Plugin oriented App Topic is solved

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xaviou
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Post by xaviou » Mon Jul 12, 2010 3:53 pm

Hi

Here is what I've done (I post a simplified code, but the idea is here).
The declaration file : pluginsmanager.h

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#include "pluginbase.h"
WX_DECLARE_OBJARRAY(PluginBase*, ArrayOfPlugins);
class PluginsManager
{
    public:
        PluginsManager();
        virtual ~PluginsManager();
        static PluginsManager& Get();
        static void Kill();
        int LoadPlugins(const wxString& appPath);
        void UnloadPlugins();
    private:
        ArrayOfPlugins m_plugins;
        static PluginsManager *m_instance;
}
The declaration file : pluginsmanager.cpp

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#include "pluginsmanager.h"
#include <wx/filename.h>
#include <wx/dynload.h>
#include <wx/dir.h>

PluginsManager* PluginsManager::m_instance=NULL;
#include <wx/arrimpl.cpp>
WX_DEFINE_OBJARRAY(ArrayOfPlugins);

PluginsManager::PluginsManager()
{
    //
}

PluginsManager::~PluginsManager()
{
    //
}

PluginsManager& PluginsManager::Get()
{
    if (m_instance==NULL)
    {
        m_instance=new PluginsManager();
    }
    return *m_instance;
}

void PluginsManager::Kill()
{
    if (m_instance!=NULL)
    {
        delete m_instance;
    }
    m_instance=NULL;
}

int PluginsManager::LoadPlugins(const wxString& appPath)
{
    // The folder where we can find the plugins files (*.dll or *.so)
    wxString sPlgPath=appPath;
    sPlgPath << _T("Plugins") << wxFileName::GetPathSeparator();
    wxDir dir(sPlgPath);
    // If the folder does not exists, we get out of here
    if (!wxDirExists(sPlgPath)) return 0;
    if (!dir.IsOpened()) return 0;

    wxString sFName;
#ifdef __WXMSW__
	bool bRes=dir.GetFirst(&sFName, _T("*.dll"),wxDIR_FILES);
#else
	bool bRes=dir.GetFirst(&sFName, _T("*.so"),wxDIR_FILES);
#endif

    while(bRes)
    {
        //Loading the ".dll" or ".so" file using the wxPluginManager class
        wxPluginManager::LoadLibrary(sPlgPath+sFName);
        bRes=dir.GetNext(&sFName);
    }
    // Searching, in the loaded libraries, the instances of classes
    // whitch name start with "wxTdlPlugin_"
    wxHashTable_Node* node;
    wxClassInfo::sm_classTable->BeginFind();
    int iPlgCount=0;
    while((node = wxClassInfo::sm_classTable->Next()))
    {
        wxClassInfo *classInfo = (wxClassInfo *)node->GetData();
        wxString classname = classInfo->GetClassName();
        if(classname.StartsWith(_T("wxTdlPlugin_")))
        {
            // Adding the founded instance to the plugins array
            PluginBase *object = (PluginBase*)classInfo->CreateObject();
            m_plugins.Add(object);
            iPlgCount++;
        }
    }
    return iPlgCount;
}

void PluginsManager::UnloadPlugins()
{
    PluginBase *plg;
    while(m_plugins.Count())
    {
        plg=*m_plugins.Detach(0);
        delete plg;
    }
}
As I said, this is a simplified (but working) code.

Now, here is how to use it :
The plugins files (*.dll or *.so) are in a "plugins" sub-folder of the application.
In the "OnInit" method of the wxApp derived class, you'll have to call "PluginsManager::Get()" to initialize the manager.
Then, call the "LoadPlugins" method (with the app path as parameter). It will load all the ".dll" or ".so" files founded in the plugins subfolder, and create an instance of each classes of type "wxTdlPlugin_........" (and storing a pointer of each intance created in an array, for future use).
You can do the manager initialization and the plugins loading at the same time :

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PluginsManager::Get().LoadPlugins(TheAppPath);
Do not forget to call the "UnloadPlugins" before closing the application :

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int MyApp::OnExit()
{
    PluginsManager::Get().UnloadPlugins();
    PluginsManager::Kill();
    return wxApp::OnExit();
}
Hope it will help you...
Feel free to ask for more details.

