PropertyItem-Klasse
Kapselt eine Metadateneigenschaft, die in eine Bilddatei aufgenommen werden soll. Kann nicht geerbt werden.
Namespace: System.Drawing.Imaging
Assembly: System.Drawing (in system.drawing.dll)
Syntax
'Declaration
Public NotInheritable Class PropertyItem
'Usage
Dim instance As PropertyItem
public sealed class PropertyItem
public ref class PropertyItem sealed
public final class PropertyItem
public final class PropertyItem
Hinweise
Die Daten bestehen aus einem Bezeichner, der Länge der Eigenschaft (in Bytes), dem Eigenschaftentyp und einem Zeiger auf den Eigenschaftenwert.
Beispiel
Im folgenden Codebeispiel wird veranschaulicht, wie die Metadaten mithilfe der PropertyItem-Klasse und der Image.PropertyItems-Eigenschaft in einer Bilddatei gelesen und angezeigt werden.
Dieses Beispiel ist für die Verwendung in einem Windows Form vorgesehen, das den System.Drawing.Imaging-Namespace importiert. Fügen Sie den Code in das Formular ein, und ändern Sie den Pfad in fakePhoto.jpg, um auf eine Bilddatei im System zu zeigen. Rufen Sie die ExtractMetaData-Methode beim Behandeln des Paint-Ereignisses des Formulars auf, und übergeben Sie dabei e als PaintEventArgs.
Private Sub ExtractMetaData(ByVal e As PaintEventArgs)
Try
'Create an Image object.
Dim theImage As Image = New Bitmap("c:\fakePhoto.jpg")
'Get the PropertyItems property from image.
Dim propItems As PropertyItem() = theImage.PropertyItems
'Set up the display.
Dim font As New font("Arial", 10)
Dim blackBrush As New SolidBrush(Color.Black)
Dim X As Integer = 0
Dim Y As Integer = 0
'For each PropertyItem in the array, display the id, type, and length.
Dim count As Integer = 0
Dim propItem As PropertyItem
For Each propItem In propItems
e.Graphics.DrawString("Property Item " + count.ToString(), _
font, blackBrush, X, Y)
Y += font.Height
e.Graphics.DrawString(" iD: 0x" & propItem.Id.ToString("x"), _
font, blackBrush, X, Y)
Y += font.Height
e.Graphics.DrawString(" type: " & propItem.Type.ToString(), _
font, blackBrush, X, Y)
Y += font.Height
e.Graphics.DrawString(" length: " & propItem.Len.ToString() & _
" bytes", font, blackBrush, X, Y)
Y += font.Height
count += 1
Next propItem
font.Dispose()
Catch ex As ArgumentException
MessageBox.Show("There was an error. Make sure the path to the image file is valid.")
End Try
End Sub
private void ExtractMetaData(PaintEventArgs e)
{
try
{
// Create an Image object.
Image theImage = new Bitmap("c:\\fakePhoto.jpg");
// Get the PropertyItems property from image.
PropertyItem[] propItems = theImage.PropertyItems;
// Set up the display.
Font font1 = new Font("Arial", 10);
SolidBrush blackBrush = new SolidBrush(Color.Black);
int X = 0;
int Y = 0;
// For each PropertyItem in the array, display the id,
// type, and length.
int count = 0;
foreach ( PropertyItem propItem in propItems )
{
e.Graphics.DrawString("Property Item " +
count.ToString(), font1, blackBrush, X, Y);
Y += font1.Height;
e.Graphics.DrawString(" ID: 0x" +
propItem.Id.ToString("x"), font1, blackBrush, X, Y);
Y += font1.Height;
e.Graphics.DrawString(" type: " +
propItem.Type.ToString(), font1, blackBrush, X, Y);
Y += font1.Height;
e.Graphics.DrawString(" length: " +
propItem.Len.ToString() +
" bytes", font1, blackBrush, X, Y);
Y += font1.Height;
count += 1;
}
font1.Dispose();
}
catch(Exception)
{
MessageBox.Show("There was an error." +
"Make sure the path to the image file is valid.");
}
}
private:
void ExtractMetaData( PaintEventArgs^ e )
{
try
{
// Create an Image object.
