Procedimiento para agregar funcionalidades de búsqueda a un control ListView

Artículo
05/04/2023

A menudo, cuando trabaja con una lista grande de elementos en un control ListView, quiere ofrecer funcionalidades de búsqueda al usuario. El control ListView ofrece esta funcionalidad de dos maneras diferentes: coincidencia de texto y búsqueda de ubicación.

El método FindItemWithText permite realizar una búsqueda de texto en un control ListView en una vista de lista o detalles, dada una cadena de búsqueda y un índice inicial y final opcionales. En cambio, el método FindNearestItem permite buscar un elemento en un control ListView en una vista de iconos o en mosaico, dado un conjunto de coordenadas X e Y y una dirección de búsqueda.

Para buscar un elemento mediante texto

Cree un control ListView con la propiedad View establecida en Details o List y, luego, rellene el control ListView con elementos.
Llame al método FindItemWithText y pase el texto del elemento que quiere encontrar.
En el ejemplo de código siguiente se muestra cómo se crea un control ListView básico, se rellena con elementos y se usa la entrada de texto del usuario para buscar un elemento en la lista.

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

Para buscar un elemento mediante coordenadas X e Y

Cree un control ListView con la propiedad View establecida en SmallIcon o LargeIcon y, luego, rellene el control ListView con elementos.
Llame al método FindNearestItem y pase las coordenadas X e Y deseadas y la dirección que quiere buscar.
En el ejemplo de código siguiente se muestra cómo se crea un control ListView de icono básico, se rellena con elementos y se captura el evento MouseDown para buscar el elemento más cercano en dirección ascendente.

    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

Procedimiento para agregar funcionalidades de búsqueda a un control ListView

Para buscar un elemento mediante texto

Para buscar un elemento mediante coordenadas X e Y

Consulte también

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