ImageGear .NET v25.0 - Updated
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User Guide > How to Work with... > Common Operations > Loading and Saving > Loading

The ImGearFileFormats class provides the APIs that should be employed to load a document/image. This operation is mainly performed from a given .NET Stream object. ImageGear supports loading from streams having the seek ability, as well as from streams that don't have the seek ability, such as network streams. If the loading operation cannot be performed, an exception with either of the following codes is thrown: ImageGear.Core.ImGearErrorCodes.CANT_DETECT_FORMAT or ImageGear.Core.ImGearErrorCodes.CANT_FIND_FORMAT.

If the document size is close to 2GB, the System.OutOfMemoryException will be thrown.

Load a Single Page

To load a single page, use the LoadPage method as follows:

C#
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using System.IO;
using ImageGear.Core;
using ImageGear.Formats;
public ImGearPage LoadPageFromLocalFile(string filePath)
{
     // From a local file
     ImGearPage igPage;
     int pageIndex = 0;

     using (FileStream localFile = new FileStream(filePath,FileMode.Open))
     {
          igPage = ImGearFileFormats.LoadPage(localFile, pageIndex);
     }
     return igPage;
}
VB.NET
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Imports System.IO
Imports ImageGear.Core
Imports ImageGear.Formats
Public Function LoadPageFromLocalFile(filePath As String) As ImGearPage
            ' From a local file
            Dim igPage As ImGearPage
            Dim pageIndex As Integer = 0

            Using localFile As New FileStream(filePath, FileMode.Open)
                        igPage = ImGearFileFormats.LoadPage(localFile, pageIndex)
            End Using

            Return igPage
End Function

From a Web Server

ImageGear provides a specialized stream class for loading of images from the internet: ImGearWebStream class. This class is most useful for loading multi-page images, because it downloads only the necessary portion of a remote file. ImGearWebStream class only supports loading images from servers that use HTTP protocol. The following example demonstrates how to load a page from a remote document using ImGearWebStream class:

C#
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using ImageGear.Core;
using ImageGear.Formats;
public ImGearPage LoadPageFromWebServerFile(string webServerFileURL)
{
     ImGearPage igPage;
     int pageIndex = 0;

     using (ImGearWebStream igWebStream = new ImGearWebStream(webServerFileURL))
            igPage = ImGearFileFormats.LoadPage(igWebStream, pageIndex);

     return igPage;
}
VB.NET
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Imports ImageGear.Core
Imports ImageGear.Formats
Public Function LoadPageFromWebServerFile(webServerFileURL As String) As ImGearPage
            Dim igPage As ImGearPage
            Dim pageIndex As Integer = 0

            Using igWebStream As New ImGearWebStream(webServerFileURL)
                        igPage = ImGearFileFormats.LoadPage(igWebStream, pageIndex)
            End Using

            Return igPage
End Function

Furthermore, we can load a page from a remote file using WebRequest:

C#
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using System.Net;
using ImageGear.Core;
using ImageGear.Formats;
public ImGearPage LoadPageFromWebRequestrFile(string webServerFileURL)
{
     ImGearPage igPage;
     int pageIndex = 0;
     WebRequest request = WebRequest.Create(webServerFileURL);
     using (WebResponse response = request.GetResponse())
        using (Stream stream = response.GetResponseStream())
            igPage = ImGearFileFormats.LoadPage(stream, pageIndex);

     return igPage;
}
VB.NET
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Imports System.Net
Imports ImageGear.Core
Imports ImageGear.Formats
Public Function LoadPageFromWebRequestrFile(webServerFileURL As String) As ImGearPage
            Dim igPage As ImGearPage
            Dim pageIndex As Integer = 0
            Dim request As WebRequest = WebRequest.Create(webServerFileURL)
            Using response As WebResponse = request.GetResponse()
                        Using stream As Stream = response.GetResponseStream()
                                    igPage = ImGearFileFormats.LoadPage(stream, pageIndex)
                        End Using
            End Using

