context.Response.OutputStream.Write(buffer, 0, count) questions

  • Thread starter Thread starter AAaron123
  • Start date Start date
A

AAaron123

trying to understand the below shown code.
After this is run the browser opens a file-save dialog box for saving the
file.
I wonder how it knows I want the file saved?

But more important, the dialog box has as the default file name the name of
this ashx file.

I'd like to make that name more meaningfull but don't know how it gets set.
I'm looking for a Response.Write but don't find one. Maybe that why the
funny default filename?

Got a clue as to how that gets set?

Also, I see the content.Request below. Looks like a chance for the user to
request different size images. But I don't see anything happening when I run
the code!

Do you know what that code should be accomplishing?

I read the help for IHttpHandler ProcessRequest but that didn't help me

Thanks for any help at all

Sub ProcessRequest(ByVal context As HttpContext) Implements
IHttpHandler.ProcessRequest

' Set up the response settings

context.Response.ContentType = "image/jpeg"

context.Response.Cache.SetCacheability(HttpCacheability.Public)

context.Response.BufferOutput = False

' Setup the Size Parameter

Dim size As PhotoSize = PhotoSize.Original

Select Case context.Request.QueryString("Size")

Case "S"

size = PhotoSize.Small

Case "M"

size = PhotoSize.Medium

Case "L"

size = PhotoSize.Large

Case Else

size = PhotoSize.Original

End Select

' Setup the PhotoID Parameter

Dim id As Int32 = 1

Dim stream As IO.Stream = Nothing

If ((Not (context.Request.QueryString("PhotoID")) Is Nothing) _

AndAlso (context.Request.QueryString("PhotoID") <> "")) Then

id = [Convert].ToInt32(context.Request.QueryString("PhotoID"))

stream = PhotoManager.GetPhoto(id, size)

Else

id = [Convert].ToInt32(context.Request.QueryString("AlbumID"))

stream = PhotoManager.GetFirstPhoto(id, size)

End If

' Get the photo from the database, if nothing is returned, get the default
"placeholder" photo

If (stream Is Nothing) Then

stream = PhotoManager.GetPhoto(size)

End If

' Write image stream to the response stream

Dim buffersize As Integer = (1024 * 16)

Dim buffer() As Byte = New Byte((buffersize) - 1) {}

Dim count As Integer = stream.Read(buffer, 0, buffersize)


Do While (count > 0)

context.Response.OutputStream.Write(buffer, 0, count)

count = stream.Read(buffer, 0, buffersize)


Loop

End Sub
 
That's interesting, because the code did not contain that statement, as the
site suggested it should.
And it worked except for the crazy filename in the dialog box.
Do you think the context.Response.ContentType = "image/jpeg" line caused the
dialog box to open?

I see in the code lines like:
zz=context.Request.QueryString("Size")

So, just to see, I tried:
Dim s As String = context.Request.QueryString("Filename")

which of course doesn't work.

Am I close?

Is there something that does work to get the filename?



Thanks for the info



George said:
Here you go
http://support.microsoft.com/kb/260519/EN-US/

Basically this is the line you need to add
Response.AddHeader "content-disposition","attachment; filename=fname.ext"


where fname.ext is the file name you want it to be....

George.


AAaron123 said:
trying to understand the below shown code.
After this is run the browser opens a file-save dialog box for saving the
file.
I wonder how it knows I want the file saved?

But more important, the dialog box has as the default file name the name
of this ashx file.

I'd like to make that name more meaningfull but don't know how it gets
set. I'm looking for a Response.Write but don't find one. Maybe that why
the funny default filename?

Got a clue as to how that gets set?

Also, I see the content.Request below. Looks like a chance for the user
to request different size images. But I don't see anything happening when
I run the code!

Do you know what that code should be accomplishing?

I read the help for IHttpHandler ProcessRequest but that didn't help me

Thanks for any help at all

Sub ProcessRequest(ByVal context As HttpContext) Implements
IHttpHandler.ProcessRequest

' Set up the response settings

context.Response.ContentType = "image/jpeg"

context.Response.Cache.SetCacheability(HttpCacheability.Public)

context.Response.BufferOutput = False

' Setup the Size Parameter

Dim size As PhotoSize = PhotoSize.Original

Select Case context.Request.QueryString("Size")

Case "S"

size = PhotoSize.Small

Case "M"

size = PhotoSize.Medium

Case "L"

size = PhotoSize.Large

Case Else

size = PhotoSize.Original

End Select

' Setup the PhotoID Parameter

Dim id As Int32 = 1

Dim stream As IO.Stream = Nothing

If ((Not (context.Request.QueryString("PhotoID")) Is Nothing) _

AndAlso (context.Request.QueryString("PhotoID") <> "")) Then

id = [Convert].ToInt32(context.Request.QueryString("PhotoID"))

stream = PhotoManager.GetPhoto(id, size)

Else

id = [Convert].ToInt32(context.Request.QueryString("AlbumID"))

stream = PhotoManager.GetFirstPhoto(id, size)

End If

' Get the photo from the database, if nothing is returned, get the
default "placeholder" photo

If (stream Is Nothing) Then

stream = PhotoManager.GetPhoto(size)

End If

' Write image stream to the response stream

Dim buffersize As Integer = (1024 * 16)

Dim buffer() As Byte = New Byte((buffersize) - 1) {}

Dim count As Integer = stream.Read(buffer, 0, buffersize)


Do While (count > 0)

context.Response.OutputStream.Write(buffer, 0, count)

count = stream.Read(buffer, 0, buffersize)


Loop

End Sub
Click to expand...
Click to expand...
 
you need to study the http protocol more closely. a web response has headers
and content. for what you are doing there are two header. "content-type"
which defines the what is being returnd (in your case a jpeg).

the default file name in save dialog for a browser is the name of the
request. you can alter this with the "content-disposition" header.

