Develop Reference

How to pass URL from ListView item to web browser URL

How can the URL data within a list view item be passed to a web browser to open? My current code isn't working for some reason.
The name 'item' does not exist in the current context
page class
public sealed partial class MainPage : Page
{
public List<ListItem> listItemCompanies;
public MainPage()
{
this.InitializeComponent();
listItemCompanies = ItemManager.GetListItems();
}
private async void ListView_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
var resourceLoader = Windows.ApplicationModel.Resources.ResourceLoader.GetForCurrentView();
foreach (var item in e.AddedItems)
{
showWebsite();
}
}
private async void showWebsite()
{
var title = item as ListItem;
var uriWeb = new Uri(title.CompanyURL);
var uriSuccess = await Launcher.LaunchUriAsync(uriWeb);
}
}
}
list item class
namespace MyApp.Models
{
public class ListItem
{
public string CompanyTitle { get; set; }
public string CompanyURL { get; set; }
}
public class ItemManager
{
public static List<ListItem> GetListItems()
{
var items = new List<ListItem>
{
new ListItem { CompanyTitle = "Apple", CompanyURL = "www.apple.com" },
new ListItem { CompanyTitle = "Google", CompanyURL = "www.google.com" },
new ListItem { CompanyTitle = "Microsoft", CompanyURL = "www.microsoft.com" }
};
return items;
}
}
}

Based on the document of Uri, there are essentially three components to a URI, the first part is scheme. Taking the web URL as an example, the scheme part is "http://". So when you try to create a Uri class, you also need to pass the "http://" instead of only "www.apple.com". In addition, when the ListView_SelectionChanged event is triggered, you can call the SelectedItem property of ListView to get the model you current click. For example:
private void ListView_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
object item = (sender as ListView).SelectedItem;
showWebsite(item);
}
private async void showWebsite(object item)
{
var title = item as ListItem;
var uriWeb = new Uri("http://" + title.CompanyURL);
var uriSuccess = await Launcher.LaunchUriAsync(uriWeb);
}
Update:
If you want to use ItemClick event, you need to set the IsItemClickEnabled of ListView as True.
.xaml:
<ListView ... IsItemClickEnabled="True" ItemClick="ListView_ItemClick">
......
</ListView>
.cs:
private void ListView_ItemClick(object sender, ItemClickEventArgs e)
{
object item = (sender as ListView).SelectedItem;
showWebsite(item);
}

Add tooltip to FlyoutMenu

I have a FlyoutMenu in my uwp app. It works fine, but I want to add tooltips to some items. Can I do that?
If you are not working on uwp, the related question here may be of interest:
Showing a tooltip for a MenuItem
class WindowsMenuFlyoutItem: Windows.UI.Xaml.Controls.MenuFlyoutItem
{
public ICommonMenuItem InnerItem { get; set; }
public WindowsMenuFlyoutItem (MyModelObject inner) {
this.Text = inner.GetTitle().Text;
this.Tapped += WindowsMenuFlyoutItem_Tapped;
// set tooltip?
}
private void WindowsMenuFlyoutItem_Tapped(Object sender,
Windows.UI.Xaml.Input.TappedRoutedEventArgs e)
{
// handler here . . .
}
}

Try this:
private void WindowsMenuFlyoutItem_Tapped(object sender, TappedRoutedEventArgs e)
{
MenuFlyoutItem item = sender as MenuFlyoutItem;
ToolTipService.SetToolTip(item, "tooltip...");
}
Or if you want to set it immediately before the item is tapped:
public class WindowsMenuFlyoutItem : Windows.UI.Xaml.Controls.MenuFlyoutItem
{
public ICommonMenuItem InnerItem { get; set; }
public WindowsMenuFlyoutItem(MyModelObject inner)
{
this.Text = inner.GetTitle().Text;
this.Tapped += WindowsMenuFlyoutItem_Tapped;
Windows.UI.Xaml.Controls.ToolTipService.SetToolTip(this, "tooltip...");
}
}

