6502bench/CommonWinForms/NativeMethods.cs

/*
 * Copyright 2018 faddenSoft
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace CommonWinForms {
    // From https://stackoverflow.com/questions/1019388/

    /// <summary>
    /// Unpleasant hackery to make "select all" faster.  With 500K items it takes about 24
    /// seconds to select everything individually, and there isn't a better way.  With this
    /// it only takes a few milliseconds.
    /// </summary>
    public class NativeMethods {
        private const int LVM_FIRST = 0x1000;
        private const int LVM_SETITEMSTATE = LVM_FIRST + 43;

        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
        public struct LVITEM {
            public int mask;
            public int iItem;
            public int iSubItem;
            public int state;
            public int stateMask;
            [MarshalAs(UnmanagedType.LPTStr)]
            public string pszText;
            public int cchTextMax;
            public int iImage;
            public IntPtr lParam;
            public int iIndent;
            public int iGroupId;
            public int cColumns;
            public IntPtr puColumns;
        };

        [DllImport("user32.dll", EntryPoint = "SendMessage", CharSet = CharSet.Auto)]
        public static extern IntPtr SendMessageLVItem(IntPtr hWnd, int msg, int wParam, ref LVITEM lvi);

        /// <summary>
        /// Select all rows on the given listview
        /// </summary>
        /// <param name="list">The listview whose items are to be selected</param>
        public static void SelectAllItems(ListView list) {
            NativeMethods.SetItemState(list, -1, 2, 2);
        }

        /// <summary>
        /// Deselect all rows on the given listview
        /// </summary>
        /// <param name="list">The listview whose items are to be deselected</param>
        public static void DeselectAllItems(ListView list) {
            NativeMethods.SetItemState(list, -1, 2, 0);
        }

        /// <summary>
        /// Set the item state on the given item
        /// </summary>
        /// <param name="list">The listview whose item's state is to be changed</param>
        /// <param name="itemIndex">The index of the item to be changed</param>
        /// <param name="mask">Which bits of the value are to be set?</param>
        /// <param name="value">The value to be set</param>
        public static void SetItemState(ListView list, int itemIndex, int mask, int value) {
            LVITEM lvItem = new LVITEM();
            lvItem.stateMask = mask;
            lvItem.state = value;
            SendMessageLVItem(list.Handle, LVM_SETITEMSTATE, itemIndex, ref lvItem);
        }
    }
}