分享一个带有合计行功能的DataGridView扩展

因为一个Winform的项目中需要用到带有合计行的表格,并且需要满足以下需求:

1. 合计行可自动对需要求和的列进行求和计算;
2. 合计行必须固定(冻结)在表格的最底部,且其位置不受滚动条的滚动而移动;
3. 可以设置合计行单元格的数据展示格式.

本以为winform程序出来已经这么多年了,这个本也是个比较基础的功能,网上应该有很多现成的例子,便想着直接从网上找个例子用到项目中即可,无奈找了很久也没有见一个合适的实现,迫于无奈,只能动手自己写了一个DataGridView的扩展.并在这里整理出来,以分享给后续有类似需求的朋友参考,助其少走一些弯路.

1. 在开始之前,先来看一下在项目中展示效果及在程序中调用方式(当然展示的数据是随机生成的临时测试数据),各位看得顺眼再继续往后.
   
2. 实现思路.
            本文中的合计行其实是一个仅有一行数据的DataGridView,即整个控件会包含原数据表格DataGridView及合计行DataGridView组成,一开始本想通过一个UserControl来组织这两个控件,但会遇到DataGridView本身一大堆属性和事件需要在UserControl上重新定义,才能方便的在设计器中直接使用,尝试了几个属性后,发现这个工作量变得非常大,这个模式便被否定了,所以不得不重新寻找一个可行的方案.
           后经转变思维,我们可以直接将控件继承于原生态的DataGridView, 在当前控件展示的的时候,去动态创建一个合计行DataGridView,并将其添加到数据源控件下面即可.几经周折尝试后,发现确实可行,确定这个方向后,我们便一步步来实现这个功能. 完成后总结这个功能点,大致需要处理以下几个问题:
   1)  如何处理DataGridView的滚动条:滚动条需要联动,且滚动条需要位于两个DataGridView的外围;
   2)  如何确定合计行的位置,并将其添加到控件中,使其看起来和原数据表格是一体的;
   3)  当通过属性设置当前控件大小后,如何对应调整合计行的位置及大小;
   4)  拖动列宽后,对应调整合计行的列宽;
   5)  自动合计.
   在接下来的文章中,跟着分解步骤,来一起看看这个的具体实现.
3. 初始化变量并注册DataGridView相关事件,增加效果处理

   private bool _isShowSumRow = false; //是否显示合计行
   private string _sumCellFormat = "N2"; //合计单元格格式化字符串
   private int _sumRowHeight = 30; //合计行高
   private DataGridView _dgvSumRow = null; //合计行
   private VScrollBar _vScrollBar = null; //垂直滚动条
   private HScrollBar _hScrollBar = null; //水平滚动条
   private bool _initSourceGriding = false; //指示是否正在进行初始grid
   private DockStyle _dock; //Dockprivate int _dgvSourceMaxHeight = 0; //dgvSource最大高度
   private int _dgvSourceMaxWidth = 0; //dgvSource最大宽度/// <summary>
   /// 初始化
   /// </summary>
   public PDSumDataGridView()
   {
   base.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
   this.ColumnWidthChanged += new DataGridViewColumnEventHandler(this_ColumnWidthChanged);
   this.DataSourceChanged += new EventHandler(this_DataSourceChanged);
   this.RowHeadersWidthChanged += new EventHandler(this_RowHeadersWidthChanged);
   this.MouseWheel += new MouseEventHandler(dgvSource_MouseWheel);
   }

4. 禁用DataGridView 默认的滚动条,改为手动添加横向滚动条及纵向滚动条.并将其添加到和DateGridView 相同的父控件上,示例代码如下.