Image Binding Not Working on Reload Window

I have an Image element that's bound to an ImageSource element inside a class that I've created. The ImageSource gets updated every time a slider is changed. When I first instantiate my window, the ImageSource is blank until the user loads a file. Once the file is loaded, the image appears and the user can scroll the slider and see the image change. They can then select "OK" on the dialog to save this pattern. This all works fine.
However, if they double-click on the item in the ListView then it will re-open this dialog to make further edits. So, it creates a new dialog and then reloads the pertinent info about the image. However, for whatever reason... the image binding no longer works. I can put a breakpoint on the ImageSource getter and everytime I change the slider, the image does get updated... However, it just doesn't appear the be binding correctly. Why would it bind correctly on the first time the window is opened, but not on subsequent openings. I'll try to lay out my code.
In my .XAML code:
<UserControl x:Class="MyControls.CreatePattern"
x:Name="PatternCreation"
...
d:DesignHeight="160" d:DesignWidth="350">
<Slider Value="{Binding ElementName=PatternCreation, Path=Pattern.ZNorm, Mode=TwoWay}" Maximum="1" Name="Slider" VerticalAlignment="Stretch" />
<Image Name="PatternPreview" Source="{Binding ElementName=PatternCreation, Path=Pattern.WPFSlice}" Stretch="Uniform"></Image>
</UserControl
In my code behind I define the Pattern to be bound:
protected PatternVoxelBased mPattern = new PatternVoxelBased();
public PatternVoxelBased Pattern
{
get { return mPattern ; }
set { mPattern = value; }
}
In my PatternVoxelBased class, I have a WPFSlice and ZNorm properties defined like this:
protected ImageSource mWPFSlice;
public ImageSource WPFSlice
{
get { return mWPFSlice; }
set
{
mWPFSlice = value;
NotifyPropertyChanged("WPFSlice");
}
}
protected double mZNorm = 0.5;
public double ZNorm
{
get { return mZNorm; }
set
{
if (mZNorm == value) return;
mZNorm = value;
NotifyPropertyChanged("ZNorm");
WPFSlice = BuildImageAtZ(mZNorm);
}
}
I have an event to load the dialog window the first time:
private void CreatePattern_Click(object sender, RoutedEventArgs e)
{
CCreateVoxelPattern dlg = new CCreateVoxelPattern();
dlg.DataContext = DataContext;
dlg.CShow(PatternLibraryMenu);
}
My ListView Double-Click function to reload the dialog window:
private void ListViewPatternLibrary_MouseDoubleClick(object sender, MouseButtonEventArgs e)
{
PatternVoxelBased item = ((ListView)sender).SelectedValue as PatternVoxelBased;
CCreateVoxelPattern dlg = new CCreateVoxelPattern();
dlg.DataContext = DataContext;
dlg.Main.Pattern = item;
dlg.Main.LoadPattern();
dlg.CShow(PatternLibraryMenu);
}
public void LoadPattern()
{
if (Pattern == null) return;
Pattern.WPFSlice = Pattern.BuildImageAtZ(Pattern.ZNorm);
}

In your class where this is
protected PatternVoxelBased mPattern = new PatternVoxelBased();
public PatternVoxelBased Pattern
{
get { return mPattern ; }
set { mPattern = value; }
}
you have to implement INotifyPropertyChanged.
Example
public class YourClass: INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(PropertyChangedEventArgs e)
{
if (PropertyChanged != null)
{
PropertyChanged(this, e);
}
}
protected PatternVoxelBased mPattern = new PatternVoxelBased();
public PatternVoxelBased Pattern
{
get { return mPattern ; }
set { mPattern = value; OnPropertyChanged(new PropertyChangedEventArgs("Pattern"));}
}
}
EDIT
In your Pattern-class, you have to implement that too on every Property.

ListBox forcing update of items

I created a ListBoxItem where I have a property Name and override ToString() to give back name. That works nicely when I add new items.
But now I need to force the ListBox to update the labels when I change the name of my ship. I thought Refresh or Update would do that but that doesn't work.
I might be missing something very easy here.
public class ShipListBoxItem
{
public ListBox Parent { get; set; }
public ShipType Ship { get; set; }
public ShipListBoxItem()
{
Ship = new ShipType();
}
public ShipListBoxItem(ShipType st)
{
Ship = st;
}
public override string ToString()
{
return Ship.Name;
}
public void UpdateListBox()
{
Parent.Refresh(); //My problem is here. Update doesn't work either.
}
public static ShipListBoxItem AddToListBox(ListBox lb, ShipType ship)
{
ShipListBoxItem li = new ShipListBoxItem(ship);
li.Parent = lb;
lb.Items.Add(li);
return li;
}
}

