BitmapMetadata.GetQuery(String) Method

Definition

Provides access to a metadata query reader that can extract metadata from a bitmap image file.

C#
[System.Security.SecurityCritical]
public object GetQuery(string query);
C#
public object GetQuery(string query);

Parameters

query
String

Identifies the string that is being queried in the current BitmapMetadata object.

Returns

The metadata at the specified query location.

Attributes

Exceptions

query is null.

Examples

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

C#
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();

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

C#

// 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();

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

Product Versions
.NET Framework 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
Windows Desktop 3.0, 3.1, 5, 6, 7, 8, 9, 10

See also