Нажмите кнопку и перетащите его на экран

Question

Я хочу сделать приложение, в котором пользователь может размещать элементы.

Вот моя проблема: Я хочу нажать кнопку (mousedown), и пока я двигаю мышь, кнопка должна двигаться вместе с моими движениями мыши.

Как я могу запрограммировать это в c# WPF? Нужно ли использовать свойство margin?

Привет

Answer 1

MainWindow.xaml.cs:

namespace dragdropButton
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        /// Tells whether the button is being pressed or not
        private bool buttonPressed;

        #region Imports method to determinate the mouse position
        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        internal static extern bool GetCursorPos(ref Win32Point pt);

        [StructLayout(LayoutKind.Sequential)]
        internal struct Win32Point
        {
            public Int32 X;
            public Int32 Y;
        };

        /// <summary>
        /// Obtains the mouse current position
        /// </summary>
        /// <returns>Position coordinates</returns>
        public static Point GetMousePosition()
        {
            Win32Point w32Mouse = new Win32Point();
            GetCursorPos(ref w32Mouse);
            return new Point(w32Mouse.X, w32Mouse.Y);
        }
        #endregion

        public MainWindow()
        {
            InitializeComponent();
        }

        /// <summary>
        /// Calculates the distance between two 2-dimensional points A and B
        /// </summary>
        /// <param name="pt">Point A</param>
        /// <param name="x">X coordinate of B</param>
        /// <param name="y">Y coordinate of B</param>
        /// <returns></returns>
        private double EuclideanDist(Point pt, double x, double y)
        {
            return Math.Sqrt(Math.Pow(pt.X - x, 2) + Math.Pow(pt.Y - y, 2));
        }

        /// <summary>
        /// Maps the left margin to the current mouse position
        /// </summary>
        /// <param name="pt">Mouse current position</param>
        /// <returns>Left margin</returns>
        private double GetLeftMargin(Point pt)
        {
            double x = 0;
            double y = pt.Y;
            return EuclideanDist(pt, x, y);
        }

        /// <summary>
        /// Maps the top margin to the current mouse position
        /// </summary>
        /// <param name="pt">Mouse current position</param>
        /// <returns>Top margin</returns>
        private double GetTopMargin(Point pt)
        {
            double x = pt.X;
            double y = 0;
            return EuclideanDist(pt, x, y);
        }

        /// <summary>
        /// Fires when mouse moves within this WPF window
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Window_PreviewMouseMove(object sender, MouseEventArgs e)
        {
            // if button is being pressed
            if (buttonPressed)
            {
                // get the mouse current position
                Point pt = GetMousePosition();

                // set the new button position
                this.button.Margin = new Thickness(GetLeftMargin(pt), GetTopMargin(pt), 0, 0);
            }
        }

        /// <summary>
        /// Fires whe button is pressed by mouse right click
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button_MouseDown(object sender, MouseButtonEventArgs e)
        {
            buttonPressed = true;
        }

        /// <summary>
        /// Firew when the button is released by mouse right click
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button_MouseUp(object sender, MouseButtonEventArgs e)
        {
            buttonPressed = false;
        }
    }
}

MainWindow.xaml:

<Window x:Class="dragdropButton.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:dragdropButton"
        mc:Ignorable="d"
        Title="MainWindow" Height="418" Width="779"
        PreviewMouseMove="Window_PreviewMouseMove">
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition/>
            <ColumnDefinition Width="0*"/>
            <ColumnDefinition Width="0*"/>
        </Grid.ColumnDefinitions>
        <Button x:Name="button" HorizontalAlignment="Left" Margin="241,167,0,0" VerticalAlignment="Top" Width="75" MouseUp="button_MouseUp" MouseDown="button_MouseDown" Height="40"/>
    </Grid>
</Window>