DataGridView带图标的单元格实现代码

目的：

扩展 C# WinForm 自带的表格控件，使其可以自动判断数据的上下界限值，并标识溢出。

这里使用的方法是：扩展 表格的列 对象：DataGridViewColumn。

1.创建类：DecimalCheckCell

 /// <summary>
 /// 可进行范围检查的 数值单元格
 /// </summary>
 public class DecimalCheckCell : DataGridViewTextBoxCell
 {
 private bool checkMaxValue = false;
 private bool checkMinValue = false;
 private decimal maxValue = 0;
 private decimal minValue = 0;

 public decimal MaxValue
 {
  get { return maxValue; }
  internal set { maxValue = value; }
 }

 public decimal MinValue
 {
  get { return minValue; }
  internal set { minValue = value; }
 }

 public bool CheckMaxValue
 {
  get { return checkMaxValue; }
  internal set { checkMaxValue = value; }
 }

 public bool CheckMinValue
 {
  get { return checkMinValue; }
  internal set
  {
  checkMinValue = value;
  }
 }

 public override object Clone()
 {
  DecimalCheckCell c = base.Clone() as DecimalCheckCell;
  c.checkMaxValue = this.checkMaxValue;
  c.checkMinValue = this.checkMinValue;
  c.maxValue = this.maxValue;
  c.minValue = this.minValue;
  return c;
 }

 protected override void Paint(Graphics graphics, Rectangle clipBounds,
  Rectangle cellBounds, int rowIndex, DataGridViewElementStates cellState,
  object value, object formattedValue, string errorText,
  DataGridViewCellStyle cellStyle,
  DataGridViewAdvancedBorderStyle advancedBorderStyle,
  DataGridViewPaintParts paintParts)
 {
  // Paint the base content
  base.Paint(graphics, clipBounds, cellBounds, rowIndex, cellState,
  value, formattedValue, errorText, cellStyle,
  advancedBorderStyle, paintParts);

  // 上下界限溢出判断
  if (this.RowIndex < 0 || this.OwningRow.IsNewRow) // 行序号不为-1，且不是新记录行（貌似没用）
  return;
  if (value == null) return;

  decimal vCurValue = Convert.ToDecimal(value);
  bool overValue = false;
  Image img = null;
  if (checkMaxValue)
  {
  overValue = vCurValue > maxValue;
  img = VsTest.Properties.Resources.Undo; // 图片来自 添加的资源文件
  }
  if (checkMinValue && !overValue)
  {
  overValue = vCurValue < minValue;
  img = VsTest.Properties.Resources.Redo; // 图片来自 添加的资源文件
  }

  // 将图片绘制在 数值文本后面
  if (overValue && img != null)
  {
  var vSize = graphics.MeasureString(vCurValue.ToString(), cellStyle.Font);

  System.Drawing.Drawing2D.GraphicsContainer container = graphics.BeginContainer();
  graphics.SetClip(cellBounds);
  graphics.DrawImageUnscaled(img, new Point(cellBounds.Location.X + (int)vSize.Width, cellBounds.Location.Y));
  graphics.EndContainer(container);
  }
 }

 protected override bool SetValue(int rowIndex, object value)
 {
  if (rowIndex >= 0)
  {
  try
  {
   decimal vdeci = Convert.ToDecimal(value); // 筛选非数字
   base.ErrorText = string.Empty;
  }
  catch (Exception ex)
  {
   base.ErrorText = "输入错误" + ex.Message;
   return false;
  }
  }
  return base.SetValue(rowIndex, value);
 }

 }

2.创建类：DecimalCheckColumn

 /// <summary>
 /// 可进行范围检查的 数值列
 /// </summary>
 public class DecimalCheckColumn : DataGridViewColumn
 {
  private bool checkMaxValue = false;
  private bool checkMinValue = false;
  private decimal maxValue = 0;
  private decimal minValue = 0;

  public decimal MaxValue
  {
   get { return maxValue; }
   set
   {
    maxValue = value;
    (base.CellTemplate as DecimalCheckCell).MaxValue = value;
   }
  }

  public decimal MinValue
  {
   get { return minValue; }
   set
   {
    minValue = value;
    (base.CellTemplate as DecimalCheckCell).MinValue = value;
   }
  }

  /// <summary>
  /// 是否对值上界限进行检查，与MaxValue配合使用
  /// </summary>
  public bool CheckMaxValue
  {
   get { return checkMaxValue; }
   set
   {
    checkMaxValue = value;
    (base.CellTemplate as DecimalCheckCell).CheckMaxValue = value;
   }
  }
  /// <summary>
  /// 是否对值下界限进行检查，与MinValue配合使用
  /// </summary>
  public bool CheckMinValue
  {
   get { return checkMinValue; }
   set
   {
    checkMinValue = value;
    (base.CellTemplate as DecimalCheckCell).CheckMinValue = value;
   }
  }

  public DecimalCheckColumn()
   : base(new DecimalCheckCell())
  {

  }

  public override object Clone()
  {
   DecimalCheckColumn c = base.Clone() as DecimalCheckColumn;
   c.checkMaxValue = this.checkMaxValue;
   c.checkMinValue = this.checkMinValue;
   c.maxValue = this.maxValue;
   c.minValue = this.minValue;

   return c;
  }

 }

3.现在就可以使用了，在窗体上拖一个 dataGridView 控件，添加如下代码：

 private void TestForm_Load(object sender, EventArgs e)
  {
   InitControlsProperties(); // 初始化

   // 绑定数据
   DataTable dTabel = new DataTable();
   dTabel.Columns.Add("ID",typeof(int));
   dTabel.Columns.Add("TestValue",typeof(decimal));
   Random rnd = new Random();
   for (int i = 0; i < 10; i++) // 随机10个数
   {
    var vdr = dTabel.NewRow();
    vdr[0] = i + 1;
    vdr[1] = rnd.Next(50);
    dTabel.Rows.Add(vdr);
   }
   this.dataGridView1.DataSource = dTabel;
  }

  private void InitControlsProperties()
  {
   DecimalCheckColumn ColumnRoleID = new DecimalCheckColumn();
   ColumnRoleID.DataPropertyName = "ID";
   ColumnRoleID.DefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleLeft;
   ColumnRoleID.Name = "ID";
   ColumnRoleID.HeaderText = "序号";
   ColumnRoleID.Width = 50;
   this.dataGridView1.Columns.Add(ColumnRoleID);

   DecimalCheckColumn ColumnRoleName = new DecimalCheckColumn();
   ColumnRoleName.DataPropertyName = "TestValue";
   ColumnRoleName.DefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleLeft;
   ColumnRoleName.Name = "TestValue";
   ColumnRoleName.HeaderText = "测试数据";
   ColumnRoleName.Width = 100;

   ColumnRoleName.CheckMaxValue = true; // 进行最大值检查
   ColumnRoleName.MaxValue = 41;
   ColumnRoleName.CheckMinValue = true; // 进行最小值检查
   ColumnRoleName.MinValue = 7;

   this.dataGridView1.Columns.Add(ColumnRoleName);

   //this.dataGridView1.AllowUserToAddRows = false;
   //this.dataGridView1.AllowUserToDeleteRows = false;
   //this.dataGridView1.ReadOnly = true;
   this.dataGridView1.AutoGenerateColumns = false;

  }

运行效果如下图左所示

那右边图是什么鬼？

现在还有一个问题没有解决：默认第一次加载出来的数据，并不能完全判断出是否超界限，有时会有一两个能判断，有时完全不能判断，但只需要用鼠标去点击各单元格，它又可以自动识别。暂时没有发现问题原因所在。

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