Configuration series selection wxChoice needs to set series background color for each series in list of choices

[DRNadler]

To make it easy to find the relevant series in the configuration dialog, series tab: the series name needs display with the series background color in the series selection wxChoice (and reset this background color when the series color is changed). This can be done with a custom wxChoice as shown here: colored wxChoice

Lionel: You used a tool to generate the configuration dialog. Is this tool capable of specifying a custom class to replace wxChoice (wxFormBuilder does this easily)? I don't want to break your form creation tool...

PS: To be clear, the output of your tool should change wxChoice to the derived class with color support in this line:
388: ChoiceSeries = new wxChoice(Panel4, wxID_ANY, wxDefaultPosition, wxDefaultSize, 0, 0, 0, wxDefaultValidator);

PPS: A customized wxOwnerDrawnComboBox would be better, see includes wxOwnerDrawnComboBox version

[GitHubLionel]

Hi Dave,
I am not sure of what you want to do. Do you want to have a different background colour in the drop down list of the choice list ?
It is maybe not a good idea if colour is dark.
wxOwnerDrawnComboBox allow to customize the onPaint event.
We maybe can just add the small symbol (line/square) before the name of the series like in the legend.
Could you provide an image of what you want to see ?
I have used wxSmith who is integrated in C::B to create the configuration box. And yes, it is possible to add custom widget.
Note: I can not open your Chatgpt link because I have no account.

[DRNadler]

Hi Lionel - Sorry if I was not clear. I want each choice (including the selected series in the combo box) to be shown with the background color used for the trace. An alternative would be draw a line (and maybe the optional symbol) before the normal text in each selection. Related issue is symbols in legend .

Here's some suggested code to do this (from ChatGPT, so it will probably have a few bugs but should save time we hope):

wxColoredComboBox - Implementation with Background Colors per Item

Question and Discussion

User Request:

Create wxwidgets wxColoredComboBox derived from wxOwnerDrawnComboBox with:

• wxColour background for each choice
• no magic numbers for text size,
• add item arguments should be text and background wxColour,
• member function to change item background color.
• Draw white text if background color is dark.

Create ONE MARKDOWN FILE containing H, CPP, and example usage.

Discussion Summary:

This document contains the full implementation of a custom wxColoredComboBox class in C++ using wxWidgets. It extends wxOwnerDrawnComboBox and provides per-item background coloring with appropriate foreground text color (white or black based on brightness). The header, implementation, and an example usage (main.cpp) are all included in a single markdown file.

---

wxColoredComboBox.md

// wxColoredComboBox.h

#ifndef WX_COLORED_COMBO_BOX_H
#define WX_COLORED_COMBO_BOX_H

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

class wxColoredComboBox : public wxOwnerDrawnComboBox
{
public:
    wxColoredComboBox(wxWindow* parent, wxWindowID id,
                      const wxString& value = "",
                      const wxPoint& pos = wxDefaultPosition,
                      const wxSize& size = wxDefaultSize,
                      long style = 0,
                      const wxValidator& validator = wxDefaultValidator,
                      const wxString& name = wxComboBoxNameStr);

    void AddItem(const wxString& text, const wxColour& background);
    void SetItemBackgroundColor(unsigned int index, const wxColour& color);

protected:
    wxColour GetItemBackgroundColor(unsigned int index) const;
    bool IsDarkColor(const wxColour& color) const;

    // Override drawing functions
    virtual void OnDrawItem(wxDC& dc, const wxRect& rect, int item, int flags) const override;
    virtual void OnDrawBackground(wxDC& dc, const wxRect& rect, int item, int flags) const override;
    virtual wxCoord OnMeasureItem(size_t item) const override;
    virtual wxCoord OnMeasureItemWidth(size_t item) const override;

private:
    std::vector<wxColour> m_backgroundColors;
};

