Procedura: aggiungere funzionalità di ricerca a un controllo ListView

Spesso quando si lavora con un elenco di elementi di grandi dimensioni in un ListView controllo, si vogliono offrire funzionalità di ricerca all'utente. Il ListView controllo offre questa funzionalità in due modi diversi: ricerca di testo e posizione.

Il FindItemWithText metodo consente di eseguire una ricerca di testo in una ListView visualizzazione elenco o dettagli, data una stringa di ricerca e un indice iniziale e finale facoltativo. Al contrario, il FindNearestItem metodo consente di trovare un elemento in una ListView visualizzazione icona o riquadro, dato un set di coordinate x e y e una direzione per la ricerca.

Per trovare un elemento usando testo

1. Creare un ListView oggetto con la View proprietà impostata su Details o Liste quindi popolare con gli ListView elementi .

2. Chiamare il FindItemWithText metodo , passando il testo dell'elemento che si desidera trovare.

3. Nell'esempio di codice seguente viene illustrato come creare un oggetto di base ListView, popolarlo con gli elementi e usare l'input di testo dell'utente per trovare un elemento nell'elenco.

private:
    ListView^ textListView;
    TextBox^ searchBox;

private:
    void InitializeTextSearchListView()
    {
        textListView = gcnew ListView();
        searchBox = gcnew TextBox();
        searchBox->Location = Point(150, 20);
        textListView->Scrollable = true;
        textListView->Width = 100;

        // Set the View to list to use the FindItemWithText method.
        textListView->View = View::List;

        // Populate the ListViewWithItems
        textListView->Items->AddRange(gcnew array<ListViewItem^>{
            gcnew ListViewItem("Amy Alberts"),
            gcnew ListViewItem("Amy Recker"),
            gcnew ListViewItem("Erin Hagens"),
            gcnew ListViewItem("Barry Johnson"),
            gcnew ListViewItem("Jay Hamlin"),
            gcnew ListViewItem("Brian Valentine"),
            gcnew ListViewItem("Brian Welker"),
            gcnew ListViewItem("Daniel Weisman") });

        // Handle the TextChanged to get the text for our search.
        searchBox->TextChanged += gcnew EventHandler(this, 
            &Form1::searchBox_TextChanged);

        // Add the controls to the form.
        this->Controls->Add(textListView);
        this->Controls->Add(searchBox);
    }

private:
    void searchBox_TextChanged(Object^ sender, EventArgs^ e)
    {
        // Call FindItemWithText with the contents of the textbox.
        ListViewItem^ foundItem =
            textListView->FindItemWithText(searchBox->Text, false, 0, true);
        if (foundItem != nullptr)
        {
            textListView->TopItem = foundItem;
        }
    }

private ListView textListView = new ListView();
private TextBox searchBox = new TextBox();
private void InitializeTextSearchListView()
{
    searchBox.Location = new Point(10, 60);
    textListView.Scrollable = true;
    textListView.Width = 80;
    textListView.Height = 50;

    // Set the View to list to use the FindItemWithText method.
    textListView.View = View.List;

    // Populate the ListViewWithItems
    textListView.Items.AddRange(new ListViewItem[]{
        new ListViewItem("Amy Alberts"),
        new ListViewItem("Amy Recker"),
        new ListViewItem("Erin Hagens"),
        new ListViewItem("Barry Johnson"),
        new ListViewItem("Jay Hamlin"),
        new ListViewItem("Brian Valentine"),
        new ListViewItem("Brian Welker"),
        new ListViewItem("Daniel Weisman") });

    // Handle the TextChanged to get the text for our search.
    searchBox.TextChanged += new EventHandler(searchBox_TextChanged);

    // Add the controls to the form.
    this.Controls.Add(textListView);
    this.Controls.Add(searchBox);
}

private void searchBox_TextChanged(object sender, EventArgs e)
{
    // Call FindItemWithText with the contents of the textbox.
    ListViewItem foundItem =
        textListView.FindItemWithText(searchBox.Text, false, 0, true);
    if (foundItem != null)
    {
        textListView.TopItem = foundItem;
    }
}

Private textListView As New ListView()
Private WithEvents searchBox As New TextBox()

Private Sub InitializeTextSearchListView() 
    searchBox.Location = New Point(150, 20)
    textListView.Scrollable = True
    textListView.Width = 80
    textListView.Height = 50
    
    ' Set the View to list to use the FindItemWithText method.
    textListView.View = View.List
    
    ' Populate the ListView with items.
    textListView.Items.AddRange(New ListViewItem() { _
        New ListViewItem("Amy Alberts"), _
        New ListViewItem("Amy Recker"), _
        New ListViewItem("Erin Hagens"), _
        New ListViewItem("Barry Johnson"), _
        New ListViewItem("Jay Hamlin"), _
        New ListViewItem("Brian Valentine"), _
        New ListViewItem("Brian Welker"), _
        New ListViewItem("Daniel Weisman")})

    ' Add the controls to the form.
    Me.Controls.Add(textListView)
    Me.Controls.Add(searchBox)

End Sub
 
Private Sub searchBox_TextChanged(ByVal sender As Object, ByVal e As EventArgs) _
    Handles searchBox.TextChanged

    ' Call FindItemWithText with the contents of the textbox.
    Dim foundItem As ListViewItem = _
        textListView.FindItemWithText(searchBox.Text, False, 0, True)

    If (foundItem IsNot Nothing) Then
        textListView.TopItem = foundItem
    End If

End Sub

Per trovare un elemento usando le coordinate x e y

1. Creare un ListView oggetto con la View proprietà impostata su SmallIcon o LargeIcone quindi popolare con gli ListView elementi .

2. Chiamare il FindNearestItem metodo , passando le coordinate x e y desiderate e la direzione in cui eseguire la ricerca.

3. Nell'esempio di codice seguente viene illustrato come creare un'icona ListViewdi base, popolarla con gli elementi e acquisire l'evento per trovare l'elemento MouseDown più vicino nella direzione verso l'alto.

    ListView^ iconListView;
    TextBox^ previousItemBox;

private:
    void InitializeLocationSearchListView()
    {
        previousItemBox = gcnew TextBox();
        iconListView = gcnew ListView();
        previousItemBox->Location = Point(150, 20);

        // Create an image list for the icon ListView.
        iconListView->SmallImageList = gcnew ImageList();

        // Add an image to the ListView small icon list.
        iconListView->SmallImageList->Images->Add(
            gcnew Bitmap(Control::typeid, "Edit.bmp"));

        // Set the view to small icon and add some items with the image
        // in the image list.
        iconListView->View = View::SmallIcon;
        iconListView->Items->AddRange(gcnew array<ListViewItem^>{
            gcnew ListViewItem("Amy Alberts", 0),
            gcnew ListViewItem("Amy Recker", 0),
            gcnew ListViewItem("Erin Hagens", 0),
            gcnew ListViewItem("Barry Johnson", 0),
            gcnew ListViewItem("Jay Hamlin", 0),
            gcnew ListViewItem("Brian Valentine", 0),
            gcnew ListViewItem("Brian Welker", 0),
            gcnew ListViewItem("Daniel Weisman", 0) });
         this->Controls->Add(iconListView);
         this->Controls->Add(previousItemBox);

         // Handle the MouseDown event to capture user input.
         iconListView->MouseDown += gcnew MouseEventHandler(
             this, &Form1::iconListView_MouseDown);
    }

    void iconListView_MouseDown(Object^ sender, MouseEventArgs^ e)
    {
        // Find the next item up from where the user clicked.
        ListViewItem^ foundItem = iconListView->FindNearestItem(
            SearchDirectionHint::Up, e->X, e->Y);

