Cartinese
Hello, I'm fairly new to working with plugins so sorry if it is a trivial question.
I'm creating a program in C++ that gets the current played song. I managed to load dll in program and have no problem in executing OnGetPluginInfo(), but when I want to send command to VirtualDJ with SendCommand() method I get exception that IVdjCallbacks8 cb was nullptr.
Now my question is how to get instance of IVdjCallbacks8* cb in order to be able to send commands and get results?
Plugin I want to access is almost the same as basic plugin example and I placed it in Plugins64\AutoStart
I'm creating a program in C++ that gets the current played song. I managed to load dll in program and have no problem in executing OnGetPluginInfo(), but when I want to send command to VirtualDJ with SendCommand() method I get exception that IVdjCallbacks8 cb was nullptr.
Now my question is how to get instance of IVdjCallbacks8* cb in order to be able to send commands and get results?
Plugin I want to access is almost the same as basic plugin example and I placed it in Plugins64\AutoStart
Posted Thu 30 Apr 20 @ 1:45 pm
Nicotux
What kind of plugin ?
Where do you call SendCommand () from ?
cb are not already set before OnGetPluginInfo() returned with S_OK ( plugin not initialized before that)
cb can be called from within OnLoad and following
Where do you call SendCommand () from ?
cb are not already set before OnGetPluginInfo() returned with S_OK ( plugin not initialized before that)
cb can be called from within OnLoad and following
Posted Thu 30 Apr 20 @ 2:16 pm
Cartinese
The plugin is almost the same as Basic plugin (with default interface) example in VDJPedia, it inherits after IVdjPlugin8.
I call SendCommand in main in my external program after getting plugin instance from DllGetClassObject.
I called OnGetPluginInfo() only to check if I managed to load dll correctly and it worked.
So in order to use SendCommand() there must be something more in OnLoad() method in plugin?
OnLoad() from example looks like this:
HRESULT VDJ_API CMyPlugin8::OnLoad()
{
// ADD YOUR CODE HERE WHEN THE PLUGIN IS CALLED
m_Reset = 0;
m_Dry = 0.0f;
m_Wet = 0.0f;
bool bMasterFX = isMasterFX();
DeclareParameterButton(&m_Reset,ID_BUTTON_1,"Reset","R");
DeclareParameterSlider(&m_Wet,ID_SLIDER_1,"Dry/Wet","D/W",1.0f);
OnParameter(ID_SLIDER_1);
return S_OK;
}
I call SendCommand in main in my external program after getting plugin instance from DllGetClassObject.
I called OnGetPluginInfo() only to check if I managed to load dll correctly and it worked.
So in order to use SendCommand() there must be something more in OnLoad() method in plugin?
OnLoad() from example looks like this:
HRESULT VDJ_API CMyPlugin8::OnLoad()
{
// ADD YOUR CODE HERE WHEN THE PLUGIN IS CALLED
m_Reset = 0;
m_Dry = 0.0f;
m_Wet = 0.0f;
bool bMasterFX = isMasterFX();
DeclareParameterButton(&m_Reset,ID_BUTTON_1,"Reset","R");
DeclareParameterSlider(&m_Wet,ID_SLIDER_1,"Dry/Wet","D/W",1.0f);
OnParameter(ID_SLIDER_1);
return S_OK;
}
Posted Thu 30 Apr 20 @ 2:41 pm
Nicotux
Are you trying to implement a wrapper ?? ( external program going to load vdj plugins) ?
from the "main" of your plugin, the DLL is loaded and the instance is created
but it is not already linked to VDJ Plugin chain (or your app's own one) thus all virtual IVdjCallbacks8 are NULL
There is nothing you can do with that because they will be overitten by VDJ only after DllGetClassObject had returned S_OK
(or if you are creating a wrapper, you need to PROVIDE the callback functions , not trying to use them before that)
Its free to the caller app to implement its own callbacks, they are there for the plugin to send command to the parent app
OnLoad can be call because all DeclareParameter* are not virtual they return NULL not trying to call the callback
but they wont declare anything
Posted Thu 30 Apr 20 @ 3:29 pm
Adion
Just use
cb->SendCommand()
cb->SendCommand()
Posted Thu 30 Apr 20 @ 3:38 pm
Cartinese
Yes, I'm trying to implement a wrapper, right now it looks like this:
HRESULT hr;
HMODULE vdjDLL;
CMyPlugin8* pluginInstance;
typedef HRESULT(VDJ_API* dllGetClassObjectType)(IN REFCLSID rclsid, IN REFIID riid, OUT LPVOID FAR* ppv);
vdjDLL = LoadLibrary("C:\\Users\\Cartinese\\Documents\\VirtualDJ\\Plugins64\\AutoStart\\VDJ_DLL.dll");
dllGetClassObjectType dllgetclass = (dllGetClassObjectType)GetProcAddress(vdjDLL, "DllGetClassObject");
hr = dllgetclass(CLSID_VdjPlugin8, IID_IVdjPluginBasic8, (void**)&pluginInstance);
pluginInstance->hInstance = GetModuleHandle(NULL);
pluginInstance->cb->SendCommand("get_automix_song");
And after running this I get exception:
pluginInstance->cb was nullptr.
So what needs to be done in order to use send command successfully in wrapper?
HRESULT hr;
HMODULE vdjDLL;
CMyPlugin8* pluginInstance;
typedef HRESULT(VDJ_API* dllGetClassObjectType)(IN REFCLSID rclsid, IN REFIID riid, OUT LPVOID FAR* ppv);
vdjDLL = LoadLibrary("C:\\Users\\Cartinese\\Documents\\VirtualDJ\\Plugins64\\AutoStart\\VDJ_DLL.dll");
dllGetClassObjectType dllgetclass = (dllGetClassObjectType)GetProcAddress(vdjDLL, "DllGetClassObject");
hr = dllgetclass(CLSID_VdjPlugin8, IID_IVdjPluginBasic8, (void**)&pluginInstance);
pluginInstance->hInstance = GetModuleHandle(NULL);
pluginInstance->cb->SendCommand("get_automix_song");
And after running this I get exception:
pluginInstance->cb was nullptr.
So what needs to be done in order to use send command successfully in wrapper?
Posted Thu 30 Apr 20 @ 3:57 pm
Nicotux
@ adion
in DllGetClassObject cb will be null as long as no host have set the callbacks
the cb are set (cb is initialized) only once DllGetClassObject have return
these functions have to be implemented in the host and the host have init the plugin cd before they can be used
they are not sending any command to VDJ, they only pass back parameters to parent host
// Internal structures
struct IVdjCallbacks8
{
virtual HRESULT SendCommand(const char *command)=0;
...}
class IVdjPlugin8
{
...
IVdjCallbacks8 *cb;
};
in DllGetClassObject cb will be null as long as no host have set the callbacks
the cb are set (cb is initialized) only once DllGetClassObject have return
these functions have to be implemented in the host and the host have init the plugin cd before they can be used
they are not sending any command to VDJ, they only pass back parameters to parent host
// Internal structures
struct IVdjCallbacks8
{
virtual HRESULT SendCommand(const char *command)=0;
...}
class IVdjPlugin8
{
...
IVdjCallbacks8 *cb;
};
Posted Thu 30 Apr 20 @ 4:14 pm
Adion
Ah yes understood. If you instantiate the plugin, then it is indeed up to you to set cb to the correct value.
So after
hr = dllgetclass(CLSID_VdjPlugin8, IID_IVdjPluginBasic8, (void**)&pluginInstance);
You should do
pluginInstance->cb = myhandler;
And myHandler should implement the IVdjCallbacks8 interface then.
So after
hr = dllgetclass(CLSID_VdjPlugin8, IID_IVdjPluginBasic8, (void**)&pluginInstance);
You should do
pluginInstance->cb = myhandler;
And myHandler should implement the IVdjCallbacks8 interface then.
Posted Thu 30 Apr 20 @ 4:31 pm
Cartinese
First, thank you both very much for your time and help, your advices help me a lot in understanding this subject.
So if I get what you say correctly, then in my wrapper I need to implement class like this:
class Myhandler
{
public:
Myhandler();
IVdjCallbacks8* cb;
};
And in main then:
Myhandler* myhandler = new Myhandler();
...
pluginInstance->cb = myhandler->cb;
I thought it would be good, but ended up with error:(
So if I get what you say correctly, then in my wrapper I need to implement class like this:
class Myhandler
{
public:
Myhandler();
IVdjCallbacks8* cb;
};
And in main then:
Myhandler* myhandler = new Myhandler();
...
pluginInstance->cb = myhandler->cb;
I thought it would be good, but ended up with error:(
Posted Thu 30 Apr 20 @ 5:02 pm
Nicotux
because you NEED to implement every function you will provide to the plugin in your host
something like this (syntax OK but untested )
class MyHandler : IVdjCallbacks8 {
HRESULT MyHandler::SendCommand(const char* command) { /* do something; */ return S_OK; };
HRESULT MyHandler::GetInfo(const char* command,double* result) { /* do something; */ return S_OK; };
HRESULT MyHandler::GetStringInfo(const char* command,void* result,int size) { /* do something; */ return S_OK; };
HRESULT MyHandler::DeclareParameter(void* parameter,int type,int id,const char* name,const char* shortName,float defaultvalue) { /* do something; */ return S_OK; };
HRESULT MyHandler::GetSongBuffer(int pos, int nb, short** buffer) { /* do something; */ return S_OK; };
} myhandler;
and in main() {
...
hr = dllgetclass(CLSID_VdjPlugin8, IID_IVdjPluginBasic8, (void**)&pluginInstance);
/* Provides the cb functions to the plugin */
pluginInstance->cb = reinterpret_cast<IVdjCallbacks8*>(&myhandler);
...
}
something like this (syntax OK but untested )
class MyHandler : IVdjCallbacks8 {
HRESULT MyHandler::SendCommand(const char* command) { /* do something; */ return S_OK; };
HRESULT MyHandler::GetInfo(const char* command,double* result) { /* do something; */ return S_OK; };
HRESULT MyHandler::GetStringInfo(const char* command,void* result,int size) { /* do something; */ return S_OK; };
HRESULT MyHandler::DeclareParameter(void* parameter,int type,int id,const char* name,const char* shortName,float defaultvalue) { /* do something; */ return S_OK; };
HRESULT MyHandler::GetSongBuffer(int pos, int nb, short** buffer) { /* do something; */ return S_OK; };
} myhandler;
and in main() {
...
hr = dllgetclass(CLSID_VdjPlugin8, IID_IVdjPluginBasic8, (void**)&pluginInstance);
/* Provides the cb functions to the plugin */
pluginInstance->cb = reinterpret_cast<IVdjCallbacks8*>(&myhandler);
...
}
Posted Thu 30 Apr 20 @ 5:53 pm
Cartinese
Ok, so my whole main looks now like this:
class MyHandler : IVdjCallbacks8 {
HRESULT SendCommand(const char* command) { /* do something; */ return S_OK; };
HRESULT GetInfo(const char* command, double* result) { /* do something; */ return S_OK; };
HRESULT GetStringInfo(const char* command, void* result, int size) { /* do something; */ return S_OK; };
HRESULT DeclareParameter(void* parameter, int type, int id, const char* name, const char* shortName, float defaultvalue) { /* do something; */ return S_OK; };
HRESULT GetSongBuffer(int pos, int nb, short** buffer) { /* do something; */ return S_OK; };
} myhandler;
HRESULT hr;
HMODULE vdjDLL;
CMyPlugin8* pluginInstance;
typedef HRESULT(VDJ_API* dllGetClassObjectType)(IN REFCLSID rclsid, IN REFIID riid, OUT LPVOID FAR* ppv);
vdjDLL = LoadLibrary("C:\\Users\\Cartinese\\Documents\\VirtualDJ\\Plugins64\\AutoStart\\VDJ_DLL.dll");
dllGetClassObjectType dllgetclass = (dllGetClassObjectType)GetProcAddress(vdjDLL, "DllGetClassObject");
hr = dllgetclass(CLSID_VdjPlugin8, IID_IVdjPluginBasic8, (void**)&pluginInstance);
pluginInstance->cb = reinterpret_cast<IVdjCallbacks8*>(&myhandler);
pluginInstance->hInstance = GetModuleHandle(NULL);
char const* command = "get_version";
char result[20];
pluginInstance->cb->GetStringInfo(command, result, 20);
After this variable result should be something like "8.0....", but instead it equals: ĚĚĚĚĚĚĚĚĚĚĚĚĚĚĚĚĚĚĚĚ and I can't figure why.
For other commands the result is also the same Ě.
class MyHandler : IVdjCallbacks8 {
HRESULT SendCommand(const char* command) { /* do something; */ return S_OK; };
HRESULT GetInfo(const char* command, double* result) { /* do something; */ return S_OK; };
HRESULT GetStringInfo(const char* command, void* result, int size) { /* do something; */ return S_OK; };
HRESULT DeclareParameter(void* parameter, int type, int id, const char* name, const char* shortName, float defaultvalue) { /* do something; */ return S_OK; };
HRESULT GetSongBuffer(int pos, int nb, short** buffer) { /* do something; */ return S_OK; };
} myhandler;
HRESULT hr;
HMODULE vdjDLL;
CMyPlugin8* pluginInstance;
typedef HRESULT(VDJ_API* dllGetClassObjectType)(IN REFCLSID rclsid, IN REFIID riid, OUT LPVOID FAR* ppv);
vdjDLL = LoadLibrary("C:\\Users\\Cartinese\\Documents\\VirtualDJ\\Plugins64\\AutoStart\\VDJ_DLL.dll");
dllGetClassObjectType dllgetclass = (dllGetClassObjectType)GetProcAddress(vdjDLL, "DllGetClassObject");
hr = dllgetclass(CLSID_VdjPlugin8, IID_IVdjPluginBasic8, (void**)&pluginInstance);
pluginInstance->cb = reinterpret_cast<IVdjCallbacks8*>(&myhandler);
pluginInstance->hInstance = GetModuleHandle(NULL);
char const* command = "get_version";
char result[20];
pluginInstance->cb->GetStringInfo(command, result, 20);
After this variable result should be something like "8.0....", but instead it equals: ĚĚĚĚĚĚĚĚĚĚĚĚĚĚĚĚĚĚĚĚ and I can't figure why.
For other commands the result is also the same Ě.
Posted Thu 30 Apr 20 @ 11:10 pm
Adion
What is the "do something" in your GetStringInfo implementation?
Currently you didn't write anything there, so it will just leave result untouched.
Currently you didn't write anything there, so it will just leave result untouched.
Posted Fri 01 May 20 @ 2:54 am
Cartinese
I tried, but have no idea what is needed in it in order to make it work.
Should it be somehow similar to implementation in base plugin?
In vdjPlugin8.h it looks like this:
HRESULT GetStringInfo(const char *command, char *result, int size) {return cb->GetStringInfo(command,result,size);}
Should it be somehow similar to implementation in base plugin?
In vdjPlugin8.h it looks like this:
HRESULT GetStringInfo(const char *command, char *result, int size) {return cb->GetStringInfo(command,result,size);}
Posted Fri 01 May 20 @ 11:55 am
Adion
It should check what is passed in command and based on that fill in result.
I'm not sure what you are trying to achieve exactly though. You want to use vdj plugins in your own software?
I'm not sure what you are trying to achieve exactly though. You want to use vdj plugins in your own software?
Posted Fri 01 May 20 @ 12:25 pm
Cartinese
Yes, I want to use vdj plugin in my software.
What I am trying to create is program (wrapper) in C++, which gets song that is playing now (and other parameters if possible but song is priority) from vdj plugin and saves it to string or txt file.
Plugin that I use is almost same as example Basic plugin (with default interface).
The reason why I'm struggling is because its my first time working with plugins.
What I am trying to create is program (wrapper) in C++, which gets song that is playing now (and other parameters if possible but song is priority) from vdj plugin and saves it to string or txt file.
Plugin that I use is almost same as example Basic plugin (with default interface).
The reason why I'm struggling is because its my first time working with plugins.
Posted Fri 01 May 20 @ 2:35 pm
Adion
If your program hosts the plugin, then it is your program that would be playing the songs and replying to the queries of the loaded plugin.
If you want your program to get information from VirtualDJ, then your program should be a plugin itself, not load other plugins.
If you want your program to get information from VirtualDJ, then your program should be a plugin itself, not load other plugins.
Posted Fri 01 May 20 @ 3:11 pm
Cartinese
Oh ok, second option is exactly what I want.
So is it possible to modify basic plugin from example to save song title to txt each time new song is played?
And if I understand correctly this solution doesn't require external program/wrapper (because plugin will do it by itself).
So is it possible to modify basic plugin from example to save song title to txt each time new song is played?
And if I understand correctly this solution doesn't require external program/wrapper (because plugin will do it by itself).
Posted Fri 01 May 20 @ 3:42 pm