我的自定义控件在页面中为何不能显示?

Posted 2023-04-25

参考技术A 我分析有以下几个可能的原因:
1.也许你把控件的可见属性设为了不可见,VISABLE;
2.有一些控件本身就为看不见的,比如时间控件;
3.也许你其他控件的属性设置与你看不见的那个属性相冲突,这样也有可能看不见.

C# 在 DataGridView 上显示我的自定义控件，即使不编辑

【中文标题】C# 在 DataGridView 上显示我的自定义控件，即使不编辑

【英文标题】：C# show my custom control on DataGridView even if not editing

【发布时间】：2021-08-11 13:13:08

【问题描述】：

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);
        
    

【参考方案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");