wxWidgets widgets II

last modified October 18, 2023

In this chapter, we continue introducing various other widgets. We mention a wxListBox, a wxNotebook, and a wxScrolledWindow.

wxListBox

A wxListBox widget is used for displaying and working with a list of items. As its name indicates, it is a rectangle that has a list of strings inside. We could use it for displaying a list of MP3 files, book names, module names of a larger project or names of our friends. A wxListBox can be created in two different states. In a single selection state or a multiple selection state. The single selection state is the default state. There are two significant events in wxListBox. The first one is the wxEVT_COMMAND_LISTBOX_SELECTED event. This event is generated when we select a string in a wxListBox. The second one is the wxEVT_COMMAND_LISTBOX_DOUBLE_CLICKED event. It is generated when we double click an item in a wxListBox. The number of elements inside a wxListBox is limited on GTK platform. According to the documentation, it is currently around 2000 elements. The elements are numbered from zero. Scrollbars are displayed automatically if needed.

#include <wx/wx.h>
#include <wx/listbox.h>
class MyPanel : public wxPanel
{
public:
 MyPanel(wxPanel *parent);
 void OnNew(wxCommandEvent& event);
 void OnRename(wxCommandEvent& event);
 void OnClear(wxCommandEvent& event);
 void OnDelete(wxCommandEvent& event);
 wxListBox *m_lb;
 wxButton *m_newb;
 wxButton *m_renameb;
 wxButton *m_clearb;
 wxButton *m_deleteb;
};
class Listbox : public wxFrame
{
public:
 Listbox(const wxString& title);
 void OnDblClick(wxCommandEvent& event);
 wxListBox *listbox;
 MyPanel *btnPanel;
};
const int ID_RENAME = 1;
const int ID_LISTBOX = 5;

#include "listbox.h"
#include <wx/textdlg.h>
Listbox::Listbox(const wxString& title)
 : wxFrame(NULL, wxID_ANY, title, wxDefaultPosition, wxSize(270, 200))
{
 wxPanel * panel = new wxPanel(this, -1);
 wxBoxSizer *hbox = new wxBoxSizer(wxHORIZONTAL);
 listbox = new wxListBox(panel, ID_LISTBOX, 
 wxPoint(-1, -1), wxSize(-1, -1)); 
 hbox->Add(listbox, 3, wxEXPAND | wxALL, 20);
 btnPanel = new MyPanel(panel);
 hbox->Add(btnPanel, 2, wxEXPAND | wxRIGHT, 10);
 Connect(wxEVT_COMMAND_LISTBOX_DOUBLECLICKED, 
 wxCommandEventHandler(Listbox::OnDblClick));
 panel->SetSizer(hbox);
 Center(); 
}
MyPanel::MyPanel(wxPanel * parent)
 : wxPanel(parent, wxID_ANY)
{
 wxBoxSizer *vbox = new wxBoxSizer(wxVERTICAL);
 Listbox *lb = (Listbox *) parent->GetParent();
 m_lb = lb->listbox;
 m_newb = new wxButton(this, wxID_NEW, wxT("New"));
 m_renameb = new wxButton(this, ID_RENAME, wxT("Rename"));
 m_deleteb = new wxButton(this, wxID_DELETE, wxT("Delete"));
 m_clearb = new wxButton(this, wxID_CLEAR, wxT("Clear"));
 Connect(wxID_NEW, wxEVT_COMMAND_BUTTON_CLICKED, 
 wxCommandEventHandler(MyPanel::OnNew) );
 Connect(ID_RENAME, wxEVT_COMMAND_BUTTON_CLICKED, 
 wxCommandEventHandler(MyPanel::OnRename) );
 Connect(wxID_CLEAR, wxEVT_COMMAND_BUTTON_CLICKED, 
 wxCommandEventHandler(MyPanel::OnClear) );
 Connect(wxID_DELETE, wxEVT_COMMAND_BUTTON_CLICKED, 
 wxCommandEventHandler(MyPanel::OnDelete) );
 vbox->Add(-1, 20);
 vbox->Add(m_newb);
 vbox->Add(m_renameb, 0, wxTOP, 5);
 vbox->Add(m_deleteb, 0, wxTOP, 5);
 vbox->Add(m_clearb, 0, wxTOP, 5);
 SetSizer(vbox);
}
void MyPanel::OnNew(wxCommandEvent& event) 
{
 wxString str = wxGetTextFromUser(wxT("Add new item"));
 if (str.Len()> 0)
 m_lb->Append(str); 
}
void MyPanel::OnClear(wxCommandEvent& event) 
{
 m_lb->Clear();
}
void MyPanel::OnRename(wxCommandEvent& event) 
{
 wxString text;
 wxString renamed;
 
