OpenEuphoria

2. Re: Array from C++ DLL to Euphoria

• Posted by jimcbrown (admin) Jul 10, 2013
• 1802 views

Not that I know of. A physical copy of the data (typically via some form of peek() ) is required to get this into a sequence.

4. Re: Array from C++ DLL to Euphoria

• Posted by mattlewis (admin) Jul 10, 2013
• 1801 views

You can get a pointer to it by using define_c_var. In order to do anything with it, you'll need to use peeks and pokes. Eventually, when memstructs are figured out, there will be ways to work with it in a more natural fashion.

Could you tell us more about what you are trying to do? Based on what you've said, I think you'll want to probably not peek the whole thing, but just what you need when you need it, and poke values back as required. But that's just my speculation based on what you've said.

Matt

6. Re: Array from C++ DLL to Euphoria

• Posted by TheresNoTime Jul 11, 2013
• 1778 views

unsigned long

8. Re: Array from C++ DLL to Euphoria

• Posted by mattlewis (admin) Jul 11, 2013
• 1719 views

SAFEARRAY* DisplayBuffer = NULL; 
 
int __stdcall takeScreen() { 
  if (DisplayBuffer) { 
    SafeArrayDestroy(DisplayBuffer); 
    DisplayBuffer=NULL; 
  } 
  HRESULT rc = VirtualDisplay->TakeScreenShotToArray(0, DisplayWidth, DisplayHeight, &DisplayBuffer); 
  return SUCCEEDED(rc) ? EU_TRUE : EU_FALSE; 
}

Egad! A SafeArray. I recommend that you download EuCOM. It has stuff for handling them. In particular, they are in variant.ew. To wrap, you should be able to:

include variant.ew 
constant DisplayBuffer = define_c_var( the_dll, "DisplayBuffer" ) 
 
? get_array( peek4u( DisplayBuffer ) ) 

Matt

10. Re: Array from C++ DLL to Euphoria

• Posted by DerekParnell (admin) Jul 12, 2013
• 1651 views

For C++, an array is just a set of contiguous bytes, so all Euphoria needs to know is the RAM address of the first element, the size (in bytes) of each element, and how many elements in the array.

12. Re: Array from C++ DLL to Euphoria

• Posted by TheresNoTime Jul 13, 2013
• 1643 views

I have idea: transform SAFEARRAY with screenshot to more compact array. I needn't full information about pixels. It is possible to squeeze RGB to one byte. I can see two methods:

1. Eight bits composed by three bits from R, three from G and two from B. May be even this: four bits of R and four bits G. I know in advance that the blue color will rarely see in my screenshots.

2. (R+G+B)/3. So, we get brightness (from 0 to 255). Other formula: (R+G+B)>>2 (from 0 to 191).

Do you think this makes sense? Whether such transformation will be compensated by simplifying and/or accelerating export of an byte[] to Euphoria program?

14. Re: Array from C++ DLL to Euphoria

• Posted by mattlewis (admin) Jul 13, 2013
• 1636 views

It's not exactly clear to me what you're proposing to do. The current get_array() routine pulls the entire thing. If you only need part of it, and it's not very big, you should be able to modify the code fairly simply.

But a SAFEARRAY is not a native C++ array. It's a COM thing, so it can be used by C++, C or VB. I think that it's really more of a native VB array, as I don't think you need to use any special API when dealing with a SAFEARRAY in VB (I could be wrong on this). But for C/C++ you need to use the SafeArray API.

The individual elements are Variants, which are like the COM version of a euphoria object. It can hold anything. Take a look at the VT_* constants in variant.ew to get an idea of the stuff that a Variant can hold. Note that variant.ew also has stuff for reading and writing to Variants.

Matt