MFC - 显示模式对话框时使主窗口变暗

MFC - dim main window when showing modal dialog(MFC - 显示模式对话框时使主窗口变暗)

问题描述

我有一个相当标准的 MFC 应用程序，它由一个主窗口组成，偶尔会显示模式对话框.众所周知，在模态对话框关闭之前，无法在其之外进行任何操作.

I have a fairly standard MFC application that consists of a main window, and occasionally brings up modal dialogs. As we all know nothing can be done outside a modal dialog until it is closed.

因此，一个不错的 UI 功能是使对话框后面的主窗口的其余部分变暗"，以直观地指示您在完成模式对话框之前无法使用它.一些 web 应用程序和 java/mac 应用程序会这样做，但我从未见过在传统的 C++/MFC 应用程序中这样做.我想试一试，即使它对平台来说是不寻常的.

Therefore, a nice UI feature is to "dim" the rest of the main window behind the dialog, to visually indicate you can't use it until you're done with the modal dialog. Some web apps and java/mac apps do this, but I've never seen it done in a traditional C++/MFC application. I'd like to give it a try, even if it's unusual for the platform.

如何做到这一点?我在应用程序中有几个模态对话框，用于这种模式:

How can this be done? I have several modal dialogs in the application, used in this pattern:

// pMainFrame is available as a pointer to the CWnd of the main window
CMyDialog dialog;
dialog.DoModal(); // invoke modal dialog; returns after dialog closed

有没有一种简单的方法可以在任何 DoModal() 之前使窗口变暗并在之后恢复?我正在使用 Visual Studio 2010，以防更新后的 MFC 有任何可能有帮助的功能.

Is there an easy way to have the window dimmed before any DoModal() and restored afterwards? I'm using Visual Studio 2010 in case the updated MFC has any features that might help.

我已经根据 oystein 的回答发布了一个解决方案，但我正在开始赏金，以防有人可以改进它 - 特别是平滑淡入/淡出.

推荐答案

你可以在你想变暗的窗口之上再创建一个全黑的窗口，并用 SetLayeredWindowAttributes.当然，它不一定是黑色，但我想这是最好的调光颜色.

You can create another window, completely black, on top of the window you want to dim, and set the black window's opacity with SetLayeredWindowAttributes. It doesn't have to be black, of course, but I guess that's the best dimming color.

我编写了一个示例 - 但请注意，我不是 MFC 开发人员，我通常直接使用 Windows API.不过，它似乎工作正常.这里是一个pastebin.随意添加淡入等.另请注意，这会使整个屏幕变暗，如果您不想要这种行为，则必须调整我的调光窗口的大小.查看代码注释.

I hacked together an example - but note that I am not an MFC developer, I usually use the Windows API directly. It seems to work okay, though. Here is a pastebin. Feel free to add fade-ins etc. yourself. Also note that this dims the entire screen, you'll have to resize my dimming-window if you don't want this behaviour. See code comments.

/**********************************************************************************************

    MFC screen dim test
        :: oystein          :: November 2010

    Creates a simple window - click it to toggle whether a translucent black "dimmer" window 
    is shown. The dimmer-window covers the entire screen, but the taskbar ("superbar" in 
    Windows 7) will jump on top of it if clicked - it seems. Simple suggestions to fix that
    are welcome.

    Should work on Windows 2000 and later. 

    Disclaimer: This is my first MFC program ever, so if anything seems wrong, it probably is.
    I have previously only coded with pure Win32 API, and hacked this together using online
    tutorials. Code provided "as-is" with no guarantees - I can not be held responsible for 
    anything bad that happens if you run this program.

***********************************************************************************************/

#include "stdafx.h"

#undef WINVER
#define WINVER 0x500 // Windows 2000 & above, because of layered windows


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
//
//                       Black window used to dim everything else 
//
class CDimWnd : public CFrameWnd
{               
public: 
    CDimWnd()
    {
        // Get screen res into rect
        RECT rc;
        GetDesktopWindow()->GetWindowRect(&rc);

        CreateEx(WS_EX_LAYERED |        // Layered window for translucency
                 WS_EX_TRANSPARENT |    // Click through
                 WS_EX_TOPMOST |        // Always on top
                 WS_EX_TOOLWINDOW,      // Do not appear in taskbar & similar
                 NULL, TEXT(""), 
                 WS_POPUP,              // No frame/borders - though there is 
                                        // still some border left - we'll remove 
                                        // it with regions

                 0, 0, rc.right + 10, rc.bottom + 10, // Make the window 10px larger 
                                                      // than screen resolution in both 
                                                      // directions - it is still positioned 
                                                      // at 0,0
                 NULL, NULL);

        // Grab a part of the window the size of the desktop - but 5px into it  
        // Because the window is larger than the desktop res, the borders are removed 
        CRgn rgn;                         
        rgn.CreateRectRgn(rc.left + 5, rc.top + 5, rc.right + 5, rc.bottom + 5);
        SetWindowRgn((HRGN)rgn, FALSE);
        rgn.Detach();                               

