Question

我有一个测试程序，它构建一个数据表（26行乘6列）作为DataGridView的数据源。
可以通过选择单元格并从3个NumUpDown控件之一输入值来编辑数据网格每个控件都有特定的颜色。为了保存信息，我将表格保存在用户设置中我将每个单元格的颜色信息保存在额外的表格单元格中问题：当我显示数据网格时，它会从表中读取OK值，但是应该根据额外的单元格信息以编程方式添加的单元格颜色不显示。
（我在诊断中可以看到单元格获得了正确的颜色，但它没有显示在数据网格中看起来datagird有一些颜色覆盖（？）随附的是完整的工作代码请参阅代码中的更多信息任何人都可以善于运行这个并找到为什么颜色没有显示在数据网格中？感谢。

using System;
using System.Data;
using System.Drawing;
using System.Web.UI.WebControls;
using System.Windows.Forms;

//This is a test program to do the following:
//1. Build an empty data table of 26 rows by 6 columns.
//2. The Table is bind (as DataSource) to a DataGridView.
//3. The DataGrid Colomns 0-3 can be filled with decimals by one of 3 NumericUpDown  controls.
//3. For each cell in cols 0-2 there is one in cols 3-5 that holds info which NumUpDn  was used.
//4. Each NumUpDn has specific color. The corresponding cells have the same backcolor.
//5. When the program starts, it builds the table from the Settings, and displays the  table in the datagrid.
//6. The cells in cols 0-2 are supposed to get the colors ad indicated in cols 3-5, but   they do not.
//To run, make a WinForm with a datagrid 'fareGrid' and 3 NumUpDn controls with background colors.  


namespace DataGridViewTest
{
public partial class Form1 : Form
{
    DataTable fareTable = new DataTable();

    int rowIndex;
    int colIndex;

    public Form1()
    {
        InitializeComponent();
        buildFareTable("fareTable");
        // Load the table (if exists)
        if (Properties.Settings.Default.fareTable != null)
            fareTable = Properties.Settings.Default.fareTable;
        paintFareTableCells(fareTable);

    }

    //Build the initial data table of 26R X 6C
    //Columns 3-5 are used to hold the color information of cols 0-2
    public void buildFareTable(string fareTableName)
    {
        fareTable.TableName = fareTableName;
        fareTable.Columns.Add("Weekday", typeof(Decimal));
        fareTable.Columns.Add("HalfDay", typeof(Decimal));
        fareTable.Columns.Add("Weekend", typeof(Decimal));

        //Adding 3 indexing columns that will hold the tables cell group
        fareTable.Columns.Add("IWeekday", typeof(String));
        fareTable.Columns.Add("IHalfDay", typeof(String));
        fareTable.Columns.Add("Iweekend", typeof(String));

        for (rowIndex = 0; rowIndex < 26; rowIndex++)
        {
            fareTable.Rows.Add();
        }
    }

    public void paintFareTableCells(DataTable fareTable)
    {
        fareDataGrid.DataSource = fareTable;

        for (rowIndex = 0; rowIndex < 26; rowIndex++)
        {
            for (colIndex = 0; colIndex < 3; colIndex++)
            {
                switch (fareTable.Rows[rowIndex][colIndex + 3].ToString())   //Check the color index columns 3-5
                {
                    case "low": fareDataGrid[colIndex, rowIndex].Style.BackColor = Color.Green;  
                        break;
                    case "med": fareDataGrid[colIndex, rowIndex].Style.BackColor = Color.Yellow; 
                        break;
                    case "high": fareDataGrid[colIndex, rowIndex].Style.BackColor = Color.Red;  
                        break;
                    default:
                        break;
                }

                // Diagnostics: Check cell's color. At this point, Colors are OK!  
                Color color = fareDataGrid[colIndex, rowIndex].Style.BackColor;  
            }
        }
    }

   //Update the cells by 3 NumUpDn controls.
    private void numericUpDownFareHigh_ValueChanged(object sender, EventArgs e)
    {
        editFareTableCells(sender);
    }
    private void numericUpDownFareMed_ValueChanged(object sender, EventArgs e)
    {
        editFareTableCells(sender);
    }

    private void numericUpDownFareLow_ValueChanged(object sender, EventArgs e)
    {
        editFareTableCells(sender);
    }

    public void editFareTableCells(Object sender)
    {
        foreach (DataGridViewCell cell in fareDataGrid.SelectedCells)
        {
            if (cell.ColumnIndex < 3)
            {
                cell.Value = ((NumericUpDown)sender).Value;
                cell.Style.BackColor = ((NumericUpDown)sender).BackColor;
                fareDataGrid[cell.ColumnIndex + 3, cell.RowIndex].Value = ((NumericUpDown)sender).Tag;   //Uses cols 3-5 to hold cost level info.
            }
        }
    }

    //Use settings to preserve the data
    private void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
        Properties.Settings.Default.fareTable = this.fareTable;
        Properties.Settings.Default.Save();
    }
}
}

Answer 1

变色代码必须位于事件处理程序中;特别是DataBindingComplete事件处理程序。我按如下方式重新编写了代码：

public void paintFareTableCells(DataTable fareTable)
{
    fareDataGrid.DataSource = fareTable;
}

void fareDataGrid_DataBindingComplete(object sender, DataGridViewBindingCompleteEventArgs e)
{
    for (rowIndex = 0; rowIndex < 26; rowIndex++)
    {
        for (colIndex = 0; colIndex < 3; colIndex++)
        {
            switch (fareTable.Rows[rowIndex][colIndex + 3].ToString())   //Check the color index columns 3-5
            {
                case "low":
                    fareDataGrid[colIndex, rowIndex].Style.BackColor = Color.Green;
                    break;
                case "med":
                    fareDataGrid[colIndex, rowIndex].Style.BackColor = Color.Yellow;
                    break;
                case "high":
                    fareDataGrid[colIndex, rowIndex].Style.BackColor = Color.Red;
                    break;
                default:
                    break;
            }

            // Diagnostics: Check cell's color. At this point, Colors are OK!  
            Color color = fareDataGrid[colIndex, rowIndex].Style.BackColor;
        }
    }
}

现在，单元格会根据需要更改颜色。

顺便说一下，不要忘记在构造函数中订阅事件处理程序：

fareDataGrid.DataBindingComplete += new DataGridViewBindingCompleteEventHandler(fareDataGrid_DataBindingComplete);

Answer 2

在paintFareTableCells中，案例陈述可能会落到default，因此不会设置任何值。使用断点确认并相应地修改列索引。

我希望这会有所帮助。

Answer 3

不幸的是，我不确定为什么你的细胞没有按照它们应该涂的那样，但我最好的猜测是你在处理它们的油漆事件之前试图改变它们的属性。正如Joe Sisk建议的那样，我设法用事件改变了细胞的颜色，它对我来说很好。我希望它对你有所帮助。不同之处在于我使用了CellPainting事件，这是我所做的简短版本，我希望它可以帮助你自己完成剩下的工作......

    private void DataGridView1_CellPainting(object sender, DataGridViewCellPaintingEventArgs e)
    {
        if (e.Value != null) // if condition is met, this cell will be painted
        {
            e.CellStyle.BackColor = Color.Black; // i used black color, feel free to replace it :)
        }
    }

我希望这对你有用吗？

DataGridView单元格颜色更改

3 个答案: