C# 在 DataGridView 上显示我的自定义控件，即使不编辑

Question

我正在使用以下类来创建一个带有数字上下控件的自定义列。这工作得很好，但我想一直显示数字上下控制（即使不编辑）。以下代码将字符串值放在控件上，单击单元格后将显示数字控件进行编辑。我认为我需要重写 Paint 方法但我不知道如何实现它

using System;
using System.Drawing;
using System.Windows.Forms;

namespace Utilities.General.Classes
{
    public class NumericUpDownColumn : DataGridViewColumn
    {
        public NumericUpDownColumn() : base(new NumericUpDownCell())
        { }
        public override DataGridViewCell CellTemplate
        {
            get { return base.CellTemplate; }
            set
            {
                //Ensure that the cell used for the template is a NumericUpDown
                if(value?.GetType().IsAssignableFrom(typeof(NumericUpDownCell)) == false)
                {
                    throw new InvalidCastException("Must be a string");
                }
                base.CellTemplate = value;
            }
        }
    }

    public class NumericUpDownCell : DataGridViewTextBoxCell
    {
        public override void InitializeEditingControl(int rowIndex, object initialFormattedValue,
            DataGridViewCellStyle dataGridViewCellStyle)
        {
            base.InitializeEditingControl(rowIndex, initialFormattedValue, dataGridViewCellStyle);
            if(DataGridView.EditingControl is NumericUpDown numeric)
            {
                numeric.Value = Convert.ToDecimal(Value ?? DefaultNewRowValue);
                numeric.Minimum = MinValue;
                numeric.Maximum = MaxValue;
            }
        }

        protected override void OnEnter(int rowIndex, bool throughMouseClick)
        {
            if(throughMouseClick)
            {
                DataGridView.BeginEdit(false);
            }
        }

        public override Type EditType
        {
            get { return typeof(NumericUpDownEditingControl); }
        }

        public override Type ValueType
        {
            get { return typeof(string); }
        }

        public override object DefaultNewRowValue
        {
            get { return 0; }
        }

        private int MinValue { get; set; }
        private int MaxValue { get; set; }

        public void UpdateValues(int minValue, int maxValue)
        {
            MinValue = minValue;
            MaxValue = maxValue;
            ReadOnly = MinValue == MaxValue;
            if(ReadOnly)
            {
                Style.ForeColor = Color.DimGray;
            }
        }
    }

    public class NumericUpDownEditingControl : NumericUpDown, IDataGridViewEditingControl
    {
        public object EditingControlFormattedValue
        {
            get => Value;
            set
            {
                if(value is decimal number)
                {
                    try
                    {
                        Value = number;
                    }
                    catch
                    {
                        Value = 0;
                    }
                }
            }
        }

        public object GetEditingControlFormattedValue(DataGridViewDataErrorContexts context)
        {
            if((context & DataGridViewDataErrorContexts.Parsing) != 0)
            {
                return Value.ToString();
            }
            return EditingControlFormattedValue;
        }

        public decimal MinValue
        {
            get => Minimum;
            set => Minimum = value;
        }

        public decimal MaxValue
        {
            get => Maximum;
            set => Maximum = value;
        }

        public void ApplyCellStyleToEditingControl(DataGridViewCellStyle dataGridViewCellStyle)
        {
            Font = dataGridViewCellStyle.Font;
            ForeColor = dataGridViewCellStyle.ForeColor;
            BackColor = dataGridViewCellStyle.BackColor;
        }

        public int EditingControlRowIndex { get; set; }

        public bool EditingControlWantsInputKey(Keys key, bool datagridviewWantsInputKey)
        {
            switch(key & Keys.KeyCode)
            {
                case Keys.Left:
                case Keys.Up:
                case Keys.Down:
                case Keys.Right:
                case Keys.Home:
                case Keys.End:
                case Keys.PageDown:
                case Keys.PageUp:
                    return true;
                default:
                    return !datagridviewWantsInputKey;
            }
        }

        public void PrepareEditingControlForEdit(bool selectAll)
        {
        }

        public bool RepositionEditingControlOnValueChange => false;

        public DataGridView EditingControlDataGridView { get; set; }

        public bool EditingControlValueChanged { get; set; }

        public Cursor EditingPanelCursor => base.Cursor;

        protected override void OnValueChanged(EventArgs eventargs)
        {
            EditingControlValueChanged = true;
            EditingControlDataGridView.NotifyCurrentCellDirty(true);
            base.OnValueChanged(eventargs);
        }
    }
}

Answer 1

这似乎有效：

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)
{
    if(decimal.TryParse(value.ToString(), out var val))
    {
        var ctrl = new NumericUpDown()
        {
            Value = val
        };
        var img = new Bitmap(cellBounds.Width, cellBounds.Height);
        ctrl.DrawToBitmap(img, new Rectangle(0, 0, ctrl.Width, ctrl.Height));
        graphics.DrawImage(img, cellBounds.Location);
    }
    else
    {
        throw new InvalidCastException($"{value} is not decimal type");
    }
}