从 Rectangle.Intersection 中找到剩余的外部矩形

Question

我有一个外矩形和一个内矩形。如何 return 切割相交矩形后剩余的所有矩形？

Answer 1

我创建了这个函数，return 一个不包括相交列表的列表。

 private IEnumerable<Rectangle> GetExternalRectangles(Rectangle surface, Rectangle test)
    {
        var result = new List<Rectangle>();

        if (!test.IntersectsWith(surface)) return new List<Rectangle> { surface };
        #region Top and Bottom

        if (test.Top>surface.Top && test.Bottom < surface.Bottom) // test inside surface vertically
        {
            result.Add(new Rectangle(surface.Location, new Size(surface.Width, test.Top - surface.Top)));
            result.Add(new Rectangle(new Point(surface.Left,test.Bottom), new Size(surface.Width, surface.Bottom-test.Bottom)));
        }
        if (test.Top > surface.Top && test.Bottom > surface.Bottom) // test inside surface vertically, overflow bottom
        {
            result.Add(new Rectangle(surface.Location, new Size(surface.Width, test.Top - surface.Top)));
            //result.Add(new Rectangle(new Point(surface.Left,test.Bottom), new Size(surface.Width, surface.Bottom-test.Bottom)));
        }
        if (test.Top < surface.Top && test.Bottom < surface.Bottom) // test inside surface vertically, overflow top
        {
            //result.Add(new Rectangle(surface.Location, new Size(surface.Width, test.Top - surface.Top)));
            result.Add(new Rectangle(new Point(surface.Left, test.Bottom), new Size(surface.Width, surface.Bottom - test.Bottom)));
        }

        #endregion

        #region Lateral
        if (test.Left > surface.Left && test.Right < surface.Right) // test inside surface horizontally
        {
            result.Add(new Rectangle(new Point(surface.Left,Math.Max(surface.Top,test.Top)), new Size(test.Left-surface.Left, Math.Min(surface.Bottom, test.Bottom)- Math.Max(surface.Top, test.Top))));
            result.Add(new Rectangle(new Point(test.Right, Math.Max(surface.Top, test.Top)), new Size(surface.Right - test.Right, Math.Min(surface.Bottom, test.Bottom) - Math.Max(surface.Top, test.Top))));
        }
        if (test.Left > surface.Left && test.Right > surface.Right) // test inside surface horizontally, overflow right
        {
            result.Add(new Rectangle(new Point(surface.Left, Math.Max(surface.Top, test.Top)), new Size(test.Left - surface.Left, Math.Min(surface.Bottom, test.Bottom) - Math.Max(surface.Top, test.Top))));
            //result.Add(new Rectangle(new Point(test.Right, Math.Max(surface.Top, test.Top)), new Size(surface.Right - test.Right, Math.Min(surface.Bottom, test.Bottom) - Math.Max(surface.Top, test.Top))));
        }
        if (test.Left < surface.Left && test.Right < surface.Right) // test inside surface horizontally, overflow left
        {
            //result.Add(new Rectangle(new Point(surface.Left, Math.Max(surface.Top, test.Top)), new Size(test.Left - surface.Left, Math.Min(surface.Bottom, test.Bottom) - Math.Max(surface.Top, test.Top))));
            result.Add(new Rectangle(new Point(test.Right, Math.Max(surface.Top, test.Top)), new Size(surface.Right - test.Right, Math.Min(surface.Bottom, test.Bottom) - Math.Max(surface.Top, test.Top))));
        }
        #endregion
        return result;
    }

Answer 2

表示此内容的自然方式是使用 Region class，例如：

var result = new Region(outer);
result.Exclude(inner);

如果你真的想要一个 Rectangle 结构的列表，你可以看看使用单位矩阵使用 GetRegionScans 转换为 RectangleFs，然后将它们转换为 Rectangles 使用 Ceiling 或 Floor.

从 Rectangle.Intersection 中找到剩余的外部矩形

Find remaining outer rectangles from Rectangle.Intersection

c#

system.drawing