Develop Reference

Add an OnLeave function to 140 objects?

I got a windows form with around 140 numericUpDown elements and want all of them to do this:
private void numericUpDown_B1_RS_LS_Leave(object sender, EventArgs e)
{
if (numericUpDown_B1_RS_LS.Value < 1 || numericUpDown_B1_RS_LS.Value > 6)
{
numericUpDown_B1_RS_LS.BackColor = Color.Red;
}
else
{
numericUpDown_B1_RS_LS.BackColor = Color.White;
}
}
Is there a more comfortable way of doing this than just adding 140 functions to the form manually?

Assuming you want the same method for all NUDs on your form this will do it:
public Form1()
{
InitializeComponent();
foreach (Control ctl in this.Controls)
if (ctl.GetType() == typeof(NumericUpDown) ) ctl.Leave += numericUpDown_Leave;
}
private void numericUpDown_Leave(object sender, EventArgs e)
{
NumericUpDown NumericUD = (NumericUpDown) sender ;
if (NumericUD.Value < 1 || NumericUD.Value > 6)
{
NumericUD.BackColor = Color.Red;
}
else
{
NumericUD.BackColor = Color.White;
}
}
You can just as easily iterate over the Controls collection of another container, say a Panel or a GroupBox if the NUDs are not directly sitting on the Form. And if some NUDs should be excepted from that behaviour you could mark them in some way, maybe in their Tag or Name and check for that before adding their handlers ..

You should not write multiple functions for same code. Instead you can create just one function and assign it to the event method of your numericUpDown element i.e. "UpDown" event.
So whenever any of the element's "UpDown" event will fire, your same function will be executed. And as far as you want to write different methods for different elements, then consider that in your method
Method(object sender, EventArguments e)
sender is the actual sender object of your updownElement type, and that code will be executed for that particular object only.
You can take for loop to iterate your all 140 elements and assign this function to the "UpDown" element.

maybe you could write a static method to handle the adding of event handler recursively, something like:
private void frmMain_Load(object sender, EventArgs e)
{
AddHandleNumericUpdownLeave(this);
}
public static void AddHandleNumericUpdownLeave(Control theContrl)
{
if (theContrl.Controls != null && theContrl.Controls.Count > 0)
{
foreach (Control cControl in theContrl.Controls)
{
AddHandleNumericUpdownLeave(cControl);
}
}
else
{
NumericUpDown nudCtrl = theContrl as NumericUpDown;
if (nudCtrl != null)
{
nudCtrl.Leave += (object senderT, EventArgs eT) =>
{
var tmpCtrl = senderT as NumericUpDown;
if (tmpCtrl != null)
{
if (tmpCtrl.Value < 1 || tmpCtrl.Value > 6)
{
tmpCtrl.BackColor = Color.Red;
}
else
{
tmpCtrl.BackColor = Color.White;
}
}
}
}
}
}
but this might be costly if you have too many controls in a form...

Custom ComboBox not closing properly

I am trying to make my custom ComboBox inheriting from ContainerControl. I used this article as a base but rewrote it, but I use a ToolStripControlHost, my own custom ListBox & a ToolStripDropDown.
Now the ComboBox is a button where you click on to show the DropDowncontaining my ListBox, works fine with overriding OnMouseClick.
The problems starts when I try to close the DropDown, with the DropDown's 'AutoClose' property to true, the DropDown closes if you click somewhere outside the DropDown (including the button) ...
protected override void OnMouseClick(MouseEventArgs e)
{
base.OnMouseClick(e);
/* listboxControl = ToolStripDropDown */
if (!listboxControl.Visible)
{
listboxControl.Show(this, GetDropLocation(), ToolStripDropDownDirection.BelowRight);
//listbox.Capture = true;
}
}
This is the code for the click on the button .. so what happens if you click it ?
If the DropDown is shown, it first closes the DropDown, then it fires the OnMouseClick event. Meaning: listboxControl.Visible is already false & it will show the DropDown again. All of this causing a quick close-open.
I have been stuck with this problem for some time now and google doesn't seem to know a lot about this subject (that article on CodeProject has the same bug).
What I have tried is disabling AutoClose and capturing the mouse after I show the DropDown, this works partially but it affects the working of my hosted ListBox. The ListBox contains a set of controls (the items), these items have a hover paint effect. Capturing the mouse in the ListBox control prevents the OnMouseEnter to be fired.
All input would be greatly appreciated !

