确定裁剪矩形是否完全包含在旋转的 UIView 中

Question

前提：我正在构建一个裁剪工具，可以处理图像的两指任意旋转以及任意裁剪。

有时，图像最终会以插入空白空间的方式旋转，以填充旋转图像和裁剪矩形之间的间隙（请参阅下面的示例）。

我需要确保图像视图在旋转时完全适合裁剪矩形。如果没有，我需要重新转换图像（缩放）以使其适合裁剪范围。

使用这个答案，我实现了检查旋转的 UIImageView 是否与裁剪 CGRect 相交的功能，但不幸的是，这并没有告诉我裁剪矩形是否完全包含在旋转的图像视图中。希望我可以对此答案进行一些简单的修改？

OK 的直观示例：

不好，我需要检测和处理：

更新：不起作用的方法

- (BOOL)rotatedView:(UIView*)rotatedView containsViewCompletely:(UIView*)containedView {

    CGRect rotatedBounds = rotatedView.bounds;
    CGPoint polyContainedView[4];

    polyContainedView[0] = [containedView convertPoint:rotatedBounds.origin toView:rotatedView];
    polyContainedView[1] = [containedView convertPoint:CGPointMake(rotatedBounds.origin.x + rotatedBounds.size.width, rotatedBounds.origin.y) toView:rotatedView];
    polyContainedView[2] = [containedView convertPoint:CGPointMake(rotatedBounds.origin.x + rotatedBounds.size.width, rotatedBounds.origin.y + rotatedBounds.size.height) toView:rotatedView];
    polyContainedView[3] = [containedView convertPoint:CGPointMake(rotatedBounds.origin.x, rotatedBounds.origin.y + rotatedBounds.size.height) toView:rotatedView];

    if (CGRectContainsPoint(rotatedView.bounds, polyContainedView[0]) &&
        CGRectContainsPoint(rotatedView.bounds, polyContainedView[1]) &&
        CGRectContainsPoint(rotatedView.bounds, polyContainedView[2]) &&
        CGRectContainsPoint(rotatedView.bounds, polyContainedView[3]))
        return YES;
    else
        return NO;
}

Answer 1

这应该比检查交集更容易（如在引用的线程中）。

（旋转的）图像视图是凸四边形。因此，只需检查裁剪矩形的所有 4 个角点是否位于旋转图像视图内即可。

• 用于[cropView convertPoint:point toView:imageView]将裁剪矩形的角点转换为（旋转的）图像视图的坐标系。
• 用于CGRectContainsPoint()检查 4 个转换后的角点是否位于bounds图像视图的矩形内。

示例代码：

- (BOOL)rotatedView:(UIView *)rotatedView containsCompletely:(UIView *)cropView {

    CGPoint cropRotated[4];
    CGRect rotatedBounds = rotatedView.bounds;
    CGRect cropBounds = cropView.bounds;

    // Convert corner points of cropView to the coordinate system of rotatedView:
    cropRotated[0] = [cropView convertPoint:cropBounds.origin toView:rotatedView];
    cropRotated[1] = [cropView convertPoint:CGPointMake(cropBounds.origin.x + cropBounds.size.width, cropBounds.origin.y) toView:rotatedView];
    cropRotated[2] = [cropView convertPoint:CGPointMake(cropBounds.origin.x + cropBounds.size.width, cropBounds.origin.y + cropBounds.size.height) toView:rotatedView];
    cropRotated[3] = [cropView convertPoint:CGPointMake(cropBounds.origin.x, cropBounds.origin.y + cropBounds.size.height) toView:rotatedView];

    // Check if all converted points are within the bounds of rotatedView:
    return (CGRectContainsPoint(rotatedBounds, cropRotated[0]) &&
            CGRectContainsPoint(rotatedBounds, cropRotated[1]) &&
            CGRectContainsPoint(rotatedBounds, cropRotated[2]) &&
            CGRectContainsPoint(rotatedBounds, cropRotated[3]));
}