An image panel

Here's how to draw an image, make an image component or paint on the background of a panel.

(If all you want is place an icon somewhere, create a simple wxStaticBitmap and add it to a sizer, i.e. no need for a wxPanel. On most platforms, wxStaticBitmap will also work fine, except on Windows because it doesn't accept big images, so ideally use wxStaticBitmap only for icons)

A simple image panel

#include <wx/wx.h>
#include <wx/sizer.h>

class wxImagePanel : public wxPanel
    {
        wxBitmap image;
        
    public:
        wxImagePanel(wxFrame* parent, wxString file, wxBitmapType format);
        
        void paintEvent(wxPaintEvent & evt);
        void paintNow();
        
        void render(wxDC& dc);
        
        // some useful events
        /*
         void mouseMoved(wxMouseEvent& event);
         void mouseDown(wxMouseEvent& event);
         void mouseWheelMoved(wxMouseEvent& event);
         void mouseReleased(wxMouseEvent& event);
         void rightClick(wxMouseEvent& event);
         void mouseLeftWindow(wxMouseEvent& event);
         void keyPressed(wxKeyEvent& event);
         void keyReleased(wxKeyEvent& event);
         */
        
        DECLARE_EVENT_TABLE()
    };


BEGIN_EVENT_TABLE(wxImagePanel, wxPanel)
// some useful events
/*
 EVT_MOTION(wxImagePanel::mouseMoved)
 EVT_LEFT_DOWN(wxImagePanel::mouseDown)
 EVT_LEFT_UP(wxImagePanel::mouseReleased)
 EVT_RIGHT_DOWN(wxImagePanel::rightClick)
 EVT_LEAVE_WINDOW(wxImagePanel::mouseLeftWindow)
 EVT_KEY_DOWN(wxImagePanel::keyPressed)
 EVT_KEY_UP(wxImagePanel::keyReleased)
 EVT_MOUSEWHEEL(wxImagePanel::mouseWheelMoved)
 */

// catch paint events
EVT_PAINT(wxImagePanel::paintEvent)

END_EVENT_TABLE()


// some useful events
/*
 void wxImagePanel::mouseMoved(wxMouseEvent& event) {}
 void wxImagePanel::mouseDown(wxMouseEvent& event) {}
 void wxImagePanel::mouseWheelMoved(wxMouseEvent& event) {}
 void wxImagePanel::mouseReleased(wxMouseEvent& event) {}
 void wxImagePanel::rightClick(wxMouseEvent& event) {}
 void wxImagePanel::mouseLeftWindow(wxMouseEvent& event) {}
 void wxImagePanel::keyPressed(wxKeyEvent& event) {}
 void wxImagePanel::keyReleased(wxKeyEvent& event) {}
 */

wxImagePanel::wxImagePanel(wxFrame* parent, wxString file, wxBitmapType format) :
wxPanel(parent)
{
    // load the file... ideally add a check to see if loading was successful
    image.LoadFile(file, format);
}

/*
 * Called by the system of by wxWidgets when the panel needs
 * to be redrawn. You can also trigger this call by
 * calling Refresh()/Update().
 */

void wxImagePanel::paintEvent(wxPaintEvent & evt)
{
    // depending on your system you may need to look at double-buffered dcs
    wxPaintDC dc(this);
    render(dc);
}

/*
 * Alternatively, you can use a clientDC to paint on the panel
 * at any time. Using this generally does not free you from
 * catching paint events, since it is possible that e.g. the window
 * manager throws away your drawing when the window comes to the
 * background, and expects you will redraw it when the window comes
 * back (by sending a paint event).
 */
void wxImagePanel::paintNow()
{
    // depending on your system you may need to look at double-buffered dcs
    wxClientDC dc(this);
    render(dc);
}

/*
 * Here we do the actual rendering. I put it in a separate
 * method so that it can work no matter what type of DC
 * (e.g. wxPaintDC or wxClientDC) is used.
 */
void wxImagePanel::render(wxDC&  dc)
{
    dc.DrawBitmap( image, 0, 0, false );
}



// ----------------------------------------
// how-to-use example

class MyApp: public wxApp
    {
        
        wxFrame *frame;
        wxImagePanel * drawPane;
    public:
        bool OnInit()
        {
            // make sure to call this first
            wxInitAllImageHandlers();
            
            wxBoxSizer* sizer = new wxBoxSizer(wxHORIZONTAL);
            frame = new wxFrame(NULL, wxID_ANY, wxT("Hello wxDC"), wxPoint(50,50), wxSize(800,600));
            
            // then simply create like this
            drawPane = new wxImagePanel( frame, wxT("image.jpg"), wxBITMAP_TYPE_JPEG);
            sizer->Add(drawPane, 1, wxEXPAND);
            
            frame->SetSizer(sizer);
            
            frame->Show();
            return true;
        } 
        
    };

IMPLEMENT_APP(MyApp)

