Best way to keep focus on DatePicker when validation error - c#

I found this related question, and it seems to work (mostly) for the TextBox in a DataGridTextColumn.
How would I implement the similar behavior for a DataGridTemplateColumn that has a DatePicker in the CellEditingTemplate?
This code seems to get called endlessly, suggesting that we are trying to set the focus to the wrong element:
private void DatePickerLostFocusHandler(object sender, RoutedEventArgs routedEventArgs)
{
// What is the correct property to use here?
// datePicker.GetBindingExpression(TextBox.TextProperty).UpdateSource();
if (Validation.GetHasError(datePicker))
{
// Looks like this is setting focus to wrong element -- it ends up getting called repeatedly.
var element = (sender as DatePicker);
var restoreFocus = (System.Threading.ThreadStart)delegate { element.Focus(); };
Dispatcher.BeginInvoke(restoreFocus);
}
}
Thanks for any insights ---

Related

Binding to checked propert messes up ui, binding to text is fine

UPDATE:
I think i have found the problem.
All my forms events that affect the binding source have this in the end:
BndSource.ResetBindings(false);
If i comment this line in my CheckedChanged event handler, the issue stops. But why?
I have a very strange bug.
I have a class property:
public SqlByte AutomaticFlag { get; set; }
I wanted to use checkbox to facilitate for showing this so in initial inding i do this:
dtaAutomaticFlag.DataBindings.Add("Checked", BndSource, "AutomaticFlag", true);
dtaAutomaticFlag.DataBindings[0].Format += (s, e) =>
{
if ((SqlByte)e.Value == 1)
{
e.Value = true;
}
else
{
e.Value = false;
}
};
the problem is that during iteration through all records of the binding source my ui is half updated, meaning its not complete. See picture:
VERY strangely when i change the above binding property from checked to text like this:
dtaAutomaticFlag.DataBindings.Add("Text", BndSource, "AutomaticFlag", true);
the ui is ok!!
Picture:
I'm not sure if this applies to this particular situation. But rather than adding the binding as you did:
dtaAutomaticFlag.DataBindings.Add("Text", BndSource, "AutomaticFlag", true);
Does creating a "new" binding instance help at all?
dtaAutomaticFlag.DataBindings.Add(new Binding("Text", BndSource, "AutomaticFlag", true));