            Return igPage
End Function

Load a Document (Multiple Pages as a Document)

For this purpose, we should use the LoadDocument method. See What's the Best Format for...? for a list of the multi-page formats supported by ImageGear .NET:

C#
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using System.IO;
using ImageGear.Core;
using ImageGear.Formats;
public ImGearDocument LoadDocumentFromFile(string filePath)
{
     ImGearDocument igDocument;
            using (FileStream localFile = new FileStream(filePath, FileMode.Open))
            {
                        int pageCount = ImGearFileFormats.GetPageCount(localFile, ImGearFormats.UNKNOWN);
                        igDocument = ImGearFileFormats.LoadDocument(localFile, 0, pageCount);
            }

     return igDocument;
}
VB.NET
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Imports System.IO
Imports ImageGear.Core
Imports ImageGear.Formats
Public Function LoadDocumentFromFile(filePath As String) As ImGearDocument
            Dim igDocument As ImGearDocument
            Using localFile As New FileStream(filePath, FileMode.Open)
                        Dim pageCount As Integer = ImGearFileFormats.GetPageCount(localFile, ImGearFormats.UNKNOWN)
                        igDocument = ImGearFileFormats.LoadDocument(localFile, 0, pageCount)
            End Using

            Return igDocument
End Function

For both the LoadPage method and the LoadDocument method, there is an overload receiving another parameter, ImGearLoadOptions object that allows you to be more specific about the loading operation.

Use Optional Parameters

We can use ImGearLoadOptions for setting certain options related to a loading operation.

The following example demonstrates how to load a format file by setting an instance of ImGearRawLoadOptions object. For this purpose, ImageGear provides a special dialog OpenRawFileDialog.

C#
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using ImageGear.Core;
using ImageGear.Formats;
using ImageGear.Windows.Forms;
public void LoadRawImage()
{
     // Create and Fill an instance of ImGearRawLoadOptions
     ImGearRawLoadOptions optionsForLoadRawFile = null;
     optionsForLoadRawFile = new ImGearRawLoadOptions();
     optionsForLoadRawFile.Format = ImGearFormats.RAW;
     optionsForLoadRawFile.Compression = ImGearCompressions.LZW;
     optionsForLoadRawFile.ColorSpace = new ImGearColorSpace(ImGearColorSpaceIDs.Gy);
     optionsForLoadRawFile.BitsPerChannel = 9;
     optionsForLoadRawFile.Alignment = ImGearRawAlignment.DoubleWord;
     optionsForLoadRawFile.Offset = 0;
     optionsForLoadRawFile.Width = 400;
     optionsForLoadRawFile.Height = 300;
     filePathNameForLoadRawFile = string.Empty;

     // Open a dialog especially designed for raw file formats.
     // A common Open File Dialog can be used instead if desired.
     using (OpenRawFileDialog dialog = new OpenRawFileDialog())
     {
          dialog.Compression = optionsForLoadRawFile.Compression;
          dialog.ColorSpace = optionsForLoadRawFile.ColorSpace;
          dialog.BitsPerChannel = optionsForLoadRawFile.BitsPerChannel;
          dialog.Alignment = optionsForLoadRawFile.Alignment;
          dialog.Offset = optionsForLoadRawFile.Offset;
          dialog.ImageWidth = optionsForLoadRawFile.Width;
          dialog.ImageHeight = optionsForLoadRawFile.Height;
          dialog.FillOrder = optionsForLoadRawFile.FillOrder;
          dialog.IsRasterPacked = optionsForLoadRawFile.IsRasterPacked;
          dialog.FilePathName = filePathNameForLoadRawFile;

