XAML WPF CheckBox Validation - c#

I have a list of CheckBox'es. I would like the user to select at least one before click the next button.
I would want the Button to remain Enabled, but use a TextBlock below the CheckBox to show the prompt to select at least one CheckBox.
How can I check that.
Code:
XAML
<CheckBox x:Name="CheckBox1" Content="CheckBox1" />
<CheckBox x:Name="CheckBox2" Content="CheckBox2" />
<CheckBox x:Name="CheckBox3" Content="CheckBox3" />
<CheckBox x:Name="CheckBox4" Content="CheckBox4" />
<Button x:Name="NextButton" Click="NextButton_Click"/>
Code Behind
private void NextButton_Click(object sender, RoutedEventArgs e) {
if (CheckBox1.IsChecked ?? false) {
// do something
}
// same for other checkBoxes
}

private void NextButton_Click(object sender, RoutedEventArgs e)
{
if (!CheckBox1.IsChecked && !CheckBox2.IsChecked && !CheckBox3.IsChecked && !CheckBox4.IsChecked)
{
// update TextBlock to alert the user
}
else
{
if (CheckBox1.IsChecked)
{
// do something
}
// same for other checkboxes
}
}

You can also do the following, based on the example of just one CheckBox:
XAML
<CheckBox x:Name="CheckBox1" Content="CheckBox1" Checked="CheckBox1_OnChecked"/>
// after all your CheckBoxes insert TextBlock below
// which is Visible by default (but invisible once any CheckBox is checked)
<TextBlock x:Name="TextBlock" Visibility="Visible" Text="Please, select at least 1 checkbox"/>
<Button x:Name="NextButton" Click="NextButton_Click" Height="Auto" Width="Auto" Content="Button"/>
Code Behind
private void NextButton_Click(object sender, RoutedEventArgs e)
{
// your code
}
// We make Visibility of TextBox hidden
// Think for yourself how to take into account
// several CheckBoxes checked vs unchecked
private void CheckBox1_OnChecked(object sender, RoutedEventArgs e)
{
TextBlock.Visibility = Visibility.Hidden;
}
Think for yourself how to take into account several CheckBoxes checked vs unchecked, you may also use CheckBoxes event handler for Unchecked event: Unchecked="CheckBox1_OnUnchecked"

Related

Flyout causing the app to crash [Windows 10] C# XAML

I want the program to show the attached Flyout when user Holding the control (on the mobile) or when the user Right-click the control (on PC).
Here is my XAML :
<DataTemplate x:DataType="data:Cards" x:Key="card">
<StackPanel x:Name="cardstack" Holding="cardstack_Holding" KeyDown="cardstack_KeyDown" >
<StackPanel Background="Blue" Height="100" />
<FlyoutBase.AttachedFlyout>
<MenuFlyout x:Name="optionpass">
<MenuFlyoutItem x:Name="delete" Text="Delete" Click="delete_Click"/>
</MenuFlyout>
</FlyoutBase.AttachedFlyout>
</StackPanel>
</DataTemplate>
and this is my C# :
private void cardstack_Holding(object sender, HoldingRoutedEventArgs e)
{
FlyoutBase.ShowAttachedFlyout(sender as FrameworkElement);
}
private void cardstack_KeyDown(object sender, KeyRoutedEventArgs e)
{
if (e.Key == Windows.System.VirtualKey.RightButton)
{
FlyoutBase.ShowAttachedFlyout(sender as FrameworkElement);
}
}
When I tap and Hold the Stackpanel on the mobile simulator, the Holding event works, but when I Right-click on my PC, it crashes! It says that "There are no attached Flyout!". I do not know what is wrong.
"Have you tried RightTapped event? Is it working?"
Yes and No :(
I just found out the solution to solve my problem.
Turns out you have to name the MenuFlyout like my one is x:Name = "option_menu", and the Flyoutbase.AttachedFlyout cannot be in the DataTemplate, means you have to put it anywhere else except in the DataTemplate, so that the .cs file can find the name of the MenuFlyout.
Here is my C# :
public void cardstack_Holding(object sender, HoldingRoutedEventArgs e)
{
option_menu.ShowAt(sender as FrameworkElement);
e.Handled = true;
}
private void cardstack_PointerPressed(object sender, PointerRoutedEventArgs e)
{
Pointer pointr = e.Pointer;
if (pointr.PointerDeviceType == Windows.Devices.Input.PointerDeviceType.Mouse)
{
Windows.UI.Input.PointerPoint pointrd = e.GetCurrentPoint(sender as UIElement);
if (pointrd.Properties.IsRightButtonPressed)
{
option_menu.ShowAt(sender as FrameworkElement);
}
}
e.Handled = true;
}
Notice that before this I use ShowAttachedFlyout, now I use option_menu.ShowAt.
KeyDown event somehow did not work with my app, so I used PointerPressed instead.
Hope this helps. (0w0)/

C# / WPF Unmask password inside the passwordBox

How could I unmasked and masked the password inside the passwordBox whenever I click the checkBox? I'm using C# WPF template.
Here is my .XAML code:
<PasswordBox x:Name="passwordBox_password" Grid.Row="2" Grid.Column="1" Grid.ColumnSpan="2" Margin="5" Height="25" />
<CheckBox x:Name="checkBox_showPassword" Grid.Row="3" Grid.Column="1" Margin="5,0,5,5" Content="show password" Checked="checkBox_showPassword_Checked" Unchecked="checkBox_showPassword_Unchecked" />
Here is my .CS code:
private void checkBox_showPassword_Checked(object sender, RoutedEventArgs e)
{
// what to do here ?
}
private void checkBox_showPassword_Unchecked(object sender, RoutedEventArgs e)
{
// what to do here ?
}
Or is there another way to do it in WPF?
It's very simple to do that.
First you should to add the value PasswordChar in your PasswordBox:
<PasswordBox Name="PasswordHidden" PasswordChar="•"/>
Next under the PasswordBox tag you should to add a TextBox with Visibility value setted to Hidden:
<TextBox Name="PasswordUnmask" Visibility="Hidden"/>
And a trigger to show / hide the password, for example a simple text or a button. In my case I'm using a simple text.
<TextBlock Name="ShowPassword"/>
Next you need to add 3 different events in the trigger element, for example (this is valid for TextBlock or Image, if you want to use a Button you should to choose another events):
<TextBlock x:Name="ShowPassword" Text="SHOW" PreviewMouseDown="ShowPassword_PreviewMouseDown" PreviewMouseUp="ShowPassword_PreviewMouseUp" MouseLeave="ShowPassword_MouseLeave"/>
The events are PreviewMouseDown PreviewMouseUp and MouseLeave but you can choose the appropriate event for your situation.
Now in your code you need to program the functions:
private void ShowPassword_PreviewMouseDown(object sender, MouseButtonEventArgs e) => ShowPasswordFunction();
private void ShowPassword_PreviewMouseUp(object sender, MouseButtonEventArgs e) => HidePasswordFunction();
private void ShowPassword_MouseLeave(object sender, MouseEventArgs e) => HidePasswordFunction();
private void ShowPasswordFunction()
{
ShowPassword.Text = "HIDE";
PasswordUnmask.Visibility = Visibility.Visible;
PasswordHidden.Visibility = Visibility.Hidden;
PasswordUnmask.Text = PasswordHidden.Password;
}
private void HidePasswordFunction()
{
ShowPassword.Text = "SHOW";
PasswordUnmask.Visibility = Visibility.Hidden;
PasswordHidden.Visibility = Visibility.Visible;
}
The following link will bring you to the answer you are looking for my good sir. Mr Lamas did a great job of answering the how-to so I'd rather redirect you to the answer :)
showing password characters on some event for passwordbox
I recommend Using MahApps.Metro ... after installing it from nuget.org ... you must use it in the head of your xaml like this
xmlns:controls="http://metro.mahapps.com/winf/xaml/controls"
and then ... just use it's style for your PasswordBox control
<PasswordBox Style="{StaticResource MetroButtonRevealedPasswordBox}" />
you can even change the content for the show icon using the controls:PasswordBoxHelper.RevealButtonContent attached property

How to Get Tapped Item from Tapped Event in StackPanel

I have a ListPicker in an application page, but the SelectionChanged event gets called multiple times as the page loads. To avoid this, I have been following a previous question I asked here ListPicker SelectionChanged Event Called Multiple Times During Navigation in which the suggestion was instead of making ThemeListPicker_SelectionChanged make a parent stackpanel inside the datatemplate..', create a tap event in the StackPanel called stk_Tap, and 'use this tap stk_Tap to do your action as, this event would also get called every time the selection changed gets called but, it wont exhibit the buggy behavior like that of selection changed event'
Now I have adjusted my solution accordingly, but I do not know how to determine which item of the ListPicker is being selected or is currently selected. Also I removed the ListPicker SelectionChanged event in the ListPicker because I thought the StackPanel could get the item, but I am not sure if this is correct or how to do this?
XAML
<phone:PhoneApplicationPage.Resources>
<DataTemplate x:Name="PickerItemTemplate">
<TextBlock Text="{Binding Name}"/>
</DataTemplate>
</phone:PhoneApplicationPage.Resources>
<toolkit:ListPicker x:Name="ThemeListPicker" Header="Theme"
ItemTemplate="{StaticResource PickerItemTemplate}"
SelectionChanged="ThemeListPicker_SelectionChanged"/>
XAML.CS
private void ThemeListPicker_SelectionChanged(object sender,
SelectionChangedEventArgs e)
{
if(ThemeListPicker.SelectedIndex != -1)
{
var theme = (sender as ListPicker).SelectedItem;
if (index == 0)
{
Settings.LightTheme.Value = true;
MessageBox.Show("light");
}
else
{
Settings.LightTheme.Value = false;
MessageBox.Show("dark");
}
}
}
*EDIT: How I updated my solution
<phone:PhoneApplicationPage.Resources>
<DataTemplate x:Name="PickerItemTemplate">
<StackPanel tap="stk_Tap">
<TextBlock Text="{Binding Name}"/>
</StackPanel>
</DataTemplate>
</phone:PhoneApplicationPage.Resources>
<toolkit:ListPicker x:Name="ThemeListPicker" Header="Theme"
ItemTemplate="{StaticResource PickerItemTemplate}"
/>
So, even when I left the ListPicker SelectionChanged event in the code behind after making the modifications, I did not see the event being called twice upon the page loading/navigating to, but I am not sure how to get the currently selected item now?
EDIT2**
protected override void OnNavigatedTo(NavigationEventArgs e)
{
base.OnNavigatedTo(e);
themeList = new List<TestApp.Common.Theme>();
themeList.Add(new TestApp.Common.Theme() { Name = "Darker", name = "dark" });
themeList.Add(new TestApp.Common.Theme() { Name = "Lighter", name = "light" });
ThemeListPicker.ItemsSource = themeList;
}
private void stk_Tap(object sender, System.Windows.Input.GestureEventArgs e)
{
if (ThemeListPicker.SelectedIndex != -1)
{
//Need to get the current ThemeListPicker's 'name'
var selectedItem1 = (sender as StackPanel).DataContext as ListPicker;
//use selectedItem1
}
}
No need to extra tap event for such kind of work.
private void ThemeListPicker_SelectionChanged(object sender,
SelectionChangedEventArgs e)
{
if(ThemeListPicker.SelectedIndex==-1)
return;
var theme = (sender as ListPicker).SelectedItem;
if (index == 0)
{
Settings.LightTheme.Value = true;
MessageBox.Show("light");
}
else
{
Settings.LightTheme.Value = false;
MessageBox.Show("dark");
}
ThemeListPicker.SelectedIndex=-1
}
ListPicker SelectionChanged Event Called Multiple Times During Navigation
for above problem if i guess right you set listpicker's itemssource on OnNavigatedTo event. so modify you r onNavigatedTo method with
protected override void OnNavigatedTo(NavigationEventArgs e)
{
base.OnNavigatedTo(e);
if (e.NavigationMode != NavigationMode.Back)
{
// Your code goes here
}
}
//Stack panel tap event
private void stack_Tap(object sender, System.Windows.Input.GestureEventArgs e)
{
var selectedIrem = (Cast as your type)(sender as StackPanel).DataContext;
}

How to select an item from a listbox in windows phone?

I've a list of data,
Each row will show a data and will have a button, when i click the data shown i want give some data to the previous page and when i click the button in the same row i want to send that same data to next page.
My Xaml code,
<ListBox x:Name="List" HorizontalAlignment="Left" Height="612" Margin="6,7,0,0" VerticalAlignment="Top" Width="443" SelectionChanged="List_SelectionChanged_1">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Width="420" Height="50">
<TextBlock x:Name="tbName" Width="400" Height="44" FontSize="22" FontWeight="Bold" Text="{Binding Name}" />
<Button x:Name="DetailButton" Height="44" Width="20" Content=">" FontWeight="Bold" Click="DetailButton_Click_1"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
and the code for List_SelectionChanged_1 event handler is,
private void List_SelectionChanged_1(object sender, SelectionChangedEventArgs e)
{
Display selectedItemData = (sender as ListBox).SelectedValue as Display;
NavigationService.Navigate("/Page1.xaml",selectedItemData);
}
and my DetailButton_Click_1 event handler is,
private void DetailButton_Click_1(object sender, RoutedEventArgs e)
{
Display selectedItemData = (sender as ListBox).SelectedValue as Display;
NavigationService.Navigate("/page3.xaml", selectedItemData);
}
Things work fine for *List_SelectionChanged_1*, but i get an exception while executing
Display selectedItemData = (sender as ListBox).SelectedValue as Display;
of the DetailButton_Click_1 , i get an exception a null exception,
An exception of type 'System.NullReferenceException' occurred in ExpenseApp.DLL but was not handled in user code
What should i do make it work?
The underlying problem is that the sender of the button click event is the button, not the ListBox.
Also note that clicking the button on your data template will not necessarily select that item in the list. Try to grab the clicked item's data context and use that instead of .SelectedItem
private void DetailButton_Click_1(object sender, RoutedEventArgs e)
{
var clickedUIElement = sender as Button;
if (null == clickedUIElement) { Return; }
Display selectedItemData = clickedUIElement.DataContext as Display;
if(null != selectedItemData)
{
NavigationService.Navigate("/page3.xaml", selectedItemData);
}
}
Your code, as it stands, will have a null reference since you can't cast a Button as a ListBox.
try verify if the selectvalue is null before execute the code:
private void DetailButton_Click_1(object sender, RoutedEventArgs e)
{
If ((sender as ListBox).SelectedValue != null){
Display selectedItemData = (sender as ListBox).SelectedValue as Display;
NavigationService.Navigate("/page3.xaml", selectedItemData);
}
}

WPF Radiobutton equivalent

What is the WPF equivalent for WinForms radio button CheckedChanged?
I have your basic 2 radio button set up, where when one is selected a textbox is enabled and when the other is selected it is disabled.
For the time being I was using RadioButton_Checked, except, I set IsChecked true for one button in the xaml. When I reference the textbox in that Checked method it throws NullReferenceException...
edit:
XAML:
<RadioButton Name="rb1" IsChecked="True" GroupName="1" Checked="rb1_Checked"></RadioButton>
<RadioButton Name="rb2" GroupName="1" Checked="rb2_Checked"></RadioButton>
C#:
private void rb2_Checked(object sender, RoutedEventArgs e)
{
txt.IsEnabled = false;
}
private void rb1_Checked(object sender, RoutedEventArgs e)
{
txt.IsEnabled = true; //null reference here on load
}
Can't you bind the enabled property of the textbox to the checked property of the appropriate radio button in your xaml?
<Textbox IsEnabled="{Binding ElementName=rb2, Path=IsChecked}" />

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