C# Dynamic form (reflection) - linking controls

Sorry for the poor quality of the title. I couldn't think of a better way to phrase this.
For a project I'm currently working on with a few friends, I got myself in the situation where I have created a dynamic form (with reflection) which I now want to validate.
Example (ignore the black box, it contains old form elements which are now irrelevant and i didn't want to confuse you guys):
As you may have guessed already, it is an application for creating a mysql database.
Which is where I get to my problem(s). I want to disable checkboxes if others are checked.
For example: If I check "PrimaryKey" I want to disable the checkbox "Null".
Changing from unsigned to signed changes the numericupdown minimum and maximum etc.
But with reflection and all, I find it difficult to know exactly which checkbox to disable.
I was hoping you guys would have some suggestions.
I have been thinking about this for a while and a few thoughts have come to mind. Maybe these are better solutions than the current one.
Thought 1: I create UserControls for every datatype. Pro's: no problems with reflection and easy identifying of every control in the UserControl for validation. Con's: Copy-Pasting, Lots of UserControls, with a lot of the same controls.
Thought 2: Doing something with the description tags for every property of the classes. Creating rules in the description that allow me to link the checkboxes together. Here I'll only have to copy the rules to every class property and then it should be ok.
I had been thinking of other solutions but I failed to remember them.
I hope you guys can give me a few good pointers/suggestions.
[Edit]
Maybe my code can explain a bit more.
My code:
PropertyInfo[] properties = DataTypes.DataTypes.GetTypeFromString(modelElement.DataType.ToString()).GetType().GetProperties();
foreach (PropertyInfo prop in properties)
{
if (prop.Name != "Label" && prop.Name != "Project" && prop.Name != "Panel")
{
var value = prop.GetValue(modelElement.DataType, null);
if (value != null)
{
tableLayoutPanel1.Controls.Add(new Label { Text = prop.Name, Anchor = AnchorStyles.Left, AutoSize = true });
switch (value.GetType().ToString())
{
case "System.Int32":
NumericUpDown numericUpDown = new NumericUpDown();
numericUpDown.Text = value.ToString();
numericUpDown.Dock = DockStyle.None;
tableLayoutPanel1.Controls.Add(numericUpDown);
break;
case "System.Boolean":
CheckBox checkBox = new CheckBox();
checkBox.Dock = DockStyle.None;
// checkbox will become huge if not for these changes
checkBox.AutoSize = false;
checkBox.Size = new Size(16, 16);
if (value.Equals(true))
{
checkBox.CheckState = CheckState.Checked;
}
tableLayoutPanel1.Controls.Add(checkBox);
break;
default:
MessageBox.Show(#"The following type has not been implemented yet: " + value.GetType());
break;
}
}
}
}
Here is a mockup from my comments:
// The ViewModel is responsible for handling the actual visual layout of the form.
public class ViewModel {
// Fire this when your ViewModel changes
public event EventHandler WindowUpdated;
public Boolean IsIsNullCheckBoxVisible { get; private set; }
// This method would contain the actual logic for handling window changes.
public void CalculateFormLayout() {
Boolean someLogic = true;
// If the logic is true, set the isNullCheckbox to true
if (someLogic) {
IsIsNullCheckBoxVisible = true;
}
// Inform the UI to update
UpdateVisual();
}
// This fires the 'WindowUpdated' event.
public void UpdateVisual() {
if (WindowUpdated != null) {
WindowUpdated(this, new EventArgs());
}
}
}
public class TheUI : Form {
// Attach to the viewModel;
ViewModel myViewModel = new ViewModel();
CheckBox isNullCheckBox = new CheckBox();
public TheUI() {
this.myViewModel.WindowUpdated += myViewModel_WindowUpdated;
}
void myViewModel_WindowUpdated(object sender, EventArgs e) {
// Update the view here.
// Notie that all we do in the UI is to update the visual based on the
// results from the ViewModel;
this.isNullCheckBox.Visible = myViewModel.IsIsNullCheckBoxVisible;
}
}
The basic idea here is that you ensure that the UI does as little as possible. It's role should just be to update. Update what? That's for the ViewModel class to decide. We perform all of the updating logic in the ViewModel class, and then when the updating computations are done, we call the UpdateVisual() event, which tells the UI that it needs to represent itself. When the WindowUpdated Event occurs, the UI just responds by displaying the configuration set up by the ViewModel.
This may seem like a lot of work to set up initially, but once in place it will save you tons and tons of time down the road. Let me know if you have any questions.
Try relating the event of one checkbox to disable the other; something like this:
private void primaryKeyBox_AfterCheck(object sender, EventArgs e)
{
nullBox.Enabled = false;
}
This is a very simple example and would have to be changed a bit, but for what I think you're asking it should work. You would also have to add to an event for the boxes being unchecked. You would also need logic to only get data from certain checkboxes based on the ones that are and are not checked.
For all the other things, such as changing the numbers based on the dropdown, change them based on events as well.
For WinForms I would use data binding.
Create an object and implement INotifyPropertyChanged and work with that object.
Then, If you have an object instance aObj:
To bind the last name property to a textbox on the form do this:
Private WithEvents txtLastNameBinding As Binding
txtLastNameBinding = New Binding("Text", aObj, "LastName", True, DataSourceUpdateMode.OnValidation, "")
txtLastName.DataBindings.Add(txtLastNameBinding)
Take a look here for more info.
INotifyPropertyChanged

When to render custom WPF TextBlock?