Regards

Xav'
My wxWidgets stuff web page : [email protected]'s wxStuff

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Post by evstevemd » Mon Jul 12, 2010 4:39 pm

Thanks man,
I can see I have some stuffs to learn on RTTI
But please help me elaborate this point in code, I cannot grasp it fully.
Thanks :P

Code: Select all

PluginsManager* PluginsManager::m_instance=NULL;
#include <wx/arrimpl.cpp>
WX_DEFINE_OBJARRAY(ArrayOfPlugins);



    // Searching, in the loaded libraries, the instances of classes
    // whitch name start with "wxTdlPlugin_"
    wxHashTable_Node* node;
    wxClassInfo::sm_classTable->BeginFind();
    int iPlgCount=0;
    while((node = wxClassInfo::sm_classTable->Next()))
    {
        wxClassInfo *classInfo = (wxClassInfo *)node->GetData();
        wxString classname = classInfo->GetClassName();
        if(classname.StartsWith(_T("wxTdlPlugin_")))
        {
            // Adding the founded instance to the plugins array
            PluginBase *object = (PluginBase*)classInfo->CreateObject();
            m_plugins.Add(object);
            iPlgCount++;
        }
    }
    return iPlgCount;
}
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Post by xaviou » Mon Jul 12, 2010 5:40 pm

Code: Select all

PluginsManager* PluginsManager::m_instance=NULL;
The "PluginsManager" is defined as a singleton : only one object is created, and the same object is always returned by "PluginsManager::Get()"
The first time this method is called, the object is created and stored in tis var (as you can see in the header file, it is a static member)

Code: Select all

#include <wx/arrimpl.cpp>
WX_DEFINE_OBJARRAY(ArrayOfPlugins);
This (and the WX_DECLARE_OBJARRAY macro in the header file) creates a new "type" named "ArrayOfPlugins". It will be used to store an array of objects of type "PluginBase*"

For the rest of the code, as I remember what I've understood the first time I used this :
When loading a library with "wxPluginManager::LoadLibrary()", a list of "dynamic classes" is created.
So, this code iterats into this list to find the desired class (witch name starts with "wxTdlPlugin_" in my case).

Regards

Xav'
My wxWidgets stuff web page : [email protected]'s wxStuff

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Post by evstevemd » Tue Jul 13, 2010 10:02 am

xaviou wrote:

Code: Select all

PluginsManager* PluginsManager::m_instance=NULL;
The "PluginsManager" is defined as a singleton : only one object is created, and the same object is always returned by "PluginsManager::Get()"
The first time this method is called, the object is created and stored in tis var (as you can see in the header file, it is a static member)

Code: Select all

#include <wx/arrimpl.cpp>
WX_DEFINE_OBJARRAY(ArrayOfPlugins);
This (and the WX_DECLARE_OBJARRAY macro in the header file) creates a new "type" named "ArrayOfPlugins". It will be used to store an array of objects of type "PluginBase*"

For the rest of the code, as I remember what I've understood the first time I used this :
When loading a library with "wxPluginManager::LoadLibrary()", a list of "dynamic classes" is created.
So, this code iterats into this list to find the desired class (witch name starts with "wxTdlPlugin_" in my case).

Regards

Xav'
I understand now, thanks.

I was looking at the macro and found wxDocs are against MyClass* and propose wxArrey for that. Check here

http://docs.wxwidgets.org/trunk/dynarra ... c42179abde

They say

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class MyClass;
    WX_DECLARE_OBJARRAY(MyClass, wxArrayOfMyClass); // note: not "MyClass *"!
They propose

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class MyClass;
    WX_DEFINE_ARRAY(MyClass *, ArrayOfMyClass);
I hope I have to read to get their point. I wanted to point because I see it used in your code
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Post by evstevemd » Tue Jul 20, 2010 3:38 pm

Now, when I'm making concrete class that depends on wxWindow* then How do I supply it to that plugin? For example in the code belo, how do I supply wxFrame* to CreatePluginPanel(wxWindow* parent) method since plugins are loaded by manager?

