Question

我在一个封闭的Rect B中有一个Rect A.封闭的Rect B是允许移动Rect A的区域。当试图将Rect A移动到包围Rect B的边界之外时，它应该卡在包围Rect B的边界或角落，并且不再移动。在移动时我手头有以下参数：包围Rect B的属性，移动前Rect A的属性，移动后Rect A的潜在topleft位置。请注意，移动不一定是每像素，也可能在任何方向上（例如）20像素。请告诉我如何有效地做到这一点，但不要过于复杂？

PS：这些只是在WPF画布上绘制的几何图形，因此也允许使用变换，但我在此特定位只有Rect变量，而不是RectangleGeometries。

Answer 1

最终我创建了一个封闭的A和B矩形，然后在this question中应用了解决方案，如下所示：

    private static Point CorrectForAllowedArea(Point previousLocation, Point newLocation, Rect allowedArea, Rect newBox)
    {
        // get area that encloses both rectangles
        Rect enclosingRect = Rect.Union(allowedArea, newBox);
        // get corners of outer rectangle, index matters for getting opposite corner
        var outsideCorners = new[] { enclosingRect.TopLeft, enclosingRect.TopRight, enclosingRect.BottomRight, enclosingRect.BottomLeft }.ToList();
        // get corners of inner rectangle
        var insideCorners = new[] { allowedArea.TopLeft, allowedArea.TopRight, allowedArea.BottomRight, allowedArea.BottomLeft }.ToList();
        // get the first found corner that both rectangles share
        Point sharedCorner = outsideCorners.First((corner) => insideCorners.Contains(corner));
        // find the index of the opposite corner
        int oppositeCornerIndex = (outsideCorners.IndexOf(sharedCorner) + 2) % 4;
        // calculate the displacement of the inside and outside opposite corner, this is the displacement outside the allowed area
        Vector rectDisplacement = outsideCorners[oppositeCornerIndex] - insideCorners[oppositeCornerIndex];
        // subtract that displacement from the total displacement that moved the shape outside the allowed area to get the displacement inside the allowed area
        Vector allowedDisplacement = (newLocation - previousLocation) - rectDisplacement;
        // use that displacement on the display location of the shape
        return previousLocation + allowedDisplacement;
        // move or resize the shape inside the allowed area, right upto the border, using the new returned location
    }

最简单的方法是将Rect移动到封闭Rect的边界，以便移出它

1 个答案: