DataGridBoolColumn.cs source code in C# .NET

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                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / WinForms / Managed / System / WinForms / DataGridBoolColumn.cs / 1305376 / DataGridBoolColumn.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Windows.Forms { 
 
    using System.Diagnostics;
 
    using System;

    using System.Windows.Forms;
    using System.ComponentModel; 
    using System.Drawing;
    using Microsoft.Win32; 
 
    /// 
    ///  
    ///    Specifies a column in
    ///       which each cell contains a check box for representing
    ///       a boolean value.
    ///  
    public class DataGridBoolColumn : DataGridColumnStyle {
        private static readonly int idealCheckSize = 14; 
 
        private bool isEditing = false;
        private bool isSelected = false; 
        private bool allowNull = true;
        private int  editingRow = -1;
        private object currentValue = Convert.DBNull;
 
        private object trueValue = true;
        private object falseValue = false; 
        private object nullValue = Convert.DBNull; 

        private static readonly object  EventTrueValue      = new object(); 
        private static readonly object  EventFalseValue     = new object();
        private static readonly object  EventAllowNull      = new object();

        ///  
        /// 
        /// Initializes a new instance of the  class. 
        ///  
        public DataGridBoolColumn() : base() {}
 
        /// 
        /// 
        /// Initializes a new instance of a  with the specified .
        ///  
        public DataGridBoolColumn(PropertyDescriptor prop)
            : base(prop) {} 
 
        /// 
        ///  
        ///    [To be supplied.]
        /// 
        public DataGridBoolColumn(PropertyDescriptor prop, bool isDefault)
            : base(prop, isDefault){} 

        ///  
        ///  
        ///    Gets or sets the actual value used when setting the
        ///       value of the column to  . 
        /// 
        [TypeConverterAttribute(typeof(StringConverter)),
        DefaultValue(true)]
        public object TrueValue { 
            get {
                return trueValue; 
            } 
            set {
                if (!trueValue.Equals(value)) { 
                    this.trueValue = value;
                    OnTrueValueChanged(EventArgs.Empty);
                    Invalidate();
                } 
            }
        } 
 
        /// 
        public event EventHandler TrueValueChanged { 
            add {
                Events.AddHandler(EventTrueValue, value);
            }
            remove { 
                Events.RemoveHandler(EventTrueValue, value);
            } 
        } 

        ///  
        /// 
        ///    Gets or sets the actual value used when setting the value of the column to
        ///    .
        ///  
        [TypeConverterAttribute(typeof(StringConverter)), DefaultValue(false)]
        public object FalseValue { 
            get { 
                return falseValue;
            } 
            set {
                if (!falseValue.Equals(value)) {
                    this.falseValue = value;
                    OnFalseValueChanged(EventArgs.Empty); 
                    Invalidate();
                } 
            } 
        }
 
        /// 
        public event EventHandler FalseValueChanged {
            add {
                Events.AddHandler(EventFalseValue, value); 
            }
            remove { 
                Events.RemoveHandler(EventFalseValue, value); 
            }
        } 

        /// 
        /// 
        ///    Gets or sets the actual value used when setting the value of the column to 
        ///    .
        ///  
        [TypeConverterAttribute(typeof(StringConverter))] 
        public object NullValue {
            get { 
                return nullValue;
            }
            set {
                if (!nullValue.Equals(value)) { 
                    this.nullValue = value;
                    OnFalseValueChanged(EventArgs.Empty); 
                    Invalidate(); 
                }
            } 
        }

        // =-----------------------------------------------------------------
        // =        Methods 
        // =-----------------------------------------------------------------
 
        // when the grid is in addNewRow it means that the user did not start typing 
        // so there is no data to be pushed back into the backEnd.
        // make isEditing false so that in the Commit call we do not do any work. 
        //
        /// 
        protected internal override void ConcedeFocus() {
            base.ConcedeFocus(); 
            this.isSelected = false;
            this.isEditing = false; 
        } 

        private Rectangle GetCheckBoxBounds(Rectangle bounds, bool alignToRight) { 
            if (alignToRight)
                return new Rectangle(bounds.X +((bounds.Width - idealCheckSize) /2),
                                     bounds.Y +((bounds.Height - idealCheckSize) / 2),
                                     bounds.Width < idealCheckSize ? bounds.Width : idealCheckSize, 
                                     idealCheckSize);
            else 
                return new Rectangle(Math.Max(0,bounds.X +((bounds.Width - idealCheckSize) /2)), 
                                     Math.Max(0,bounds.Y +((bounds.Height - idealCheckSize) / 2)),
                                     bounds.Width < idealCheckSize ? bounds.Width : idealCheckSize, 
                                     idealCheckSize);
        }

