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Problem with datagrid row select

P: n/a
Hi all,
I was wondering if anyone can help me with a really annoying problem I have
been having. I made a derived datagrid class that will select the row when
a user clicks anywhere on a cell (multi-select without modifier keys). I
got that working fine, but I also wanted to keep rows selected after a sort,
which I do by storing the row's id in an arraylist. The idea was to do the
sort and then go back and re-select the rows with that row id, which will
now be in a different location. The problem is that to walk through the
datagrid I have to set the current cell and for some reason that is messing
up the array's values. I am at a total loss. Anyone know why this is
happening and/or know a fix? Have I screwed the code up somewhere? Any
help would be dearly appreciated. Here is my code:

public class RowSelectDataGrid : DataGrid

{

private const int OFFSET = 5;

private bool multiselect;

private string id_field;

private ArrayList data_id_array;
// these are used for single selects

private int lastrow;

private int lastID;

/// <summary>

/// Constructor for the row select data grid

/// </summary>

/// <param name="id_field_name">Name of the field that holds a record id for
your dataset</param>

/// <param name="multi">Boolean value to enable the multiselect feature of
the datagrid</param>

public RowSelectDataGrid(string id_field_name, bool multi) : base()

{

this.data_id_array = new ArrayList();

this.lastrow = -1; // default value

this.lastID = -1; // default value

this.id_field = id_field_name;

this.multiselect = multi;

}

/// <summary>

/// Select the rows that contain ids in the selections array of ints

/// </summary>

/// <param name="selections">ArrayList of the record ids to be
selected</param>

public void SetSelectionList( ArrayList selections )

{

this.data_id_array.Clear();

foreach( int id in selections )

{

if( this.multiselect )

this.data_id_array.Add( id );

else // single select only has 1 entry max

this.data_id_array[0] = id;

}

RefreshSelects();

}

/// <summary>

/// Get or Set the multiselect datagrid option

/// </summary>

public bool MultiSelect

{

get

{

return this.multiselect;

}

set

{

// when this changes, the selections are cleared

this.data_id_array.Clear();

this.multiselect = value;

}

}

/// <summary>

/// Reprocess the entire datagrid line by line, selecting previously

/// specified rows

/// </summary>

public void RefreshSelects()

{

// Debugging -- this works, just selects the wrong row

// this.Select(this.lastrow);

// go through each line and select if it is in the list, unselect otherwise

int iRow;

DataGridCell checkCell = new DataGridCell();

checkCell.ColumnNumber = 1;

BindingManagerBase bm;

DataRowView drv;

DataTable myTable = ((DataSet) this.DataSource).Tables[this.DataMember];

for( iRow = 0; iRow < myTable.Rows.Count; iRow++ )

{

// position at the first column of the current row

checkCell.RowNumber = iRow;

this.CurrentCell = checkCell; // ***************** THIS IS THE PROBLEM
LINE -- HOW DOES IT CHANGE THE PRIVATE ARRAYLIST???

bm = BindingContext[this.DataSource, this.DataMember];

drv = (DataRowView) bm.Current;

// if this row has an id in the selection list, make sure it is selected

if( this.data_id_array.Contains( Int32.Parse(
drv[this.id_field].ToString() ) ) )

{

this.Select( iRow );

// if single select, update the row (don't need to update the value)

if( !this.multiselect )

this.lastrow = iRow;

}

// else

// this.UnSelect( iRow );

}

}

/*

* Note that we can just use the datagrid's select(int row) method to do

* multiple selects and unselect to remove them.

* You should capture a column header click so that you can make sure

* the correct rows are selected after the sort

* */

protected override void OnMouseDown(System.Windows.Forms.MouseEventArgs e)

{

DataGrid.HitTestInfo hti = this.HitTest(e.X, e.Y);

if( hti.Type == HitTestType.Cell )

{

// set up the data row view

DataGridCell clickedCell = new DataGridCell();

clickedCell.RowNumber = hti.Row;

clickedCell.ColumnNumber = hti.Column;

this.CurrentCell = clickedCell;

BindingManagerBase bm = BindingContext[this.DataSource, this.DataMember];

DataRowView drv = (DataRowView) bm.Current;

// if click on the append row (couldn't get it to not show) do nothing

if( drv[this.id_field].ToString() == "" )

return;

