Leadtools.Codecs Namespace > RasterCodecs Class > LoadAsync Method : LoadAsync(ILeadStream,LeadRect) Method |
'Declaration Public Overloads Function LoadAsync( _ ByVal stream As ILeadStream, _ ByVal tile As LeadRect _ ) As IAsyncOperation(Of RasterImage)
'Usage Dim instance As RasterCodecs Dim stream As ILeadStream Dim tile As LeadRect Dim value As IAsyncOperation(Of RasterImage) value = instance.LoadAsync(stream, tile)
This method loads a section of an image file (any format). The section begins is defined by tile rectangle.
LEADTOOLS will attempt to load corrupted files so you can see at least a portion of the image. For these images, the load methods succeed, but LoadStatus will return an error code.
Use the CodecsLoadOptions class to set up other load option parameters before calling this method.
Support for 12 and 16-bit grayscale images is only available in the Document/Medical Imaging editions.
For supported formats, refer to Summary of All Supported Image File Formats.
LEADTOOLS loads all PDF files as Raster PDF uncompressed RasterImageFormat.RasPdf, regardless of the compression and color space used when saving the file.
The RasterCodecs class supports loading image files asynchronously using the LoadAsync methods. When calling any of these methods, the caller thread will not be blocked and the method will return instantly with an instance of Leadtools.RasterImage that is in a loading status (RasterImage.IsLoading set to true). You should not use the other properties of this object while the object is in loading status.
When the RasterCodecs object finishes loading the image, the various properties of the Leadtools.RasterImage will be populated with the image information and data and the RasterImage.IsLoading property will be set to false.
Do not poll the RasterImage.IsLoading property to determine whether the image has finished loading. Instead, subscribe to the IAsyncOperation.Completed event to get notification when the LoadAsync(String,LeadRect,Int32,CodecsLoadByteOrder,Int32,Int32,Object) operation has completed and whether any errors occurred.
When this method completes, it returns the image as a Leadtools.RasterImage.
The CodecsLoadOptions.AllPages property controls whether RasterCodecs will try to load all pages or just the first page if the image data contains multiple pages.
RasterCodecsExamples.prototype.LoadTileFile1Example = function ( ) { Tools.SetLicense ( ) ; with (Leadtools) { with (Leadtools.Codecs) { var codecs = new RasterCodecs(); var image; var loadFile; var info; var srcFileName = "Assets\\Image1.cmp"; var destFileName = "Image1_LoadTileFile1.bmp"; // Get the image dimension return Tools.AppInstallFolder().getFileAsync(srcFileName).then(function (ldFile) { loadFile = ldFile; return codecs.getInformationAsync(LeadStreamFactory.create(loadFile), false, 1) }) .then(function (inf) { info = inf; // Load the lower right corner of the image var rc = LeadRectHelper.create( info.width / 2, info.height / 2, info.width / 2, info.height / 2); return codecs.loadAsync(LeadStreamFactory.create(loadFile), rc) }) .then(function (img) { image = img; console.assert(image.width == (info.width / 2), "image.Width == (info.Width / 2)"); console.assert(image.height == (info.height / 2), "image.Height == (info.Height / 2)"); // Save this image back to disk return Tools.AppLocalFolder().createFileAsync(destFileName) }) .then(function (saveFile) { return codecs.saveAsync(image, LeadStreamFactory.create(saveFile), RasterImageFormat.bmp, 24) }) .then(function () { image.close(); // Clean up codecs.close(); }); } } }
using Leadtools; using Leadtools.Codecs; using Leadtools.ImageProcessing; using Leadtools.ImageProcessing.Color; public async Task LoadTileFile1Example() { RasterCodecs codecs = new RasterCodecs(); string srcFileName = @"Assets\Image1.cmp"; string destFileName = @"Image1_LoadTileFile1.bmp"; // Get the image dimension StorageFile loadFile = await Tools.AppInstallFolder.GetFileAsync(srcFileName); CodecsImageInfo info = await codecs.GetInformationAsync(LeadStreamFactory.Create(loadFile), false, 1); // Load the lower right corner of the image LeadRect rc = LeadRectHelper.Create( info.Width / 2, info.Height / 2, info.Width / 2, info.Height / 2); RasterImage image = await codecs.LoadAsync(LeadStreamFactory.Create(loadFile), rc); Assert.IsTrue(image.Width == (info.Width / 2)); Assert.IsTrue(image.Height == (info.Height / 2)); // Save this image back to disk StorageFile saveFile = await Tools.AppLocalFolder.CreateFileAsync(destFileName); await codecs.SaveAsync(image, LeadStreamFactory.Create(saveFile), RasterImageFormat.Bmp, 24); image.Dispose(); // Clean up codecs.Dispose(); }