Property Bag Explained in VB

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Property Bag Tutorial
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1.) ABOUT PROPERTY BAG
Property bag can be considered to be a kind of bag.
It can be used to hold items that are placed there by a user.
These items consist of a "Label" and a Value.
When you wish to extract an item from the bag you call upon the label to find it.
The Value can consist of a picture, string, or even binary.
Once the bag has been filled it can be written to another file that when executed
or called to do so will ready the item of your choice.
Also the values pulled out of the Property Bag may be assigned to a picture,
textbox, caption, or even put into the binary of a file.

2.) USES OF THE PROPERTY BAG
a.) Create A File Archive Of Some Type
b.) Create A DLL Type File
c.) Hold Program Informaion
d.) Create An Editable EXE File
e.) Others....

3.) CREATING AND FILLING THE PROPERTY BAG
To physicaly create the property bag you must DIM a variable as a
"New PropertyBag" (Dim PropBag As New PropertyBag).
To write to the property bag just type
<Label Of New Property Bag>.WriteProperty <Label>, <Value>
(PropBag.WriteProperty "Text1", Text1.text).
Now you have created the Property Bag, Next is to add the Property Bag to a file.
First you must DIM a variable as Long (Dim BeginPos As Long), this variable will
hold the information that the put the property bag at the end of the Files binary.
Nest you must DIM a variable as a Variant (Dim varTemp As Variant) to hold the
Property Bag's Code. After that you should open the file of your choice "For Binary"
(Open App.Path & "Project1.exe" For Binary As #1). With the Long Variable you created
put the Legnth Of The File in it (BeginPos = LOF(1)). Next Add the Property Bag's Code
To the Variant you created (varTemp = PropBag.Contents). In order to put the property
bag as the last part of the file you must find the end of the file (Seek #1, LOF(1)).
Once found you must put the Property Bag's code in the files binary (Put #1, , varTemp).
The Place the legnth of the orginal file as the last part of the code (Put #1, , BeginPos).
Then close the file (Close #1).
SAMPLE CODE
Dim PropBag As New PropertyBag
Dim BeginPos As Long
Dim varTemp As Variant
PropBag.WriteProperty "Text1", Text1.text
Open App.Path & "\Project1.exe" For Binary As #1
BeginPos = LOF(1)
varTemp = PropBag.Contents
Seek #1, LOF(1)
Put #1, , varTemp
Put #1, , BeginPos
Close #1


4.) READING PROPERTY BAG
To read the property bag in a file you must DIM a variable as a New PropertyBag,
this will act as an emptybag that will be filled with the code later read in the file.
To read the code in the file you must open the file for Binary
(Open App.Path & "\Project1.exe" For Binary As #1). Next you have to seek the data that
tells you where to code for the property bag starts (Get #1, LOF(1) - 3, BeginPos).
Dim another variable as Long to hold the information about where the Property Bag starts
(Dim BeginPos As Long). Place the information found in the code into the variable
(Get #1, LOF(1) - 3, BeginPos). Then Find the position of the Property Bag's Code
(Seek #1, BeginPos). Next DIM a Variable as a Variant to hold the Property Bag's code
once extracted from the file (Dim VarTemp As Variant). Next place the code in the variable
(Get #1, , VarTemp). Once found DIM a variable as a Byte (Dim ByteArr() As Byte ) and add
the numbers of Bytes the the variable (ByteArr = VarTemp). Next add the code to the New
PropertyBag variable (PropBag.Contents = ByteArr). Next write the Legnth of The File to the
Property Bag (PropBag.WriteProperty "LOF", LOF(1)) then write the start position of the
Property Bag's code into the Property Bag (PropBag.WriteProperty "BeginPos", BeginPos).
Last clode the open file (Close #1). To Read a variable from the Property Bag to a
variable just use <Variable> = <New PropertyBag Variable>.ReadProperty(<Label>)
eg.(Text5.Text = PropBag.ReadProperty("Text1"))

SAMPLE CODE
Dim PropBag As New PropertyBag
Dim VarTemp As Variant
Dim BeginPos As Long
Dim ByteArr() As Byte
Open App.Path & "\Project1.exe" For Binary As #1
Get #1, LOF(1) - 3, BeginPos
Seek #1, BeginPos
Get #1, , VarTemp
ByteArr = VarTemp
PropBag.Contents = ByteArr
PropBag.WriteProperty "LOF", LOF(1)
PropBag.WriteProperty "BeginPos", BeginPos
Close #1
Text5.Text = PropBag.ReadProperty("Text1")

5.) OTHER THINGS
READ PROPBAG IN SELF------------------------------------------------------------

When creating a Property Bag you can place the code into a file created in VB.
Before you do so put this code in that VB file:

Sub Form_OnLoad
Dim PropBag As New PropertyBag
Dim VarTemp As Variant
Dim BeginPos As Long
Dim ByteArr() As Byte
Open App.Path & "\" & App.ExeName & ".exe" For Binary As #1
Get #1, LOF(1) - 3, BeginPos
Seek #1, BeginPos
Get #1, , VarTemp
ByteArr = VarTemp
PropBag.Contents = ByteArr
PropBag.WriteProperty "LOF", LOF(1)
PropBag.WriteProperty "BeginPos", BeginPos
Close #1
Me.Caption = PropBag.ReadProperty("Text1")
End Sub

If you do so, after you write the Property Bag to that VB file, when you run it the
program will read the Property Bag in itself and change it's caption to whatever you
have it set for.

READ/WRITE PICTURES------------------------------------------------------------

You may also add pictures to a Property Bag like this:
When you writting to a Property Bag use this -
PropBag.WriteProperty "Picture1", Picture1.Picture
Abd when you read from the Property Bag use this -
Picture5.Picture = LoadPicture(PropBag.ReadProperty("Picture1"))

WRITE BINARY------------------------------------------------------------

To add the binary of a file to the Property Bag use -

Open App.Path & "\Temp\Temp.Dat" For Binary As #1 'Opens File To Read
filedata$ = String(LOF(1), " ") 'Selects All Of Binary
Get #1, , filedata$ 'Sets Binary To Variable
Close #1 'Closes File
PropBag.WriteProperty "File", filedata$ 'Puts Binary In Property Bag

To extract the binary and creat a file out of it use -

File$ = PropBag.ReadProperty("File") 'Reads Binary From Property Bag
Open App.Path & "\Temp.Dat" For Output As #1 'Creats an Empty File
Close #1
Open App.Path & "\Temp.Dat" For Binary As #1 'Opens Empty File To Write To
Put #1, , File$ 'Puts Binary In Empty File
Close #1 'Closes File

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Created By Szafran - ew16301@yahoo.com Please E-Mail If Any Questions
July 10, 2003
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