Cross platform printing

General
1

Hi,
as the object says i’m trying (without success) to code a function in Xojo 2017r3 so that my program can print an invoice who look the same on Windows and Mac.
After hours and hours of trying i still don’t understand how i can achive that result.
I’m coding on OS X 10.13.3 and Xojo 2017r3 but i need to compile my app for a customer who only has Windows 7/10.
When i debug my app on my mac it looks like it should but when i compile it and run on a demo pc i have here in the office the print is smaller and out of position even if i’m printing on the same printer.
I read on the forum something about dpi but it is a little above my skill … could please someone help me in a more easy to understand way ?

What i do is something like that :

Dim ps As New PrinterSetup Dim invoice as New Graphics ps.MaxHorizontalResolution = -1 ps.MaxVerticalResolution = -1 invoice = OpenPrinterDialog(ps)

after that i do some Drawstring, PenHeight DrawRoundRect etc … just to place things where i want them to be.

is there a way to print so that the layout is the same in Windows and Mac ?

Thanks
Mattia

2

Use the same font ?

What did you get different ?

3

is not a font problem.
i have left and upper margin wrong. the size of a box is different. If i set the “correct” size for a box on mac is smaller in Windows. If i set it for windows when i print on the mac is bigger and so it goes out of the page

4

You have full control on margins, so set them your way.

How do you set the size of the box ?

Same Printer / Printer software ?

Can you print to pdf and check if the printing is the same or <> ?

Resolution to -1: can ypu get the real number (or set it to 300 for each platform and check what is printed ?

Care to add code used to print a string (or two) and a box: I have a Windows (current) and macOS (what is your used version ?)

5

If you do not want to hear about DPI just yet

create a variable

dim dfFactor as double if TargetWin32 then dfFactor = 96/72 else dfFactor = 1 end if

Multiply all your sizes by dfFactor

g.drawrect 10* dfFactor, 20 * dfFactor, 200 * dfFactor, 200 * dfFactor

This is not ‘the best’ solution but it will probably do well enough for you until you are ready to look at it in more detail

6

Changed to:

dim dfFactor as double if TargetWin32 then dfFactor = 96/72 else dfFactor = 1 end if

Otherwise dfFactor was 0.00 on a Mac

7

[quote=373517:@Jeff Tullin]If you do not want to hear about DPI just yet

create a variable

dim dfFactor as double if TargetWin32 then dfFactor = 96/72

Multiply all your sizes by dfFactor

g.drawrect 10* dfFactor, 20 * dfFactor, 200 * dfFactor, 200 * dfFactor

This is not ‘the best’ solution but it will probably do well enough for you until you are ready to look at it in more detail[/quote]

Hi Jeff,
thank you for your answer. Using your solution it works ! Thanks!

Suppose i’m ready to hear about DPI … is there a more elegant way to create a universal printing module ?

Thanks again
Mattia

8

shouldn’t this be

dim dfFactor as double
#if TargetWindows then 
dfFactor = 96/72
#else
dfFactor = 1
#en if

or even

#if TargetWindows then 
const dfFactor as double= 96/72
#else
const dfFactor as double = 1
#endif
10

[quote=373538:@Dave S]shouldn’t this be

dim dfFactor as double
#if TargetWindows then 
dfFactor = 96/72
#else
dfFactor = 1
#en if

or even

#if TargetWindows then const dfFactor as double= 96/72 #else const dfFactor as double = 1 #endif [/quote]

I figured that out by myself :slight_smile:
I’m now more interested in the dpi thing …

11

Yep.
Changed it 6 mins before you asked… :slight_smile:

Left to the basics, Mac will give you a page of dots expressed in 72 dots per inch.
An 8 inch wide paper will be 8 * 72 dots across

Direct2D versions of Xojo on Windows, the page size is expressed in 96 dpi
An 8 inch wide paper will have 8 * 96 dots, which is why things print smaller

On both, a 2 inch square is 2 * (dpi) dots

If you ask for a higher resolution, you may get a page at 300 , 150, 600 , 360 dots per inch
Same rules apply
A 2 inch square at 360dpi is 720 dots across.

One common way to handle this variation is to design your code around a known page size , assuming 72 dpi, and use the multiplier to get the ‘right’ number of dots.

eg if your resolution comes in at 300, that dfFactor would be 300/72

PDF resolves this by always being 72dpi but by using doubles as co-ordinates.
There is ‘less than 1 pixel’ resolution in a PDF.