EnsureVisible for ListViewSubItem

• 下载源代码 - 957 B

介绍 

它扩展了 ListView 控件，并添加了一个 EnsureVisible 方法，用于水平滚动到子项。

背景   

我经常使用 Code Project 来寻找好的示例，但没有找到这个的示例。所以我想回馈一些东西。   

使用代码 

用于滚动 ListView 的原生 Windows 消息是

        const Int32 LVM_FIRST = 0x1000;
        const Int32 LVM_SCROLL = LVM_FIRST + 20;

        [DllImport("user32")]
        static extern IntPtr SendMessage(IntPtr Handle, Int32 msg, IntPtr wParam,
        IntPtr lParam);

        private void ScrollHorizontal(int pixelsToScroll)
        {
            SendMessage(this.Handle, LVM_SCROLL, (IntPtr)pixelsToScroll,
            IntPtr.Zero);
        }   

要滚动到的项目的公共方法如下

        /// <summary>
        /// Ensure visible of a ListViewItem and SubItem Index.
        /// </summary>
        /// <param name="item"></param>
        /// <param name="subItemIndex"></param>
        public void EnsureVisible(ListViewItem item, int subItemIndex)
        {
            if (item == null || subItemIndex > item.SubItems.Count - 1)
            {
                throw new ArgumentException();
            }

            // scroll to the item row.
            item.EnsureVisible();
            Rectangle bounds = item.SubItems[subItemIndex].Bounds;

            // need to set width from columnheader, first subitem includes
            // all subitems.
            bounds.Width = this.Columns[subItemIndex].Width;

            ScrollToRectangle(bounds);
        }

        /// <summary>
        /// Scrolls the listview.
        /// </summary>
        /// <param name="bounds"></param>
        private void ScrollToRectangle(Rectangle bounds)
        {
            int scrollToLeft = bounds.X + bounds.Width + MARGIN;
            if (scrollToLeft > this.Bounds.Width)
            {
                this.ScrollHorizontal(scrollToLeft - this.Bounds.Width);
            }
            else
            {
                int scrollToRight = bounds.X - MARGIN;
                if (scrollToRight < 0)
                {
                    this.ScrollHorizontal(scrollToRight);
                }
            }
        }
    }

历史

• 2008年9月30日：初始发布