pulsar/ObservatoryCore/UI/PluginListView.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Security.Permissions;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Observatory.UI
{
    internal class PluginListView : ListView
    {
        public PluginListView()
        {
            OwnerDraw = true;
            GridLines = false;
            DrawItem += PluginListView_DrawItem;
            DrawSubItem += PluginListView_DrawSubItem;
            DrawColumnHeader += PluginListView_DrawColumnHeader;
            
            
            DoubleBuffered = true;
            base.GridLines = false;//We should prevent the default drawing of gridlines.
        }

        // Stash for performance when doing large UI updates.
        private IComparer? comparer = null;

        public void SuspendDrawing()
        {
            BeginUpdate();
            comparer = ListViewItemSorter;
        }

        public void ResumeDrawing()
        {
            if (comparer != null)
            {
                ListViewItemSorter = comparer;
                comparer = null;
            }
            EndUpdate();
        }

        private static void DrawBorder(Graphics graphics, Pen pen, Rectangle bounds, bool header = false)
        {
            
            Point topRight = new(bounds.Right, bounds.Top);
            Point bottomRight = new(bounds.Right, bounds.Bottom);
            
            graphics.DrawLine(pen, topRight, bottomRight);
            
            if (header)
            {
                Point bottomLeft = new(bounds.Left, bounds.Bottom);
                // Point topLeft = new(bounds.Left, bounds.Top);
                // graphics.DrawLine(pen, topLeft, topRight);
                // graphics.DrawLine(pen, topLeft, bottomLeft);
                graphics.DrawLine(pen, bottomLeft, bottomRight);
            }
        }

        private void PluginListView_DrawColumnHeader(object? sender, DrawListViewColumnHeaderEventArgs e)
        {
            using (var g = e.Graphics)
                if (g != null)
                {
                    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
                    Pen pen = new(new SolidBrush(Color.LightGray));
                    DrawBorder(g, pen, e.Bounds);
                    using (var font = new Font(this.Font, FontStyle.Bold))
                    {
                        Brush textBrush = new SolidBrush(ForeColor);
                        g.DrawString(e.Header?.Text, font, textBrush, e.Bounds);
                    }
                }
        }

        private void PluginListView_DrawSubItem(object? sender, DrawListViewSubItemEventArgs e)
        {
            using (var g = e.Graphics)
                if (g != null)
                {
                    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
                    Pen pen = new(new SolidBrush(Color.LightGray));
                    DrawBorder(g, pen, e.Bounds, false);
                    
                    e.DrawText();
                }
        }

        private void PluginListView_DrawItem(object? sender, DrawListViewItemEventArgs e)
        {
            var offsetColor = (int value) =>
            {
                if (value > 127)
                {
                    return value - 20;
                }
                else
                {
                    return value + 20;
                }
            };

            using (var g = e.Graphics)
            {
                if (e.ItemIndex % 2 == 0)
                {
                    e.Item.BackColor = BackColor;
                }
                else
                {
                    e.Item.BackColor = Color.FromArgb(offsetColor(BackColor.R), offsetColor(BackColor.G), offsetColor(BackColor.B));
                }

                if (g != null)
                {
                    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
                    Pen pen = new(new SolidBrush(Color.LightGray));
                    e.DrawBackground();
                }
            }
   
        }
    }
}