SoftArtisans ImgWriter Guide

The Image Collection Object

Loading Images

The sample script imagecollection.asp uses the method LoadImage to add images to the image collection. (Note: You will find the original images for this and other samples in doc-samples\samples\tutorial\Images, and the generated images in doc-samples\samples\tutorial\GeneratedImages.)

tutorial/loadimgs.asp

[Run Sample] | [View Source]

Creating an Instance of the Images Object

LoadImage is a method of the image collection object Images. The image cache can be used at Application, Session, or Page scope. This sample will create an instance of the object in the Application_OnStart method(found in global.asa) and store the reference in a Session variable:

Sub Application_OnStart()
	Set Application("SAImgs") = Server.CreateObject("SoftArtisans.Images")
End Sub

Load Images

This reference can then be used in other ASP pages to add images to the cache. LoadMethod allows you to add an image to the collection from a file, an ADO Recordset field, or a binary array. The sample checks that the key does not already exist in the collection and loades three images into the collection from files:

If Application("SAImgs").Exists("CityHall") = False then
Application("SAImgs").LoadImage "CityHall", Server.MapPath(Application("vroot") & _
	"samples/tutorial/images/stadshus.jpg")
End If
If Application("SAImgs").Exists("ConsertHall") = False then
Application("SAImgs").LoadImage "ConsertHall", Server.MapPath(Application("vroot") & _
	"samples/tutorial/images/konsert.jpg")
End If
If Application("SAImgs").Exists("Square") = False then
Application("SAImgs").LoadImage "Square", Server.MapPath(Application("vroot") & _
	"samples/tutorial/images/storget.jpg")
End If

Access Binary Data

Once an image has been added to the collection, it can be access in another page using array syntax with the image's name as the key. The sample uses and HTML img tag to add an image to the page. The img tag's src attribute points to the ASP page where the image will be retrieved from the image collection:

<IMG SRC="GetSquare.asp">

In GetSquare.asp, the image data is written to the ASP Response object:

Response.Buffer = True
Response.ContentType = "image/jpeg"
Response.BinaryWrite Application("SAImgs")("Square")
Response.End

Wrapping Up

It is considered good programming practice to explicitly destroy the object when it is no longer necessary. Since we have stored an object reference in a Session variable in Session_OnEnd, we should destroy it in Session_OnEnd:

Sub Application_OnEnd()
	Set Application("SAImgs") = Nothing
End Sub