        // Display the results in a textbox..
        if (foundItem != nullptr)
        {
            previousItemBox->Text = foundItem->Text;
        }
        else
        {
            previousItemBox->Text = "No item found";
        }
    }

ListView iconListView = new ListView();
TextBox previousItemBox = new TextBox();

private void InitializeLocationSearchListView()
{
    previousItemBox.Location = new Point(150, 20);

    // Create an image list for the icon ListView.
    iconListView.LargeImageList = new ImageList();
    iconListView.Height = 400;

    // Add an image to the ListView large icon list.
    iconListView.LargeImageList.Images.Add(
        new Bitmap(typeof(Control), "Edit.bmp"));

    // Set the view to large icon and add some items with the image
    // in the image list.
    iconListView.View = View.LargeIcon;
    iconListView.Items.AddRange(new ListViewItem[]{
        new ListViewItem("Amy Alberts", 0),
        new ListViewItem("Amy Recker", 0),
        new ListViewItem("Erin Hagens", 0),
        new ListViewItem("Barry Johnson", 0),
        new ListViewItem("Jay Hamlin", 0),
        new ListViewItem("Brian Valentine", 0),
        new ListViewItem("Brian Welker", 0),
        new ListViewItem("Daniel Weisman", 0) });
    this.Controls.Add(iconListView);
    this.Controls.Add(previousItemBox);

    // Handle the MouseDown event to capture user input.
   iconListView.MouseDown +=
       new MouseEventHandler(iconListView_MouseDown);
    //iconListView.MouseWheel += new MouseEventHandler(iconListView_MouseWheel);
}

void iconListView_MouseDown(object sender, MouseEventArgs e)
{

    // Find the an item above where the user clicked.
    ListViewItem foundItem =
        iconListView.FindNearestItem(SearchDirectionHint.Up, e.X, e.Y);

    // Display the results in a textbox..
    if (foundItem != null)
        previousItemBox.Text = foundItem.Text;
    else
        previousItemBox.Text = "No item found";
}

Private WithEvents iconListView As New ListView()
Private previousItemBox As New TextBox()


Private Sub InitializeLocationSearchListView()
    previousItemBox.Location = New Point(150, 20)

    ' Create an image list for the icon ListView.
    iconListView.LargeImageList = New ImageList()

    ' Add an image to the ListView large icon list.
    iconListView.LargeImageList.Images.Add(New Bitmap(GetType(Control), "Edit.bmp"))

    ' Set the view to large icon and add some items with the image
    ' in the image list.
    iconListView.View = View.SmallIcon
    iconListView.Items.AddRange(New ListViewItem() { _
        New ListViewItem("Amy Alberts", 0), _
        New ListViewItem("Amy Recker", 0), _
        New ListViewItem("Erin Hagens", 0), _
        New ListViewItem("Barry Johnson", 0), _
        New ListViewItem("Jay Hamlin", 0), _
        New ListViewItem("Brian Valentine", 0), _
        New ListViewItem("Brian Welker", 0), _
        New ListViewItem("Daniel Weisman", 0)})

    Me.Controls.Add(iconListView)
    Me.Controls.Add(previousItemBox)
End Sub

Sub iconListView_MouseDown(ByVal sender As Object, ByVal e As MouseEventArgs) _
    Handles iconListView.MouseDown

    ' Find the next item up from where the user clicked.
    Dim foundItem As ListViewItem = _
    iconListView.FindNearestItem(SearchDirectionHint.Up, e.X, e.Y)

    ' Display the results in a textbox.
    If (foundItem IsNot Nothing) Then
        previousItemBox.Text = foundItem.Text
    Else
        previousItemBox.Text = "No item found"
    End If


End Sub

Vedi anche

• ListView
• FindItemWithText
• FindNearestItem
• Controllo ListView
• Panoramica del controllo ListView
• Procedura: Aggiungere e rimuovere elementi con il controllo ListView di Windows Form