Sample to verify wxGridBagSizer behaviour.

gistfile1.txt

/////////////////////////////////////////////////////////////////////////////
// Name:        minimal.cpp
// Purpose:     Minimal wxWidgets sample
// Author:      Julian Smart
// Modified by:
// Created:     04/01/98
// Copyright:   (c) Julian Smart
// Licence:     wxWindows licence
/////////////////////////////////////////////////////////////////////////////

// ============================================================================
// declarations
// ============================================================================

// ----------------------------------------------------------------------------
// headers
// ----------------------------------------------------------------------------

// For compilers that support precompilation, includes "wx/wx.h".
#include "wx/wxprec.h"


// for all others, include the necessary headers (this file is usually all you
// need because it includes almost all "standard" wxWidgets headers)
#ifndef WX_PRECOMP
    #include "wx/wx.h"
#endif
#include "wx/gbsizer.h"
// ----------------------------------------------------------------------------
// resources
// ----------------------------------------------------------------------------

// the application icon (under Windows it is in resources and even
// though we could still include the XPM here it would be unused)
#ifndef wxHAS_IMAGES_IN_RESOURCES
    #include "../sample.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() wxOVERRIDE;
};

const int kGridCellWidth = 24;
const int kGridCellHeight = 18;
// Define a new frame type: this is going to be our main frame
class MyFrame : public wxFrame
{
private:
    struct DrawingLayoutInfo_
    {
        wxPoint pos{ 0,0 };
        wxSize size{ 0,0 };
        wxColour color{ wxT("#000000") };
    };

    const int kDefaultPenThickness = 1;

public:
    // ctor(s)
    MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size);

    void DrawSizerLayout(wxPanel* basePanel, const int& drawAreaWidth, const int& drawAreaHeight);
    // event handlers (these functions should _not_ be virtual)
    void OnQuit(wxCommandEvent& event);
    void OnAbout(wxCommandEvent& event);

private:
    void AddDrawLayouts_(wxPanel* baseWindow, const std::vector<DrawingLayoutInfo_>& layoutInfos, bool forceDraw)
    {
        baseWindow->Bind(wxEVT_PAINT, [this, baseWindow, layoutInfos](wxPaintEvent& inEvent)
            {
                wxPaintDC dc(baseWindow);
                dc.SetBrush(*wxTRANSPARENT_BRUSH);

                for (auto layoutInfo : layoutInfos)
                {
                    dc.SetPen(wxPen(layoutInfo.color, kDefaultPenThickness));
                    dc.DrawRectangle({ layoutInfo.pos.x,layoutInfo.pos.y }, layoutInfo.size);
                }
            }
        );

        if (forceDraw)
        {
            baseWindow->Refresh();
            baseWindow->Update();
        }
    }
    // any class wishing to process wxWidgets events must use this macro
    wxDECLARE_EVENT_TABLE();
};

// ----------------------------------------------------------------------------
// constants
// ----------------------------------------------------------------------------

// IDs for the controls and the menu commands
enum
{
    // menu items
    Minimal_Quit = wxID_EXIT,

    // it is important for the id corresponding to the "About" command to have
    // this standard value as otherwise it won't be handled properly under Mac
    // (where it is special and put into the "Apple" menu)
    Minimal_About = wxID_ABOUT
};

// ----------------------------------------------------------------------------
// event tables and other macros for wxWidgets
// ----------------------------------------------------------------------------

// the event tables connect the wxWidgets events with the functions (event
// handlers) which process them. It can be also done at run-time, but for the
// simple menu events like this the static method is much simpler.
wxBEGIN_EVENT_TABLE(MyFrame, wxFrame)
    EVT_MENU(Minimal_Quit,  MyFrame::OnQuit)
    EVT_MENU(Minimal_About, MyFrame::OnAbout)
wxEND_EVENT_TABLE()

// Create a new application object: this macro will allow wxWidgets to create
// the application object during program execution (it's better than using a
// static object for many reasons) and also implements the accessor function
// wxGetApp() which will return the reference of the right type (i.e. MyApp and
// not wxApp)
wxIMPLEMENT_APP(MyApp);

// ============================================================================
// implementation
// ============================================================================

// ----------------------------------------------------------------------------
// the application class
// ----------------------------------------------------------------------------

// 'Main program' equivalent: the program execution "starts" here
bool MyApp::OnInit()
{
    // call the base class initialization method, currently it only parses a
    // few common command-line options but it could be do more in the future
    if ( !wxApp::OnInit() )
        return false;

    // create the main application window
    MyFrame *frame = new MyFrame("Minimal wxWidgets App", wxDefaultPosition, wxSize(600,500));

    // and show it (the frames, unlike simple controls, are not shown when
    // created initially)
    frame->Show(true);

    // success: wxApp::OnRun() will be called which will enter the main message
    // loop and the application will run. If we returned false here, the
    // application would exit immediately.
    return true;
}

// ----------------------------------------------------------------------------
// main frame
// ----------------------------------------------------------------------------

// frame constructor
MyFrame::MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size)
       : wxFrame(NULL, wxID_ANY, title, pos, size)
{
    // set the frame icon
    SetIcon(wxICON(sample));

#if wxUSE_MENUBAR
    // create a menu bar
    wxMenu *fileMenu = new wxMenu;

    // the "About" item should be in the help menu
    wxMenu *helpMenu = new wxMenu;
    helpMenu->Append(Minimal_About, "&About\tF1", "Show about dialog");

    fileMenu->Append(Minimal_Quit, "E&xit\tAlt-X", "Quit this program");

    // now append the freshly created menu to the menu bar...
    wxMenuBar *menuBar = new wxMenuBar();
    menuBar->Append(fileMenu, "&File");
    menuBar->Append(helpMenu, "&Help");

