ImageField Konstruktor
Definisi
Penting
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Menginisialisasi instans baru dari kelas ImageField.
public:
ImageField();public ImageField();Public Sub New ()Contoh
Contoh berikut menunjukkan cara menggunakan konstruktor ini untuk menambahkan ImageField objek secara dinamis ke Columns kumpulan GridView kontrol.
<%@ Page language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
void Page_Load(Object sender, EventArgs e)
{
if (!IsPostBack)
{
// Dynamically create a GridView control.
GridView employeesView = new GridView();
employeesView.ID = "EmployeesGrid";
employeesView.AutoGenerateColumns = false;
employeesView.DataSourceID = "EmployeeSource";
// Dynamically create field columns to display the desired
// fields from the data source.
// Create an ImageField object to display an employee's photo.
ImageField photoImageField = new ImageField();
photoImageField.DataImageUrlField = "PhotoPath";
photoImageField.AlternateText = "Employee Photo";
photoImageField.NullDisplayText = "No image on file.";
photoImageField.HeaderText = "Photo";
photoImageField.ReadOnly = true;
// Create a BoundField object to display an employee's last name.
BoundField lastNameBoundField = new BoundField();
lastNameBoundField.DataField = "LastName";
lastNameBoundField.HeaderText = "Last Name";
// Create a BoundField object to display an employee's first name.
BoundField firstNameBoundField = new BoundField();
firstNameBoundField.DataField = "FirstName";
firstNameBoundField.HeaderText = "First Name";
// Add the field columns to the Fields collection of the
// GridView control.
employeesView.Columns.Add(photoImageField);
employeesView.Columns.Add(lastNameBoundField);
employeesView.Columns.Add(firstNameBoundField);
// Add the GridView control to the Controls collection
// of the PlaceHolder control.
GridViewPlaceHolder.Controls.Add(employeesView);
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>ImageField Constructor Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>ImageField Constructor Example</h3>
<asp:placeholder id="GridViewPlaceHolder"
runat="server"/>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the Northwind sample database. Use an ASP.NET -->
<!-- expression to retrieve the connection string value -->
<!-- from the Web.config file. -->
<asp:sqldatasource id="EmployeeSource"
selectcommand="Select [EmployeeID], [LastName], [FirstName], [PhotoPath] From [Employees]"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
<%@ Page language="VB" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
If Not IsPostBack Then
' Dynamically create a GridView control.
Dim employeesView As GridView = New GridView()
employeesView.ID = "EmployeesGrid"
employeesView.AutoGenerateColumns = False
employeesView.DataSourceID = "EmployeeSource"
' Dynamically create field columns to display the desired
' fields from the data source.
' Create an ImageField object to display an employee's photo.
Dim photoImageField As ImageField = New ImageField()
photoImageField.DataImageUrlField = "PhotoPath"
photoImageField.AlternateText = "Employee Photo"
photoImageField.NullDisplayText = "No image on file."
photoImageField.HeaderText = "Photo"
photoImageField.ReadOnly = True
' Create a BoundField object to display an employee's last name.
Dim lastNameBoundField As BoundField = New BoundField()
lastNameBoundField.DataField = "LastName"
lastNameBoundField.HeaderText = "Last Name"
' Create a BoundField object to display an employee's first name.
Dim firstNameBoundField As BoundField = New BoundField()
firstNameBoundField.DataField = "FirstName"
firstNameBoundField.HeaderText = "First Name"
' Add the field columns to the Fields collection of the
' GridView control.
employeesView.Columns.Add(photoImageField)
employeesView.Columns.Add(lastNameBoundField)
employeesView.Columns.Add(firstNameBoundField)
' Add the GridView control to the Controls collection
' of the PlaceHolder control.
GridViewPlaceHolder.Controls.Add(employeesView)
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>ImageField Constructor Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>ImageField Constructor Example</h3>
<asp:placeholder id="GridViewPlaceHolder"
runat="server"/>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the Northwind sample database. Use an ASP.NET -->
<!-- expression to retrieve the connection string value -->
<!-- from the Web.config file. -->
<asp:sqldatasource id="EmployeeSource"
selectcommand="Select [EmployeeID], [LastName], [FirstName], [PhotoPath] From [Employees]"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
Keterangan
Gunakan konstruktor ini untuk menginisialisasi instans ImageField baru kelas. Konstruktor ini umumnya digunakan saat menambahkan bidang ke kontrol terikat data yang dibuat secara dinamis.
Untuk menambahkan ImageField objek secara dinamis ke kontrol terikat data, buat objek baru ImageField , atur propertinya, lalu tambahkan ke kumpulan bidang kontrol terikat data. Misalnya, jika Anda menggunakan GridView kontrol, tambahkan ImageField objek ke Columns koleksi.
Note
Meskipun Anda dapat menambahkan bidang secara dinamis ke kontrol terikat data, sangat disarankan agar bidang dideklarasikan secara statis lalu ditampilkan atau disembunyikan, sebagaimana mewajibkan. Mendeklarasikan semua bidang Anda secara statis mengurangi ukuran status tampilan untuk kontrol terikat data induk.
