String to Picture

Databases
1

I have a database with a String-type column which contains serialized data from a PNG. How do I construct a picture from this data?
I tried:

var MB as memoryblock
var MyPicture as new Picture
MB = MyRowSet.Column("PicData").ToString
MyPicture.FromData(MB)

But MB is empty. I tried to put the PicData in a String var first and read that into a MB but it fails.

2

I use encodebase64 and decodebase64 to store pictures in a database
because if you use strings, you can have characters that are filtered
base64 ensure you only have ascii characters in the string.

1 Like
3

Don’t you want MyRowSet.Column("PicData").StringValue?
MyRowset.Column() returns an object, so ToString isn’t going to do what you expect.

2 Likes
4

Yes, typo. The thing is, I load a rowset into a String type multidim array. So far so good. The array element contains the PNG data. But when I try to convert it back into a Picture, the array won’t release the data.

MB = OrganisatiesArray(i,7) 'type string and holds data - verified
MapImage = Picture.FromData(MB)

MB is empty. When I do

var TempString as String
TempString = OrganisatiesArray(i,7) 
MB = TempString
MapImage = Picture.FromData(MB)

TempString is empty, so MB is empty too. It looks like the array won’t release the data (250kB).
No idea why this is.

5

I use PictureToJPEGStringMBS and JPEGStringToPictureMBS and it works great. Very fast and at 100% quality no quality loss. additionally a jpeg string take less db storage space. If you have the MBS plugins I’d recommed you try it.

// p is a picture, 100 is the jpeg quality
Var pstrng As String = PictureToJPEGStringMBS(p,100)
// Store the string into the DB
// convert the string back to a picture after retrieving it from the DB
Var p As Picture = JPEGStringToPictureMBS(dbstrng)
// Use the picture