 int sel = m_lb->GetSelection();
 if (sel != -1) {
 text = m_lb->GetString(sel);
 renamed = wxGetTextFromUser(wxT("Rename item"), 
 wxT("Rename dialog"), text);
 }
 if (!renamed.IsEmpty()) {
 m_lb->Delete(sel);
 m_lb->Insert(renamed, sel);
 }
}
void MyPanel::OnDelete(wxCommandEvent& event) 
{
 int sel = m_lb->GetSelection();
 if (sel != -1) {
 m_lb->Delete(sel);
 }
}
void Listbox::OnDblClick(wxCommandEvent& event) 
{
 wxString text;
 wxString renamed;
 int sel = listbox->GetSelection();
 if (sel != -1) {
 text = listbox->GetString(sel);
 renamed = wxGetTextFromUser(wxT("Rename item"), 
 wxT("Rename dialog"), text);
 } 
 if (!renamed.IsEmpty()) {
 listbox->Delete(sel);
 listbox->Insert(renamed, sel);
 }
}

#include <wx/wx.h>
class MyApp : public wxApp
{
 public:
 virtual bool OnInit();
};

#include "main.h"
#include "Listbox.h"
IMPLEMENT_APP(MyApp)
bool MyApp::OnInit()
{
 Listbox *listbox = new Listbox(wxT("Listbox"));
 listbox->Show(true);
 return true;
}

listbox = new wxListBox(panel, ID_LISTBOX, 
 wxPoint(-1, -1), wxSize(-1, -1));

This is the constructor of the listbox widget.

In our example, we have a list box and four buttons. The buttons are used to add, rename, delete and clear all items in the listbox.

wxString str = wxGetTextFromUser(wxT("Add new item"));
if (str.Len()> 0)
 m_lb->Append(str); 

To add a new string to the listbox, we display a wxGetTextFromUser dialog. We call the Append method to append string to the listbox.

m_lb->Clear();

To clear all items is the easiest action to do. We just call the Clear method.

int sel = m_lb->GetSelection();
if (sel != -1) {
 m_lb->Delete(sel);
}

To delete an item, we figure out the selected item. Then we call the Delete method.

Renaming an item requires several steps.

wxString text;
wxString renamed;

We define two local variables.

int sel = listbox->GetSelection();
if (sel != -1) {
 text = listbox->GetString(sel);
 renamed = wxGetTextFromUser(wxT("Rename item"), 
 wxT("Rename dialog"), text);
} 

We get the selected string and save it to the renamed variable.

if (!renamed.IsEmpty()) {
 m_lb->Delete(sel);
 m_lb->Insert(renamed, sel);
}

We check whether the renamed variable is empty. This is to avoid inserting empty strings. Then we delete the old item and insert a new one.

Listbox

wxNotebook

The wxNotebook widget joins multiple windows with corresponding tabs. You can position the Notebook widget using the following style flags:

• wxNB_LEFT
• wxNB_RIGHT
• wxNB_TOP
• wxNB_BOTTOM

The default position is wxNB_TOP.

#include <wx/wx.h>
#include <wx/notebook.h>
#include <wx/grid.h>
class Notebook : public wxFrame
{
public:
 Notebook(const wxString& title);
 void OnQuit(wxCommandEvent& event);
};
class MyGrid : public wxGrid
{
public:
 MyGrid(wxNotebook *parent);
};

