Metis_xctg/Measurement/HistoryMementos/FlipLayerHistoryMemento.cs

using PaintDotNet.Measurement.Enum;
using System;

namespace PaintDotNet.Measurement.HistoryMementos
{
    public class FlipLayerHistoryMemento
        : HistoryMemento
    {
        private IDocumentWorkspace historyWorkspace;
        private int layerIndex;
        private FlipType flipType;

        private void Flip(Surface surface)
        {
            switch (this.flipType)
            {
                case FlipType.Horizontal:
                    for (int y = 0; y < surface.Height; ++y)
                    {
                        for (int x = 0; x < surface.Width / 2; ++x)
                        {
                            ColorBgra temp = surface[x, y];
                            surface[x, y] = surface[surface.Width - x - 1, y];
                            surface[surface.Width - x - 1, y] = temp;
                        }
                    }
                    break;
                case FlipType.Vertical:
                    for (int x = 0; x < surface.Width; ++x)
                    {
                        for (int y = 0; y < surface.Height / 2; ++y)
                        {
                            ColorBgra temp = surface[x, y];
                            surface[x, y] = surface[x, surface.Height - y - 1];
                            surface[x, surface.Height - y - 1] = temp;
                        }
                    }
                    break;
                case FlipType.Center:
                    for (int y = 0; y < surface.Height; ++y)
                    {
                        for (int x = 0; x < surface.Width / 2; ++x)
                        {
                            ColorBgra temp = surface[x, y];
                            surface[x, y] = surface[surface.Width - x - 1, surface.Height - y - 1];
                            surface[surface.Width - x - 1, surface.Height - y - 1] = temp;
                        }
                    }
                    break;
                default:
                    throw new InvalidOperationException("FlipType was invalid");
            }

            return;
        }

        protected override HistoryMemento OnUndo()
        {
            FlipLayerHistoryMemento fha = new FlipLayerHistoryMemento(this.Name, this.Image,
                this.historyWorkspace, layerIndex, flipType);

            BitmapLayer layer = (BitmapLayer)this.historyWorkspace.GetDocument().Layers[layerIndex];
            Flip(layer.Surface);
            layer.Invalidate();
            return fha;
        }

        public FlipLayerHistoryMemento(string name, ImageResource image, IDocumentWorkspace historyWorkspace, int layerIndex, FlipType flipType)
            : base(name, image)
        {
            this.historyWorkspace = historyWorkspace;
            this.layerIndex = layerIndex;
            this.flipType = flipType;
        }
    }
}