   /// <summary>
   /// 初始化合计行
   /// </summary>
   private void InitSumRowDgv()
   {
   _dgvSumRow = new DataGridView();
   _dgvSumRow.BackgroundColor = this.BackgroundColor;
   _dgvSumRow.ColumnHeadersVisible = false;
   _dgvSumRow.AllowUserToResizeColumns = false;
   _dgvSumRow.AllowUserToResizeRows = false;
   _dgvSumRow.ScrollBars = System.Windows.Forms.ScrollBars.None;
   _dgvSumRow.Visible = false;
   _dgvSumRow.Height = _sumRowHeight;
   _dgvSumRow.RowTemplate.Height = _sumRowHeight;
   _dgvSumRow.AllowUserToAddRows = false;
   _dgvSumRow.RowHeadersWidthSizeMode = DataGridViewRowHeadersWidthSizeMode.DisableResizing;
   _dgvSumRow.ReadOnly = true;
   _dgvSumRow.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
   _dgvSumRow.DefaultCellStyle.SelectionBackColor = _dgvSumRow.DefaultCellStyle.BackColor;
   _dgvSumRow.DefaultCellStyle.SelectionForeColor = _dgvSumRow.DefaultCellStyle.ForeColor;
   _dgvSumRow.Font = new Font("宋体", 10, FontStyle.Bold);
   _dgvSumRow.RowPostPaint += new DataGridViewRowPostPaintEventHandler(dgvSumRow_RowPostPaint);
   } /// <summary>
   /// 初始化合计dgv及滚动条
   /// </summary>
   private void InitSumDgvAndScrolBar()
   {
   if (this.Parent == null)
   {
   return;
   } //滚动条
   _vScrollBar = new VScrollBar();
   _hScrollBar = new HScrollBar();
   if (DesignMode)
   {
   base.ScrollBars = System.Windows.Forms.ScrollBars.Both;
   }
   else
   {
   this.ScrollBars = ScrollBars.None; //禁用dgv默认滚动条
   }
   this.Parent.Controls.Add(_vScrollBar);
   this.Parent.Controls.Add(_hScrollBar); _vScrollBar.Visible = false;
   _hScrollBar.Visible = false; //注册滚动条事件已代替dgv默认的滚动条
   _vScrollBar.Scroll += new ScrollEventHandler(vScrollBar_Scroll);
   _hScrollBar.Scroll += new ScrollEventHandler(hScrollBar_Scroll);
   InitSumRowDgv();
   this.Parent.Controls.Add(_dgvSumRow); this.SizeChanged += (s, e) =>
   {
   if (!_initSourceGriding)
   {
   InitScrollWithSourceGrid();
   this.Update();
   }
   };
   }

5. 根据数据量确定是否需要展示横向及纵向滚动条,同时确定合计行

   /// <summary>
   /// 根据源Grid设置是否需展示滚动条
   /// </summary>
   private void InitScrollWithSourceGrid()
   {
   if (_initSourceGriding || this.Parent == null)
   {
   return;
   } //初始化合计行
   if (_dgvSumRow == null)
   {
   InitSumDgvAndScrolBar();
   }
   _initSourceGriding = true; if (_dock == DockStyle.Fill)
   {
   this.Height = Parent.Height;
   this.Width = Parent.Width;
   this.Location = new Point(0, 0);
   } _dgvSourceMaxHeight = this.Height; //dgvSource最大高度
   _dgvSourceMaxWidth = this.Width; //dgvSource最大宽度 if (_isShowSumRow)
   {
   _dgvSourceMaxHeight -= _sumRowHeight;
   }
   if (_dgvSourceMaxHeight < RowHeight * 2)
   {
   _initSourceGriding = false;
   return;
   } this.Height = _dgvSourceMaxHeight;
   var displayDgvSumRowHeight = (_isShowSumRow && !DesignMode) ? _dgvSumRow.Height : 0; // this.MouseWheel -= new MouseEventHandler(dgvSource_MouseWheel);
   #region 验证是否需要显示水平滚动条 //需要展示水平滚动条
   if (this.DisplayedColumnCount(true) < this.Columns.Count)
   {
   _dgvSourceMaxHeight -= _hScrollBar.Height;
   this.Height = _dgvSourceMaxHeight; _hScrollBar.Location = new Point(this.Location.X, this.Location.Y + this.Height + displayDgvSumRowHeight);
   _hScrollBar.Width = _dgvSourceMaxWidth;
   _hScrollBar.Visible = true;
   _hScrollBar.BringToFront();
   _hScrollBar.Minimum = 0;
   _hScrollBar.SmallChange = AvgColWidth;
   _hScrollBar.LargeChange = AvgColWidth * 2;
   _hScrollBar.Maximum = ColsWidth;
   }
   else
   {
   _hScrollBar.Visible = false;
   }
   #endregion //根据源dgv设置合计行
   _dgvSumRow.RowHeadersWidth = this.RowHeadersWidth - 1; #region 验证是否需要显示纵向滚动条 var dgvSourceDisplayedRowCount = this.DisplayedRowCount(false); //最多显示行数 //不需要展示垂直滚动条
   if (dgvSourceDisplayedRowCount >= this.Rows.Count)
   {
   _vScrollBar.Visible = false;
   this.Width = _dgvSourceMaxWidth;
   _dgvSumRow.Width = _dgvSourceMaxWidth;
   }
   else
   {
   //需要展示垂直滚动条
   _dgvSourceMaxWidth = this.Width - _vScrollBar.Width; this.Width = _dgvSourceMaxWidth;
   _vScrollBar.Height = this.Height + (_isShowSumRow ? _dgvSumRow.Height : 0);
   _vScrollBar.Location = new Point(this.Location.X + this.Width, this.Location.Y);
   _vScrollBar.Visible = true;
   _vScrollBar.Maximum = (this.Rows.Count - dgvSourceDisplayedRowCount + 2) * RowHeight;
   _vScrollBar.Minimum = 0;
   _vScrollBar.SmallChange = RowHeight;
   _vScrollBar.LargeChange = RowHeight * 2;
   _vScrollBar.BringToFront();
   }
   #endregion if (_isShowSumRow && !DesignMode)
   {
   _dgvSumRow.Location = new Point(this.Location.X, this.Location.Y + _dgvSourceMaxHeight - 1);
   _dgvSumRow.Width = this.Width;
   _dgvSumRow.Visible = true;
   _dgvSumRow.BringToFront();
   }
   else
   {
   _dgvSumRow.Visible = false;
   }
   _initSourceGriding = false;
   }