Image^ theImage = gcnew Bitmap( "c:\\fakePhoto.jpg" );
// Get the PropertyItems property from image.
array<PropertyItem^>^propItems = theImage->PropertyItems;
// Set up the display.
System::Drawing::Font^ font1 = gcnew System::Drawing::Font( "Arial",10 );
SolidBrush^ blackBrush = gcnew SolidBrush( Color::Black );
int X = 0;
int Y = 0;
// For each PropertyItem in the array, display the id,
// type, and length.
int count = 0;
System::Collections::IEnumerator^ myEnum = propItems->GetEnumerator();
while ( myEnum->MoveNext() )
{
PropertyItem^ propItem = safe_cast<PropertyItem^>(myEnum->Current);
e->Graphics->DrawString( String::Format( "Property Item {0}", count ), font1, blackBrush, (float)X, (float)Y );
Y += font1->Height;
e->Graphics->DrawString( String::Format( " ID: 0x{0}", propItem->Id.ToString( "x" ) ), font1, blackBrush, (float)X, (float)Y );
Y += font1->Height;
e->Graphics->DrawString( String::Format( " type: {0}", propItem->Type ), font1, blackBrush, (float)X, (float)Y );
Y += font1->Height;
e->Graphics->DrawString( String::Format( " length: {0} bytes", propItem->Len ), font1, blackBrush, (float)X, (float)Y );
Y += font1->Height;
count += 1;
}
delete font1;
}
catch ( Exception^ )
{
MessageBox::Show( "There was an error."
"Make sure the path to the image file is valid." );
}
}
private void ExtractMetaData(PaintEventArgs e)
{
try {
// Create an Image object.
Image theImage = new Bitmap("c:\\fakePhoto.jpg");
// Get the PropertyItems property from image.
PropertyItem propItems[] = theImage.get_PropertyItems();
// Set up the display.
Font font1 = new Font("Arial", 10);
SolidBrush blackBrush = new SolidBrush(Color.get_Black());
int X = 0;
int Y = 0;
// For each PropertyItem in the array, display the id,
// type, and length.
int count = 0;
//foreach (PropertyItem propItem in propItems)
for (int iCtr = 0; iCtr < propItems.length; iCtr++) {
PropertyItem propItem = propItems[iCtr];
e.get_Graphics().DrawString("Property Item "
+ System.Convert.ToString(count), font1, blackBrush, X, Y);
Y += font1.get_Height();
e.get_Graphics().DrawString(" ID: 0x"
+ ((System.Int32)propItem.get_Id()).ToString("x"), font1,
blackBrush, X, Y);
Y += font1.get_Height();
e.get_Graphics().DrawString(" type: "
+ System.Convert.ToString(propItem.get_Type()), font1,
blackBrush, X, Y);
Y += font1.get_Height();
e.get_Graphics().DrawString(" length: "
+ System.Convert.ToString(propItem.get_Len()) + " bytes",
font1, blackBrush, X, Y);
Y += font1.get_Height();
count += 1;
}
font1.Dispose();
}
catch (System.Exception exp) {
MessageBox.Show(("There was an error."
+ "Make sure the path to the image file is valid."));
}
} //ExtractMetaData
Vererbungshierarchie
System.Object
System.Drawing.Imaging.PropertyItem
Threadsicherheit
Alle öffentlichen statischen (Shared in Visual Basic) Member dieses Typs sind threadsicher. Bei Instanzmembern ist die Threadsicherheit nicht gewährleistet.
Plattformen
Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.
Versionsinformationen
.NET Framework
Unterstützt in: 2.0, 1.1, 1.0
Siehe auch
Referenz
PropertyItem-Member
System.Drawing.Imaging-Namespace