Classes: wxXmlResource, wxXmlResourceHandler
The XML-based resource system, known as XRC, allows user interface elements such as dialogs, menu bars and toolbars, to be stored in text files and loaded into the application at run-time. XRC files can also be compiled into binary XRS files or C++ code (the former makes it possible to store all resources in a single file and the latter is useful when you want to embed the resources into the executable).
There are several advantages to using XRC resources:
XRC was written by Vaclav Slavik.
See also the separate XRC File Format page for details about the XRC file format.
These are the typical steps for using XRC files in your application.
EVT_MENU(XRCID("quit"), MyFrame::OnQuit)
.To create an XRC file, you can use one of the following methods.
A complete list of third-party tools that write to XRC can be found at <http://www.wxwidgets.org/wiki/index.php/Tools>.
It is highly recommended that you use a resource editing tool, since it's fiddly writing XRC files by hand.
You can use wxXmlResource::Load in a number of ways. You can pass an XRC file (XML-based text resource file) or a zip-compressed file (see Using Binary Resource Files), with extension ZIP or XRS, containing other XRC.
You can also use embedded C++ resources (see Using Embedded Resources).
To compile binary resource files, use the command-line wxrc
utility. It takes one or more file parameters (the input XRC files) and the following switches and options:
For example:
$ wxrc resource.xrc $ wxrc resource.xrc -o resource.xrs $ wxrc resource.xrc -v -c -o resource.cpp
#include <wx/filesys.h> #include <wx/fs_arc.h> ... wxFileSystem::AddHandler(new wxArchiveFSHandler);
It is sometimes useful to embed resources in the executable itself instead of loading an external file (e.g. when your app is small and consists only of one exe file). XRC provides means to convert resources into regular C++ file that can be compiled and included in the executable.
Use the -c
switch to wxrc
utility to produce C++ file with embedded resources. This file will contain a function called InitXmlResource
(unless you override this with a command line switch). Use it to load the resource:
extern void InitXmlResource(); // defined in generated file ... wxXmlResource::Get()->InitAllHandlers(); InitXmlResource(); ...
This is the C++ source file (xrcdemo.cpp) for the XRC sample.
#include "wx/wx.h" #include "wx/image.h" #include "wx/xrc/xmlres.h" // the application icon #if defined(__WXGTK__) || defined(__WXMOTIF__) || defined(__WXMAC__) #include "rc/appicon.xpm" #endif // ---------------------------------------------------------------------------- // private classes // ---------------------------------------------------------------------------- // Define a new application type, each program should derive a class from wxApp class MyApp : public wxApp { public: // override base class virtuals // ---------------------------- // this one is called on application startup and is a good place for the // app initialization (doing it here and not in the ctor allows to have an // error return: if OnInit() returns false, the application terminates) virtual bool OnInit(); }; // Define a new frame type: this is going to be our main frame class MyFrame : public wxFrame { public: // ctor(s) MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size); // event handlers (these functions should _not_ be virtual) void OnQuit(wxCommandEvent& event); void OnAbout(wxCommandEvent& event); void OnDlg1(wxCommandEvent& event); void OnDlg2(wxCommandEvent& event); private: // any class wishing to process wxWidgets events must use this macro DECLARE_EVENT_TABLE() }; // ---------------------------------------------------------------------------- // event tables and other macros for wxWidgets // ---------------------------------------------------------------------------- BEGIN_EVENT_TABLE(MyFrame, wxFrame) EVT_MENU(XRCID("menu_quit"), MyFrame::OnQuit) EVT_MENU(XRCID("menu_about"), MyFrame::OnAbout) EVT_MENU(XRCID("menu_dlg1"), MyFrame::OnDlg1) EVT_MENU(XRCID("menu_dlg2"), MyFrame::OnDlg2) END_EVENT_TABLE() IMPLEMENT_APP(MyApp) // ---------------------------------------------------------------------------- // the application class // ---------------------------------------------------------------------------- // 'Main program' equivalent: the program execution "starts" here bool MyApp::OnInit() { wxImage::AddHandler(new wxGIFHandler); wxXmlResource::Get()->InitAllHandlers(); wxXmlResource::Get()->Load("rc/resource.xrc"); MyFrame *frame = new MyFrame("XML resources demo", wxPoint(50, 50), wxSize(450, 340)); frame->Show(true); return true; } // ---------------------------------------------------------------------------- // main frame // ---------------------------------------------------------------------------- // frame constructor MyFrame::MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size) : wxFrame((wxFrame *)NULL, -1, title, pos, size) { SetIcon(wxICON(appicon)); SetMenuBar(wxXmlResource::Get()->LoadMenuBar("mainmenu")); SetToolBar(wxXmlResource::Get()->LoadToolBar(this, "toolbar")); } // event handlers void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event)) { // true is to force the frame to close Close(true); } void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event)) { wxString msg; msg.Printf( wxT("This is the about dialog of XML resources demo.\n") wxT("Welcome to %s"), wxVERSION_STRING); wxMessageBox(msg, "About XML resources demo", wxOK | wxICON_INFORMATION, this); } void MyFrame::OnDlg1(wxCommandEvent& WXUNUSED(event)) { wxDialog dlg; wxXmlResource::Get()->LoadDialog(&dlg, this, "dlg1"); dlg.ShowModal(); } void MyFrame::OnDlg2(wxCommandEvent& WXUNUSED(event)) { wxDialog dlg; wxXmlResource::Get()->LoadDialog(&dlg, this, "dlg2"); dlg.ShowModal(); }
This is the XML file (resource.xrc) for the XRC sample.
<?xml version="1.0"?> <resource version="2.3.0.1"> <object class="wxMenuBar" name="mainmenu"> <style>wxMB_DOCKABLE</style> <object class="wxMenu" name="menu_file"> <label>_File</label> <style>wxMENU_TEAROFF</style> <object class="wxMenuItem" name="menu_about"> <label>_About...</label> <bitmap>filesave.gif</bitmap> </object> <object class="separator"/> <object class="wxMenuItem" name="menu_dlg1"> <label>Dialog 1</label> </object> <object class="wxMenuItem" name="menu_dlg2"> <label>Dialog 2</label> </object> <object class="separator"/> <object class="wxMenuItem" name="menu_quit"> <label>E_xit\tAlt-X</label> </object> </object> </object> <object class="wxToolBar" name="toolbar"> <style>wxTB_FLAT|wxTB_DOCKABLE</style> <margins>2,2</margins> <object class="tool" name="menu_open"> <bitmap>fileopen.gif</bitmap> <tooltip>Open catalog</tooltip> </object> <object class="tool" name="menu_save"> <bitmap>filesave.gif</bitmap> <tooltip>Save catalog</tooltip> </object> <object class="tool" name="menu_update"> <bitmap>update.gif</bitmap> <tooltip>Update catalog - synchronize it with sources</tooltip> </object> <separator/> <object class="tool" name="menu_quotes"> <bitmap>quotes.gif</bitmap> <toggle>1</toggle> <tooltip>Display quotes around the string?</tooltip> </object> <object class="separator"/> <object class="tool" name="menu_fuzzy"> <bitmap>fuzzy.gif</bitmap> <tooltip>Toggled if selected string is fuzzy translation</tooltip> <toggle>1</toggle> </object> </object> <object class="wxDialog" name="dlg1"> <object class="wxBoxSizer"> <object class="sizeritem"> <object class="wxBitmapButton"> <bitmap>fuzzy.gif</bitmap> <focus>fileopen.gif</focus> </object> </object> <object class="sizeritem"> <object class="wxPanel"> <object class="wxStaticText"> <label>fdgdfgdfgdfg</label> </object> <style>wxBORDER\_SUNKEN</style> </object> <flag>wxALIGN_CENTER</flag> </object> <object class="sizeritem"> <object class="wxButton"> <label>Buttonek</label> </object> <border>10d</border> <flag>wxALL</flag> </object> <object class="sizeritem"> <object class="wxHtmlWindow"> <htmlcode><h1>Hi,</h1>man</htmlcode> <size>100,45d</size> </object> </object> <object class="sizeritem"> <object class="wxNotebook"> <object class="notebookpage"> <object class="wxPanel"> <object class="wxBoxSizer"> <object class="sizeritem"> <object class="wxHtmlWindow"> <htmlcode>Hello, we are inside a <u>NOTEBOOK</u>...