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;                        //Dock
   
   private 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.