HttpPost Class

This class allows can post image data to a server without user interaction.

Inheritance Hierarchy

SystemObject
Atalasoft.TwainHttpPost

Namespace: Atalasoft.Twain
Assembly: Atalasoft.DotTwain (in Atalasoft.DotTwain.dll) Version: 11.4.0.9.0.377 (.NET 4.5.2, x86)

Syntax

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public class HttpPost

Public Class HttpPost

The HttpPost type exposes the following members.

Constructors

	Name	Description
	HttpPost	Creates a new instance of HttpPost.
	HttpPost(ImageFormat)	Creates a new instance of HttpPost specifying encoder.

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Properties

	Name	Description
	FormData	Gets the FormDataCollection object that will be posted to the server.
	SessionCookies	Gets or sets the session cookies to use for this transfer.
	Timeout	Gets or sets the seconds to wait before timing out on the transfer.

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Methods

	Name	Description
	Equals	Determines whether the specified object is equal to the current object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
	GetData	This method can be used to retrieve information from a server.
	GetHashCode	Serves as the default hash function. (Inherited from Object.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	PostData	This method will send the internal FormDataCollection entries to a server for processing.
	SetImageFormat(ImageFormat)
	SetImageFormat(String)	Sets the image format that will be used to post the Bitmap data in the FormDataCollection.
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Remarks

The data is posted as if it were being sent from an HTML Form, allowing any form handling component to be used on the server.

Examples

Posting an image (C#)

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// Load the image we want to upload.
Bitmap bmp = new Bitmap(@"C:\myimage.jpg");

// We are going to save the image as JPEG on the server.
HttpPost post = new HttpPost(System.Drawing.Imaging.ImageFormat.Jpeg);
post.FormData.Add("image1", bmp, "myimage.jpg");

// Now lets add the additional information set by the client.
post.FormData.Add("comment", this.textComment.Text);
post.FormData.Add("author", this.textAuthor.Text);

// Upload the image and check the return value to see if it worked.
string retVal = post.PostData("http://www.mysite.com/handleupload.aspx");
if (retVal != "Success")
    MessageBox.Show(this, retVal, "Upload Error");

// Free the image.
bmp.Dispose();

Posting an image (Visual Basic)

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' Load the image we want to upload.
Dim bmp As Bitmap = New Bitmap("C:\myimage.jpg")

' We are going to save the image as JPEG on the server.
Dim post As HttpPost = New HttpPost(System.Drawing.Imaging.ImageFormat.Jpeg)
post.FormData.Add("image1", bmp, "myimage.jpg")

' Now lets add the additional information set by the client.
post.FormData.Add("comment", Me.textComment.Text)
post.FormData.Add("author", Me.textAuthor.Text)

' Upload the image and check the return value to see if it worked.
Dim retVal As String = post.PostData("http://www.mysite.com/handleupload.aspx")
If retVal <> "Success" Then
    MessageBox.Show(this, retVal, "Upload Error")
End If

' Free the image.
bmp.Dispose()

This example will show you how to acquire an image from a web page and post it to the server.

Posting from a browser (JScript)

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<!-- The main Acquisition object. -->
<object id="Twain" height="1" width="1" classid="Atalasoft.Twain.dll#Atalasoft.Twain.Acquisition" VIEWASTEXT>
</object>

<!-- Create an instance of the HttpPost object -->
<object id="PostIt" height="1" width="1" classid="Atalasoft.Twain.dll#Atalasoft.Twain.HttpPost" VIEWASTEXT>
</object>

...

<script type="text/javascript">
var count = 0;
function AcquireImage()
{
    // Acquire the image.
    var img = document.Twain.AcquireModal(false);
    if (img == null)
    {
        alert(&apos;Image was not acquired.&apos;);
        return;
    }

    // Send the image to the server.
    count++;
    var filename = &apos;image&apos; + count + &apos;.png&apos;;
    document.PostIt.FormData.AddFromBrowser(&apos;postImage&apos;, img, filename);

    var response = "";
    response = document.PostIt.PostData(&apos;http://localhost/TwainDemo/savepost.aspx&apos;);

    // Free the form data.
    document.PostIt.FormData.Clear();

    // Update the image.
    if (response.length > 0)
    {
        var el = document.getElementById(&apos;preview&apos;);
        el.src = response;
    } else {
        alert("PostDataFromBrowser failed");
    }
}
</script>

Examples

Posting an image (C#)

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// Load the image we want to upload.
Bitmap bmp = new Bitmap(@"C:\myimage.jpg");

// We are going to save the image as JPEG on the server.
HttpPost post = new HttpPost(System.Drawing.Imaging.ImageFormat.Jpeg);
post.FormData.Add("image1", bmp, "myimage.jpg");

// Now lets add the additional information set by the client.
post.FormData.Add("comment", this.textComment.Text);
post.FormData.Add("author", this.textAuthor.Text);

// Upload the image and check the return value to see if it worked.
string retVal = post.PostData("http://www.mysite.com/handleupload.aspx");
if (retVal != "Success")
    MessageBox.Show(this, retVal, "Upload Error");

// Free the image.
bmp.Dispose();

Posting an image (Visual Basic)

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' Load the image we want to upload.
Dim bmp As Bitmap = New Bitmap("C:\myimage.jpg")

' We are going to save the image as JPEG on the server.
Dim post As HttpPost = New HttpPost(System.Drawing.Imaging.ImageFormat.Jpeg)
post.FormData.Add("image1", bmp, "myimage.jpg")

' Now lets add the additional information set by the client.
post.FormData.Add("comment", Me.textComment.Text)
post.FormData.Add("author", Me.textAuthor.Text)

' Upload the image and check the return value to see if it worked.
Dim retVal As String = post.PostData("http://www.mysite.com/handleupload.aspx")
If retVal <> "Success" Then
    MessageBox.Show(this, retVal, "Upload Error")
End If

' Free the image.
bmp.Dispose()

This example will show you how to acquire an image from a web page and post it to the server.

Posting from a browser (JScript)

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<!-- The main Acquisition object. -->
<object id="Twain" height="1" width="1" classid="Atalasoft.Twain.dll#Atalasoft.Twain.Acquisition" VIEWASTEXT>
</object>

<!-- Create an instance of the HttpPost object -->
<object id="PostIt" height="1" width="1" classid="Atalasoft.Twain.dll#Atalasoft.Twain.HttpPost" VIEWASTEXT>
</object>

...

<script type="text/javascript">
var count = 0;
function AcquireImage()
{
    // Acquire the image.
    var img = document.Twain.AcquireModal(false);
    if (img == null)
    {
        alert(&apos;Image was not acquired.&apos;);
        return;
    }

    // Send the image to the server.
    count++;
    var filename = &apos;image&apos; + count + &apos;.png&apos;;
    document.PostIt.FormData.AddFromBrowser(&apos;postImage&apos;, img, filename);

    var response = "";
    response = document.PostIt.PostData(&apos;http://localhost/TwainDemo/savepost.aspx&apos;);

    // Free the form data.
    document.PostIt.FormData.Clear();

    // Update the image.
    if (response.length > 0)
    {
        var el = document.getElementById(&apos;preview&apos;);
        el.src = response;
    } else {
        alert("PostDataFromBrowser failed");
    }
}
</script>

Reference

Atalasoft.Twain Namespace

FormDataCollection Class

HttpPost Class