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。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。