winfrom重绘datagridview的滚动条替换原来的滚动条

要替换DataGridView的滚动条，可以使用以下步骤：

1. 创建一个派生自DataGridView的自定义控件。
2. 在自定义控件的构造函数中，禁用DataGridView的默认滚动条，创建一个自定义的滚动条控件，并将其添加到自定义控件中。
3. 在自定义控件中重写OnPaint方法，以便在重绘时绘制自定义滚动条控件。
4. 在自定义滚动条控件中处理滚动事件，并更新DataGridView的滚动位置。

以下是一个示例代码，可以作为参考：

public class CustomDataGridView : DataGridView
{
    private CustomScrollBar customScrollBar;

    public CustomDataGridView()
    {
        // 禁用默认滚动条
        this.ScrollBars = ScrollBars.None;

        // 创建自定义滚动条控件并添加到自定义控件中
        customScrollBar = new CustomScrollBar();
        customScrollBar.Scroll += CustomScrollBar_Scroll;
        this.Controls.Add(customScrollBar);
    }

    // 在重绘时绘制自定义滚动条控件
    protected override void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);

        // 绘制自定义滚动条控件
        customScrollBar.Location = new Point(this.Width - customScrollBar.Width, 0);
        customScrollBar.Height = this.Height;
        customScrollBar.Maximum = this.Rows.Count - this.DisplayedRowCount(false);
        customScrollBar.LargeChange = this.DisplayedRowCount(false);
        customScrollBar.SmallChange = 1;
        customScrollBar.Value = this.FirstDisplayedScrollingRowIndex;
        customScrollBar.Visible = true;
    }

    // 处理自定义滚动条控件的滚动事件
    private void CustomScrollBar_Scroll(object sender, ScrollEventArgs e)
    {
        this.FirstDisplayedScrollingRowIndex = customScrollBar.Value;
    }
}

public class CustomScrollBar : Control
{
    private int maximum = 0;
    private int largeChange = 0;
    private int smallChange = 0;
    private int value = 0;

    public int Maximum
    {
        get { return maximum; }
        set
        {
            maximum = value;
            if (maximum < 0)
            {
                maximum = 0;
            }
            if (value < this.value)
            {
                this.value = maximum;
            }
            this.Invalidate();
        }
    }

    public int LargeChange
    {
        get { return largeChange; }
        set
        {
            largeChange = value;
            if (largeChange < 0)
            {
                largeChange = 0;
            }
            if (largeChange > maximum)
            {
                largeChange = maximum;
            }
            this.Invalidate();
        }
    }

    public int SmallChange
    {
        get { return smallChange; }
        set
        {
            smallChange = value;
            if (smallChange < 0)
            {
                smallChange = 0;
            }
            if (smallChange > largeChange)
            {
                largeChange = smallChange;
            }
            this.Invalidate();
        }
    }

    public int Value
    {
        get { return value; }
        set
        {
            this.value = value;
            if (this.value < 0)
            {
                this.value = 0;
            }
            if (this.value > maximum - largeChange)
            {
                this.value = maximum - largeChange;
            }
            this.Invalidate();
        }
    }

    public event ScrollEventHandler Scroll;

    protected override void OnMouseDown(MouseEventArgs e)
    {
        base.OnMouseDown(e);

        if (e.Button == MouseButtons.Left)
        {
            int thumbTop = GetThumbTop();
            if (e.Y < thumbTop)
            {
                Value -= LargeChange;
            }
            else if (e.Y > thumbTop + GetThumbSize())
            {
                Value += LargeChange;
            }
            else
            {
                // 开始拖动滑块
                this.Capture = true;
            }
        }
    }

    protected override void OnMouseMove(MouseEventArgs e)
    {
        base.OnMouseMove(e);

        if (this.Capture)
        {
            int y = e.Y - GetThumbSize() / 2;
            int maxTop = this.Height - GetThumbSize();
            if (y < 0)
            {
                y = 0;
            }
            if (y > maxTop)
            {
                y = maxTop;
            }
            int thumbTop = GetThumbTop();
            if (y != thumbTop)
            {
                SetThumbTop(y);
                int newValue = ValueFromThumb();
                if (newValue != Value)
                {
                    Value = newValue;
                    OnScroll(new ScrollEventArgs(ScrollEventType.ThumbTrack, Value));
                }
            }
        }
    }

    protected override void OnMouseUp(MouseEventArgs e)
    {
        base.OnMouseUp(e);

        if (e.Button == MouseButtons.Left)
        {
            this.Capture = false;
        }
    }

    protected override void OnMouseWheel(MouseEventArgs e)
    {
        base.OnMouseWheel(e);

        if (e.Delta > 0)
        {
            Value -= SmallChange;
        }
        else if (e.Delta < 0)
        {
            Value += SmallChange;
        }
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);

        // 绘制背景
        using (SolidBrush brush = new SolidBrush(this.BackColor))
        {
            e.Graphics.FillRectangle(brush, ClientRectangle);
        }

        // 绘制滑轨
        Rectangle trackRect = GetTrackRect();
        using (SolidBrush brush = new SolidBrush(Color.LightGray))
        {
            e.Graphics.FillRectangle(brush, trackRect);
        }

        // 绘制滑块
        Rectangle thumbRect = GetThumbRect();
        using (SolidBrush brush = new SolidBrush(Color.Gray))
        {
            e.Graphics.FillRectangle(brush, thumbRect);
        }
    }

    protected virtual void OnScroll(ScrollEventArgs e)
    {
        Scroll?.Invoke(this, e);
    }

    private int GetThumbTop()
    {
        int trackHeight = GetTrackSize();
        int thumbHeight = GetThumbSize();
        int range = maximum - largeChange;
        if (range == 0)
        {
            return 0;
        }
        return (int)((double)value / range * (trackHeight - thumbHeight));
    }

    private void SetThumbTop(int top)
    {
        int trackHeight = GetTrackSize();
        int thumbHeight = GetThumbSize();
        int range = maximum - largeChange;
        if (range == 0)
        {
            return;
        }
        value = (int)((double)top / (trackHeight - thumbHeight) * range);
    }

    private int ValueFromThumb()
    {
        int trackHeight = GetTrackSize();
        int thumbHeight = GetThumbSize();
        int range = maximum - largeChange;
        if (range == 0)
        {
            return 0;
        }
        int thumbTop = GetThumbTop();
        return (int)((double)(thumbTop + thumbHeight / 2) / (trackHeight - thumbHeight) * range);
    }

    private int GetTrackSize()
    {
        return this.Height;
    }

    private Rectangle GetTrackRect()
    {
        return new Rectangle(0, 0, this.Width, GetTrackSize());
    }

    private int GetThumbSize()
    {
        int trackHeight = GetTrackSize();
        int range = maximum - largeChange;
        if (range == 0)
        {
            return trackHeight;
        }
        return Math.Max(trackHeight * largeChange / maximum, 20);
    }

    private Rectangle GetThumbRect()
    {
        int thumbTop = GetThumbTop();
        int thumbHeight = GetThumbSize();
        return new Rectangle(0, thumbTop, this.Width, thumbHeight);
    }
}