6. 处理滚动条事件,同步作用于两个DataGridView

   /// <summary>
   /// DataGridView 列总宽.用于确定横向滚动条滚动值
   /// </summary>
   private int ColsWidth
   {
   get
   {
   int width = 0;
   foreach (DataGridViewColumn col in this.Columns)
   {
   if (!col.Visible)
   {
   continue;
   }
   width += col.Width;
   }
   return width;
   }
   }/// <summary>
   /// DataGridView 列平均总宽,用于确定横向滚动条滚动值
   /// </summary>
   private int AvgColWidth
   {
   get
   {
   int width = 80;
   width = ColsWidth / this.Columns.Count;
   return width;
   }
   }/// <summary>
   /// 每行高度.用于确定纵向滚动条滚动值
   /// </summary>
   private int RowHeight
   {
   get
   {
   int height = 20;
   if (this.Rows.Count > 0)
   {
   height = (this.Rows[0].Height - 3);
   }
   return height;
   }
   }/// <summary>
   /// 处理纵向滚动条事件
   /// </summary>
   /// <param name="sender"></param>
   /// <param name="e"></param>
   private void vScrollBar_Scroll(object sender, ScrollEventArgs e)
   {
   this.FirstDisplayedScrollingRowIndex = e.NewValue / RowHeight;
   }/// <summary>
   /// 处理横向滚动条事件
   /// </summary>
   /// <param name="sender"></param>
   /// <param name="e"></param>
   private void hScrollBar_Scroll(object sender, ScrollEventArgs e)
   {
   int value = e.NewValue;
   this.HorizontalScrollingOffset = value; if (_isShowSumRow && _dgvSumRow != null)
   {
   _dgvSumRow.HorizontalScrollingOffset = value;
   }
   }/// <summary>
   /// 处理源dgv鼠标滚轮滚动事件,同步带动横向滚动条及纵向滚动条
   /// </summary>
   /// <param name="sender"></param>
   /// <param name="e"></param>
   private void dgvSource_MouseWheel(object sender, MouseEventArgs e)
   {
   if (!_vScrollBar.Visible) return; if ((_vScrollBar.Value - RowHeight) < 0 && e.Delta > 0)
   {
   _vScrollBar.Value = _vScrollBar.Minimum;
   }
   else if ((_vScrollBar.Value + RowHeight * 2) > _vScrollBar.Maximum && e.Delta < 0)
   {
   _vScrollBar.Value = _vScrollBar.Maximum;
   }
   else
   {
   _vScrollBar.Value -= Convert.ToInt32((e.Delta / Math.Abs(e.Delta))) * RowHeight;
   }
   this.FirstDisplayedScrollingRowIndex = _vScrollBar.Value / RowHeight;
   }

7. 拖动列宽改变的时候,同步更新合计行的列宽

   private void this_ColumnWidthChanged(object sender, DataGridViewColumnEventArgs e)
   {
   if (_dgvSumRow != null)
   {
   _dgvSumRow.Columns[e.Column.Index].Width = e.Column.Width;
   }
   }private void this_RowHeadersWidthChanged(object sender, EventArgs e)
   {
   if (_dgvSumRow != null)
   {
   _dgvSumRow.RowHeadersWidth = this.RowHeadersWidth - 1;
   }
   }

