Jay Tennant wrote:
From: Mike Caron <[email protected]>
Sent: Thursday, December 31, 2009 3:54 PM

Jay Tennant wrote:
From: Mike Caron <[email protected]>
Sent: Thursday, December 31, 2009 3:29 PM

[email protected] wrote:
jay
2009-12-31 13:25:13 -0800 (Thu, 31 Dec 2009)
801
gfx_directx backend, v1.6a; and backend interfaces, update. Added message 
system to gfx backend, though I don't know how to declare void pointers in 
freebasic (gfx.new.bi, gfx.new_x.bi). Also added another callback sent at 
backend initialization: DefGfxMessageProc(). This function will handle all 
messages that the backend doesn't understand. It is implemented by the engine.
As far as pointers go, 'Any' is equivalent to 'void'. So, "foo as Any ptr". Obviously, cannot be dereferenced without a cast of some kind:

cptr(foo, integer ptr)
Ah. I'll get to work on fixing the interfaces.

gfx_msg.h defines the different messages that may be sent. More can be added, 
but they include support for all backend's different functionality (including 
fb's bit depth, border, sdl's zoom, etc.).

"Get" style messages are allowed and defined, too.

Also added command line options functionality back into the gfx_directx--now 
that a messaging system is in place, these commands are parsed and sent to the 
new interfaces.
I still don't know that I find the idea of messages attractive. How close are these to Windows messages? Is there a queue? Do you need to maintain a message pump? Can you Send Messages, or just Post them?
It's a blocking send call, much like window's SendMessage(). I suppose we could 
build a message queue, especially if the backends work on their own thread. But 
a blocking call is probably better (and easier).
Okay. Just... I still don't see the need for this at all. Windows uses messages to facilitate communication between arbitrary programs who
could have any kind of internal structure.

I don't think the backend system is so complex as to warrant this solution, especially for something like command line parsing.

True, the backend is not to be a complex entity. I agree with simple 
interfacing. Yet I'd have to disagree in that messaging (without queues) is a 
simple solution. More so than string parsing.

Did you mean complex? Messaging is more complex, IMO, than parsing a command line.

A better idea would be the one I suggested yesterday, which I can now flesh out seeing as I am now at a keyboard:

Function ParameterExists(param as string) as integer
Function GetParameter(param as string) as string

The command line is parsed into key/value pairs which are stashed somewhere and recalled on demand.

-foo bar

key = foo
value = bar

-baz "The rain in spain"

key = baz
value = The rain in spain

etc.

As for different options being intended for different backends... What's the problem? If backend A doesn't know what "zoom" means, it won't ask for it.

Is this parsing that the engine is doing? If so, how would the parsed info make 
it to the backend? If not, does the backend implement those functions--thus 
manage the parsing?

How does a backend "ask" for an option? There aren't any callbacks currently 
that support that ability. Are you proposing a new callback? Or are you referring to the 
current mechanism of returning 0 if the backend doesn't understand the string?

Serializing data is fine. A bug may appear if a backend parses string 
differently. If the engine were to understand the string request, it could 
alert the backend of possible options in a definite key and value, as 
gfx_SendMessage() proposes.

This is also moving in the direction of .ini files that save preferences. The 
gfx_SendMessage() method allows values to be returned. Currently, there isn't 
another method that returns possible option values.

No, this is a proposed system whereby the OHR core parses the command line, and the backends ask the core for the different options.

Yes, the messaging system allows for the core to query the backend for information. But, there's other ways to do it. Just add functions to query the information!

Messaging is a complex solution which works for windows because it's a standard method of interprocess communication. It works so well that a program written in 1986 on Windows 2.0 can send messages to a program written today under Windows 7, even though the programs look nothing alike internally.

In fact, this was a requirement in the design plan: Since Microsoft does not control all possible applications that will run on Windows, they need a very general solution to communication.

We don't have this restriction since we control all the backend interfaces. If we need to query information, just query the information! No need for an additional level of indirection.

DISCLAIMER:

I am not advocating total transparency between backends and the core. I'm just saying that we have the flexibility to change the interface between the backends and the core at will.


---
U   wip/gfx.new.bi
U   wip/gfx.new.h
U   wip/gfx.new_x.bi
U   wip/gfx_directx/source/gfx_directx.cpp
U   wip/gfx_directx/source/gfx_directx.new.cpp
U   wip/gfx_directx/source/gfx_directx.new.h
U   wip/gfx_directx.dll
A   wip/gfx_msg.h
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