If you use a List<T> as the DataSource for the listbox it is pretty easy to have changes to items show up. It also means there is no real reason to have a special class for adding a ShipListBoxItem to a ListBox, your basic Ship class may work:
class ShipItem
{
public enum ShipTypes { BattleShip, Carrier, Destroyer, Submarine, Frigate };
public ShipTypes Ship { get; set; }
public string Name { get; set; }
public ShipItem(string n, ShipTypes st)
{
Name = n;
Ship = st;
}
public override string ToString()
{
return String.Format("{0}: {1}", Ship.ToString(), Name);
}
}
The form related stuff:
private void Form1_Load(object sender, EventArgs e)
{
// add some ships
Ships = new List<ShipItem>();
Ships.Add(new ShipItem("USS Missouri", ShipTypes.BattleShip));
Ships.Add(new ShipItem("USS Ronald Reagan", ShipTypes.Carrier));
lb.DataSource = Ships;
}
private void button1_Click(object sender, EventArgs e)
{
// change a ship name
lb.DataSource = null; // suspend binding
this.Ships[0].Name = "USS Iowa";
lb.DataSource = Ships; // rebind
lb.Refresh();
}
As an alternative, you can also tell the Listbox to use a specific property for the display using DisplayMember:
lb.DataSource = Ships;
lb.DisplayMember = "Name";
This would use the Name property in the listbox instead of the ToString method. If your list is changing a lot, use a BindingList instead. It will allow changes to the list show up in the ListBox as you add them without toggling the DataSource.

Try this
ListBox.RefreshItems()
msdn
EDIT: You can use an extended class like this:
public class FooLisBox : System.Windows.Forms.ListBox
{
public void RefreshAllItems()
{
RefreshItems();
}
}
private void button1_Click(object sender, EventArgs e)
{
(listBox1.Items[0] as ShipListBoxItem).Ship.Name = "AAAA";
listBox1.RefreshAllItems();
}

I managed to solve my problem.
Mostly, thanks Jose M.
I ran into a problem however. RefreshItems() triggers OnSelectedIndexChanged()
so my overridden class looks like this
public class MyListBox : ListBox
{
public bool DoEvents{ get; set; } // Made it public so in the future I can block event triggering externally
public MyListBox()
{
DoEvents = true;
}
public void RefreshAllItems()
{
SuspendLayout();
DoEvents = false;
base.RefreshItems(); // this triggers OnSelectedIndexChanged as it selects the selected item again
DoEvents = true;
ResumeLayout();
}
// I only use this event but you can add all events you need to block
protected override void OnSelectedIndexChanged(EventArgs e)
{
if (DoEvents)
base.OnSelectedIndexChanged(e);
}
}

NavigateTo() Function is being called before constructor?

