确定哪个控件最接近鼠标指针

您需要找到以下内容:
-到最近角的距离
-到最近边缘的距离
-(可选)到中心的距离

基本上,您需要这三个值中较小的一个。取两个控件的最小值来确定哪个更接近。

在加载表单时,首先迭代表单上的所有控件,然后创建下面的类集合。

要查找最接近某个点的控件,请迭代集合(参见底部的代码)。以你目前为止发现的最小距离追踪控制。如果需要,可以测试containsPoint()。如果你找到一个控制点在控制范围内,你就得到了控制点(只要你没有重叠的控制点)。否则,当您到达集合的末尾时,找到距离中心/边缘最短的控件就是您的控件。

public class HitControl {

    public Control ThisControl;

    private Rectangle ControlBounds;
    private Point Center;

    public HitControl (Control FormControl) {
        ControlBounds = FormControl.Bounds;
        Center = new Point(ControlBounds.X + (ControlBounds.Width/2), ControlBounds.Y + (ControlBounds.Height/2));
    }

    //  Calculate the minimum distance from the left, right, and center
    public double DistanceFrom(Point TestPoint) {

        //  Note:  You don't need to consider control center points unless
        //  you plan to allow for controls placed over other controls... 
        //  Then you need to test the distance to the centers, as well, 
        //  and pick the shortest distance of to-edge, to-side, to-corner

        bool withinWidth = TestPoint.X > ControlBounds.X && TestPoint.X < ControlBounds.X + ControlBounds.Width;
        bool withinHeight = TestPoint.Y > ControlBounds.Y && TestPoint.Y < ControlBounds.Y + ControlBounds.Height;

        int EdgeLeftXDistance = Math.Abs(ControlBounds.X - TestPoint.X);
        int EdgeRightXDistance = Math.Abs(ControlBounds.X + ControlBounds.Width - TestPoint.X);

        int EdgeTopYDistance = Math.Abs(ControlBounds.Y - TestPoint.Y);
        int EdgeBottomYDistance = Math.Abs(ControlBounds.Y + ControlBounds.Height - TestPoint.Y);

        int EdgeXDistance = Math.Min(EdgeLeftXDistance, EdgeRightXDistance);
        int EdgeYDistance = Math.Min(EdgeTopYDistance, EdgeBottomYDistance);


        // Some points to consider for rectangle (100, 100, 100, 100):
        //  - (140, 90):  Distance to top edge
        //  - (105, 10):  Distance to top edge
        //  - (50, 50):   Distance to upper left corner
        //  - (250, 50):  Distance to upper right corner
        //  - (10, 105):  Distance to left edge
        //  - (140, 105):  Distance to top edge
        //  - (105, 140):  Distance to left edge
        //  - (290, 105):  Distance to right edge
        //  - (205, 150):  Distance to right edge
        //  ... and so forth


        //  You're within the control
        if (withinWidth && withinHeight) {
            return Math.Min(EdgeXDistance, EdgeYDistance);
        }

        //  You're above or below the control
        if (withinWidth) {
            return EdgeYDistance;
        }

        //  You're to the left or right of the control
        if (withinHeight) {
            return EdgeXDistance;
        }

        //  You're in one of the four outside corners around the control.
        //  Find the distance to the closest corner
        return Math.Sqrt(EdgeXDistance ^ 2 + EdgeYDistance ^ 2);


    }

    public bool ContainsPoint (Point TestPoint) {
        return ControlBounds.Contains(TestPoint);
    }


}



//  Initialize and use this collection
List<HitControl> hitControls = (from Control control in Controls
                                select new HitControl(control)).ToList();

Point testPoint = new Point(175, 619);
double distance;
double shortestDistance = 0;
HitControl closestControl = null;

foreach (HitControl hitControl in hitControls) {

    //  Optional... works so long as you don't have overlapping controls
    //  If you do, comment this block out
    if (hitControl.ContainsPoint(testPoint)) {
        closestControl = hitControl;
        break;
    }

    distance = hitControl.DistanceFrom(testPoint);
    if (shortestDistance == 0 || distance < shortestDistance) {
        shortestDistance = distance;
        closestControl = hitControl;
    }
}

if (closestControl != null) {
    Control foundControl = closestControl.ThisControl;
}

首先检查点是否在任何 rectangle . 如果没有,可以使用中的算法查找点与每个线段之间的距离。 this . 您还可以找到控件的4个段,因此您有一个由四个段(确定控件边)组成的列表(第一次启动),现在您可以找到最近的段,它的最近矩形。

你必须用矩形来思考:)

1. 测试:鼠标在控制范围内吗?
2. 如果没有:离任何一个边缘有多远?

然后您必须知道您对哪个控件感兴趣,例如,表单是一个控件。

对于初学者,创建将计算从矩形边缘到某个任意点的距离的方法。此方法的签名应为:

double DistanceFrom(Rect r, Point p);

然后,对于最简单的尝试,迭代所有控件,计算距离,记住提供它的最小距离和控件。

对于矩形距离,请检查 this 出来。

编辑:

事实上,您可以维护一个已排序的控件列表,这样您就可以始终拥有第一个更靠近顶部的控件,并在鼠标移动时维护该列表-这可能证明在速度方面更有效。有趣的问题是:)

我同意丹尼尔的观点,我们需要: 两倍距离(矩形R,点P);

但在此之前,我们需要: 两倍距离(R线,P点); 和 两点之间的双角(点p1,点p2);