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class DataPlugin : public  PluginBase
{
        public:
                DataPlugin() : PluginBase(PT_DATAS) { }
                virtual wxPanel* CreatePluginPanel(wxWindow* parent)=0;
                //...
};
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Post by xaviou » Tue Jul 20, 2010 9:17 pm

Hi

Well, as I said when I gave you the code of my PluginsManager, I posted a simplified code.

The "real" PluginsManager has a method named "CreateDatasPluginsPanels", witch takes 2 parameters :
  • A pointer to the future parent of the panels
  • A pointer to the wxSizer associated with the parent window
The PluginsManager iterates through its "ArrayOfPlugins", and for each one (if it has the correct type), calls the "CreatePluginPanel" method, and add the returned wxPanel to the sizer

Here is the code of the "CreateDatasPluginsPanels" method :

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void PluginsManager::CreateDatasPluginsPanels(wxWindow* parent, wxSizer* szr)
{
    PluginBase *plg;
    DataPlugin *dplg;
    wxPanel* pnl;
    // Getting the total number of loaded plugins
    int iPlgCount=m_plugins.GetCount();
    // Iterate through the list of plugins
    for (int i=0;i<iPlgCount; i++)
    {
        plg=m_plugins[i];
        // If the plugin has the correct type
        if (plg->GetPluginType()==wxTDL_PT_DATAS)
        {
            dplg=(DataPlugin*) plg;
            // Asks the plugin to create its panel
            pnl=dplg->CreatePluginPanel(parent);
            // If successfull
            if (pnl!=NULL)
            {
                // Add the created panel to the sizer associated with the parent
                szr->Add(pnl, 0, wxALL|wxEXPAND, 0);
            }
        }
    }
}
Regards

Xav'
My wxWidgets stuff web page : [email protected]'s wxStuff

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Post by evstevemd » Wed Jul 21, 2010 6:42 am

thanks Xav,
I can see now the way to Go!
Thanks
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Post by evstevemd » Wed Aug 04, 2010 5:36 pm

Hi Xav and everybody,
I see definition

Code: Select all

private:
        ArrayOfPlugins m_plugins; 
How do you access this seeing that it is private member?
I believe main app does not inherit its class nor it is a friend.
So How do you go about using plugins in the array?

Thanks
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Post by xaviou » Tue Aug 10, 2010 9:59 am

Hi, and sorry for the late response.

The application does not access directly the array of plugins.
It just calls methods of the plugins manager, and this one makes all the job.

For example, the datas plugins have a panel that is displayed onto the main interface.
So, the application calls a "CreateDatasPluginsPanels" method of the manager, with the parent and the sizer as parameters.
The manager iterates into the array of plugins, and if it finds one that has the correct type, it calls its "CreatePluginPanel" method with the "parent" parameter, and then, adds the created panel to the sizer :

Code: Select all

void PluginsManager::CreateDatasPluginsPanels(wxWindow* parent, wxSizer* szr)
{
    PluginBase *plg;
    DataPlugin *dplg;
    wxPanel* pnl;
    // Iterate into the whole array
    for (int i=0;i<m_iPlgCount; i++)
    {
        // Get the current plugins
        plg=m_plugins[i];
        // Check if it has the correct type
        if (plg->GetPluginType()==wxTDL_PT_DATAS)
        {
            // If Ok, cast the plugin with the correct var type
            dplg=(DataPlugin*) plg;
            // The ask it to create the panel
            pnl=dplg->CreatePluginPanel(parent);
            // If successful, add the panel to the sizer
            if (pnl!=NULL)
            {
                szr->Add(pnl, 0, wxALL|wxEXPAND, 0);
            }
        }
    }
}
Sorry again for the late response.
Regards

Xav'
My wxWidgets stuff web page : [email protected]'s wxStuff

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Post by Auria » Tue Aug 10, 2010 12:25 pm

Xaviou,

plugin based apps is a question that seems to come up often, maybe you could take your little example and add it to the wiki? Just a thought like that, would be great :)
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Post by evstevemd » Tue Aug 10, 2010 1:02 pm

Auria wrote:Xaviou,

plugin based apps is a question that seems to come up often, maybe you could take your little example and add it to the wiki? Just a thought like that, would be great :)
I second that!
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Post by evstevemd » Tue Aug 10, 2010 1:03 pm

xaviou wrote:Hi, and sorry for the late response.

