Attempts to convert a specified object to an instance of RasterImage.
public override object ConvertFrom(
ITypeDescriptorContext context,
CultureInfo culture,
object value
)
public:
Object^ ConvertFrom(
ITypeDescriptorContext^ context,
CultureInfo^ culture,
Object^ value
) override
context
Type context information used for conversion.
culture
Cultural information that is respected during conversion.
value
The object being converted.
A new instance of RasterImage.
The ConvertFrom method will try to convert the object passed into the value parameter to a valid RasterImage object. For more information, refer to RasterImageTypeConverter.
using Leadtools;
using Leadtools.Codecs;
using Leadtools.ImageProcessing.Core;
public void RasterImageTypeConverterExample()
{
string srcFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif");
// Construct the source URL to use the source file and load the image
Uri uri = new Uri(srcFileName);
RasterCodecs codecs = new RasterCodecs();
// Create a new instance of the RasterImageTypeConverter class
RasterImageTypeConverter rasterImageConverter = new RasterImageTypeConverter(codecs);
// We should be able to convert from a URL
Debug.Assert(rasterImageConverter.CanConvertFrom(uri.GetType()));
// Convert the image
// The return value from RasterImageTypeConverter.ConvertFrom might be an image that is
// still loading. So, we must subscribe to the RasterCodecs.LoadAsyncCompleteted
// event to obtain the finished image
codecs.LoadAsyncCompleted += new EventHandler<CodecsLoadAsyncCompletedEventArgs>(rasterImageTypeConverterExample_LoadAsyncCompleted);
object rasterImageObject = rasterImageConverter.ConvertFrom(uri);
// Notice that the returned rasterImageObject is a RasterImage with IsLoading set to true at this point
// The IsLoading will be false (and hence, the object will be usable) when the LoadAsyncCompleteted
// fires.
}
private void rasterImageTypeConverterExample_LoadAsyncCompleted(object sender, CodecsLoadAsyncCompletedEventArgs e)
{
// Check if the user canceled or if we have errors
if (e.Cancelled)
{
Debug.WriteLine("Canceled by the user");
}
else if (e.Error != null)
{
Debug.WriteLine("Error: " + e.Error.Message);
}
else
{
// Everything is OK, get the image
RasterImage image = e.Image;
Debug.WriteLine("Image at {0} loaded OK, size: {1} by {2}", e.Uri, image.Width, image.Height);
image.Dispose();
}
// Unsubscribe to the event and dispose the RasterCodecs object
RasterCodecs codecs = sender as RasterCodecs;
codecs.LoadAsyncCompleted -= new EventHandler<CodecsLoadAsyncCompletedEventArgs>(rasterImageTypeConverterExample_LoadAsyncCompleted);
codecs.Dispose();
}
static class LEAD_VARS
{
public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images";
}
Help Collections
Raster .NET | C API | C++ Class Library | HTML5 JavaScript
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Imaging, Medical, and Document
C API/C++ Class Libraries
Imaging, Medical, and Document
HTML5 JavaScript Libraries
Imaging, Medical, and Document
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