        ///  
        /// 
        ///    Gets the value at the specified row. 
        ///  
        protected internal override object GetColumnValueAtRow(CurrencyManager lm, int row) {
            object baseValue = base.GetColumnValueAtRow(lm, row); 
            object value = Convert.DBNull;
            if (baseValue.Equals(trueValue)) {
                value = true;
            } 
            else if (baseValue.Equals(falseValue)) {
                value = false; 
            } 
            return value;
        } 

        private bool IsReadOnly() {
            bool ret = this.ReadOnly;
            if (this.DataGridTableStyle != null) { 
                ret = ret || this.DataGridTableStyle.ReadOnly;
                if (this.DataGridTableStyle.DataGrid != null) 
                    ret = ret || this.DataGridTableStyle.DataGrid.ReadOnly; 
            }
            return ret; 
        }

        /// 
        ///  
        ///    Sets the value a a specified row.
        ///  
        protected internal override void SetColumnValueAtRow(CurrencyManager lm, int row, object value) { 
            object baseValue = null;
            if (true.Equals(value)) { 
                baseValue = TrueValue;
            }
            else if (false.Equals(value)) {
                baseValue = FalseValue; 
            }
            else if (Convert.IsDBNull(value)) { 
                baseValue = NullValue; 
            }
            currentValue = baseValue; 
            base.SetColumnValueAtRow(lm, row, baseValue);
        }

        ///  
        /// 
        ///    Gets the optimum width and height of a cell given 
        ///       a specific value to contain. 
        /// 
        protected internal override Size GetPreferredSize(Graphics g, object value) { 
            return new Size(idealCheckSize+2, idealCheckSize+2);
        }

        ///  
        /// 
        ///    Gets 
        ///       the height of a cell in a column. 
        /// 
        protected internal override int GetMinimumHeight() { 
            return idealCheckSize+2;
        }

        ///  
        /// 
        ///     
        ///       Gets the height used when resizing columns. 
        ///    
        ///  
        protected internal override int GetPreferredHeight(Graphics g, object value)
        {
            return idealCheckSize + 2;
        } 

        ///  
        ///  
        ///    
        ///       Initiates a request to interrupt an edit procedure. 
        ///    
        /// 
        protected internal override void Abort(int rowNum) {
            isSelected = false; 
            isEditing = false;
            Invalidate(); 
            return; 
        }
 
        /// 
        /// 
        ///    
        ///       Initiates a request to complete an editing procedure. 
        ///    
        ///  
        protected internal override bool Commit(CurrencyManager dataSource, int rowNum) { 
            isSelected = false;
            // always invalidate 
            Invalidate();
            if (!isEditing)
                return true;
 
            SetColumnValueAtRow(dataSource, rowNum, currentValue);
            isEditing = false; 
            return true; 
        }
 
        /// 
        /// 
        ///    
        ///       Prepares the cell for editing a value. 
        ///    
        ///  
        protected internal override void Edit(CurrencyManager source, 
                                    int rowNum,
                                    Rectangle bounds, 
                                    bool readOnly,
                                    string displayText,
                                    bool cellIsVisible)
        { 
            // toggle state right now...
            isSelected = true; 
 
            // move the focus away from the previous column and give it to the grid
            // 
            DataGrid grid = this.DataGridTableStyle.DataGrid;
            if (!grid.Focused)
                grid.FocusInternal();
 
            if (!readOnly && !IsReadOnly()) {
                editingRow = rowNum; 
                currentValue = GetColumnValueAtRow(source, rowNum); 
            }
 
            base.Invalidate();
        }

        ///  
        ///    
        ///       Provides a handler for determining which key was pressed, and whether to 
        ///       process it. 
        ///    
        ///  
        internal override bool KeyPress(int rowNum, Keys keyData) {
            if (isSelected && editingRow == rowNum && !IsReadOnly()) {
                if ((keyData & Keys.KeyCode) == Keys.Space) {
                    ToggleValue(); 
                    Invalidate();
                    return true; 
                } 
            }
            return base.KeyPress(rowNum, keyData); 
        }

        /// 
        ///  
        ///    
        ///       Indicates whether the a mouse down event occurred at the specified row, at 
        ///       the specified x and y coordinates. 
        ///    
        ///  
        internal override bool MouseDown(int rowNum, int x, int y) {
            base.MouseDown(rowNum, x, y);
            if (isSelected && editingRow == rowNum && !IsReadOnly()) {
                ToggleValue(); 
                Invalidate();
                return true; 
            } 
            return false;
        } 

        private void OnTrueValueChanged(EventArgs e) {
            EventHandler eh = this.Events[EventTrueValue] as EventHandler;
            if (eh != null) 
                eh(this, e);
        } 
        private void OnFalseValueChanged(EventArgs e) { 
            EventHandler eh = this.Events[EventFalseValue] as EventHandler;
            if (eh != null) 
                eh(this, e);
        }
        private void OnAllowNullChanged(EventArgs e) {
            EventHandler eh = this.Events[EventAllowNull] as EventHandler; 
            if (eh != null)
                eh(this, e); 
        } 