#endif // WX_COLORED_COMBO_BOX_H

// wxColoredComboBox.cpp

#include "wxColoredComboBox.h"

wxColoredComboBox::wxColoredComboBox(wxWindow* parent, wxWindowID id,
                                     const wxString& value,
                                     const wxPoint& pos,
                                     const wxSize& size,
                                     long style,
                                     const wxValidator& validator,
                                     const wxString& name)
    : wxOwnerDrawnComboBox(parent, id, value, pos, size,
                           0, nullptr, style, validator, name)
{
}

void wxColoredComboBox::AddItem(const wxString& text, const wxColour& background)
{
    Append(text);
    m_backgroundColors.push_back(background);
}

void wxColoredComboBox::SetItemBackgroundColor(unsigned int index, const wxColour& color)
{
    if (index < m_backgroundColors.size())
        m_backgroundColors[index] = color;
}

wxColour wxColoredComboBox::GetItemBackgroundColor(unsigned int index) const
{
    if (index < m_backgroundColors.size())
        return m_backgroundColors[index];
    return *wxWHITE;
}

bool wxColoredComboBox::IsDarkColor(const wxColour& color) const
{
    int brightness = static_cast<int>(0.299 * color.Red() +
                                      0.587 * color.Green() +
                                      0.114 * color.Blue());
    return brightness < 128;
}

void wxColoredComboBox::OnDrawItem(wxDC& dc, const wxRect& rect, int item, int flags) const
{
    if (item < 0 || static_cast<size_t>(item) >= GetCount())
        return;

    wxColour bg = GetItemBackgroundColor(item);
    dc.SetBrush(wxBrush(bg));
    dc.SetPen(*wxTRANSPARENT_PEN);
    dc.DrawRectangle(rect);

    wxColour textColor = IsDarkColor(bg) ? *wxWHITE : *wxBLACK;
    dc.SetTextForeground(textColor);

    wxString text = GetString(item);
    dc.DrawText(text, rect.x + 4, rect.y + (rect.height - dc.GetCharHeight()) / 2);
}

void wxColoredComboBox::OnDrawBackground(wxDC& dc, const wxRect& rect, int item, int flags) const
{
}

wxCoord wxColoredComboBox::OnMeasureItem(size_t WXUNUSED(item)) const
{
    return GetCharHeight() + 4;
}

wxCoord wxColoredComboBox::OnMeasureItemWidth(size_t item) const
{
    if (item < GetCount())
    {
        wxClientDC dc(const_cast<wxColoredComboBox*>(this));
        dc.SetFont(GetFont());
        return dc.GetTextExtent(GetString(item)).GetWidth() + 8;
    }
    return 100;
}

// main.cpp (example usage)

#include <wx/wx.h>
#include "wxColoredComboBox.h"

class MyFrame : public wxFrame
{
public:
    MyFrame()
        : wxFrame(nullptr, wxID_ANY, "wxColoredComboBox Example", wxDefaultPosition, wxSize(400, 300))
    {
        wxPanel* panel = new wxPanel(this);
        wxBoxSizer* sizer = new wxBoxSizer(wxVERTICAL);

        wxColoredComboBox* combo = new wxColoredComboBox(panel, wxID_ANY);
        combo->AddItem("Red Item", *wxRED);
        combo->AddItem("Green Item", *wxGREEN);
        combo->AddItem("Blue Item", *wxBLUE);
        combo->AddItem("Yellow Item", *wxYELLOW);
        combo->AddItem("Dark Gray Item", wxColour(50, 50, 50));
        combo->SetSelection(0);

        sizer->Add(combo, 0, wxALL | wxEXPAND, 10);
        panel->SetSizer(sizer);
    }
};

class MyApp : public wxApp
{
public:
    virtual bool OnInit()
    {
        MyFrame* frame = new MyFrame();
        frame->Show();
        return true;
    }
};

wxIMPLEMENT_APP(MyApp);

[GitHubLionel]

Hi Dave,

It seems to be very complicated !
And the most annoying thing is that it might break a lot of things and some peoples may not want this behaviour.

The only simple thing that I found is just to modify the background of the selected series with this simple code:
Just add this line at the end of the MathPlotConfigDialog constructor:
ChoiceSeries->Bind(wxEVT_PAINT, &MathPlotConfigDialog::ChoiceSeriesEvent, this);
and the method:

#include <wx/dcclient.h>
void MathPlotConfigDialog::ChoiceSeriesEvent(wxPaintEvent &WXUNUSED(event))
{
  wxPaintDC dc(ChoiceSeries);
  wxRect rect(0, 0, dc.GetSize().GetWidth(), dc.GetSize().GetHeight());

  dc.SetBrush(bSeriesPenColor->GetBackgroundColour());
  dc.SetPen(*wxBLACK_PEN);
  dc.DrawRectangle(rect);
  dc.DrawLabel(ChoiceSeries->GetStringSelection(), rect, wxALIGN_CENTER_VERTICAL);
}

But I don't think that what you want.