You need a variable to track the cursor position when the DropDown is closing.
Here is a quick and dirty example control:
public class CustomDropBox : Control {
private ListBox box = new ListBox() { IntegralHeight = false };
private ToolStripControlHost host;
private ToolStripDropDown drop;
private bool wasShowing = false;
public CustomDropBox() {
box.MinimumSize = new Size(120, 120);
box.MouseUp += box_MouseUp;
box.KeyPress += box_KeyPress;
box.Items.AddRange(new string[] { "aaa", "bbb", "ccc" });
host = new ToolStripControlHost(box) { Padding = Padding.Empty };
drop = new ToolStripDropDown() { Padding = Padding.Empty };
drop.Closing += drop_Closing;
drop.Items.Add(host);
}
private Rectangle GetDownRectangle() {
return new Rectangle(this.ClientSize.Width - 16, 0, 16, this.ClientSize.Height);
}
void drop_Closing(object sender, ToolStripDropDownClosingEventArgs e) {
if (e.CloseReason == ToolStripDropDownCloseReason.AppClicked) {
wasShowing = GetDownRectangle().Contains(this.PointToClient(Cursor.Position));
} else {
wasShowing = false;
}
}
void box_KeyPress(object sender, KeyPressEventArgs e) {
if (e.KeyChar == (char)Keys.Enter && box.SelectedIndex > -1) {
drop.Close();
}
}
void box_MouseUp(object sender, MouseEventArgs e) {
int index = box.IndexFromPoint(e.Location);
if (index > -1) {
drop.Close();
}
}
protected override void OnMouseDown(MouseEventArgs e) {
if (e.Button == MouseButtons.Left && GetDownRectangle().Contains(e.Location)) {
if (wasShowing) {
wasShowing = false;
} else {
drop.Show(this, new Point(0, this.Height));
}
}
base.OnMouseDown(e);
}
protected override void OnPaint(PaintEventArgs e) {
e.Graphics.Clear(Color.White);
ControlPaint.DrawComboButton(e.Graphics, GetDownRectangle(), ButtonState.Normal);
base.OnPaint(e);
}
}

Making more than an event on a button

Please, I want to know how to make two events on one button like: when I first click on the button display an image and while still in debugging mode the second time I click
display another image. What are some ways to do this?

You can make something like:
protected void Button1Click(object sender, EventArgs e)
{
if (Img1.Visible == false)
{
Img1.Visible = true;
}
else
{
Img2.Visible = true;
}
}

I don't think you need two (or more) events to do what you want, you only need to trace how many times you clicked the button, for example using an instance variable.
private int clicks = 0;
protected void myButton_Click(object sender, EventArgs e)
{
if(clicks == 1)
{
// do something
}
if(clicks == 2)
{
// do other things
}
if(clicks > 2)
{
// something else
}
clicks++;
}

What about something like this: just make sure to declare the counter outside the button
int clickedCount = 0;
private void button1_Click(object sender, EventArgs e)
{
clickedCount++;
if (clickedCount % 2 == 0) { pictureBox1.ImageLocation = #"path"; } else { pictureBox1.ImageLocation = #"path"; }
}