        ///  
        /// 
        /// 
        /// Draws the 
        /// with the given , 
        ///  and row number.
        ///  
        protected internal override void Paint(Graphics g, Rectangle bounds, CurrencyManager source, int rowNum) 
        {
            Paint(g,bounds,source, rowNum, false); 
        }

        /// 
        ///  
        /// 
        /// Draws the  
        /// with the given , , 
        /// row number, and alignment settings. 
        ///  
        protected internal override void Paint(Graphics g, Rectangle bounds, CurrencyManager source, int rowNum, bool alignToRight) {
            Paint(g,bounds,source, rowNum, this.DataGridTableStyle.BackBrush, this.DataGridTableStyle.ForeBrush, alignToRight);
        }
 
        /// 
        ///  
        /// Draws the  with the given , , 
        ///    row number, , and . 
        ///  
        protected internal override void Paint(Graphics g, Rectangle bounds, CurrencyManager source, int rowNum,
                                     Brush backBrush, Brush foreBrush,
                                     bool alignToRight) {
            object value = (isEditing && editingRow == rowNum) ? currentValue : GetColumnValueAtRow(source, rowNum); 
            ButtonState checkedState = ButtonState.Inactive;
            if (!Convert.IsDBNull(value)) { 
                checkedState = ((bool)value ? ButtonState.Checked : ButtonState.Normal); 
            }
 
            Rectangle box = GetCheckBoxBounds(bounds, alignToRight);

            Region r = g.Clip;
            g.ExcludeClip(box); 

            System.Drawing.Brush selectionBrush = this.DataGridTableStyle.IsDefault ? this.DataGridTableStyle.DataGrid.SelectionBackBrush : this.DataGridTableStyle.SelectionBackBrush; 
            if (isSelected && editingRow == rowNum && !IsReadOnly()) { 
                g.FillRectangle(selectionBrush, bounds);
            } 
            else
                g.FillRectangle(backBrush, bounds);
            g.Clip = r;
 
            if (checkedState == ButtonState.Inactive) {
                ControlPaint.DrawMixedCheckBox(g, box, ButtonState.Checked); 
            } else { 
                ControlPaint.DrawCheckBox(g, box, checkedState);
            } 

            // if the column is read only we should still show selection
            if (IsReadOnly() && isSelected && source.Position == rowNum) {
                bounds.Inflate(-1,-1); 
                System.Drawing.Pen pen = new System.Drawing.Pen(selectionBrush);
                pen.DashStyle = System.Drawing.Drawing2D.DashStyle.Dash; 
                g.DrawRectangle(pen, bounds); 
                pen.Dispose();
                // restore the bounds rectangle 
                bounds.Inflate(1,1);
            }
        }
 
        /// 
        ///  
        ///    Gets or sets a value indicating whether null values are allowed. 
        /// 
        [ 
        SRCategory(SR.CatBehavior),
        DefaultValue(true),
        SRDescription(SR.DataGridBoolColumnAllowNullValue)
        ] 
        public bool AllowNull {
            get { 
                return allowNull; 
            }
            set { 
                if (allowNull != value)
                {
                    allowNull = value;
                    // if we do not allow null, and the gridColumn had 
                    // a null in it, discard it
                    if (!value && Convert.IsDBNull(currentValue)) 
                    { 
                        currentValue = false;
                        Invalidate(); 
                    }
                    OnAllowNullChanged(EventArgs.Empty);
                }
            } 
        }
 
        ///  
        public event EventHandler AllowNullChanged {
            add { 
                Events.AddHandler(EventAllowNull, value);
            }
            remove {
                Events.RemoveHandler(EventAllowNull, value); 
            }
        } 
 
        /// 
        ///  
        /// Enters a  into the column.
        /// 
        protected internal override void EnterNullValue()
        { 
            // do not throw an exception when the column is marked as readOnly or
            // does not allowNull 
            if (!this.AllowNull || IsReadOnly()) 
                return;
            if (currentValue != Convert.DBNull) { 
                currentValue = Convert.DBNull;
                Invalidate();
            }
        } 

        private void ResetNullValue() { 
            NullValue = Convert.DBNull; 
        }
 
        private bool ShouldSerializeNullValue() {
            return nullValue != Convert.DBNull;
        }
 
        private void ToggleValue() {
 
            if (currentValue is bool && ((bool)currentValue) == false) { 
                currentValue = true;
            } 
            else {
                if (AllowNull) {
                    if (Convert.IsDBNull(currentValue)) {
                        currentValue = false; 
                    }
                    else { 
                        currentValue = Convert.DBNull; 
                    }
                } 
                else {
                    currentValue = false;
                }
            } 
            // we started editing
            isEditing = true; 
            // tell the dataGrid that things are changing 
            // we put Rectangle.Empty cause toggle will invalidate the row anyhow
            this.DataGridTableStyle.DataGrid.ColumnStartedEditing(Rectangle.Empty); 
        }
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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DataGridBoolColumn.cs source code in C# .NET

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