Support MFC Group Box Control in Dark Mode

MyStatic.cpp

#include "pch.h"
#include "MyStatic.h"

BEGIN_MESSAGE_MAP(CMyStatic, CStatic)
	ON_WM_PAINT()
END_MESSAGE_MAP()

void CMyStatic::OnPaint() {
	CPaintDC dc(this); // Device context for painting

	// Get the text to display
	CString text;
	GetWindowText(text);

	// Get the client area
	CRect rect;
	GetClientRect(&rect);

	// Use the same font as the parent window (dialog)
	CFont* pOldFont = dc.SelectObject(GetParent()->GetFont());

	// Calculate the text height
	CSize textSize = dc.GetTextExtent(text);
	int textHeight = textSize.cy;

	// Adjust the frame position so the top border intersects the middle of the text
	rect.top += textHeight / 2;

	// Draw the group box border
	// dc.DrawEdge(&rect, EDGE_ETCHED, BF_RECT);

	// Draw a 1-pixel-thick frame
	CPen pen(PS_SOLID, 1, GetSysColor(COLOR_3DSHADOW)); // Use a 1-pixel pen
	CPen* pOldPen = dc.SelectObject(&pen);

	// Draw the top border
	dc.MoveTo(rect.left, rect.top);
	dc.LineTo(rect.left + 8, rect.top); // Leave space for the text
	dc.MoveTo(rect.left + 8 + textSize.cx, rect.top); // Resume after the text
	dc.LineTo(rect.right, rect.top);

	// Draw the bottom border
	dc.MoveTo(rect.left, rect.bottom - 1);
	dc.LineTo(rect.right, rect.bottom - 1);

	// Draw the left border
	dc.MoveTo(rect.left, rect.top);
	dc.LineTo(rect.left, rect.bottom - 1);

	// Draw the right border
	dc.MoveTo(rect.right - 1, rect.top);
	dc.LineTo(rect.right - 1, rect.bottom - 1);

	// Restore the old pen
	dc.SelectObject(pOldPen);

	// Set the text color and background mode
	dc.SetTextColor(m_textColor);
	dc.SetBkMode(OPAQUE); // Use OPAQUE mode to draw the text with a background

	// Get the system background color for dialogs (typically COLOR_3DFACE or COLOR_BTNFACE)
	// COLORREF bgColor = GetSysColor(COLOR_3DFACE);
	COLORREF bgColor = RGB(32, 32, 32);

	// Set the background color for the text
	dc.SetBkColor(bgColor);

	// Calculate the text position
	rect.left += 8; // Indent the text slightly
	rect.top -= textHeight / 2; // Move the text back up to its original position

	// Draw the text with a background to mask out the border
	dc.DrawText(text, &rect, DT_LEFT | DT_TOP | DT_SINGLELINE);

	// Restore the old font
	dc.SelectObject(pOldFont);
}

MyStatic.h

#pragma once
#include <afxwin.h> // Include MFC headers

class CMyStatic : public CStatic
{
public:
    CMyStatic() : m_textColor(RGB(255, 255, 255)) {} // Default to white text

    void SetTextColor(COLORREF color) {
        m_textColor = color;
        if (m_hWnd != nullptr) {
            Invalidate(); // Force the control to redraw
        }
    }

protected:
    COLORREF m_textColor;

    DECLARE_MESSAGE_MAP()

    afx_msg void OnPaint(); // Handle WM_PAINT
};

TestDarkModeApp.h

// TestDarkMode.h : main header file for the PROJECT_NAME application
//

#pragma once

#ifndef __AFXWIN_H__
	#error "include 'pch.h' before including this file for PCH"
#endif

#include "resource.h"		// main symbols

#include <windows.h>
#include <dwmapi.h>
#pragma comment(lib, "dwmapi.lib")


// CTestDarkModeApp:
// See TestDarkMode.cpp for the implementation of this class
//

class CTestDarkModeApp : public CWinApp
{
public:
	CTestDarkModeApp();

// Overrides
public:
	virtual BOOL InitInstance();

// Implementation

	DECLARE_MESSAGE_MAP()

public:
	static BOOL AllowDarkModeForWindow(HWND hWnd, BOOL allow)
	{
		if (!hWnd)
			return FALSE;

		// Use DwmSetWindowAttribute to enable or disable dark mode
		return SUCCEEDED(DwmSetWindowAttribute(hWnd, 20, &allow, sizeof(allow)));
	}
};

extern CTestDarkModeApp theApp;