// otherwise select or unselect the row and add or remove it from the array

else

{

// if the row is currently in the selection list

if( this.data_id_array.Contains( Int32.Parse(
drv[this.id_field].ToString() ) ) )

{

this.data_id_array.Remove( Int32.Parse( drv[this.id_field].ToString() ) );

this.UnSelect( hti.Row );

// for single selects, clear the last selected row

if( !this.multiselect )

{

this.lastrow = -1;

this.lastID = -1;

}

}

// if it is not in the selection list

else

{

this.data_id_array.Add( Int32.Parse( drv[this.id_field].ToString() ) );

this.Select( hti.Row );

// for single selects, unselect the old, remove it from the list

// and update lastrow

if( !this.multiselect )

{

if( this.lastrow != -1 )

{

this.UnSelect( this.lastrow );

this.data_id_array.Remove( this.lastID );

}

this.lastrow = hti.Row;

this.lastID = Int32.Parse( drv[this.id_field].ToString() );

}

}

}

}

// sort and then fix the selections (since rows have changed)

else if( hti.Type == HitTestType.ColumnHeader )

{

base.OnMouseDown(e);

// this.RefreshSelects();

}

else

{

base.OnMouseDown(e);

}

}

protected override void OnCurrentCellChanged(System.EventArgs e)

{

base.OnCurrentCellChanged(e);

if(Control.MouseButtons != MouseButtons.Left)

{

Rectangle rect = this.GetCellBounds(this.CurrentCell);

MouseEventArgs e1 = new MouseEventArgs(MouseButtons.Left, 0, OFFSET, rect.Y
+ OFFSET, 0);

OnMouseDown(e1);

}

}

}


/// <summary>

/// This section of is very basic, but effective. By overriding the Edit
function, a cell in the column

/// cannot become active for editing, allowing the datagrid events to be
handled.

/// </summary>

public class DataGridNoActiveCellColumn : DataGridTextBoxColumn

{

protected override void Edit(System.Windows.Forms.CurrencyManager source,

int rowNum, System.Drawing.Rectangle bounds, bool readOnly, string
instantText,

bool cellIsVisible)

{

// Empty. Do NOT call the base class!

}

}
Nov 15 '05 #1
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2 Replies


P: n/a
Hi Chris,

Just some general observations:

1. The grid itself cannot modify data it knows nothing about. Therefore,
it's your code that actually corrupts the array list. Set breakpoints in
every function that modifies the list of identifiers and run the application
in the debugger to see how this happens.

2. The new row can be hidden by the following code:

CurrencyManager cm = (CurrencyManager)BindingContext[this.DataSource,
this.DataMember];
DataView view = (DataView)cm.List;
view.AllowNew = false;

--
Dmitriy Lapshin [C# / .NET MVP]
X-Unity Test Studio
http://x-unity.miik.com.ua/teststudio.aspx
Bring the power of unit testing to VS .NET IDE

"Chris Plowman" <ch***********@hilton.com> wrote in message
news:%2***************@TK2MSFTNGP11.phx.gbl...
Hi all,
I was wondering if anyone can help me with a really annoying problem I have been having. I made a derived datagrid class that will select the row when a user clicks anywhere on a cell (multi-select without modifier keys). I
got that working fine, but I also wanted to keep rows selected after a sort, which I do by storing the row's id in an arraylist. The idea was to do the sort and then go back and re-select the rows with that row id, which will
now be in a different location. The problem is that to walk through the
datagrid I have to set the current cell and for some reason that is messing up the array's values. I am at a total loss. Anyone know why this is
happening and/or know a fix? Have I screwed the code up somewhere? Any
help would be dearly appreciated. Here is my code:

public class RowSelectDataGrid : DataGrid

{

private const int OFFSET = 5;

private bool multiselect;

private string id_field;

private ArrayList data_id_array;
// these are used for single selects

private int lastrow;

private int lastID;

/// <summary>

/// Constructor for the row select data grid

/// </summary>

/// <param name="id_field_name">Name of the field that holds a record id for your dataset</param>

/// <param name="multi">Boolean value to enable the multiselect feature of
the datagrid</param>

public RowSelectDataGrid(string id_field_name, bool multi) : base()

{

this.data_id_array = new ArrayList();

this.lastrow = -1; // default value

this.lastID = -1; // default value

this.id_field = id_field_name;

this.multiselect = multi;