        // We have to reposition window - (0,0) of window has not changed
        SetWindowPos(NULL, -5, -5, 0, 0, SWP_NOSIZE | SWP_NOZORDER);        

        // This is where we set the opacity of the window: 0-255
        SetLayeredWindowAttributes(RGB(0,0,0), 150, LWA_ALPHA);                     
    }
    void Close()
    {
        CFrameWnd::OnClose();
    }
    BOOL CDimWnd::OnEraseBkgnd(CDC* pDC); // Set BKG color
    DECLARE_MESSAGE_MAP()
};

BOOL CDimWnd::OnEraseBkgnd(CDC* pDC)
{
    // Set brush to desired background color
    CBrush backBrush(RGB(0, 0, 0));

    // Save old brush
    CBrush* pOldBrush = pDC->SelectObject(&backBrush);

    CRect rect;
    pDC->GetClipBox(&rect);     // Erase the area needed

    pDC->PatBlt(rect.left, rect.top, rect.Width(), rect.Height(), PATCOPY);
    pDC->SelectObject(pOldBrush);   
    return TRUE;
}

BEGIN_MESSAGE_MAP(CDimWnd, CFrameWnd)
    ON_WM_ERASEBKGND()
END_MESSAGE_MAP()

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


// Global variable - is screen dimmed?
bool g_bIsDimmed = false;


// The main window
class CMainWnd : public CFrameWnd
{     
    // Contains a CDimWnd - I'm not sure if this is the "MFC way" of doing things
    CDimWnd dimmer; 

public: 
    CMainWnd()
    {
        Create(NULL, TEXT("Screen dimmer - Press left mouse button on window to toggle"), 
            WS_OVERLAPPEDWINDOW, CRect(50, 50, 400, 250));
    }
    // Left mouse button toggles dimming
    afx_msg void OnLButtonDown(UINT Flags, CPoint Point)
    {
        if(!g_bIsDimmed)
        {
            dimmer.ShowWindow(SW_SHOW);
            dimmer.BringWindowToTop();          
            g_bIsDimmed = true;
        }
        else
        {           
            dimmer.ShowWindow(SW_HIDE);     
            g_bIsDimmed = false;
        }
    }
    DECLARE_MESSAGE_MAP()
};

BEGIN_MESSAGE_MAP(CMainWnd, CFrameWnd)
    ON_WM_LBUTTONDOWN()
END_MESSAGE_MAP()


// The app
class CApp : public CWinApp
{
public:         
    virtual BOOL InitInstance();
};

BOOL CApp::InitInstance()
{               
    m_pMainWnd = new CMainWnd();              
    m_pMainWnd->ShowWindow(m_nCmdShow);           
    m_pMainWnd->UpdateWindow();        
    return TRUE;
}

CApp HelloApp;

---

更新:

我为您编写了更多代码来处理褪色问题.我仍然不是 MFC 开发人员，并且我将代码置于粗略"状态(很少有错误处理，不是很健壮)，以便您也可以做一些事情.:) 无论如何，这是一种方法，我认为它相当干净:

I hacked together some more code for you, to handle the fading. I'm still no MFC dev, and I left the code in a "rough" state (little error handling, not very robust) to give you something to do too. :) Anyway, here's one way to do it, that I think is fairly clean:

要使用它，让你的主窗口包含一个调光窗口

To use it, make your main window contain a dimmer window

class CMainFrm : public CFrameWnd
{     
    CDimWnd* dimmer; 

public: 
    CMainFrm()
    {
        // constructor code here ...
        dimmer = new CDimWnd();         
    }

// rest of class ...

};  

然后可以使用它，例如像这样:

It can then be used e.g. like this:

dimmer->Show();
MessageBox(TEXT("Hello world"));
dimmer->Hide();

或者我想你可以把这段代码(Show()/Hide() 调用)放在模态对话框的构造函数和析构函数中，如果你想保留那里的代码.如果您想要一个范围"-dim，就像您发布的示例中一样，此代码必须进入构造函数 &CDimWnd 类的析构函数，并且您需要静态成员变量之类的东西来确保一次只有一个调光器在运行(除非您想使用全局变量).

Alternatively I guess you could put this code (Show()/Hide() calls) in the constructor and destructor of the modal dialog, if you want to keep the code there. If you want a "scope"-dim, like in the example you posted, this code would have to go in the constructor & destructor of the CDimWnd class, and you would need something like a static member variable to ensure that only one dimmer is running at a time (unless you want to use a global variable).

