduct(centerPoint(POINT(i), center), centerPoint(POINT(i+1), center))));
    if ((ABS(distance - 2 * M_PI) < (M_PI / 4.0f))) circle = tcircle;

    [self setNeedsDisplay];
}

Answer 3

我用 OneFingerRotation、Scale、Resize 和 Close 功能实现了 IQStickerView .

特点：-

1) 单指旋转刻度。

2) 单指调整大小。

3) 使用属性启用/禁用旋转、缩放、调整大小。

4) 自动管理多个 IQStickerView。

5) 也可以与 UIScrollView 一起使用。

6) 快速响应。

github 仓库在这里：- https://github.com/hackiftekhar/IQStickerView

Answer 4

尝试探索UIGestureRecognizer Class。您应该可以使用 UIGestureRecognizerDelegate 自定义它

Answer 5

使用平移手势识别器实现，这是使用手势识别器附加到的另一个 UIView，但它应该与附加到要旋转的视图一起使用。

- (void) gestureRotateButtonPan:(UIPanGestureRecognizer*) gestureRecognizer {

    switch (gestureRecognizer.state) {
        case UIGestureRecognizerStatePossible:
            break;
        case UIGestureRecognizerStateBegan:
        {
            CGPoint location = [gestureRecognizer translationInView:[gestureRecognizer view]];
            _touchRotateStartPoint = [self convertPoint:location fromView:[gestureRecognizer view]];
        }
            break;
        case UIGestureRecognizerStateChanged:
        {
            CGPoint imageLocation = CGPointMake(self.mainImageView.transform.tx + self.mainImageView.center.x
                                                , self.mainImageView.transform.ty + self.mainImageView.center.y);
            CGPoint buttonLocation = [gestureRecognizer translationInView:self];
            buttonLocation.x += _touchRotateStartPoint.x;
            buttonLocation.y += _touchRotateStartPoint.y;

            CGFloat currentRotation = atan2(buttonLocation.y - imageLocation.y, buttonLocation.x - imageLocation.x)
                                        - atan2(_touchRotateStartPoint.y - imageLocation.y, _touchRotateStartPoint.x - imageLocation.x);

            CGFloat rotation = -(_lastRotation - currentRotation);
            CGAffineTransform currentTransform = self.mainImageView.transform;
            CGAffineTransform rotatedTransform = CGAffineTransformRotate(currentTransform, rotation);
            self.mainImageView.transform = rotatedTransform;

            [self setNeedsDisplay];
        }
            break;
        case UIGestureRecognizerStateCancelled:
        case UIGestureRecognizerStateEnded:
            _lastRotation = 0.0;
            break;
        case UIGestureRecognizerStateFailed:
            break;
        default:
            break;
    }
}