WinRT, C#, canvas and children inertial scrolling

Situation: WinRT application, canvas on a main page. The canvas has a number of children. When user taps on canvas and moves pointer, I’m trying to scroll them. All works fine, but I don’t know how to emulate inertial scrolling.
The code:
private GestureRecognizer gr = new GestureRecognizer();
public MainPage()
{
this.InitializeComponent();
gr.GestureSettings = GestureSettings.ManipulationTranslateInertia;
gr.AutoProcessInertia = true;
}
I’ve subscribed to some canvas events:
//Pressed
private void Canvas_PointerPressed(object sender, PointerRoutedEventArgs e)
{
if (e.Pointer.PointerDeviceType == Windows.Devices.Input.PointerDeviceType.Touch)
{
var _ps = e.GetIntermediatePoints(cnvMain);
if (_ps != null && _ps.Count > 0)
{
gr.ProcessDownEvent(_ps[0]);
e.Handled = true;
Debug.WriteLine("Pressed");
}
initialPoint = e.GetCurrentPoint(cnvMain).Position.X;
}
}
//Released
private void Canvas_PointerReleased(object sender, PointerRoutedEventArgs e)
{
if (e.Pointer.PointerDeviceType == Windows.Devices.Input.PointerDeviceType.Touch)
{
var _ps = e.GetIntermediatePoints(cnvMain);
if (_ps != null && _ps.Count > 0)
{
gr.ProcessUpEvent(_ps[0]);
e.Handled = true;
Debug.WriteLine("Released");
}
}
// Moved
private void Canvas_PointerMoved(object sender, PointerRoutedEventArgs e)
{
if (gr.IsActive || gr.IsInertial)
{
gr.ProcessMoveEvents(e.GetIntermediatePoints(null));
// Here is my code for translation of children
e.Handled = true;
}
}
So, I can translate canvas children, but there is no inertia. How can I enable it?
Unfortunately, I can't use something like GridView or ListView in this app because of specific data.

You should use the GestureRecognizer with ManipulationInertiaStarting. This should give you enough information to implement inertial scrolling.

Enabling/Disabling Moveup/MoveDown buttons on a ListView

with a form like this:
I wrote this piece of code to take care of enable/disable logic for moveup/down buttons when they click on at item ( we don't care about Avaiable list on the left, we just care about Selected list on the right)
private void SelectedLV_SelectedIndexChanged(object sender, EventArgs e)
{
// what to do wth move up button
if (SelectedLV.SelectedIndices.Count == 1 && SelectedLV.SelectedItems[0].Index > 0)
{
MoveUpBtn.Enabled = true;
}
else
{
MoveUpBtn.Enabled = false;
}
//what to do with move down button
if (SelectedLV.SelectedIndices.Count == 1 && SelectedLV.SelectedItems[0].Index < SelectedLV.Items.Count - 1)
{
MoveDownBtn.Enabled = true;
}
else
{
MoveDownBtn.Enabled = false;
}
}
I think it works fine for that scenario but my question is what about when we click off of Selected Listview, What is good logic to handle that and Disable Both Moveup/Down buttons?
I don't want them be enabled when we are not inside SelectedListView...
Also if you notice any issue with the code I pasted please let me know.
Thanks

You are about to shoot your foot with the focus requirement. These kind of UI updates are best done with the Application.Idle event, it only runs when nothing important is happening. And can help to eliminate a lot of event handlers. Like this:
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
Application.Idle += Application_Idle;
this.FormClosed += delegate { Application.Idle -= Application_Idle; };
}
void Application_Idle(object sender, EventArgs e) {
bool focusOk = this.ActiveControl == SelectedLV;
bool selectOk = SelectedLV.SelectedIndices.Count == 1;
int index = selectOk ? SelectedLV.SelectedIndices[0] : -1;
MoveUpBtn.Enabled = focusOk && selectOk && index > 0;
MoveDownBtn.Enabled = focusOk && selectOk && index < SelectedLV.Items.Count-1;
}
}
Don't forget to set the focus back in the buttons' Click event handler. And don't forget about the ListView.HideSelection property. Set it to False so that focus doesn't matter anymore.

The problem is once you click on the Move buttons, then you are outside of the SelectedListView control, so the logic should really be based on if you have a correct index value or not:
private void SelectedLV_SelectedIndexChanged(object sender, EventArgs e)
if (SelectedLV.SelectedIndicies.Count == 0) {
MoveUpBtn.Enabled = false;
MoveDownBtn.Enabled = false;
} else {
// normal processing
}