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Picture String Extensions by Seth Willits
09-18-04

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Pictures as Strings
Very often it's necessary or desired to get a picture into a string. For example, to store it in a database, or send it over a socket, you must have the data of the picture represented by a string somehow. How to do this comes up fairly often on the mailing lists, so I figured writing a tutorial explaining one of my new mega-template-project modules, PictureStringExtensions, would be useful. This module contains two methods that separately extend the Picture and String datatypes. The Data method extends Picture and returns a string for that picture, and GetPicture extends String, returning a picture if the string is valid data for an image.


The Data Method
To get a picture's data as a string simply involves reading the picture's file with a BinaryStream. However, since a picture can be created on the fly, the picture might not have a file, so we'll need to create one to read. The method extending the Picture class is as follows.



The first thing we do is save the picture to a new temporary file (using the current time as part of the file name just to make sure we don't kill any other application's temporary file that happens to be named the same). The file is then opened with a BinaryStream, read entirely into a local variable, close the stream, delete the temporary file, and return the picture's data. If an error occurs, an empty string is returned.


The GetPicture Method
The GetPicture method is simply the opposite of the Data method. We create a temporary file with a binary stream and write the data to it, thten we open the file using OpenAsPicture and return the Picture returned from it.



A word of caution: be very careful about encodings. A string has an encoding, and whatever happens, you DON'T want to convert the picture data string's encoding. If for some reason you're getting a nil picture when converting from stored data, follow the encoding and make sure it doesn't change.



Finished
It's a very simple module but it can home in handy if you have to work with sockets or databases. There are other 3rd part extensions to turn a string into a picture and vice versa, and they're probably better to use if you need convert maaany pictures in succession, but for just one at a time or something, this will work fine. As always, you can download the project here.
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