          if (dialog.ShowDialog(this) == System.Windows.Forms.DialogResult.OK)
          {
               optionsForLoadRawFile.Compression = dialog.Compression;
               optionsForLoadRawFile.ColorSpace = dialog.ColorSpace;
               optionsForLoadRawFile.BitsPerChannel = dialog.BitsPerChannel;
               optionsForLoadRawFile.Alignment = dialog.Alignment;
               optionsForLoadRawFile.Offset = dialog.Offset;
               optionsForLoadRawFile.Width = dialog.ImageWidth;
               optionsForLoadRawFile.Height = dialog.ImageHeight;
               optionsForLoadRawFile.FillOrder = dialog.FillOrder;
               optionsForLoadRawFile.IsRasterPacked = dialog.IsRasterPacked;
               filePathNameForLoadRawFile = dialog.FilePathName;
          }
     }

     using (FileStream fileStream = new FileStream(filePathNameForLoadRawFile, FileMode.Open, FileAccess.Read))
     {
          imGearPage = ImGearFileFormats.LoadPage(fileStream, 0, optionsForLoadRawFile);
     }
}
VB.NET
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Imports ImageGear.Core
Imports ImageGear.Formats
Imports ImageGear.Windows.Forms
Public Sub LoadRawImage()
            ' Create and Fill an instance of ImGearRawLoadOptions
            Dim optionsForLoadRawFile As ImGearRawLoadOptions = Nothing
            optionsForLoadRawFile = New ImGearRawLoadOptions()
            optionsForLoadRawFile.Format = ImGearFormats.RAW
            optionsForLoadRawFile.Compression = ImGearCompressions.LZW
            optionsForLoadRawFile.ColorSpace = New ImGearColorSpace(ImGearColorSpaceIDs.Gy)
            optionsForLoadRawFile.BitsPerChannel = 9
            optionsForLoadRawFile.Alignment = ImGearRawAlignment.DoubleWord
            optionsForLoadRawFile.Offset = 0
            optionsForLoadRawFile.Width = 400
            optionsForLoadRawFile.Height = 300
            filePathNameForLoadRawFile = String.Empty

            ' Open a dialog especially designed for raw file formats.
            ' A common Open File Dialog can be used instead if desired.
            Using dialog As New OpenRawFileDialog()
                        dialog.Compression = optionsForLoadRawFile.Compression
                        dialog.ColorSpace = optionsForLoadRawFile.ColorSpace
                        dialog.BitsPerChannel = optionsForLoadRawFile.BitsPerChannel
                        dialog.Alignment = optionsForLoadRawFile.Alignment
                        dialog.Offset = optionsForLoadRawFile.Offset
                        dialog.ImageWidth = optionsForLoadRawFile.Width
                        dialog.ImageHeight = optionsForLoadRawFile.Height
                        dialog.FillOrder = optionsForLoadRawFile.FillOrder
                        dialog.IsRasterPacked = optionsForLoadRawFile.IsRasterPacked
                        dialog.FilePathName = filePathNameForLoadRawFile

                        If dialog.ShowDialog(Me) = System.Windows.Forms.DialogResult.OK Then
                                    optionsForLoadRawFile.Compression = dialog.Compression
                                    optionsForLoadRawFile.ColorSpace = dialog.ColorSpace
                                    optionsForLoadRawFile.BitsPerChannel = dialog.BitsPerChannel
                                    optionsForLoadRawFile.Alignment = dialog.Alignment
                                    optionsForLoadRawFile.Offset = dialog.Offset
                                    optionsForLoadRawFile.Width = dialog.ImageWidth
                                    optionsForLoadRawFile.Height = dialog.ImageHeight
                                    optionsForLoadRawFile.FillOrder = dialog.FillOrder
                                    optionsForLoadRawFile.IsRasterPacked = dialog.IsRasterPacked
                                    filePathNameForLoadRawFile = dialog.FilePathName
                        End If
            End Using

            Using fileStream As New FileStream(filePathNameForLoadRawFile, FileMode.Open, FileAccess.Read)
                        imGearPage = ImGearFileFormats.LoadPage(fileStream, 0, optionsForLoadRawFile)
            End Using
End Sub

 

 

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