对于较暗的窗口 - 我这样做了:

For the dimmer window - I did this:

CDimWnd.h

#define TARGET_OPACITY 70   // Target opacity 0-255 for dimmed window
#define FADE_TIME 20        // Time between each fade step in milliseconds
#define FADE_STEP 5      // How much to add to/remove from opacity each fade step
#define ID_FADE_TIMER 1

// Call Show() and Hide() to fade in/fade out dimmer. 
// Creates the dimmer window in constructor.
class CDimWnd : public CFrameWnd
{         
    bool m_isDimming;       

public: 
    CDimWnd();
    void Show();
    void Hide();            

protected:
    BOOL OnEraseBkgnd(CDC* pDC);
    void OnTimer(UINT_PTR nIDEvent);
    DECLARE_MESSAGE_MAP()
};

CDimWnd.cpp

#include "stdafx.h"
#include "CDimWnd.h"
#include "MainFrm.h"

BEGIN_MESSAGE_MAP(CDimWnd, CFrameWnd)
    ON_WM_ERASEBKGND()
END_MESSAGE_MAP()

CDimWnd::CDimWnd()
{
    // Get the main frame of the application which we want to dim.
    CMainFrame* pParent = theApp.pMainFrame;

    // Don't do anything if the main frame doesn't appear to be there
    if (pParent != NULL)
    {
        // Get the client area of the window to dim.
        CRect rc;
        pParent->GetClientRect(&rc);
        pParent->ClientToScreen(&rc);       // convert to screen coordinates

        // Do some fudging to fit the client area exactly.
        // Other applications may not need this if the above client area fits already.
        rc.top += GetSystemMetrics(SM_CYFRAME);
        rc.top += GetSystemMetrics(SM_CYCAPTION);           // MFC feature pack seems to include caption in client area
        rc.left -= GetSystemMetrics(SM_CXBORDER);
        rc.right += GetSystemMetrics(SM_CXBORDER) + 1;
        rc.bottom += GetSystemMetrics(SM_CYBORDER) + 1;

        // Create a layered window for transparency, with no caption/border.
        CreateEx(WS_EX_LAYERED | WS_EX_TRANSPARENT | WS_EX_TOOLWINDOW, NULL, TEXT(""), 
            WS_POPUP, rc.left, rc.top, rc.Width(), rc.Height(),
            pParent->GetSafeHwnd(), NULL);
    }
}


void CDimWnd::Show()
{
    // If we are not already dimming, go for it
    if(!m_isDimming)
    {
        // Bring in front of main window.
        BringWindowToTop();

        // Set opacity to 0
        SetLayeredWindowAttributes(RGB(0,0,0), 0, LWA_ALPHA);

        // Show the dimmer window
        ShowWindow(SW_SHOW);

        // Create timer - the rest is handled in OnTimer() function
        SetTimer(ID_FADE_TIMER, FADE_TIME, NULL);
    }
}


void CDimWnd::Hide()
{   
    // If we are dimming, go for it
    if(m_isDimming)
    {
        // Create timer - the rest is handled in OnTimer() function
        SetTimer(ID_FADE_TIMER, FADE_TIME, NULL);
    }
}


void CDimWnd::OnTimer(UINT_PTR nIDEvent)
{
    static int fade = 0;

    if(nIDEvent == ID_FADE_TIMER)
    {
        // We are dimming => we want to fade out
        if(m_isDimming)
        {
            if(fade < 0)
            {
                // Fading finished - hide window completely, update status & destroy timer
                fade = 0;
                ShowWindow(SW_HIDE);
                KillTimer(nIDEvent);
                m_isDimming = false;
            }
            else
            {
                // Set window opacity & update fade counter
                SetLayeredWindowAttributes(RGB(0,0,0), fade, LWA_ALPHA);
                fade -= FADE_STEP;
            }
        }
        else
        // fade in
        {
            if(fade > TARGET_OPACITY)
            {   
                // Fading finished - destroy timer & update status

                fade = TARGET_OPACITY; // but first, let's be accurate.
                SetLayeredWindowAttributes(RGB(0,0,0), fade, LWA_ALPHA);

                KillTimer(nIDEvent);
                m_isDimming = true;             
            }   
            else
            {
                // Set window opacity & update fade counter
                SetLayeredWindowAttributes(RGB(0,0,0), fade, LWA_ALPHA);
                fade += FADE_STEP;
            }
        }
    }
}


BOOL CDimWnd::OnEraseBkgnd(CDC* pDC)
{
    // Fill with black
    CBrush backBrush(RGB(0, 0, 0));
    CBrush* pOldBrush = pDC->SelectObject(&backBrush);

    CRect rect;
    pDC->GetClipBox(&rect);     // Erase the area needed
    pDC->PatBlt(rect.left, rect.top, rect.Width(), rect.Height(), PATCOPY);

    pDC->SelectObject(pOldBrush);   
    return TRUE;
}

好的.正如我所说，这很快就被拼凑在一起并且处于粗略的状态，但它应该为您提供一些可以使用的代码，以及(我认为)如何在 MFC 中使用计时器的一般概念.不过，我绝对不是考虑这个问题的合适人选:)

Okay. As I said, this was thrown together fairly quickly and is in a rough state, but it should give you some code to work from, and a general idea of how (I think) timers are used in MFC. I am definitely not the right person to think anything about that, though :)

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