QuickPDF Barcode'n

[Haakon Birkeland]

Ran into an unexpected snag today, where the first line compiles â€" and works fine, while the second iteration attempt at generating an EAN with a real life value from a string variable failed to compile with; Error 480 Parameter Mismatches Definition.

I tried a fixed length string as well, due to the syntax being stated as "char * Text" â€" no luck there either.
What is it that PB don't like hereg

    RetVal = QuickPDFDrawBarcode( QPDF, 25, 25, 50, 20, "0123456", 1, 0 )
   
    Dim EAN_Value As String
            EAN_Value = "0123456"
       
    RetVal = QuickPDFDrawBarcode( QPDF, 25, 25, 50, 20, EAN_Value, 1, 0 )

Reference;

DLL
int QuickPDFDrawBarcode(int InstanceID, double Left, double Top,double Width, double Height, char * Text, int Barcode, int Options)

Parameters

Left
Horizontal co-ordinate of left edge of the barcode

Top
Vertical co-ordinate of top edge of the barcode

Width
Width of the barcode

Height
Height of the barcode

Text
The barcode data. The barcode can be rotated by appending the following to the barcode data string:
/RC = Rotate clockwise
/RA = Rotate anti-clockwise
/RU = Rotate 180 degrees

Barcode
1 = Code39 (or Code 3 of 9)
2 = EAN-13
3 = Code128
4 = PostNet
5 = Interleaved 2 of 5

Options
Code39:
0 = Default drawing

EAN-13:
0 = Only draw the barcode
1 = Extend the guard bars
2 = Draw the human-readable numbers
3 = Draw the human-readable numbers, with right spacer

Code128:
0 = Default drawing

PostNet:
0 = Default drawing

Interleaved 2 of 5:
0 = Do not add a checksum, no bearer bars
1 = Add a checksum character, no bearer bars
2 = Do not add a checksum, draw bearer bars
3 = Add a checksum character, draw bearer bars

To apply 10% bar width reduction to the barcode, increase the value of the Options parameter by 10

Return values
0 The barcode could not be drawn. Invalid Barcode or Options parameters.
1 The barcode was drawn successfully

[Haakon Birkeland]

When I hit "Post" I almost immediately got the idea to check the declaration in the include file; AsciiZ!

Declare Function QuickPDFDrawBarcode Lib "QuickPDFDLL0725.dll" Alias "QuickPDFDrawBarcode" ( _
  ByVal iInstanceID As Long, ByVal dLeft As Double, ByVal dTop As Double, _
  ByVal dWidth As Double, ByVal dHeight As Double, sText As AsciiZ, _
  ByVal iBarcode As Long, ByVal iOptions As Long) As Long

Anyone able to explain why a "direct string value", as used in my prototyping (first line), is accepted?

[José Roca]

Because in the first one you are using a string literal, not a variable, and the compiler has to allocate a temporary one to pass a pointer to it, and as it knows, for the type of parameter, that it is an asciiz, this is what it allocates.

[José Roca]

I tried a fixed length string as well, due to the syntax being stated as "char * Text" â€" no luck there either.

What do you bet that if you try BYCOPY EAN_Value with a dynamic string it will work?

[Haakon Birkeland]

I'm not used to PB being helpful at converting between variable types â€" as VB spoiled me with years ago. I did try ByVal as ByCopy didn't come to mind, but you're absolutely right Jose, it works to â€" as it does with using a ("oversized") StringZ variable.

Thanks for your info on what PB does when using string literals.

[José Roca]

I did try ByVal [...]

What do you bet that if you try BYVAL STRPTR(EAN_Value) with a dynamic string it will also work?

[...] as VB spoiled me with years ago.

A language that uses BYVAL STRING to pass an ASCIIZ string by REFERENCE (two lies in two words) is certainly not the best tool to learn parameter passing conventions

[Haakon Birkeland]

I was just so preoccupied with the thought of the function being made for passing on a regular string to it. Mix that with some lack of hardcore knowledge from being spoiled by VB, and some time pressure ...

Actually trying pointers did cross my mind in the messy thought process I had that day. Anyway, I'm glad to see there are optional ways of reaching "Rome" when the roads are bumpy. 8o)