using System;

using System.Windows;

using System.Windows.Media;

using System.Windows.Controls.Primitives;

using System.Windows.Controls;

using System.Windows.Input;



namespace EasySL.Share

{

    public static class DragHelper

    {

        public static void Drag(this FrameworkElement attachedElement)

        {

            bool isDragging = false;

            Point lastPosition = new Point(0, 0);



            attachedElement.MouseLeftButtonDown += (s, e) =>

            {

                isDragging = true;

                lastPosition = e.GetPosition(null);

                attachedElement.CaptureMouse();

            };



            attachedElement.MouseLeftButtonUp += (s, e) =>

            {

                isDragging = false;

                attachedElement.ReleaseMouseCapture();

            };



            attachedElement.MouseMove += (s, e) =>

            {

                if (!isDragging)

                    return;



                Point currentPosition = e.GetPosition(null);



                double dX = currentPosition.X - lastPosition.X;

                double dY = currentPosition.Y - lastPosition.Y;



                lastPosition = currentPosition;



                Transform oldTransform = attachedElement.RenderTransform;

                TransformGroup rt = new TransformGroup();

                TranslateTransform newPos = new TranslateTransform();

                newPos.X = dX;

                newPos.Y = dY;



                if (oldTransform != null)

                {

                    rt.Children.Add(oldTransform);

                }

                rt.Children.Add(newPos);



                MatrixTransform mt = new MatrixTransform();

                mt.Matrix = rt.Value;



                attachedElement.RenderTransform = mt;



            };

        }



        public static void Drag(this FrameworkElement attachedElement, object dragObject)

        {

            attachedElement.Drag(dragObject, null, null);

        }



        public static void Drag(this FrameworkElement attachedElement, object dragObject, MouseEventHandler onMove, MouseButtonEventHandler onDragCompleted)

        {

            Popup rootPopup = new Popup();

            rootPopup.IsOpen = false;



            ContentControl dragElement = new ContentControl();

            dragElement.Content = dragObject;



            rootPopup.Child = dragElement;



            bool isDragging = false;

            Point lastPosition = new Point(0, 0);



            attachedElement.MouseLeftButtonDown += (s, e) =>

            {

                isDragging = true;

                lastPosition = e.GetPosition(null);

                dragElement.CaptureMouse();



                Point p = e.GetPosition(attachedElement);

                rootPopup.IsOpen = true;

                rootPopup.HorizontalOffset = lastPosition.X - p.X;

                rootPopup.VerticalOffset = lastPosition.Y - p.Y;

            };



            dragElement.MouseLeftButtonUp += (s, e) =>

            {

                isDragging = false;

                dragElement.ReleaseMouseCapture();



                rootPopup.IsOpen = false;

                dragElement.RenderTransform = null;



                if (onDragCompleted != null)

                    onDragCompleted(s, e);

            };



            dragElement.MouseMove += (s, e) =>

            {

                if (!isDragging)

                    return;



                Point currentPosition = e.GetPosition(null);



                double dX = currentPosition.X - lastPosition.X;

                double dY = currentPosition.Y - lastPosition.Y;



                lastPosition = currentPosition;



                Transform oldTransform = dragElement.RenderTransform;

                TransformGroup rt = new TransformGroup();

                TranslateTransform newPos = new TranslateTransform();

                newPos.X = dX;

                newPos.Y = dY;



                if (oldTransform != null)

                {

                    rt.Children.Add(oldTransform);

                }

                rt.Children.Add(newPos);



                MatrixTransform mt = new MatrixTransform();

                mt.Matrix = rt.Value;



                dragElement.RenderTransform = mt;



                if (onMove != null)

                    onMove(s, e);

            };

        }

    }

}