BitmapPropertiesView.GetPropertiesAsync(IIterable<String>) Method

Reference

Definition

Namespace:: Windows.Graphics.Imaging

Important

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Edit

Asynchronously retrieves one or more bitmap properties.

public:
 virtual IAsyncOperation<BitmapPropertySet ^> ^ GetPropertiesAsync(IIterable<Platform::String ^> ^ propertiesToRetrieve) = GetPropertiesAsync;

/// [Windows.Foundation.Metadata.RemoteAsync]
IAsyncOperation<BitmapPropertySet> GetPropertiesAsync(IIterable<winrt::hstring> const& propertiesToRetrieve);

[Windows.Foundation.Metadata.RemoteAsync]
public IAsyncOperation<BitmapPropertySet> GetPropertiesAsync(IEnumerable<string> propertiesToRetrieve);

function getPropertiesAsync(propertiesToRetrieve)

Public Function GetPropertiesAsync (propertiesToRetrieve As IEnumerable(Of String)) As IAsyncOperation(Of BitmapPropertySet)

Parameters

propertiesToRetrieve: IIterable<String>

IEnumerable<String>

IIterable<Platform::String>

IIterable<winrt::hstring>

A collection of strings representing the property keys or queries that are being requested. Valid strings include Windows properties and Windows Imaging Component metadata queries.

Returns

IAsyncOperation<BitmapPropertySet>

Object that manages the asynchronous retrieval of the bitmap properties.

Implements

M:Windows.Graphics.Imaging.IBitmapPropertiesView.GetPropertiesAsync(System.Collections.Generic.IEnumerable{System.String}) M:Windows.Graphics.Imaging.IBitmapPropertiesView.GetPropertiesAsync(System.Collections.Generic.IEnumerable{Platform::String}) M:Windows.Graphics.Imaging.IBitmapPropertiesView.GetPropertiesAsync(System.Collections.Generic.IEnumerable{winrt::hstring})

Attributes: RemoteAsyncAttribute

Remarks

The asynchronous operation produces a collection representing the requested image property keys and their values. The values are stored as BitmapTypedValue, which contains both the actual data as well as the PropertyType of the data.

A particular image may only contain some (or none) of the requested properties. In this case the collection will only have key-value pairs for the properties which were found in the image. You need to check for the existence of the property before you attempt to get data from it:

bitmapPropertiesView.getPropertiesAsync(["System.Title"]).done(function (retrievedProperties) {
  if (retrievedProperties.hasKey("System.Title")) {
	  	var titleProperty = retrievedProperties.lookup("System.Title");
	  	var title = titleProperty.value;
	 }
});

Querying for a metadata block

If you use the metadata query language to request a metadata block instead of a property, the returned value is a BitmapPropertiesView representing the metadata within that block. You can request any metadata contained within the block from the BitmapPropertiesView:

// this is equivalent to directly requesting "/app1/ifd/{ushort=274}" from bitmapPropertiesView
bitmapPropertiesView.getPropertiesAsync(["/app1/ifd"]).done(function (retrievedProperties) {
	  // var ifdBlock is a BitmapPropertiesView
	  var ifdBlock = retrievedProperties.lookup("/app1/ifd").value;
	  return ifdBlock.getPropertiesAsync(["/{ushort=274}");
}).then(function (retrievedProperties) {
	  var orientation = retrievedProperties.lookup("/{ushort=274}").value;
});

Enumerating through all the metadata within a frame

You can request all of the contents of a metadata block, including sub-blocks and properties, by passing in an empty (zero length) collection of strings. This produces a collection containing every sub-block and property within the BitmapPropertiesView ’s scope. In this way, you are able to iteratively retrieve all of the metadata contained within an image frame.

bitmapPropertiesView.getPropertiesAsync([]).done(function (retrievedProperties) {
	  var iterator = retrievedProps.first();
	  while (iterator.hasCurrent) {
		  // iterator.current gives a key-value pair of string, BitmapTypedValue
		  // nextMetadataBlock is a BitmapPropertiesView containing the sub-block
		  var nextMetadataBlock = iterator.current.value.value;
		  iterator.moveNext();
	}
});

If the image format does not support metadata, it will fail with HRESULT WINCODEC_ERR_UNSUPPORTEDOPERATION.

Applies to