The application does not access directly the array of plugins.
It just calls methods of the plugins manager, and this one makes all the job.

For example, the datas plugins have a panel that is displayed onto the main interface.
So, the application calls a "CreateDatasPluginsPanels" method of the manager, with the parent and the sizer as parameters.
The manager iterates into the array of plugins, and if it finds one that has the correct type, it calls its "CreatePluginPanel" method with the "parent" parameter, and then, adds the created panel to the sizer :

Code: Select all

void PluginsManager::CreateDatasPluginsPanels(wxWindow* parent, wxSizer* szr)
{
    PluginBase *plg;
    DataPlugin *dplg;
    wxPanel* pnl;
    // Iterate into the whole array
    for (int i=0;i<m_iPlgCount; i++)
    {
        // Get the current plugins
        plg=m_plugins[i];
        // Check if it has the correct type
        if (plg->GetPluginType()==wxTDL_PT_DATAS)
        {
            // If Ok, cast the plugin with the correct var type
            dplg=(DataPlugin*) plg;
            // The ask it to create the panel
            pnl=dplg->CreatePluginPanel(parent);
            // If successful, add the panel to the sizer
            if (pnl!=NULL)
            {
                szr->Add(pnl, 0, wxALL|wxEXPAND, 0);
            }
        }
    }
}
Sorry again for the late response.
Regards

Xav'
No problem and thanks.
It makes sense now!
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Post by xaviou » Tue Aug 10, 2010 1:25 pm

Auria wrote:Xaviou,

plugin based apps is a question that seems to come up often, maybe you could take your little example and add it to the wiki? Just a thought like that, would be great :)
I'll try to do it as soom as I'll have the time to

Regards

Xav'
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Post by evstevemd » Thu Aug 19, 2010 4:14 pm

xaviou wrote:Hi
jfouche wrote:OUps, that's not the good way.
I agree with that...

I think you should only derive you plugins from wxEvtHandler :

Here is what I've done to create the base class of plugins that can have differents types :

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#include <wx/wx.h>

enum Pugin_Type
{
	PT_UNKNOWN=0,
	PT_DATAS,
	PT_IMPEXP,
	PT_TOOL
};

class PluginBase : public wxEvtHandler
{
	public:
		PluginBase(Pugin_Type type) { m_Type=type; }
		Pugin_Type GetPluginType() { return m_Type; }
		virtual wxString GetPluginName()=0;
	private:
		Pugin_Type m_Type;
};
Then, for each plugin type, I have something like that :
The first type of plugins have to create a wxPanel to extent the main interface :

Code: Select all

class DataPlugin : public PluginBase
{
	public:
		DataPlugin() : PluginBase(PT_DATAS) { }
		virtual wxPanel* CreatePluginPanel(wxWindow* parent)=0;
		//...
};
And, for example, the "Tool" plugin type, that only have a function to be executed from a menu :

Code: Select all

class ToolPlugin : public PluginBase
{
	public:
		ToolPlugin() : PluginBase(PT_TOOL) { }
		virtual bool ExecuteTool(wxXmlNode* datas)=0;
};
Hope it will help you understand the concept...

Regards

Xav'
Suppose I want to have one type of plugin but with alot of methods let say to access toolbar menubar and notebook but I want to leave the choice of implementation to user without forcing him *to implement* ALL of memebers. I mean user can choose to either access menubar alone or menubar and toolbar or menubear, toolbar and notebook. How do I go making it?

I have the concept, but I fail to implement it.
Thanks for helping me a lot. I'm almost there. :P

EDIT:
I view this as impossible in my above thinking, but I somehow can't connect the concepts. :x
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Post by evstevemd » Thu Sep 30, 2010 1:05 pm

Now that I can load Menus from DLL to App, I have question:
We know events are generated by App Menu and are connected to Specific wxID. So How do I ensure there is no ID conflict within plugins and that I have Unique ID?

Thanks
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