I am developing a Windows phone App and in my MainPage.xaml.cs file I have one private member that is being changed in the overrided method OnNavigateTo(). Although its value is changed, after that in the MainPage constructor its value resets to 0 (It's an int member). I guess that OnNavigateTo() method is being called BEFORE the constructor but if so I would have a nullReferenceException. What can cause that problem?
The OnNavigateTo() Function:
if (NavigationContext.QueryString.ContainsKey("leftDuration"))
{
//Get the selected value from IntroductionPage as a string
var leftRecievedInformation = NavigationContext.QueryString["leftDuration"];
//Convert the string to an enum object
var firstRunLeftChosenDuration = (LensLifetime)Enum.Parse(typeof(LensLifetime), leftRecievedInformation);
//Set the leftDuration value to the model object
_firstRunLeftDuration = getDurationAsNumber(firstRunLeftChosenDuration);
MessageBox.Show(_firstRunLeftDuration + "");
model.Left.LifeTime = _firstRunLeftDuration;
}
My problematic member is the _firstRunLeftDuration value. Although, as you can see, i set the model.Left.LifeTime value, in the MainPage.xaml I still get the default 0 value... It' like completely ignoring this line of code.. I know the code is not particularly clear but I don't think its beneficial to add extra lines of useless code.
Here's the MainPage.xaml.cs file:
public partial class MainPage : PhoneApplicationPage
{
public ContactLensesModel model;
private int _firstRunLeftDuration, _firstRunRightDuration; //Members used for the initialization of the app
public int FirstRunLeftDuration
{
get
{
return _firstRunLeftDuration;
}
set
{
_firstRunLeftDuration = value;
}
}
public int FirstRunRightDuration
{
get
{
return _firstRunRightDuration;
}
set
{
_firstRunRightDuration = value;
}
}
public ContactLensesModel Model
{
get
{
return model;
}
set
{
model = value;
}
}
// Constructor
public MainPage()
{
InitializeComponent();
// Sample code to localize the ApplicationBar
BuildLocalizedApplicationBar();
//Should check if the user starts the app for the first time....
//Create a new model
Model = new ContactLensesModel();
Model.setLeftNewStartingDate();
Model.setRightNewStartingDate();
//Should load the already saved model if the user in not entering for the first time...
//....
//....
loadModel();
//Connect the data Context
leftLensDaysRemaining.DataContext = Model.Left;
rightLensDaysRemaining.DataContext = Model.Right;
}
private int getDurationAsNumber(LensLifetime duration)
{
if (duration.Equals(LensLifetime.Day))
return 1;
else if (duration.Equals(LensLifetime.Two_Weeks))
return 14;
else
return DateTime.DaysInMonth(DateTime.Now.Year, DateTime.Now.Month);
}
protected override void OnNavigatedTo(NavigationEventArgs e)
{
//Get the arguments as strings and convert them to an enum, is true only when the user enters app for the first time.
if (NavigationContext.QueryString.ContainsKey("leftDuration"))
{
//Get the selected value from IntroductionPage as a string
var leftRecievedInformation = NavigationContext.QueryString["leftDuration"];
//Convert the string to an enum object
var firstRunLeftChosenDuration = (LensLifetime)Enum.Parse(typeof(LensLifetime), leftRecievedInformation);
//Set the leftDuration value to the model object
FirstRunLeftDuration = getDurationAsNumber(firstRunLeftChosenDuration);
Model.Left.LifeTime = FirstRunLeftDuration;
}
if (NavigationContext.QueryString.ContainsKey("rightDuration"))
{
//Get the selected value from IntroductionPage as a string
var rightRecievedInformation = NavigationContext.QueryString["rightDuration"];
//Convert the string to an enum object
var firstRunRightChosenDuration = (LensLifetime)Enum.Parse(typeof(LensLifetime), rightRecievedInformation);
//Set the leftDuration value to the model object
_firstRunRightDuration = getDurationAsNumber(firstRunRightChosenDuration);
Model.Right.LifeTime = _firstRunRightDuration;
}
}
/// <summary>
/// Loads the model from the isolated Storage
/// </summary>
private void loadModel()
{
//Load the model...
}
private void BuildLocalizedApplicationBar()
{
// Set the page's ApplicationBar to a new instance of ApplicationBar.
ApplicationBar = new ApplicationBar();
// Create a new button and set the text value to the localized string from AppResources.
ApplicationBarIconButton appBarSettingsButton = new ApplicationBarIconButton(new Uri("/Assets/Icons/settingsIcon4.png", UriKind.Relative));
appBarSettingsButton.Text = AppResources.AppBarSettingsButtonText;
appBarSettingsButton.Click += appBarButton_Click;
ApplicationBar.Buttons.Add(appBarSettingsButton);
// Create a new menu item with the localized string from AppResources.
//ApplicationBarMenuItem appBarMenuItem = new ApplicationBarMenuItem(AppResources.AppBarMenuItemText);
//ApplicationBar.MenuItems.Add(appBarMenuItem);
}
void appBarButton_Click(object sender, EventArgs e)
{
NavigationService.Navigate(new Uri("/SettingsPage.xaml", UriKind.RelativeOrAbsolute));
}
private void leftButtonChange_Click(object sender, RoutedEventArgs e)
{
model.setLeftNewStartingDate();
}
private void rightChangeButton_Click(object sender, RoutedEventArgs e)
{
model.setRightNewStartingDate();
}
}
}

The OnNavigatedTo method cannot be called before the constructor. The constructor is always executed first. I think your model.Left.LifeTime doesn't raise a PropertyChanged event. Hence, your View won't know you are giving it a value. Therefore it will show the default value of model.Left.Lifetime which is probably 0.
On the other hand, it's hard to tell without seeing the rest of your code.