3. Implement Plugins.
With the foundation of the first two chapters, this is better.
First understand a little basic concept:
Q: What is plugins
A: This is a different functionality, or an additional function, typical, such as a simulator, is typically a variety of plug-ins (display, input ...).
Q: why we use plugins
A: In order to make the program modular, it is easy to expand. You don't need to re-issue the entire product when upgrading the component.
Q: How to do it?
A: Different DLLs, implementation / (expansion) functions that use LoadLibrary to load with the same interface (usually functions, but we will use the C class implementation).
example:
D: / EPSXE / PLUGINS> DUMPBIN SPUSEAL.DLL / EXPORTS
Microsoft (R) Coff Binary File Dumper Version 6.00.8447
Copyright (c) Microsoft Corp 1992-1998. All Rights Reserved.
Dump of file spuseAl.dll
FILE TYPE: DLL
Section Contains the Following Exports for SpuseAl.dll
0 Characteristics
36A22A22 TIME DATE Stamp Sun Jan 17 10:21:22 1999
0.00 Version
2 Ordinal Base
22 Number of Functions
22 Number of Names
Ordinal Hint Rva Name
3 0 00001700 psegetlibname
2 1 00001710 PSegetLibType
4 2 00001720 PsegetLibversion
6 3 00001800 SPUAbout
11 4 00001EE0 spuClose
5 5 00001730 SpuConfigure
18 6 00002090 SPUGETONE
77 00001910 Spuinit
10 8 00001B90 SPUOpen
23 9 00002270 SpuPlayAdpcmchannel
12 a 0000250 SpuplaySample
17 B 00002050 Spuputone
19 c 000020b0 spusetaddr
20 d 000020E0 spusetpitch
21 E 00002110 SpusetVolumel
22 f 00002150 spusetvolumer
8 10 00001B80 SPUSHUSHUTDOWN
13 11 00002190 SPUSTARTCHANNELS1
14 12 000021C0 SPUSTARTCHANNELS2
15 13 000021F0 SPUSTOPCHANNELS1
16 14 0000220 SPUSTOPCHANNELS2
9 15 00001880 SPUTEST
Summary
1000.RSRC
96000 UPX0
5000 UPX1
D: / EPSXE / PLUGINS>
This is an output table of an Sound plugin of EPSXE. You can see that EPSXE is communicated with DLL through these functions.
To the point:
It is a very annoying thing to output so many functions from a DLL, and one by one is very troublesome.
Can you use simple ways?
Of course, it is ok, you can use the DLL output class technology that we described above.
Still look at the code, we are doing an Input's Plugins class.
; // Input.h
Class Input {
Virtual int AddRef () = 0;
Virtual Int release () = 0;
Virtual dword queryclsid () = 0; // Identify this is a input plugins
Virtual DWORD ISSUPPORT (DWORD FLAGS) = 0;
Virtual Bool Getxy (int & x, int & y) = 0;
Virtual dWord getButtonStat () = 0;
Virtual Bool Adeffect (DWORD ID, DWORD Level) = 0;
Virtual Bool QueryInterface (DWORD CLSID, LPVOID * PPVOID); // Remodes the expansion. More and more like CoM.
Virtual bool doconfig ();
protected:
INPUT ();
Virtual ~ infut ();
}
-------------------------------------------------- --------
; // mouseinput.h
Class MouseInput
: Public Input
{
protected:
Friend Input * CreateInput (LPVOID PVOID);
; // ...............
}
-------------------------------------------------- --------
; // mouseinput.cpp
INPUT * CREATEINPUT (LPVOID PVOID) {Return New MouseInput;
-------------------------------------------------- --------
; // Keyinput.h
Class Keyinput
: Public Input
{
protected:
Friend Input * CreateInput (LPVOID PVOID);
; // ...............
}
-------------------------------------------------- --------
; // Keyinput.cpp
INPUT * CREATEINPUT (LPVOID PVOID) {Return New KeyInput;
After compiling, I got MouseInput.dll and Keyinput.dll.
They output the MouseInput class and the KeyInput class, and the external program calls them through the interface of the input, thereby implementing the Plugins functionality.
I don't know if there is anything I miss, please advise. . . . . .
More comments :)