</htmlcode> <size>50,50d</size> </object> <option>1</option> </object> </object> </object> <label>Page</label> <image>0</image> </object> <object class="notebookpage"> <object class="wxPanel"> <object class="wxBoxSizer"> <object class="sizeritem"> <object class="wxHtmlWindow"> <htmlcode>Hello, we are inside a <u>NOTEBOOK</u>...</htmlcode> <size>50,50d</size> </object> </object> </object> </object> <label>Page 2</label> <image>1</image> </object> <usenotebooksizer>1</usenotebooksizer> <imagelist> <size>16,16</size> <bitmap stock_id="wxART_QUESTION"/> <bitmap stock_id="wxART_WARNING"/> </imagelist> </object> <flag>wxEXPAND</flag> </object> <orient>wxVERTICAL</orient> </object> </object> <object class="wxDialog" name="dlg2"> <object class="wxBoxSizer"> <orient>wxVERTICAL</orient> <object class="sizeritem" name="dfgdfg"> <object class="wxTextCtrl"> <size>200,200d</size> <style>wxTE_MULTILINE|wxBORDER_SUNKEN</style> <value>Hello, this is an ordinary multiline\n textctrl....</value> </object> <option>1</option> <flag>wxEXPAND|wxALL</flag> <border>10</border> </object> <object class="sizeritem"> <object class="wxBoxSizer"> <object class="sizeritem"> <object class="wxButton" name="wxID_OK"> <label>Ok</label> <default>1</default> </object> </object> <object class="sizeritem"> <object class="wxButton" name="wxID_CANCEL"> <label>Cancel</label> </object> <border>10</border> <flag>wxLEFT</flag> </object> </object> <flag>wxLEFT|wxRIGHT|wxBOTTOM|wxALIGN_RIGHT</flag> <border>10</border> </object> </object> <title>Second testing dialog</title> </object> </resource>
Using the -e
switch together with -c
, a C++ header file is written containing class definitions for the GUI windows defined in the XRC file. This code generation can make it easier to use XRC and automate program development. The classes can be used as basis for development, freeing the programmer from dealing with most of the XRC specifics (e.g. XRCCTRL
).
For each top level window defined in the XRC file a C++ class definition is generated, containing as class members the named widgets of the window. A default constructor for each class is also generated. Inside the constructor all XRC loading is done and all class members representing widgets are initialized.
A simple example will help understand how the scheme works. Suppose you have a XRC file defining a top level window TestWnd_Base
, which subclasses wxFrame (any other class like wxDialog
will do also), and has subwidgets wxTextCtrl A and wxButton B.
The XRC file and corresponding class definition in the header file will be something like:
<?xml version="1.0"?> <resource version="2.3.0.1"> <object class="wxFrame" name="TestWnd_Base"> <size>-1,-1</size> <title>Test</title> <object class="wxBoxSizer"> <orient>wxHORIZONTAL</orient> <object class="sizeritem"> <object class="wxTextCtrl" name="A"> <label>Test label</label> </object> </object> <object class="sizeritem"> <object class="wxButton" name="B"> <label>Test button</label> </object> </object> </object> </object> </resource> class TestWnd_Base : public wxFrame { protected: wxTextCtrl* A; wxButton* B; private: void InitWidgetsFromXRC() { wxXmlResource::Get()->LoadObject(this, NULL, "TestWnd", "wxFrame"); A = XRCCTRL(*this, "A", wxTextCtrl); B = XRCCTRL(*this, "B", wxButton); } public: TestWnd::TestWnd() { InitWidgetsFromXRC(); } };
The generated window class can be used as basis for the full window class. The class members which represent widgets may be accessed by name instead of using XRCCTRL
every time you wish to reference them (note that they are protected
class members), though you must still use XRCID
to refer to widget IDs in the event table.
