Develop Reference

How to set repeater control back colour by item index?

I am using a DataRepeater control to show a popup. I am able to set BackColor of the current item by this code
private void dataRepeater1_CurrentItemIndexChanged(object sender, EventArgs e)
{
dataRepeater1.CurrentItem.BackColor = Color.Red;
}
but I am unable to add BackColor white for the previous item. Also I want to change the BackColor of the item form the list I am hovering mouse.

One way to solve this is to have one more property in your class, maybe called DataRepeater1_PreviousItem:
class YourClass
{
DataRepeaterItem DataRepeater1_PreviousItem { get; set; }
// ... some other code
private void dataRepeater1_CurrentItemIndexChanged(object sender, EventArgs e)
{
if (DataRepeater1_PreviousItem != null)
DataRepeater1_PreviousItem.BackColor = Color.White;
dataRepeater1.CurrentItem.BackColor = Color.Red;
DataRepeater1_PreviousItem = dataRepeater1.CurrentItem;
}
}

C# WInforms Change border style on button click event

I'm trying to change the border color of a text box (txtUser) on button click event (something like a form validation, if the input is empty then call the method that colors the border red). I did some googling and found this:
void myControl1_Paint(object sender, PaintEventArgs e)
{
ControlPaint.DrawBorder(e.Graphics, this.txtUser.ClientRectangle, Color.Black, ButtonBorderStyle.Solid);
}
But I'm having trouble understaing where or how should I call this method, or methods with (object sender, PaintEventArgs e) as params. Any explanation is appreciated.

You need to inherit from TextBox and then override the OnPaint method. Something like this should work:
public class ValidateEdit : TextBox
{
bool _InError;
public ValidateEdit()
{
SetStyle(ControlStyles.UserPaint, true);
}
public bool InError {
get {
return _InError;
}
set
{
_InError = value;
Refresh();
}
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
if (InError)
ControlPaint.DrawBorder(e.Graphics, this.DisplayRectangle, Color.Red, ButtonBorderStyle.Solid);
}
}

Can I override ToolStripSystemRenderer to change the color of a dropdown backgroud, without changing the toolstrip background color?

I created a class that inherits ToolStripSystemRenderer and have added overriden various events to style my toolstrip the way I want. But I can't seem to change background of a button's dropdown menu, without changing the background color of the toolstrip itself.
Here's an example of the menu. I want to change that system color.
My renderer class is pretty simple at the moment.
public class AvertToolStripRenderer : ToolStripSystemRenderer
{
protected override void OnRenderToolStripBorder(ToolStripRenderEventArgs e)
{
//base.OnRenderToolStripBorder(e);
}
protected override void OnRenderItemText(ToolStripItemTextRenderEventArgs e)
{
e.TextColor = Color.Black;
base.OnRenderItemText(e);
}
protected override void OnRenderArrow(ToolStripArrowRenderEventArgs e)
{
e.ArrowColor = Color.White;
base.OnRenderArrow(e);
}
}

You need to set the renderer of your toolstrip(just in case you forgot about this detail):
YourToolstrip.Renderer = new AvertToolStripRenderer();
Next on your custom renderer class:
public class AvertToolStripRenderer : ToolStripProfessionalRenderer
{
//rest of your implementation...
protected override void OnRenderToolStripBackground(ToolStripRenderEventArgs e)
{
ToolStripDropDown dr = e.ToolStrip as ToolStripDropDown;
if (dr != null)
{
e.Graphics.FillRectangle(Brushes.Beige, e.AffectedBounds);
}
}
}

firing ondrawitem event of custom combo

How do I raise a ondraw event
Scenario: I am using a custom combobox with a onDrawItem in my form.
The drawitem is such
protected override void OnDrawItem(DrawItemEventArgs e)
{...
}
Question: How do I make the custom combobox ComboLineStyle redraw
itself on selectedindex changed of another cmbBoxLineColor. Ultimately I need a way to redraw all rows of the combobox on every selectedindex changed
.
private void cmbBoxLineColor_SelectedIndexChanged(object sender, EventArgs e)
{
Here I want the custom combobox-ComboLineStyle control to redraw itself
}
EDIT
I need the dropdown to draw itself again when the color in another linecolorcombo changes.Color
lineColorSel = cmbBoxLineColor.SelectedValue;
ComboBoxItemLineStyle itemSolid = new ComboBoxItemLineStyle ("Solid Line", lineColorSel);
The color property in my linestylecomboboxitem will have the selectedvalue of the linecolor combo. So the linestyle combo should refresh/invalidate itself and redraw itself with this lineColorSel.
Thank u

You can call Invalidate() on anything that inherits System.Windows.Forms.Control to force it to redraw
Heres and example of how I would do a custom draw for a selected item
protected override void OnDrawItem(DrawItemEventArgs e)
{
if (e.State == DrawItemState.Selected)
{
...
}
else
{
...
}
//or you could do it like this
//if(e.Index == this.SelectedIndex)
//{
//}
...
}
protected override void OnSelectedIndexChanged(EventArgs e)
{
base.OnSelectedIndexChanged(e);
base.Invalidate();
}

WPF : Disable Undo in an editable ComboBox

I have implemented an undo system based on the Memento pattern. I disable the built in Undo on TextBox and was wondering how to do this on a ComboBox. The Combobox I have is editable, so it contains a TextBox, how do I access this to disable the Undo on it as well.
I know I can derive from ComboBox add a property and override the control template and set the property on the TextBox, but I would like a way to do this on the standard ComboBox from the xaml.

You can look it up from the template like this:
public Window1()
{
this.InitializeComponent();
comboBox1.Loaded += new RoutedEventHandler(comboBox1_Loaded);
}
void comboBox1_Loaded(object sender, RoutedEventArgs e)
{
var textBox = comboBox1.Template.FindName("PART_EditableTextBox", comboBox1) as TextBox;
}

I know this is 3+ years old but maybe it'll help someone. It is basically Rick's answer as a Behavoir that decyclone mentioned:
public class ComboBoxDisableUndoBehavoir : Behavior<ComboBox>
{
public ComboBoxDisableUndoBehavoir()
{
}
protected override void OnAttached()
{
if (AssociatedObject != null)
{
AssociatedObject.Loaded += AssociatedObject_Loaded;
}
base.OnAttached();
}
void AssociatedObject_Loaded(object sender, System.Windows.RoutedEventArgs e)
{
var tb = AssociatedObject.Template.FindName("PART_EditableTextBox", AssociatedObject) as TextBox;
if (tb != null)
{
tb.IsUndoEnabled = false;
}
}
}