When should I be building Inlines in a TextBlock? I have a TextBlock-derived class that, when given text in a certain field, call it MyText, converts the text into a set of inlines when MyText has changed.
Whenever MyText changes, I clear the Inlines and build them, colorizing each word as needed. For this example, consider:
private void MyTextBlock_MyTextChanged(object sender, EventArgs e)
{
Inlines.Clear();
if (!string.IsNullOrEmpty(this.MyText))
{
var run = new Run();
run.Foreground = Brushes.DarkRed;
run.Text = this.MyText;
Inlines.Add(run);
}
}
This has worked very well. However, recently we placed the Control into a DataGrid, and some strange things have started happening. Apparently the DataGrid swaps out the context and for the most part this works. However, when we add or delete data from the DataGrid ItemsSource, something goes awry, and TextChanged doesn't seem like it is called (or at least not called at the same time). MyText can be one value, and the Inlines either blank or a different value.
I think that the place to build the Inlines is NOT during MyTextChanged, but maybe when the rendering of the Control starts. I've also tried when the DataContextChanged, but this does not help.
In my constructor, I have
this.myTextDescriptor = DependencyPropertyDescriptor.FromProperty(
MyTextProperty, typeof(MyTextBlock));
if (this.myTextDescriptor != null)
{
this.myTextDescriptor.AddValueChanged(this, this.MyTextBlock_MyTextChanged);
}
corresponding to a dependency property I have in the class
public string MyText
{
get { return (string)GetValue(MyTextProperty); }
set { SetValue(MyTextProperty, value); }
}
public static readonly DependencyProperty MyTextProperty =
DependencyProperty.Register("MyText", typeof(string), typeof(MyTextBlock));
private readonly DependencyPropertyDescriptor myTextDescriptor;
Update: If it is any kind of clue, the problem DataGrid cells seem to be the ones that are off-screen when the addition or removal happens. I also tried OnApplyTemplate, but that didn't help.
Update2: Perhaps a better solution might be to create bindable inlines?
DataGrids virtualize their content, so if a row is not visible it will not be loaded. That being the case, have you tried also rebuilding the inlines when the Loaded event fires?

WP7 Auto Grow ListBox upon reaching the last item

I'm trying to achieve an effect where more items are appended to the list when the user scrolls down to the last item. I haven't found a way to determine if the user has scrolled to the end of the list. I don't see a event on ListBox that is fired when the user reaches the bottom of the list. Something that tells me when an item has been scrolled into view would be great, but as far as I can tell, there is nothing like that.
Is this even possible in WP7?
Edit: Another way of saying this is, can we detect when a list has "bounced"?
Daniel Vaughan has posted an example of how to detect for this at http://danielvaughan.orpius.com/post/Scroll-Based-Data-Loading-in-Windows-Phone-7.aspx
It isn't super easy to get going since there are a lot of moving parts, but here is what you can do, assuming you want a short list that loads more from your data as you get scrolling down, similar to a lot of twitter apps, etc.
Write your own subclass of ObservableCollection that only offers up a few items (like 20), keeping the rest held back until requested
Hook up to the scroll viewer (inside the listbox or container) and its visual state changed events, you can get the NotScrolling and Scrolling changes; for an example see this code by ptorr
When scrolling stops, use viewer scroll extensions code to see where things are extended (at the bottom or not) or just the raw scroll viewer properties to see if it is extended to the bottom
If so, trigger your observable collection to release another set of items.
Sorry I don't have a complete sample ready to blog yet. Good luck!
I've just implemented this for Overflow7.
The approach I took was similar to http://blog.slimcode.com/2010/09/11/detect-when-a-listbox-scrolls-to-its-end-wp7/
However, instead of using a Style I did the hook up in code.
Basically derived my parent UserControl from:
public class BaseExtendedListUserControl : UserControl
{
DependencyProperty ListVerticalOffsetProperty = DependencyProperty.Register(
"ListVerticalOffset",
typeof(double),
typeof(BaseExtendedListUserControl),
new PropertyMetadata(new PropertyChangedCallback(OnListVerticalOffsetChanged)));
private ScrollViewer _listScrollViewer;
protected void EnsureBoundToScrollViewer()
{
if (_listScrollViewer != null)
return;
var elements = VisualTreeHelper.FindElementsInHostCoordinates(new Rect(0,0,this.Width, this.Height), this);
_listScrollViewer = elements.Where(x => x is ScrollViewer).FirstOrDefault() as ScrollViewer;
if (_listScrollViewer == null)
return;
Binding binding = new Binding();
binding.Source = _listScrollViewer;
binding.Path = new PropertyPath("VerticalOffset");
binding.Mode = BindingMode.OneWay;
this.SetBinding(ListVerticalOffsetProperty, binding);
}
public double ListVerticalOffset
{
get { return (double)this.GetValue(ListVerticalOffsetProperty); }
set { this.SetValue(ListVerticalOffsetProperty, value); }
}
private static void OnListVerticalOffsetChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
BaseExtendedListUserControl control = obj as BaseExtendedListUserControl;
control.OnListVerticalOffsetChanged();
}
private void OnListVerticalOffsetChanged()
{
OnListVerticalOffsetChanged(_listScrollViewer);
}
protected virtual void OnListVerticalOffsetChanged(ScrollViewer s)
{
// do nothing
}
}
this then meant that in the user control itself I could just use:
protected override void OnListVerticalOffsetChanged(ScrollViewer viewer)
{
// Trigger when at the end of the viewport
if (viewer.VerticalOffset >= viewer.ScrollableHeight)
{
if (MoreClick != null)
{
MoreClick(this, new RoutedEventArgs());
}
}
}
private void ListBox1_ManipulationCompleted(object sender, ManipulationCompletedEventArgs e)
{
EnsureBoundToScrollViewer();
}
The "hacky" thing here was that I had to use ListBox1_ManipulationCompleted and VisualTreeHelper to find my ScrollViewer - I'm sure there are better ways...
Have a look at this detect Listbox compression state from msdn blog
Use the DeferredLoadListBox.