8. 根据设置的需要合计列,自动合计数据

   /// <summary>
   /// 需要添加合计的datagridviewrow 列名称
   /// </summary>
   [Description("获取或设置需要用于求和的列名")]
   public string[] SumColumns
   {
   get;
   set;
   }/// <summary>
   /// 合计数据
   /// </summary>
   private void SumData()
   {
   if (this.Columns.Count <= 0)
   {
   return;
   } if (_dgvSumRow.Columns.Count != this.Columns.Count)
   {
   AddDgvSumRowColumns();
   } if (_dgvSumRow.Rows.Count != 1)
   {
   _dgvSumRow.Rows.Clear();
   _dgvSumRow.Rows.Add(1);
   } if (this.Rows.Count <= 0 || SumColumns == null || SumColumns.Length == 0)
   {
   return;
   } var sumRowDataDic = new Dictionary<int, decimal>(); #region 按设置的需要合计的列求和
   Array.ForEach(SumColumns, col =>
   {
   if (!_dgvSumRow.Columns.Contains(col))
   {
   return;
   }
   var tempSumVal = 0m;
   var colIndex = _dgvSumRow.Columns[col].Index;
   for (int i = 0; i < this.Rows.Count; i++)
   {
   if (this[colIndex, i].Value == null)
   {
   continue;
   } var tempVal = 0m;
   try
   {
   tempVal = (decimal)Convert.ChangeType(this[colIndex, i].Value, typeof(decimal));
   }
   catch { }
   tempSumVal += tempVal;
   }
   sumRowDataDic[colIndex] = tempSumVal;
   });
   #endregion if (sumRowDataDic.Count > 0)
   {
   sumRowDataDic.Keys.ToList().ForEach(colIndex =>
   {
   _dgvSumRow[colIndex, 0].Value = sumRowDataDic[colIndex];
   });
   }
   }/// <summary>
   /// 获取合计行
   /// </summary>
   [Browsable(false), EditorBrowsable(EditorBrowsableState.Never)]
   public DataGridViewRow SumRow
   {
   get
   {
   return (_isShowSumRow && _dgvSumRow.Rows.Count > 0) ? _dgvSumRow.Rows[0] : null;
   }
   }

9. 当数据源改变,重新计算合计,与合计行列头重绘

   private void this_DataSourceChanged(object sender, EventArgs e)
   {
   SumData();
   }/// <summary>
   /// 绘制合计行行头
   /// </summary>
   /// <param name="sender"></param>
   /// <param name="e"></param>
   private void dgvSumRow_RowPostPaint(object sender, DataGridViewRowPostPaintEventArgs e)
   {
   var rectangle = new Rectangle(e.RowBounds.Location.X + 1, e.RowBounds.Location.Y + 1,
   _dgvSumRow.RowHeadersWidth - 3, e.RowBounds.Height - 3); e.Graphics.FillRectangle(new SolidBrush(_dgvSumRow.RowHeadersDefaultCellStyle.BackColor), rectangle); TextRenderer.DrawText(e.Graphics, "合计",
   _dgvSumRow.RowHeadersDefaultCellStyle.Font,
   rectangle,
   _dgvSumRow.RowHeadersDefaultCellStyle.ForeColor,
   TextFormatFlags.VerticalCenter | TextFormatFlags.HorizontalCenter);
   }

10. 为了便于在设计器中使用,重写部分属性,并禁用可能影响展示效果的属性,同时增加上新的属性设置.

    /// <summary>
    /// 获取或设置Dock,该属性已被重新
    /// </summary>
    [Description("获取或设置Dock,该属性已被重写")]
    public new DockStyle Dock
    {
    get { return _dock; }
    set
    {
    _dock = value;
    if (value == DockStyle.Fill)
    {
    if (Parent != null)
    {
    this.Size = new Size(Parent.Width, Parent.Height);
    this.Location = new Point(0, 0);
    }
    this.Anchor = AnchorStyles.Top | AnchorStyles.Left | AnchorStyles.Right | AnchorStyles.Bottom;
    }
    else
    {
    this.Height = Parent.Height - 20;
    this.Width = Parent.Width - 20;
    }
    }
    }/// <summary>
    /// BorderStyle属性已被重写,该值固定为None,设置无效
    /// </summary>
    [Description("BorderStyle属性已被重写,该值固定为None,设置无效")]
    public new BorderStyle BorderStyle
    {
    get { return System.Windows.Forms.BorderStyle.None; }
    set { }
    }/// <summary>
    /// 获取或设置合计行单元格格式化字符串
    /// </summary>
    [Description("获取或设置合计行单元格格式化字符串")]
    public string SumRowCellFormat
    {
    get { return _sumCellFormat; }
    set { _sumCellFormat = value; }
    }/// <summary>
    /// 获取或设置是否显示合计行
    /// </summary>
    [Description("获取或设置是否显示合计行")]
    public bool IsShowSumRow
    {
    get { return _isShowSumRow; }
    set
    {
    _isShowSumRow = value;
    InitScrollWithSourceGrid();
    }
    }

后记,以上就是为DataGridView增加合计行功能扩展的关键代码,还望能帮助到有类似需求的朋友,或许本文于你的帮助仅为一个思路,并不完全代表你必须像我这么处理,各位看官还望斟酌.

另外本文不提供直接源码包下载,因为感觉如果你真的想学习还是自己这部分代码可能比较直接,直接复制文件的这种形式,估计能学到的可能性也比较小.希望直接获取源码包的朋友请绕道,还望见谅.