#include "Notebook.h"
Notebook::Notebook(const wxString& title)
 : wxFrame(NULL, wxID_ANY, title, wxDefaultPosition, wxSize(400, 350))
{
 wxNotebook *nb = new wxNotebook(this, -1, wxPoint(-1, -1), 
 wxSize(-1, -1), wxNB_BOTTOM);
 wxMenuBar *menubar = new wxMenuBar;
 wxMenu *file = new wxMenu;
 file->Append(wxID_EXIT, wxT("Quit"), wxT(""));
 menubar->Append(file, wxT("&File"));
 SetMenuBar(menubar);
 Connect(wxEVT_COMMAND_MENU_SELECTED, 
 wxCommandEventHandler(Notebook::OnQuit)); 
 MyGrid *grid1 = new MyGrid(nb);
 MyGrid *grid2 = new MyGrid(nb);
 MyGrid *grid3 = new MyGrid(nb);
 nb->AddPage(grid1, wxT("Sheet1"));
 nb->AddPage(grid2, wxT("Sheet2"));
 nb->AddPage(grid3, wxT("Sheet3"));
 CreateStatusBar();
 Center();
}
void Notebook::OnQuit(wxCommandEvent& event) 
{
 Close(true);
}
MyGrid::MyGrid(wxNotebook * parent)
 : wxGrid(parent, wxID_ANY)
{
 CreateGrid(30, 30);
 SetRowLabelSize(50);
 SetColLabelSize(25);
 SetRowLabelAlignment(wxALIGN_RIGHT, wxALIGN_CENTRE);
 SetLabelFont(wxFont(9, wxFONTFAMILY_DEFAULT, 
 wxFONTSTYLE_NORMAL, wxFONTWEIGHT_BOLD));
 for (int i = 0; i < 30 ; i++) {
 this->SetRowSize(i, 25);
 }
}

#include <wx/wx.h>
class MyApp : public wxApp
{
 public:
 virtual bool OnInit();
};

#include "main.h"
#include "Notebook.h"
IMPLEMENT_APP(MyApp)
bool MyApp::OnInit()
{
 Notebook *notebook = new Notebook(wxT("Notebook"));
 notebook->Show(true);
 return true;
}

In this example, we have created a notebook widget with three grids. The notebook widget is positioned at the bottom.

wxNotebook *nb = new wxNotebook(this, -1, wxPoint(-1, -1), 
 wxSize(-1, -1), wxNB_BOTTOM);

Here we create the notebook widget.

nb->AddPage(grid1, wxT("Sheet1"));
nb->AddPage(grid2, wxT("Sheet2"));
nb->AddPage(grid3, wxT("Sheet3"));

We add three grid objects into the notebook widget.

Notebook

wxScrolledWindow

This is one of the container widgets. It can be useful, when we have a larger area than a window can display. In our example, we demonstrate such a case. We place a large image into our window. When the window is smaller than our image, Scrollbars are displayed automatically.

#include <wx/wx.h>
class ScrWindow : public wxFrame
{
public:
 ScrWindow(const wxString& title);
};

#include "scrolledwindow.h"
ScrWindow::ScrWindow(const wxString& title)
 : wxFrame(NULL, wxID_ANY, title, wxDefaultPosition, wxSize(300, 200))
{
 wxImage::AddHandler(new wxJPEGHandler);
 wxScrolledWindow *sw = new wxScrolledWindow(this);
 
 wxBitmap bmp(wxT("castle.jpg"), wxBITMAP_TYPE_JPEG);
 wxStaticBitmap *sb = new wxStaticBitmap(sw, -1, bmp);
 int width = bmp.GetWidth();
 int height = bmp.GetHeight();
 sw->SetScrollbars(10, 10, width/10, height/10);
 sw->Scroll(50,10);
 Center();
}

#include <wx/wx.h>
class MyApp : public wxApp
{
 public:
 virtual bool OnInit();
};

#include "main.h"
#include "scrolledwindow.h"
IMPLEMENT_APP(MyApp)
bool MyApp::OnInit()
{
 ScrWindow *sw = new ScrWindow(wxT("ScrolledWindow"));
 sw->Show(true);
 return true;
}

In our example, we display a picture of a Spis castle.

wxImage::AddHandler(new wxJPEGHandler);

To handle JPG images, we must initiate the wxJPEGHandler.

wxScrolledWindow *sw = new wxScrolledWindow(this);
wxBitmap bmp(wxT("castle.jpg"), wxBITMAP_TYPE_JPEG);
wxStaticBitmap *sb = new wxStaticBitmap(sw, -1, bmp);

We create a scroll window and put a static bitmap into it.

sw->SetScrollbars(10, 10, width/10, height/10);

We set the scrollbars.

sw->Scroll(50,10);

We scroll the window a bit.

In this chapter, we continued covering widgets in wxWidgets library.