}

/// <summary>

/// Select the rows that contain ids in the selections array of ints

/// </summary>

/// <param name="selections">ArrayList of the record ids to be
selected</param>

public void SetSelectionList( ArrayList selections )

{

this.data_id_array.Clear();

foreach( int id in selections )

{

if( this.multiselect )

this.data_id_array.Add( id );

else // single select only has 1 entry max

this.data_id_array[0] = id;

}

RefreshSelects();

}

/// <summary>

/// Get or Set the multiselect datagrid option

/// </summary>

public bool MultiSelect

{

get

{

return this.multiselect;

}

set

{

// when this changes, the selections are cleared

this.data_id_array.Clear();

this.multiselect = value;

}

}

/// <summary>

/// Reprocess the entire datagrid line by line, selecting previously

/// specified rows

/// </summary>

public void RefreshSelects()

{

// Debugging -- this works, just selects the wrong row

// this.Select(this.lastrow);

// go through each line and select if it is in the list, unselect otherwise
int iRow;

DataGridCell checkCell = new DataGridCell();

checkCell.ColumnNumber = 1;

BindingManagerBase bm;

DataRowView drv;

DataTable myTable = ((DataSet) this.DataSource).Tables[this.DataMember];

for( iRow = 0; iRow < myTable.Rows.Count; iRow++ )

{

// position at the first column of the current row

checkCell.RowNumber = iRow;

this.CurrentCell = checkCell; // ***************** THIS IS THE PROBLEM
LINE -- HOW DOES IT CHANGE THE PRIVATE ARRAYLIST???

bm = BindingContext[this.DataSource, this.DataMember];

drv = (DataRowView) bm.Current;

// if this row has an id in the selection list, make sure it is selected

if( this.data_id_array.Contains( Int32.Parse(
drv[this.id_field].ToString() ) ) )

{

this.Select( iRow );

// if single select, update the row (don't need to update the value)

if( !this.multiselect )

this.lastrow = iRow;

}

// else

// this.UnSelect( iRow );

}

}

/*

* Note that we can just use the datagrid's select(int row) method to do

* multiple selects and unselect to remove them.

* You should capture a column header click so that you can make sure

* the correct rows are selected after the sort

* */

protected override void OnMouseDown(System.Windows.Forms.MouseEventArgs e)

{

DataGrid.HitTestInfo hti = this.HitTest(e.X, e.Y);

if( hti.Type == HitTestType.Cell )

{

// set up the data row view

DataGridCell clickedCell = new DataGridCell();

clickedCell.RowNumber = hti.Row;

clickedCell.ColumnNumber = hti.Column;

this.CurrentCell = clickedCell;

BindingManagerBase bm = BindingContext[this.DataSource, this.DataMember];

DataRowView drv = (DataRowView) bm.Current;

// if click on the append row (couldn't get it to not show) do nothing

if( drv[this.id_field].ToString() == "" )

return;

// otherwise select or unselect the row and add or remove it from the array
else

{

// if the row is currently in the selection list

if( this.data_id_array.Contains( Int32.Parse(
drv[this.id_field].ToString() ) ) )

{

this.data_id_array.Remove( Int32.Parse( drv[this.id_field].ToString() ) );

this.UnSelect( hti.Row );

// for single selects, clear the last selected row

if( !this.multiselect )

{

this.lastrow = -1;

this.lastID = -1;

}

}

// if it is not in the selection list

else

{

this.data_id_array.Add( Int32.Parse( drv[this.id_field].ToString() ) );

this.Select( hti.Row );

// for single selects, unselect the old, remove it from the list

// and update lastrow

if( !this.multiselect )

{

if( this.lastrow != -1 )

{

this.UnSelect( this.lastrow );

this.data_id_array.Remove( this.lastID );

}

this.lastrow = hti.Row;

this.lastID = Int32.Parse( drv[this.id_field].ToString() );

}

}

}

}

// sort and then fix the selections (since rows have changed)

else if( hti.Type == HitTestType.ColumnHeader )

{

base.OnMouseDown(e);

// this.RefreshSelects();

}

else

{

base.OnMouseDown(e);

}

}

protected override void OnCurrentCellChanged(System.EventArgs e)

{

base.OnCurrentCellChanged(e);

if(Control.MouseButtons != MouseButtons.Left)

{

Rectangle rect = this.GetCellBounds(this.CurrentCell);

MouseEventArgs e1 = new MouseEventArgs(MouseButtons.Left, 0, OFFSET, rect.Y + OFFSET, 0);

OnMouseDown(e1);

}

}

}


/// <summary>

/// This section of is very basic, but effective. By overriding the Edit
function, a cell in the column

/// cannot become active for editing, allowing the datagrid events to be
handled.

/// </summary>

public class DataGridNoActiveCellColumn : DataGridTextBoxColumn

{

protected override void Edit(System.Windows.Forms.CurrencyManager source,

int rowNum, System.Drawing.Rectangle bounds, bool readOnly, string
instantText,

bool cellIsVisible)

{

// Empty. Do NOT call the base class!

}

}


Nov 15 '05 #2

P: n/a
thanks for the info -- I was able to fix the problem using a temp variable
in the function itself as a copy of the datagrid's local arraylist and using
that. At the end of the function I overwrite the now screwed up local
arraylist with the copy, restoring it to its original data. I also tracked
down the error is caused because setting the current cell of the datagrid
(this.CurrentCell = checkCell;) causes the OnCurrentCellChange event to
fire, which in turn calls the mousedown event! Pitiful oversight on my
part. Thanks for the help.

Thank you for the info about hiding the new row, I will definetly give that
a try.

"Dmitriy Lapshin [C# / .NET MVP]" <x-****@no-spam-please.hotpop.com> wrote
in message news:e7**************@TK2MSFTNGP10.phx.gbl...
Hi Chris,

Just some general observations:

1. The grid itself cannot modify data it knows nothing about. Therefore,
it's your code that actually corrupts the array list. Set breakpoints in
every function that modifies the list of identifiers and run the application in the debugger to see how this happens.

2. The new row can be hidden by the following code:

CurrencyManager cm = (CurrencyManager)BindingContext[this.DataSource,
this.DataMember];
DataView view = (DataView)cm.List;
view.AllowNew = false;

--
Dmitriy Lapshin [C# / .NET MVP]
X-Unity Test Studio
http://x-unity.miik.com.ua/teststudio.aspx
Bring the power of unit testing to VS .NET IDE

"Chris Plowman" <ch***********@hilton.com> wrote in message
news:%2***************@TK2MSFTNGP11.phx.gbl...
Hi all,
I was wondering if anyone can help me with a really annoying problem I

have
been having. I made a derived datagrid class that will select the row

when
a user clicks anywhere on a cell (multi-select without modifier keys). I got that working fine, but I also wanted to keep rows selected after a

sort,
which I do by storing the row's id in an arraylist. The idea was to do

the
sort and then go back and re-select the rows with that row id, which will now be in a different location. The problem is that to walk through the
datagrid I have to set the current cell and for some reason that is

messing
up the array's values. I am at a total loss. Anyone know why this is
happening and/or know a fix? Have I screwed the code up somewhere? Any
help would be dearly appreciated. Here is my code:

public class RowSelectDataGrid : DataGrid

{

private const int OFFSET = 5;

private bool multiselect;

private string id_field;

private ArrayList data_id_array;
// these are used for single selects

private int lastrow;

private int lastID;

/// <summary>

/// Constructor for the row select data grid

/// </summary>

/// <param name="id_field_name">Name of the field that holds a record id

for
your dataset</param>

/// <param name="multi">Boolean value to enable the multiselect feature of the datagrid</param>

public RowSelectDataGrid(string id_field_name, bool multi) : base()

{

this.data_id_array = new ArrayList();

this.lastrow = -1; // default value

this.lastID = -1; // default value

this.id_field = id_field_name;

this.multiselect = multi;

}

/// <summary>

/// Select the rows that contain ids in the selections array of ints

/// </summary>

/// <param name="selections">ArrayList of the record ids to be
selected</param>

public void SetSelectionList( ArrayList selections )

{

this.data_id_array.Clear();

foreach( int id in selections )

{

if( this.multiselect )

this.data_id_array.Add( id );

else // single select only has 1 entry max

this.data_id_array[0] = id;

}

RefreshSelects();

}

/// <summary>

/// Get or Set the multiselect datagrid option

/// </summary>

public bool MultiSelect

{

get

{

return this.multiselect;

}

set

{

// when this changes, the selections are cleared

this.data_id_array.Clear();

this.multiselect = value;

}

}

/// <summary>

/// Reprocess the entire datagrid line by line, selecting previously

/// specified rows

/// </summary>

public void RefreshSelects()

{

// Debugging -- this works, just selects the wrong row

// this.Select(this.lastrow);

// go through each line and select if it is in the list, unselect

otherwise

int iRow;

DataGridCell checkCell = new DataGridCell();

checkCell.ColumnNumber = 1;

BindingManagerBase bm;

DataRowView drv;

DataTable myTable = ((DataSet) this.DataSource).Tables[this.DataMember];

for( iRow = 0; iRow < myTable.Rows.Count; iRow++ )

{

// position at the first column of the current row

checkCell.RowNumber = iRow;

this.CurrentCell = checkCell; // ***************** THIS IS THE PROBLEM
LINE -- HOW DOES IT CHANGE THE PRIVATE ARRAYLIST???

bm = BindingContext[this.DataSource, this.DataMember];

drv = (DataRowView) bm.Current;

// if this row has an id in the selection list, make sure it is selected

if( this.data_id_array.Contains( Int32.Parse(
drv[this.id_field].ToString() ) ) )

{

this.Select( iRow );

// if single select, update the row (don't need to update the value)

if( !this.multiselect )

this.lastrow = iRow;

}

// else

// this.UnSelect( iRow );

}

}

/*

* Note that we can just use the datagrid's select(int row) method to do

* multiple selects and unselect to remove them.

* You should capture a column header click so that you can make sure

* the correct rows are selected after the sort

* */

protected override void OnMouseDown(System.Windows.Forms.MouseEventArgs e)
{

DataGrid.HitTestInfo hti = this.HitTest(e.X, e.Y);

if( hti.Type == HitTestType.Cell )

{

// set up the data row view

DataGridCell clickedCell = new DataGridCell();

clickedCell.RowNumber = hti.Row;

clickedCell.ColumnNumber = hti.Column;

this.CurrentCell = clickedCell;

BindingManagerBase bm = BindingContext[this.DataSource, this.DataMember];
DataRowView drv = (DataRowView) bm.Current;

// if click on the append row (couldn't get it to not show) do nothing

if( drv[this.id_field].ToString() == "" )

return;

// otherwise select or unselect the row and add or remove it from the

array

else

{

// if the row is currently in the selection list

if( this.data_id_array.Contains( Int32.Parse(
drv[this.id_field].ToString() ) ) )

{

this.data_id_array.Remove( Int32.Parse( drv[this.id_field].ToString() ) );
this.UnSelect( hti.Row );

// for single selects, clear the last selected row

if( !this.multiselect )

{

this.lastrow = -1;

this.lastID = -1;

}

}

// if it is not in the selection list

else

{

this.data_id_array.Add( Int32.Parse( drv[this.id_field].ToString() ) );

this.Select( hti.Row );

// for single selects, unselect the old, remove it from the list

// and update lastrow

if( !this.multiselect )

{

if( this.lastrow != -1 )

{

this.UnSelect( this.lastrow );

this.data_id_array.Remove( this.lastID );

}

this.lastrow = hti.Row;

this.lastID = Int32.Parse( drv[this.id_field].ToString() );

}

}

}

}

// sort and then fix the selections (since rows have changed)

else if( hti.Type == HitTestType.ColumnHeader )

{

base.OnMouseDown(e);

// this.RefreshSelects();

}

else

{

base.OnMouseDown(e);

}

}

protected override void OnCurrentCellChanged(System.EventArgs e)

{

base.OnCurrentCellChanged(e);

if(Control.MouseButtons != MouseButtons.Left)

{

Rectangle rect = this.GetCellBounds(this.CurrentCell);

MouseEventArgs e1 = new MouseEventArgs(MouseButtons.Left, 0, OFFSET,

rect.Y
+ OFFSET, 0);

OnMouseDown(e1);

}

}

}


/// <summary>

/// This section of is very basic, but effective. By overriding the Edit function, a cell in the column

/// cannot become active for editing, allowing the datagrid events to be
handled.

/// </summary>

public class DataGridNoActiveCellColumn : DataGridTextBoxColumn

{

protected override void Edit(System.Windows.Forms.CurrencyManager source,
int rowNum, System.Drawing.Rectangle bounds, bool readOnly, string
instantText,

bool cellIsVisible)

{

// Empty. Do NOT call the base class!

}

}

Nov 15 '05 #3

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