How to disable a checkbox in a checkedlistbox?

I have some items in a CheckedListBox, I want to disable the CheckBox of first item in it.
i.e. I want to disable the first item in the CheckedListBox, because I want to tell the user visually that option is not available.
Combining 2 of the above partial answers worked great for me.
Add your items to the list with:
myCheckedListBox.Items.Add(myItem, myState);
Where myState is CheckState.Indeterminate for items that should be disabled.
Then add an event handler to keep those items from being changed:
myCheckedListBox.ItemCheck += (s, e) => { if (e.CurrentValue == CheckState.Indeterminate) e.NewValue = CheckState.Indeterminate; };
This does not allow you to use 'Indeterminate' in this list for its normal purpose but it does give a look very similar to what one would expect for a disabled item and it provides the correct behavior!
Though this post is pretty old, the last added answer has been submitted in April this year,
and I hope this will help someone.
I was after something similar : a checked list box that behaves like
a lot of installers, which offer a list of options where some features are required and
thus are both checked and disabled.
Thanks to this post (Can I use a DrawItem event handler with a CheckedListBox?)
I managed to do that, subclassing a CheckedListBox control.
As the OP in the linked post states, in the CheckedListBox control the OnDrawItem event is never fired,
so subclassing is necessary.
It's very basic, but it works.
This is what it looks like (the CheckBox above is for comparison) :
NOTE: the disabled item is really disabled : clicking on it has no effects whatsoever (as far as I can tell).
And this is the code :
public class CheckedListBoxDisabledItems : CheckedListBox {
private List<string> _checkedAndDisabledItems = new List<string>();
private List<int> _checkedAndDisabledIndexes = new List<int>();
public void CheckAndDisable(string item) {
_checkedAndDisabledItems.Add(item);
this.Refresh();
}
public void CheckAndDisable(int index) {
_checkedAndDisabledIndexes.Add(index);
this.Refresh();
}
protected override void OnDrawItem(DrawItemEventArgs e) {
string s = Items[e.Index].ToString();
if (_checkedAndDisabledItems.Contains(s) || _checkedAndDisabledIndexes.Contains(e.Index)) {
System.Windows.Forms.VisualStyles.CheckBoxState state = System.Windows.Forms.VisualStyles.CheckBoxState.CheckedDisabled;
Size glyphSize = CheckBoxRenderer.GetGlyphSize(e.Graphics, state);
CheckBoxRenderer.DrawCheckBox(
e.Graphics,
new Point(e.Bounds.X + 1, e.Bounds.Y + 1), // add one pixel to align the check gliph properly
new Rectangle(
new Point(e.Bounds.X + glyphSize.Width + 3, e.Bounds.Y), // add three pixels to align text properly
new Size(e.Bounds.Width - glyphSize.Width, e.Bounds.Height)),
s,
this.Font,
TextFormatFlags.Left, // text is centered by default
false,
state);
}
else {
base.OnDrawItem(e);
}
}
public void ClearDisabledItems() {
_checkedAndDisabledIndexes.Clear();
_checkedAndDisabledItems.Clear();
this.Refresh();
}
}
Use it like this:
checkedListBox.Items.Add("Larry");
checkedListBox.Items.Add("Curly");
checkedListBox.Items.Add("Moe");
// these lines are equivalent
checkedListBox.CheckAndDisable("Larry");
checkedListBox.CheckAndDisable(0);
Hope this can help someone.
Disabling items isn't a great idea, the user will have no good feedback that click the check box won't have any effect. You cannot use custom drawing to make it obvious. Best thing to do is to simply omit the item.