A panel in which the image resizes

#include <wx/wx.h>
#include <wx/sizer.h>

class wxImagePanel : public wxPanel
{
    wxImage image;
    wxBitmap resized;
    int w, h;
    
public:
    wxImagePanel(wxFrame* parent, wxString file, wxBitmapType format);
    
    void paintEvent(wxPaintEvent & evt);
    void paintNow();
    void OnSize(wxSizeEvent& event);
    void render(wxDC& dc);
    
    // some useful events
    /*
     void mouseMoved(wxMouseEvent& event);
     void mouseDown(wxMouseEvent& event);
     void mouseWheelMoved(wxMouseEvent& event);
     void mouseReleased(wxMouseEvent& event);
     void rightClick(wxMouseEvent& event);
     void mouseLeftWindow(wxMouseEvent& event);
     void keyPressed(wxKeyEvent& event);
     void keyReleased(wxKeyEvent& event);
     */
    
    DECLARE_EVENT_TABLE()
};


BEGIN_EVENT_TABLE(wxImagePanel, wxPanel)
// some useful events
/*
 EVT_MOTION(wxImagePanel::mouseMoved)
 EVT_LEFT_DOWN(wxImagePanel::mouseDown)
 EVT_LEFT_UP(wxImagePanel::mouseReleased)
 EVT_RIGHT_DOWN(wxImagePanel::rightClick)
 EVT_LEAVE_WINDOW(wxImagePanel::mouseLeftWindow)
 EVT_KEY_DOWN(wxImagePanel::keyPressed)
 EVT_KEY_UP(wxImagePanel::keyReleased)
 EVT_MOUSEWHEEL(wxImagePanel::mouseWheelMoved)
 */

// catch paint events
EVT_PAINT(wxImagePanel::paintEvent)
//Size event
EVT_SIZE(wxImagePanel::OnSize)
END_EVENT_TABLE()


// some useful events
/*
 void wxImagePanel::mouseMoved(wxMouseEvent& event) {}
 void wxImagePanel::mouseDown(wxMouseEvent& event) {}
 void wxImagePanel::mouseWheelMoved(wxMouseEvent& event) {}
 void wxImagePanel::mouseReleased(wxMouseEvent& event) {}
 void wxImagePanel::rightClick(wxMouseEvent& event) {}
 void wxImagePanel::mouseLeftWindow(wxMouseEvent& event) {}
 void wxImagePanel::keyPressed(wxKeyEvent& event) {}
 void wxImagePanel::keyReleased(wxKeyEvent& event) {}
 */

wxImagePanel::wxImagePanel(wxFrame* parent, wxString file, wxBitmapType format) :
wxPanel(parent)
{
    // load the file... ideally add a check to see if loading was successful
    image.LoadFile(file, format);
    w = -1;
    h = -1;
}

/*
 * Called by the system of by wxWidgets when the panel needs
 * to be redrawn. You can also trigger this call by
 * calling Refresh()/Update().
 */

void wxImagePanel::paintEvent(wxPaintEvent & evt)
{
    // depending on your system you may need to look at double-buffered dcs
    wxPaintDC dc(this);
    render(dc);
}

/*
 * Alternatively, you can use a clientDC to paint on the panel
 * at any time. Using this generally does not free you from
 * catching paint events, since it is possible that e.g. the window
 * manager throws away your drawing when the window comes to the
 * background, and expects you will redraw it when the window comes
 * back (by sending a paint event).
 */
void wxImagePanel::paintNow()
{
    // depending on your system you may need to look at double-buffered dcs
    wxClientDC dc(this);
    render(dc);
}

/*
 * Here we do the actual rendering. I put it in a separate
 * method so that it can work no matter what type of DC
 * (e.g. wxPaintDC or wxClientDC) is used.
 */
void wxImagePanel::render(wxDC&  dc)
{
    int neww, newh;
    dc.GetSize( &neww, &newh );
    
    if( neww != w || newh != h )
    {
        resized = wxBitmap( image.Scale( neww, newh /*, wxIMAGE_QUALITY_HIGH*/ ) );
        w = neww;
        h = newh;
        dc.DrawBitmap( resized, 0, 0, false );
    }else{
        dc.DrawBitmap( resized, 0, 0, false );
    }
}

/*
 * Here we call refresh to tell the panel to draw itself again.
 * So when the user resizes the image panel the image should be resized too.
 */
void wxImagePanel::OnSize(wxSizeEvent& event){
    Refresh();
    //skip the event.
    event.Skip();
}

// ----------------------------------------
// how-to-use example

class MyApp: public wxApp
{
    
    wxFrame *frame;
    wxImagePanel * drawPane;
public:
    bool OnInit()
    {
        // make sure to call this first
        wxInitAllImageHandlers();
        
        wxBoxSizer* sizer = new wxBoxSizer(wxHORIZONTAL);
        frame = new wxFrame(NULL, wxID_ANY, wxT("Hello wxDC"), wxPoint(50,50), wxSize(800,600));
        
        // then simply create like this
        drawPane = new wxImagePanel( frame, wxT("image.jpg"), wxBITMAP_TYPE_JPEG);
        sizer->Add(drawPane, 1, wxEXPAND);
        
        frame->SetSizer(sizer);
        
        frame->Show();
        return true;
    } 
    
};

IMPLEMENT_APP(MyApp)