Using Caché Objects - InterSystems Documentation

Streams and Visual Basic
15.4 Streams and Visual Basic
To make it easy to use streams efficiently within Visual Basic applications, the Caché ActiveX
Binding projects stream properties using two special ActiveX stream objects:
CacheActiveX.CharStream and CacheActiveX.BinaryStream. From your Visual Basic application
you simply make calls to the methods provided by these objects.
For example, suppose you have a Person object containing a character stream property, Memo.
In addition to the standard stream methods Read and Write, you can use the client-side
method Data, which will fetch the entire stream in one operation:
' Visual Basic code
Dim person As Object
Dim memo As String1
' Open a Person object and copy its memo into a local variable
Set person=Factory.OpenId(id)
memo=person.Memo.Data
The GetPicture method is a similar mechanism that efficiently copies binary data containing
a bitmap image into a picture control. For example, if the Person object has a binary stream
property, Picture, containing a bitmap image (such as a .jpg or .png file), you can display this
image in Visual Basic as follows:
' Visual Basic code
Dim person As Object
Dim memo As String
' Open a Person object and show its picture in an Image control
Set person=Factory.OpenId(id)
Image1.Picture = person.Picture.GetPicture
The SetPicture method can be used to copy an image in the other direction, from an Image
control to a binary stream property:
' Visual Basic code
person.Picture.SetPicture Image1.Picture
Using Caché Objects 139