Question

我正在尝试绘制一个跟随屏幕触摸的尺子。在第一次触摸时，我设置了第一个点，在另一个点上，ruller跟随手指在屏幕上调整大小并围绕第一个点旋转，具体取决于手指的位置。

我试着这样做：

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    CGPoint p = [touch locationInView:self.view];

    self.regleFirstPoint = p;
    UIImageView* img = [[UIImageView alloc] initWithImage:self.regleImg];
    img.frame = CGRectMake(self.regleFirstPoint.x, self.regleFirstPoint.y, 0, self.regleImg.size.height);
    [self.view addSubview:img];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    CGPoint p = [touch locationInView:self.view];

    // Width
    float deltaY = p.y - self.regleFirstPoint.y;
    float deltaX = p.x - self.regleFirstPoint.x;
    float width = sqrt((deltaX * deltaX) + (deltaY * deltaY));

    // Angle
    float angleInRadians = atanf(deltaY / deltaX);
    float angleInDegrees = angleInRadians * 180 / M_PI; // JUST FOR INFO
    NSLog(@"angle : %f / %f", angleInRadians, angleInDegrees);

    // Resizing image
    UIImageView* img = [self.regles lastObject];
    img.frame = CGRectMake(self.regleFirstPoint.x, self.regleFirstPoint.y, width, self.regleImg.size.height/2);
    img.center = self.regleFirstPoint;
    CGAffineTransform transform = CGAffineTransformIdentity;
    img.transform = CGAffineTransformRotate(transform, angleInRadians);
}

ruller没有正确地按照手指，我想我错过了什么。我的代码出了什么问题？

编辑：经过一些研究后我也试过这个：

// Resizing images
img.frame = CGRectMake(self.regleFirstPoint.x, self.regleFirstPoint.y, largeur, self.regleImg.size.height/2);
[img.layer setAnchorPoint:CGPointMake(self.regleFirstPoint.x / img.bounds.size.width, self.regleFirstPoint.y / img.bounds.size.height)];
img.transform = CGAffineTransformRotate(img.transform, angleInRadians);

Answer 1

这只是一个有序的问题：

将视图转换为标识
更改视图框架
最后，应用您的转换

这是一段更新的代码，只使用了UIView而不是你的图像：

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [touches anyObject];

    // Hold first touch
    self.regleFirstPoint = [touch locationInView:self.view];

    // Reset view / image
    _rulerView.transform = CGAffineTransformIdentity;
    _rulerView.frame = CGRectMake(self.regleFirstPoint.x, self.regleFirstPoint.y, 0, CGRectGetHeight(_rulerView.frame));
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [touches anyObject];
    CGPoint p = [touch locationInView:self.view];

    // Compute width
    float deltaX = p.x - self.regleFirstPoint.x;
    float deltaY = p.y - self.regleFirstPoint.y;
    float width = sqrt((deltaX * deltaX) + (deltaY * deltaY));

    // Compute angle
    float angleInRadians = atan2(deltaY, deltaX);
    NSLog(@"angle (rad) : %f", angleInRadians);
    NSLog(@"angle (deg) : %f", angleInRadians * 180 / M_PI);

    // First reset the transformation to identity
    _rulerView.transform = CGAffineTransformIdentity;

    // Set anchor point
    _rulerView.layer.anchorPoint = CGPointMake(0.0f, 0.5f);

    // Resizing view / image
    _rulerView.frame = CGRectMake(self.regleFirstPoint.x, self.regleFirstPoint.y, width, CGRectGetHeight(_rulerView.frame));

    // Reset the layer position to the first point
    _rulerView.layer.position = self.regleFirstPoint;

    // Apply rotation transformation
    _rulerView.transform = CGAffineTransformMakeRotation(angleInRadians);
}

希望有所帮助。

西里尔

接下来的UIImage

1 个答案: