Custom NumericUpDown Cell Flickering

问题

I'm implementing a custom NumericUpDown cell into my dataGridView using this tutorial from Microsoft: https://msdn.microsoft.com/en-us/library/aa730881(v=vs.80).aspx

It's working good, but the problem is that when Im NOT editing its value, my form/grid start to flick like crazy, and when I click to edit the value it stop.

My form is already "Double Buffered", so I'm not sure what to do anymore.

The code can be find in the link above, but I'm posting both classes I'm using to make it work:

http://pastebin.com/bdhWbgJU and http://pastebin.com/FeH3qHEb

回答1:

The code posted in pastebin seems overly complicated. You might want to try rewriting the control. I created a template for you, and the simplistic version does not seem to have any flicker.

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Windows.Forms;

    namespace Opulos.Core.UI {

    public class FormDgvNud : Form {
        DataGridView dgv = new DataGridViewNumericUpDown { Dock = DockStyle.Fill };
        public FormDgvNud() {
            Controls.Add(dgv);
        }
    }

    public class DataGridViewNumericUpDown : DataGridView {
        public DataGridViewNumericUpDown() : base() {
            Columns.Add(new NumericUpDownColumn() { HeaderText = "NUD1", DataPropertyName = "Column1", Name = "Column1" });
            Rows.Add();
        }
    }

    public class NumericUpDownColumn : DataGridViewColumn {

        public NumericUpDownColumn() : base(new NumericUpDownCell()) {
            this.ValueType = typeof(decimal?);
        }

        public override DataGridViewCell CellTemplate {
            get {
                return base.CellTemplate;
            }
            set {
                if (!(value is NumericUpDownCell))
                    throw new InvalidCastException("Must be a NumericUpDownCell");

                base.CellTemplate = value;
            }
        }
    }

    public class NumericUpDownCell : DataGridViewTextBoxCell {

        public override void InitializeEditingControl(int rowIndex, Object initialFormattedValue, DataGridViewCellStyle dataGridViewCellStyle) {
            // required to initialize the editing control:
            base.InitializeEditingControl(rowIndex, initialFormattedValue, dataGridViewCellStyle);
            var ctl = (NumericUpDownEditingControl) DataGridView.EditingControl;
            //NumericUpDownColumn cc = (NumericUpDownColumn) this.OwningColumn;
            if (this.Value == null || this.Value == DBNull.Value) {
                ctl.Value = (ctl.Minimum <= 0 && ctl.Maximum >= 0 ? 0 : ctl.Minimum);
            }
            else {
                Object trueValue = this.Value;
                ctl.Value = (decimal) trueValue;
            }
        }

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

        public override Type ValueType {
            get {
                return base.ValueType;
            }
            set {
                base.ValueType = value;
            }
        }

        public override Object DefaultNewRowValue {
            get {
                return DBNull.Value;
            }
        }
    }

    public class NumericUpDownEditingControl : NumericUpDown, IDataGridViewEditingControl {

        private bool Cancelling = false;

        public NumericUpDownEditingControl() {
        }

        // Implements the IDataGridViewEditingControl.EditingControlFormattedValue property.
        public Object EditingControlFormattedValue {
            get {
                // must return a String
                // it doesn't matter if the value is formatted, it will be replaced
                // by the formatting events
                String s = "" + this.Value.ToString();
                return s;
            }

            set {
                decimal val = 0;
                if (value is decimal)
                    this.Value = (decimal) value;
                else {
                    String s = "" + value;
                    if (s.Length > 0) {
                        if (decimal.TryParse(s, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.CurrentCulture, out val))
                            this.Value = val;
                    }
                }
            }
        }

        protected override void OnLeave(EventArgs e) {
            if (!Cancelling) {
                var dgv = this.EditingControlDataGridView;
                var cell = (NumericUpDownCell) dgv.CurrentCell;
                cell.Value = this.Value;
            }

            base.OnLeave(e);
            Cancelling = false;
        }

        private void ProcessValue(Direction transferFocusDirection) {
            var dgv = this.EditingControlDataGridView;
            var cell = (NumericUpDownCell) dgv.CurrentCell;

            if (!Cancelling)
                cell.Value = this.Value;
        }

        protected override void OnKeyDown(KeyEventArgs e) {
            if (e.KeyCode == Keys.Escape) {
                Cancelling = true;
                e.Handled = true;
                e.SuppressKeyPress = true;
                var dgv = this.EditingControlDataGridView;
                dgv.CancelEdit();
                dgv.EndEdit();
            }

            base.OnKeyDown(e);
        }

        // Implements the  IDataGridViewEditingControl.GetEditingControlFormattedValue method. 
        public Object GetEditingControlFormattedValue(DataGridViewDataErrorContexts context) {
            return EditingControlFormattedValue;
        }

        // Implements the IDataGridViewEditingControl.ApplyCellStyleToEditingControl method. 
        public void ApplyCellStyleToEditingControl(DataGridViewCellStyle dataGridViewCellStyle) {
            this.Font = dataGridViewCellStyle.Font;
            this.ForeColor = dataGridViewCellStyle.ForeColor;
            this.BackColor = dataGridViewCellStyle.BackColor;
        }

        // Implements the IDataGridViewEditingControl.EditingControlRowIndex property. 
        public int EditingControlRowIndex { get; set; }

        // Implements the IDataGridViewEditingControl.EditingControlWantsInputKey method. 
        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:
                case Keys.Escape:
                    return true;
                default:
                    return !dataGridViewWantsInputKey;
            }
        }

        // Implements the IDataGridViewEditingControl.PrepareEditingControlForEdit method. 
        public void PrepareEditingControlForEdit(bool selectAll) {
            // No preparation needs to be done.
        }

        // Implements the IDataGridViewEditingControl.RepositionEditingControlOnValueChange property. 
        public bool RepositionEditingControlOnValueChange {
            get {
                return false;
            }
        }

        // Implements the IDataGridViewEditingControl.EditingControlDataGridView property. 
        public DataGridView EditingControlDataGridView { get; set; }

        // Implements the IDataGridViewEditingControl.EditingControlValueChanged property. 
        public bool EditingControlValueChanged { get; set; }

        // Implements the IDataGridViewEditingControl.EditingPanelCursor property. 
        public Cursor EditingPanelCursor {
            get {
                return base.Cursor;
            }
        }
    }


public enum Direction {
    Down = 0,
    Right,
    Up,
    Left,
    None
}
    }

来源：https://stackoverflow.com/questions/32160261/custom-numericupdown-cell-flickering