Response.AddHeader("content-disposition","attachment; filename=myImg.jpg");



-- bruce (sqlwork.com)


AAaron123 said:
trying to understand the below shown code.
After this is run the browser opens a file-save dialog box for saving the
file.
I wonder how it knows I want the file saved?

But more important, the dialog box has as the default file name the name of
this ashx file.

I'd like to make that name more meaningfull but don't know how it gets set.
I'm looking for a Response.Write but don't find one. Maybe that why the
funny default filename?

Got a clue as to how that gets set?

Also, I see the content.Request below. Looks like a chance for the user to
request different size images. But I don't see anything happening when I run
the code!

Do you know what that code should be accomplishing?

I read the help for IHttpHandler ProcessRequest but that didn't help me

Thanks for any help at all

Sub ProcessRequest(ByVal context As HttpContext) Implements
IHttpHandler.ProcessRequest

' Set up the response settings

context.Response.ContentType = "image/jpeg"

context.Response.Cache.SetCacheability(HttpCacheability.Public)

context.Response.BufferOutput = False

' Setup the Size Parameter

Dim size As PhotoSize = PhotoSize.Original

Select Case context.Request.QueryString("Size")

Case "S"

size = PhotoSize.Small

Case "M"

size = PhotoSize.Medium

Case "L"

size = PhotoSize.Large

Case Else

size = PhotoSize.Original

End Select

' Setup the PhotoID Parameter

Dim id As Int32 = 1

Dim stream As IO.Stream = Nothing

If ((Not (context.Request.QueryString("PhotoID")) Is Nothing) _

AndAlso (context.Request.QueryString("PhotoID") <> "")) Then

id = [Convert].ToInt32(context.Request.QueryString("PhotoID"))

stream = PhotoManager.GetPhoto(id, size)

Else

id = [Convert].ToInt32(context.Request.QueryString("AlbumID"))

stream = PhotoManager.GetFirstPhoto(id, size)

End If

' Get the photo from the database, if nothing is returned, get the default
"placeholder" photo

If (stream Is Nothing) Then

stream = PhotoManager.GetPhoto(size)

End If

' Write image stream to the response stream

Dim buffersize As Integer = (1024 * 16)

Dim buffer() As Byte = New Byte((buffersize) - 1) {}

Dim count As Integer = stream.Read(buffer, 0, buffersize)


Do While (count > 0)

context.Response.OutputStream.Write(buffer, 0, count)

count = stream.Read(buffer, 0, buffersize)


Loop

End Sub
Click to expand...
 
bruce barker said:
you need to study the http protocol more closely. a web response has
headers
Click to expand...

That suggestion was helpful. I googled "http protocol", read it, then read
about QueryString and ran a little code and it looks like the request
contains only an image number and the size. So in your future replies please
continue to point people to what they should read about. Now I have to find
out what caused the request and what determins what is included. I think I
know where to look.

thanks

and content. for what you are doing there are two header. "content-type"
which defines the what is being returnd (in your case a jpeg).

the default file name in save dialog for a browser is the name of the
request. you can alter this with the "content-disposition" header.

Response.AddHeader("content-disposition","attachment;
filename=myImg.jpg");



-- bruce (sqlwork.com)


AAaron123 said:
trying to understand the below shown code.
After this is run the browser opens a file-save dialog box for saving the
file.
I wonder how it knows I want the file saved?

But more important, the dialog box has as the default file name the name
of
this ashx file.

I'd like to make that name more meaningfull but don't know how it gets
set.
I'm looking for a Response.Write but don't find one. Maybe that why the
funny default filename?

Got a clue as to how that gets set?

Also, I see the content.Request below. Looks like a chance for the user
to
request different size images. But I don't see anything happening when I
run
the code!

Do you know what that code should be accomplishing?

I read the help for IHttpHandler ProcessRequest but that didn't help me

Thanks for any help at all

Sub ProcessRequest(ByVal context As HttpContext) Implements
IHttpHandler.ProcessRequest

' Set up the response settings

context.Response.ContentType = "image/jpeg"

context.Response.Cache.SetCacheability(HttpCacheability.Public)

context.Response.BufferOutput = False

' Setup the Size Parameter

Dim size As PhotoSize = PhotoSize.Original

Select Case context.Request.QueryString("Size")

Case "S"

size = PhotoSize.Small

Case "M"

size = PhotoSize.Medium

Case "L"

size = PhotoSize.Large

Case Else

size = PhotoSize.Original

End Select

' Setup the PhotoID Parameter

Dim id As Int32 = 1

Dim stream As IO.Stream = Nothing

If ((Not (context.Request.QueryString("PhotoID")) Is Nothing) _

AndAlso (context.Request.QueryString("PhotoID") <> "")) Then

id = [Convert].ToInt32(context.Request.QueryString("PhotoID"))

stream = PhotoManager.GetPhoto(id, size)

Else

id = [Convert].ToInt32(context.Request.QueryString("AlbumID"))

stream = PhotoManager.GetFirstPhoto(id, size)

End If

' Get the photo from the database, if nothing is returned, get the
default
"placeholder" photo

If (stream Is Nothing) Then

stream = PhotoManager.GetPhoto(size)

End If

' Write image stream to the response stream

Dim buffersize As Integer = (1024 * 16)

Dim buffer() As Byte = New Byte((buffersize) - 1) {}

Dim count As Integer = stream.Read(buffer, 0, buffersize)


Do While (count > 0)

context.Response.OutputStream.Write(buffer, 0, count)

count = stream.Read(buffer, 0, buffersize)


Loop

End Sub
Click to expand...
Click to expand...
 
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