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BitmapMetadata.SetQuery(String, Object) Method

  • Reference

Definition

Namespace:
System.Windows.Media.Imaging
Assembly:
PresentationCore.dll

Provides access to a metadata query writer that can write metadata to a bitmap image file.

public:
 void SetQuery(System::String ^ query, System::Object ^ value);
[System.Security.SecurityCritical]
public void SetQuery (string query, object value);
public void SetQuery (string query, object value);
[<System.Security.SecurityCritical>]
member this.SetQuery : string * obj -> unit
member this.SetQuery : string * obj -> unit
Public Sub SetQuery (query As String, value As Object)

Parameters

query
String

Identifies the location of the metadata to be written.

value
Object

The value of the metadata to be written.

Attributes
SecurityCriticalAttribute

Examples

The following code example demonstrates how to use the SetQuery method to write metadata to a Portable Network Graphics (PNG) file.

Stream^ pngStream = gcnew FileStream("smiley.png", FileMode::Open, FileAccess::ReadWrite, FileShare::ReadWrite);
PngBitmapDecoder^ pngDecoder = gcnew PngBitmapDecoder(pngStream, BitmapCreateOptions::PreservePixelFormat, BitmapCacheOption::Default);
BitmapFrame^ pngFrame = pngDecoder->Frames[0];
InPlaceBitmapMetadataWriter^ pngInplace = pngFrame->CreateInPlaceBitmapMetadataWriter();
if (pngInplace->TrySave())
{
   pngInplace->SetQuery("/Text/Description", "Have a nice day.");
}
pngStream->Close();

Stream pngStream = new System.IO.FileStream("smiley.png", FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite);
PngBitmapDecoder pngDecoder = new PngBitmapDecoder(pngStream, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default);
BitmapFrame pngFrame = pngDecoder.Frames[0];
InPlaceBitmapMetadataWriter pngInplace = pngFrame.CreateInPlaceBitmapMetadataWriter();
if (pngInplace.TrySave())
{ pngInplace.SetQuery("/Text/Description", "Have a nice day."); }
pngStream.Close();

Dim pngStream As New System.IO.FileStream("smiley.png", FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite)
Dim pngDecoder As New PngBitmapDecoder(pngStream, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default)
Dim pngFrame As BitmapFrame = pngDecoder.Frames(0)
Dim pngInplace As InPlaceBitmapMetadataWriter = pngFrame.CreateInPlaceBitmapMetadataWriter()
If pngInplace.TrySave() = True Then
    pngInplace.SetQuery("/Text/Description", "Have a nice day.")
End If
pngStream.Close()

After the metadata is written, the GetQuery method is used to read that data and emit it as a text string.


// Add the metadata of the bitmap image to the text block.
TextBlock^ myTextBlock = gcnew TextBlock();
myTextBlock->Text = "The Description metadata of this image is: " + pngInplace->GetQuery("/Text/Description")->ToString();


// Add the metadata of the bitmap image to the text block.
TextBlock myTextBlock = new TextBlock();
myTextBlock.Text = "The Description metadata of this image is: " + pngInplace.GetQuery("/Text/Description").ToString();

' Add the metadata of the bitmap image to the text block.
Dim myTextBlock As New TextBlock()
myTextBlock.Text = "The Description metadata of this image is: " + pngInplace.GetQuery("/Text/Description").ToString()

Remarks

Metadata that is associated with an image is data that describes the image but that is not necessary for display of the image. Each supported bitmap image format handles metadata differently, but the facility for reading and writing metadata is the same.

Windows Presentation Foundation (WPF) supports the following image metadata schemas: Exchangeable image file (Exif), tEXt (PNG Textual Data), image file directory (IFD), International Press Telecommunications Council (IPTC), and Extensible Metadata Platform (XMP).

Applies to

See also