Example:
#include "resource.h" class TestWnd : public TestWnd_Base { public: TestWnd() { // A, B already initialised at this point A->SetValue("Updated in TestWnd::TestWnd"); B->SetValue("Nice :)"); } void OnBPressed(wxEvent& event) { Close(); } DECLARE_EVENT_TABLE(); }; BEGIN_EVENT_TABLE(TestWnd,TestWnd_Base) EVT_BUTTON(XRCID("B"), TestWnd::OnBPressed) END_EVENT_TABLE()
It is also possible to access the wxSizerItem of a sizer that is part of a resource. This can be done using XRCSIZERITEM
as shown.
The resource file can have something like this for a sizer item.
<object class="spacer" name="area"> <size>400, 300</size> </object>
The code can then access the sizer item by using XRCSIZERITEM
and XRCID
together.
wxSizerItem* item = XRCSIZERITEM(*this, "area");
Adding a new resource handler is pretty easy.
Typically, to add an handler for the MyControl
class, you'll want to create the xh_mycontrol.h
and xh_mycontrol.cpp
files.
The header needs to contains the MyControlXmlHandler
class definition:
class MyControlXmlHandler : public wxXmlResourceHandler { public: // Constructor. MyControlXmlHandler(); // Creates the control and returns a pointer to it. virtual wxObject *DoCreateResource(); // Returns true if we know how to create a control for the given node. virtual bool CanHandle(wxXmlNode *node); // Register with wxWidgets' dynamic class subsystem. DECLARE_DYNAMIC_CLASS(MyControlXmlHandler) };
The implementation of your custom XML handler will typically look as:
// Register with wxWidgets' dynamic class subsystem. IMPLEMENT_DYNAMIC_CLASS(MyControlXmlHandler, wxXmlResourceHandler) MyControlXmlHandler::MyControlXmlHandler() { // this call adds support for all wxWindows class styles // (e.g. wxBORDER_SIMPLE, wxBORDER_SUNKEN, wxWS_EX_* etc etc) AddWindowStyles(); // if MyControl class supports e.g. MYCONTROL_DEFAULT_STYLE // you should use: // XRC_ADD_STYLE(MYCONTROL_DEFAULT_STYLE); } wxObject *MyControlXmlHandler::DoCreateResource() { // the following macro will init a pointer named "control" // with a new instance of the MyControl class, but will NOT // Create() it! XRC_MAKE_INSTANCE(control, MyControl) // this is the point where you'll typically need to do the most // important changes: here the control is created and initialized. // You'll want to use the wxXmlResourceHandler's getters to // do most of your work. // If e.g. the MyControl::Create function looks like: // // bool MyControl::Create(wxWindow *parent, int id, // const wxBitmap &first, const wxPoint &posFirst, // const wxBitmap &second, const wxPoint &posSecond, // const wxString &theTitle, const wxFont &titleFont, // const wxPoint &pos, const wxSize &size, // long style = MYCONTROL_DEFAULT_STYLE, // const wxString &name = wxT("MyControl")); // // Then the XRC for your component should look like: // // <object class="MyControl" name="some_name"> // <first-bitmap>first.xpm</first-bitmap> // <second-bitmap>text.xpm</second-bitmap> // <first-pos>3,3</first-pos> // <second-pos>4,4</second-pos> // <the-title>a title</the-title> // <title-font> // <!-- Standard XRC tags for a font: <size>, <style>, <weight>, etc --> // </title-font> // <!-- XRC also accepts other usual tags for wxWindow-derived classes: // like e.g. <name>, <style>, <size>, <position>, etc --> // </object> // // And the code to read your custom tags from the XRC file is just: control->Create(m_parentAsWindow, GetID(), GetBitmap(wxT("first-bitmap")), GetPosition(wxT("first-pos")), GetBitmap(wxT("second-bitmap")), GetPosition(wxT("second-pos")), GetText(wxT("the-title")), GetFont(wxT("title-font")), GetPosition(), GetSize(), GetStyle(), GetName()); SetupWindow(control); return control; } bool MyControlXmlHandler::CanHandle(wxXmlNode *node) { // this function tells XRC system that this handler can parse // the <object class="MyControl"> tags return IsOfClass(node, wxT("MyControl")); }
You may want to check the wxXmlResourceHandler documentation to see how many built-in getters it contains. It's very easy to retrieve also complex structures out of XRC files using them.
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