    // ... and attach this menu bar to the frame
    SetMenuBar(menuBar);
#else // !wxUSE_MENUBAR
    // If menus are not available add a button to access the about box
    wxSizer* sizer = new wxBoxSizer(wxHORIZONTAL);
    wxButton* aboutBtn = new wxButton(this, wxID_ANY, "About...");
    aboutBtn->Bind(wxEVT_BUTTON, &MyFrame::OnAbout, this);
    sizer->Add(aboutBtn, wxSizerFlags().Center());
    SetSizer(sizer);
#endif // wxUSE_MENUBAR/!wxUSE_MENUBAR
    struct MyPanel : wxPanel {
        explicit MyPanel(wxWindow* parent, const wxPoint& pos, const wxSize& size)
            : wxPanel(parent, wxID_ANY, pos, size)
        {
            SetBackgroundColour(wxT("#AAAAAA"));

            wxSize tmpSize{ 50,14 };

            auto btnOne_ = new wxButton(this, wxID_ANY, "ButtonOne", wxDefaultPosition, wxDefaultSize, wxBORDER_NONE);
            btnOne_->SetBackgroundColour(wxT("#CCCCCC"));

            auto staticTextOne_ = new wxStaticText(this, wxID_ANY, "Static Text Two", wxDefaultPosition, wxDefaultSize, wxBORDER_NONE);
            staticTextOne_->SetBackgroundColour(wxT("#CCCCCC"));

            auto bitmapBtnOne_ = new wxBitmapButton(this, wxID_ANY, wxNullBitmap, wxDefaultPosition, tmpSize, wxBORDER_NONE);
            bitmapBtnOne_->SetBackgroundColour(wxT("#CCCCCC"));

            auto btnTwo_ = new wxButton(this, wxID_ANY, "ButtonOne", wxDefaultPosition, wxDefaultSize, wxBORDER_NONE);
            btnTwo_->SetBackgroundColour(wxT("#CCCCCC"));

            auto staticTextTwo_ = new wxStaticText(this, wxID_ANY, "Static Text Two", wxDefaultPosition, wxDefaultSize, wxBORDER_NONE);
            staticTextTwo_->SetBackgroundColour(wxT("#CCCCCC"));

            auto bitmapBtnTwo_ = new wxBitmapButton(this, wxID_ANY, wxNullBitmap, wxDefaultPosition, tmpSize, wxBORDER_NONE);
            bitmapBtnTwo_->SetBackgroundColour(wxT("#CCCCCC"));

            wxBoxSizer* baseSizer = new wxBoxSizer(wxVERTICAL);

            wxGridBagSizer* gridBagSizer = new wxGridBagSizer(0, 0);
            gridBagSizer->SetEmptyCellSize(wxSize(kGridCellWidth, kGridCellHeight));
            gridBagSizer->Add(btnOne_, wxGBPosition(1, 1), wxGBSpan(1, 3), wxALL, 0);
            gridBagSizer->Add(staticTextOne_, wxGBPosition(1, 5), wxGBSpan(1, 3), wxALL, 0);
            gridBagSizer->Add(bitmapBtnOne_, wxGBPosition(1, 9), wxGBSpan(1, 6), wxALL, 0);

            gridBagSizer->Add(btnTwo_, wxGBPosition(5, 1), wxGBSpan(1, 3), wxALL, 0);
            gridBagSizer->Add(staticTextTwo_, wxGBPosition(5, 5), wxGBSpan(1, 3), wxALL, 0);
            gridBagSizer->Add(bitmapBtnTwo_, wxGBPosition(5, 9), wxGBSpan(1, 6), wxALL, 0);

            baseSizer->Add(gridBagSizer, 1, wxALL, 0);

            SetSizer(baseSizer);
        }
    };

    const int panelWidth = 400;
    const int panelHeight = 300;
    auto myPanel = new MyPanel(this, wxDefaultPosition, wxSize(panelWidth, panelHeight));
    
    DrawSizerLayout(myPanel, panelWidth, panelHeight);

#if wxUSE_STATUSBAR
    // create a status bar just for fun (by default with 1 pane only)
    CreateStatusBar(2);
    SetStatusText("Welcome to wxWidgets!");
#endif // wxUSE_STATUSBAR
}

void MyFrame::DrawSizerLayout(wxPanel* basePanel, const int& drawAreaWidth, const int& drawAreaHeight)
{
    std::vector<DrawingLayoutInfo_> dawingLayoutInfos;

    int columnWidth = kGridCellWidth;
    int columnHeight = kGridCellHeight;
    int drawLimitColumnIdx = drawAreaWidth / columnWidth;
    int drawLimitRowIdx = drawAreaHeight / columnHeight;

    wxColour drawColour = { wxT("#AA0000") };

    for (int rowIdx = 0; rowIdx < drawLimitRowIdx; ++rowIdx)
    {
        for (int drawColumn = 1; drawColumn <= drawLimitColumnIdx; ++drawColumn)
        {
            dawingLayoutInfos.emplace_back(DrawingLayoutInfo_{ { 0, rowIdx * (columnHeight - 1) },{ columnWidth * drawColumn, columnHeight }, drawColour });
        }
    }

    AddDrawLayouts_(basePanel, dawingLayoutInfos, true);
}


// event handlers

void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event))
{
    // true is to force the frame to close
    Close(true);
}

void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event))
{
    wxMessageBox(wxString::Format
                 (
                    "Welcome to %s!\n"
                    "\n"
                    "This is the minimal wxWidgets sample\n"
                    "running under %s.",
                    wxGetLibraryVersionInfo().GetVersionString(),
                    wxGetOsDescription()
                 ),
                 "About wxWidgets minimal sample",
                 wxOK | wxICON_INFORMATION,
                 this);
}