WTL设置对话框背影色

MainDlg.h

// MainDlg.h : interface of the CMainDlg class
//
/////////////////////////////////////////////////////////////////////////////

#pragma once

class CMainDlg : public CDialogImpl<CMainDlg>
{
public:
	enum { IDD = IDD_MAINDLG };

	BEGIN_MSG_MAP(CMainDlg)
		MESSAGE_HANDLER(WM_INITDIALOG, OnInitDialog)
		MESSAGE_HANDLER(WM_PAINT, OnPaint)
		COMMAND_ID_HANDLER(IDCANCEL, OnCancel)
	END_MSG_MAP()

// Handler prototypes (uncomment arguments if needed):
//	LRESULT MessageHandler(UINT /*uMsg*/, WPARAM /*wParam*/, LPARAM /*lParam*/, BOOL& /*bHandled*/)
//	LRESULT CommandHandler(WORD /*wNotifyCode*/, WORD /*wID*/, HWND /*hWndCtl*/, BOOL& /*bHandled*/)
//	LRESULT NotifyHandler(int /*idCtrl*/, LPNMHDR /*pnmh*/, BOOL& /*bHandled*/)

	LRESULT OnInitDialog(UINT /*uMsg*/, WPARAM /*wParam*/, LPARAM /*lParam*/, BOOL& /*bHandled*/);
	LRESULT OnCancel(WORD /*wNotifyCode*/, WORD wID, HWND /*hWndCtl*/, BOOL& /*bHandled*/);
	LRESULT OnPaint(UINT /*uMsg*/, WPARAM /*wParam*/, LPARAM /*lParam*/, BOOL& /*bHandled*/);
};

MainDlg.cpp

// MainDlg.cpp : implementation of the CMainDlg class
//
/////////////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "resource.h"

#include "MainDlg.h"
#include <atlimage.h>
#include <time.h>

LRESULT CMainDlg::OnInitDialog(UINT /*uMsg*/, WPARAM /*wParam*/, LPARAM /*lParam*/, BOOL& /*bHandled*/)
{
	// center the dialog on the screen
	CenterWindow();

	// set icons
	HICON hIcon = AtlLoadIconImage(IDR_MAINFRAME, LR_DEFAULTCOLOR, ::GetSystemMetrics(SM_CXICON), ::GetSystemMetrics(SM_CYICON));
	SetIcon(hIcon, TRUE);
	HICON hIconSmall = AtlLoadIconImage(IDR_MAINFRAME, LR_DEFAULTCOLOR, ::GetSystemMetrics(SM_CXSMICON), ::GetSystemMetrics(SM_CYSMICON));
	SetIcon(hIconSmall, FALSE);

	return TRUE;
}

LRESULT CMainDlg::OnCancel(WORD /*wNotifyCode*/, WORD wID, HWND /*hWndCtl*/, BOOL& /*bHandled*/)
{
	EndDialog(wID);
	return 0;
}

LRESULT CMainDlg::OnPaint(UINT /*uMsg*/, WPARAM /*wParam*/, LPARAM /*lParam*/, BOOL& /*bHandled*/)
{
	srand((unsigned)time(NULL));
	CPaintDC dc(this->m_hWnd);
	CBrush brush;
	CRect rect;
	GetClientRect(&rect);
	InvalidateRect(&rect, FALSE);
	brush.CreateSolidBrush(RGB(rand() % 255, rand() % 255, rand() % 255));
	dc.FillRect(&rect, brush);
	return TRUE;
}

无限次刷新客户区，实现重绘。

class CPaintDC : public CDC
{
public:
// Data members
	HWND m_hWnd;
	PAINTSTRUCT m_ps;

// Constructor/destructor
	CPaintDC(HWND hWnd)
	{
		ATLASSERT(::IsWindow(hWnd));
		m_hWnd = hWnd;
		m_hDC = ::BeginPaint(hWnd, &m_ps);
	}

	~CPaintDC()
	{
		ATLASSERT(m_hDC != NULL);
		ATLASSERT(::IsWindow(m_hWnd));
		::EndPaint(m_hWnd, &m_ps);
		Detach();
	}
};

可见，CPaintDC封装了只能在WM_PAINT消息下处理的BeginPaint、EndPaint函数。

case WM_PAINT:
hdc = BeginPaint(hwnd, &ps);
EndPaint(hwnd, &ps);

return 0;