How to paint a specific cell of a stackpanel? - wpf

Question

In order to draw the matrix of cells , I used a Stackpanel, defined by this code:
int columns = Convert.ToInt32(columnasText.Text);
int rows = Convert.ToInt32(filasText.Text);
SolidColorBrush selected1 = new SolidColorBrush(Colors.Aquamarine);
SolidColorBrush released = new SolidColorBrush(Colors.White);
for (int i = 0; i < rows; i++)
{
StackPanel stkPanel = new StackPanel();
stkPanel.Orientation = Orientation.Horizontal;
for (int j = 0; j < columns; j++)
{
Label lbl = new Label();
lbl.Height = rejilla.Height / rows;
lbl.Width = rejilla.Width / columns;
lbl.Tag = new Point(i, j);
lbl.BorderBrush = new SolidColorBrush(Colors.Black);
lbl.BorderThickness = new Thickness(1);
lbl.Background = released;
stkPanel.Children.Add(lbl);
}
rejilla.Children.Add(stkPanel);
Once is defined, I need to change the colours of each cell depending on the values of each, and I'm not able to do it.

Answer 1

I used your variable rejilla (I am assuming it is either StackPanel or Grid). Either way, it will work.
Method 1:
The key is using .Children.OfType()
//Get your cell location
int rowIndex = 2;
int columnIndex = 8;
//Get your desired new color
SolidColorBrush selected1 = new SolidColorBrush(Colors.Aquamarine);
//Get list of your row panels
var stackPanels = rejilla.Children.OfType<StackPanel>().ToList();
//Check if desired row panel exist
if (rowIndex < stackPanels.Count && rowIndex >= 0)
{
//Get list of your labels in the desired row panel
var labels = stackPanels[rowIndex].Children.OfType<Label>().ToList();
//Check if desired cell exist or not then change background
if (columnIndex < labels.Count && columnIndex >= 0)
labels[columnIndex].Background = selected1;
}
Method 2: Using your Tag that you set (Point)
Not recommended, this method would have been useful if you placed all your labels in one stack panel instead of placing them in multiple stack panels (one stack panel for each row).
//Get your cell location
int rowIndex = 2;
int columnIndex = 8;
//Get your desired new color
SolidColorBrush selected1 = new SolidColorBrush(Colors.Aquamarine);
//Get list of your row panels
var stackPanels = rejilla.Children.OfType<StackPanel>().ToList();
//Check if desired row panel exist
if (rowIndex < stackPanels.Count && rowIndex >= 0)
{
//Get list of your labels in the desired row panel
var label = stackPanels[rowIndex].Children.OfType<Label>()
.Where(Item => (int)(Item.Tag as Nullable<Point>).GetValueOrDefault().X == rowIndex
&& (int)(Item.Tag as Nullable<Point>).GetValueOrDefault().Y == columnIndex).FirstOrDefault();
if(label != null)
label.Background = selected1;
}
You can place the code inside a method and pass your stackPanel, color, rowIndex, columnIndex:
private void SetCellColor(StackPanel stackPanel, SolidColorBrush color, int rowIndex, int columnIndex)
{
//Get list of your row panels
var stackPanels = stackPanel.Children.OfType<StackPanel>().ToList();
//Check if desired row panel exist
if (rowIndex < stackPanels.Count && rowIndex >= 0)
{
//Get list of your labels in the desired row panel
var labels = stackPanels[rowIndex].Children.OfType<Label>().ToList();
//Check if desired cell exist or not then change background
if (columnIndex < labels.Count && columnIndex >= 0)
labels[columnIndex].Background = color;
}
}
Then call it:
SetCellColor(rejilla, new SolidColorBrush(Colors.Aquamarine), rowIndex, columnIndex);
Good Luck!