You can however easily defeat the user with the ItemCheck event:
private void checkedListBox1_ItemCheck(object sender, ItemCheckEventArgs e) {
if (e.Index == 0) e.NewValue = e.CurrentValue;
}
To disable any particular item use following:
checkedListBox1.SetItemCheckState(0, CheckState.Indeterminate);
SetItemCheckState takes index of item and CheckState Enum
Indeterminate is used to show shaded appearance
I know it has been a while, but I found this in my search for a list box and thought I would add it to the discussion.
If you have a listbox and want to disable all of the checkboxes so they cannot be clicked, but not disable the control so the user can still scroll etc. you can do this:
listbox.SelectionMode = SelectionMode.None
The CheckedListBox will not work in this way. CheckedListBox.Items is a collection of strings so they cannot be "disabled" as such.
Here are some discussions about possible solutions that might help you: here and here.
This works for me:
checkedListBox1.SelectionMode = SelectionMode.None;
Which means no items can be selected
None: No items can be selected.
For more info, you can check it here: SelectionMode Enumeration.
The solution is to use the event ItemChecking:
_myCheckedListBox.ItemChecking += (s, e) => e.Cancel = true;
This will cancel all the checking on every item, but you can always do more refined solution but testing the current .SelectedItem
Here's how I did it in a helpdesk application I wrote:
First, I made it so the check box was greyed out as I added it to the list during form load:
private void frmMain_Load(object sender, EventArgs e)
{
List<string> grpList = new List<string>();
ADSI objADSI = new ADSI();
grpList = objADSI.fetchGroups();
foreach (string group in grpList)
{
if (group == "SpecificGroupName")
{
chkLst.Items.Add(group, CheckState.Indeterminate);
}
else
{
chkLst.Items.Add(group);
}
}
Then I used an event so that when clicked it ensures it stays clicked:
private void chkLst_SelectedIndexChanged(object sender, EventArgs e)
{
if (chkLst.SelectedItem.ToString() == "SpecificGroupName")
{
chkLst.SetItemCheckState(chkLst.SelectedIndex, CheckState.Indeterminate);
}
}
The idea here is that on my form it's set so that the box checks on item click/select. This way I could kill two birds with one stone. I could keep this event from causing problems when the item is first checked and added during form load. Plus making it check on select allows me to use this event instead of the item checked event. Ultimately the idea is to keep it from messing up during the load.
You'll also notice that it doesn't matter what the index number is, that variable is unknown because in my app it's grabbing a list of groups from AD that exist in a specific OU.
As to whether this is a good idea or not, that's dependent on the situation. I have another app where the item to disable is dependent on another setting. In this app I just want the helpdesk to see that this group is required so they don't go removing them from it.
Try Below Code:
Private Sub CheckedListBox1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles CheckedListBox1.MouseUp
If (Condition) Then
Me.CheckedListBox1.SelectedIndex = -1
End If
End Sub
I think an alternative solution, is using Telerik components.
A RadListControl can give you that option:

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