NodeEditor/Controls/EditorCanvas.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using NodeEditor.Extensions;

namespace NodeEditor
{
    /// <summary>
    /// Interaction logic for EditorCanvas.xaml
    /// </summary>
    public partial class EditorCanvas : UserControl
    {
        Point dragStart = new Point();
        MatrixTransform dragMatrixTransform = new MatrixTransform();
        TranslateTransform dragTranslateTransform = new TranslateTransform();

        public EditorCanvas()
        {
            InitializeComponent();
            m_EditorCanvas.MouseMove += MapCanvas_Drag;
            m_EditorCanvas.MouseDown += MapCanvas_StartDrag;
            m_EditorCanvas.MouseWheel += MapCanvas_OnScroll;

            mapCanvas.RenderTransform = MathExtensions.applyMultiTransform(dragTranslateTransform, dragMatrixTransform);
        }

        private void MapCanvas_StartDrag(object sender, MouseEventArgs e)
        {
            dragStart = e.GetPosition(this);
        }

        private void MapCanvas_Drag(object sender, MouseEventArgs e)
        {
            if (e.LeftButton == MouseButtonState.Pressed)
            {
                var element = sender as UIElement;

                var transform = dragTranslateTransform;

                var old = element.TranslatePoint(new Point(0, 0), map);
                var new_point = old + Point.Subtract(e.GetPosition(this), dragStart);
                transform.X = new_point.X;
                transform.Y = new_point.Y;

                m_EditorCanvas.RenderTransform = MathExtensions.applyMultiTransform(dragTranslateTransform, dragMatrixTransform);

                test.Text = Point.Subtract(e.GetPosition(this), dragStart).ToString();
            }


            if (e.LeftButton == MouseButtonState.Released)
                test.Text = "";
        }

        private void MapCanvas_EndDrag(object sender, MouseEventArgs e)
        {
            dragStart = new Point(0, 0);
        }

        private void MapCanvas_OnScroll(object sender, MouseWheelEventArgs e)
        {
            var element = sender as UIElement;
            var position = e.GetPosition(element);

            var transform = dragMatrixTransform;

            var matrix = transform.Matrix;
            var scale = e.Delta >= 0 ? 1.1 : (1.0 / 1.1);

            matrix.ScaleAtPrepend(scale, scale, position.X, position.Y);

            transform.Matrix = matrix;
            element.RenderTransform = MathExtensions.applyMultiTransform(dragTranslateTransform, dragMatrixTransform);
        }
    }
}