Question

我基本上是在写一个简单的浮动面板，可以通过拖动它的标题栏（这是一个网格本身）来改变它的位置。但我无法让它发挥作用！似乎MouseEventArgs.GetPosition返回错误的观点。我在这里错过了什么？

public class FloatingPanel : Grid
    {
        Grid gridTitle;

        bool dragging = false;
        Point lastPos;

        public FloatingPanel(UserControl gadget)
        {
            this.MouseMove += FloatingPanel_MouseMove;

            gridTitle = new Grid();
            gridTitle.Height = 25;
            gridTitle.VerticalAlignment = System.Windows.VerticalAlignment.Top;
            gridTitle.Background = Brushes.Cyan;
            gridTitle.MouseLeftButtonDown += gridTitle_MouseLeftButtonDown;
            gridTitle.MouseLeftButtonUp += gridTitle_MouseLeftButtonUp;
            this.Children.Add(gridTitle);

            this.Height = gadget.Height + 25;
            this.Width = gadget.Width;

            gadget.VerticalAlignment = System.Windows.VerticalAlignment.Bottom;
            this.Children.Add(gadget);
        }

        void gridTitle_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            dragging = false;
        }

        void gridTitle_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            lastPos = Mouse.GetPosition(this);
            dragging = true;
        }

        void FloatingPanel_MouseMove(object sender, MouseEventArgs e)
        {
            if(dragging)
            {
                Vector delta = e.GetPosition(this) - lastPos;
                this.Margin = new Thickness(this.Margin.Left + delta.X, this.Margin.Top + delta.Y, this.Margin.Right, this.Margin.Bottom);
                lastPos = e.GetPosition(this);
            }
        }
    }

我也尝试使用System.Windows.Forms.Cursor.Position和System.Windows.Forms.Control.MousePosition来显示屏幕上的位置。但没有运气。
解决方案：问题通过3次修改解决（如Sphinxxx指出）：
- 使用MouseEventArgs.GetPosition(null)代替MouseEventArgs.GetPosition(this)
- 使用mousedown和mouseup在Mouse.Capture(gridTitle)和Mouse.Capture(null)个事件中捕获和释放鼠标 - 设置网格的水平和垂直对齐方式。（这对我来说似乎很奇怪。为什么点头设置对齐会导致问题？）

Answer 1

在_MouseMove中，您尝试使用e.GetPosition(this)计算移动，但只能获得相对于Grid 的鼠标指针位置。您需要找到相对于其他UI元素的位置，例如包含Window以便知道网格应移动多少。

在e.GetPosition(null)和_MouseLeftButtonDown中尝试_MouseMove（ null 而不是此）来计算正确{{1 }}第

本文阐述了不同之处： Getting the Mouse Position Relative to a Specific Element

编辑：更强大delta：

在构造函数中，避免使用最终位于标题栏顶部的小工具，方法是将它们放在两个单独的FloatingPanel中（并让WPF句柄宽度和高度）：

RowDefinition

在public FloatingPanel(FrameworkElement gadget) { gridTitle = new Grid(); gridTitle.Height = 25; gridTitle.Background = Brushes.Cyan; gridTitle.MouseLeftButtonDown += gridTitle_MouseLeftButtonDown; gridTitle.MouseMove += gridTitle_MouseMove; gridTitle.MouseLeftButtonUp += gridTitle_MouseLeftButtonUp; //Create two grid rows - one to hold the title bar.. this.RowDefinitions.Add(new RowDefinition() { Height = GridLength.Auto }); Grid.SetRow(gridTitle, 0); this.Children.Add(gridTitle); //..and one two hold the gadget: this.RowDefinitions.Add(new RowDefinition() { Height = GridLength.Auto }); Grid.SetRow(gadget, 1); this.Children.Add(gadget); } / ..ButtonDown处理程序中，使标题栏“捕获”（并释放）鼠标移动，以便鼠标指针在移动速度过快时不会“滑落”：

..ButtonUp

编辑2：没有void gridTitle_MouseLeftButtonUp(object sender, MouseButtonEventArgs e) { //Relese a previous capture: Mouse.Capture(null); dragging = false; } void gridTitle_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) { lastPos = Mouse.GetPosition(null); //Capture the mouse to ensure we get all future mouse movements: Mouse.Capture(gridTitle); dragging = true; }的替代方案：

Mouse.Capture()

在网格类中拖放时鼠标位置错误

1 个答案: