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# Drag & Drop Question

Posted on 2006-07-09
Medium Priority
1,452 Views
How to determine which column and row the mouse cursor is in the TableLayoutPanel in the DragDrop event?
0
Question by:michellechan57
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LVL 96

Expert Comment

ID: 17068905
Here is an extended custom control showing one possibility:

using System;
using System.Drawing;

/// <summary>
/// Extend the TableLayoutPanel, to provide
/// functionality to determine cell bounds,
/// and to perform hit-test information (row, column)
/// based on (x,y) coordinates passed into the
/// HitTest method.
/// </summary>
public class TableLayout : System.Windows.Forms.TableLayoutPanel
{

/// <summary>
/// Get the bounds for a cell at (row, column)
/// </summary>
/// <param name="row">The row for the cell</param>
/// <param name="column">The column for the cell</param>
/// <returns>A rectangle showing the cell bounds</returns>
public Rectangle GetCellBounds(int row, int column)
{

// Make sure that row and column are valid.
if (row < 0 || row > this.RowCount - 1)
throw new ArgumentOutOfRangeException("Row", "Row out of range");

if (column < 0 || column > this.ColumnCount - 1)
throw new ArgumentOutOfRangeException("Column", "Column out of range");

// Calculate cell dimensions.
int cellWidth = this.ClientRectangle.Width / this.ColumnCount;
int cellHeight = this.ClientRectangle.Height / this.RowCount;

// Calculate cell location.
int x = column * cellWidth;
int y = row * cellHeight;

return new Rectangle(x, y, cellWidth, cellHeight);
}

public TableLayoutHitTest HitTest(int x, int y)
{

for (int row = 0; row < this.RowCount; row++)
{
for (int col = 0; col < this.ColumnCount; col++)
{
if (this.GetCellBounds(row, col).Contains(x, y))
{
return new TableLayoutHitTest(row, col);
}
}
}
return null;
}
}

/// <summary>
/// Provides row, column information for where
/// the mouse is on a TableLayoutPanel.
/// The constructor takes row, column information
/// which can be accessed through the corresponding
/// properties.
/// </summary>
public class TableLayoutHitTest
{

// Constructor accepting row and column
public TableLayoutHitTest(int row, int column)
{
_row = row;
_column = column;
}

int _row;
public int Row
{
get { return _row; }
}

int _column;
public int Column
{
get { return _column; }
}
}

Bob
0

Author Comment

ID: 17069682
Bob, thanks.
Will try the solution and come back.
0

Author Comment

ID: 17077343
Bob,
1) could you explain a little more about extended custom control? specifically - how to use the code you have posted?
2) is there a simpler way to achieve the same?
Thanks
0

LVL 96

Expert Comment

ID: 17078399
1) Custom controls can extend any behavior of a base control to enhance.  When you build a custom control, it should appear on the ToolBox, so that you can drag and drop to the form

2) That code is an example of how you can determine cell bounds.  If you want to combine, try something like this from the DragDrop method:

private void TableLayoutPanel1_DragDrop(object sender, System.Windows.Forms.DragEventArgs e)

TableLayoutPanel panel = (TableLayoutPanel) sender;

// Calculate cell dimensions.
int cellWidth = panel.ClientRectangle.Width / panel.ColumnCount;
int cellHeight = panel.ClientRectangle.Height / panel.RowCount;

for (int row = 0; row < panel.RowCount; row++)
{
for (int col = 0; col < panel.ColumnCount; col++)
{

// Calculate cell location.
int x = column * cellWidth;
int y = row * cellHeight;

Rectangle bounds = new Rectangle(x, y, cellWidth, cellHeight);

if (bound.Contains(e.X, e.Y))
{
// Do something here
}
}
}

Bob
0

Author Comment

ID: 17085889
Hi Bob,

I have modified your code a little so that my source control landed close to where the mouse pointed (drop point, not exact spot yet):

Point newPoint = tableLayoutPanel1.PointToClient(new Point(e.X, e.Y));
...
if (bounds.Contains(newPoint.X, newPoint.Y))
{
// Do something here
Label label = (Label)e.Data.GetData(typeof(Label));
label.Dock = DockStyle.Fill;

}

I will increase the point to 500 and ask (sorry for being idle): my rows height and columns width are not fixed, so how  can I determine where the mouse cursor in this case?
0

LVL 96

Expert Comment

ID: 17086007
How did you set the height and width?

Bob
0

LVL 96

Accepted Solution

Bob Learned earned 2000 total points
ID: 17086293
Try this:

private Rectangle GetCellBounds(int row, int column)
{

// Build a sum of the row height to get the y-coordinate.
int sumRow = 0;

// Look at all the rows.
for (int i = 0; i < this.tableLayoutPanel1.RowCount; i++)
{

// Calculate the row height based on the size type.
RowStyle rowStyle = this.tableLayoutPanel1.RowStyles[i];
int rowHeight = 0;

switch (rowStyle.SizeType)
{
case SizeType.Absolute:
rowHeight = Convert.ToInt32(rowStyle.Height);
break;
case SizeType.Percent:
rowHeight = Convert.ToInt32(this.tableLayoutPanel1.DisplayRectangle.Height * (rowStyle.Height / 100));
break;
default:
break;
}

int sumColumn = 0;

// Look at all the column for each row, since they may be different sizes.
for (int j = 0; j < this.tableLayoutPanel1.ColumnCount; j++)
{

// Calculate the column width based on the size type.
ColumnStyle columnStyle = this.tableLayoutPanel1.ColumnStyles[i];
int columnWidth = 0;

switch (columnStyle.SizeType)
{
case SizeType.Absolute:
columnWidth = Convert.ToInt32(columnStyle.Width);
break;
case SizeType.Percent:
columnWidth = Convert.ToInt32(this.tableLayoutPanel1.DisplayRectangle.Width * (columnStyle.Width / 100));
break;
}

// Build a rectangle indicating the bounds for selected cell.
if (row == i && column == j)
return new Rectangle(sumColumn, sumRow, columnWidth, rowHeight);

// Set the x-coordinate for the cell on the next column.
sumColumn += columnWidth;

}

// Set the y-coordinate for the cell on the next row.
sumRow += rowHeight;

}
return Rectangle.Empty;
}

Test code:
Console.WriteLine("1, 1:  " + this.GetCellBounds(0, 0).ToString());
Console.WriteLine("1, 2:  " + this.GetCellBounds(0, 1).ToString());
Console.WriteLine("2, 1:  " + this.GetCellBounds(1, 0).ToString());
Console.WriteLine("2, 2:  " + this.GetCellBounds(1, 1).ToString());

TableLayoutPanel configuration:
this.tableLayoutPanel1.ColumnCount = 2;
this.tableLayoutPanel1.Location = new System.Drawing.Point(68, 76);
this.tableLayoutPanel1.Name = "tableLayoutPanel1";
this.tableLayoutPanel1.RowCount = 2;
this.tableLayoutPanel1.Size = new System.Drawing.Size(200, 100);
this.tableLayoutPanel1.TabIndex = 1;

Bob
0

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