MFC-显示模式对话框时主窗口变暗

Question

我有一个相当标准的MFC应用程序，它包含一个主窗口，偶尔会弹出模式对话框。 众所周知，在关闭模式对话框之前，无法进行任何其他操作。

因此，一个不错的UI功能是“隐藏”对话框后面的主窗口的其余部分，以直观地指示您直到完成模态对话框后才能使用它。 一些Web应用程序和Java / Mac应用程序可以做到这一点，但是我从未见过在传统的C ++ / MFC应用程序中做到这一点。 即使平台不常见，我也想尝试一下。

如何才能做到这一点？ 我在应用程序中有几种模式对话框，用于此模式：

// 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使窗口在任何DoModal（）之前变暗并在之后恢复？ 我正在使用Visual Studio 2010，以防更新的MFC具有任何可能有用的功能。

编辑：我已经发布了一个基于oystein答案的解决方案，但是如果有人可以改进它，我将开始提供赏金-尤其是平滑的淡入/淡出效果。

Answer 1

您可以在要调暗的窗口之上创建另一个全黑窗口，并使用SetLayeredWindowAttributes设置黑窗口的不透明度。 当然，它不一定必须是黑色的，但是我想那是最好的调光颜色。

编辑：我砍了一个例子-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。 这是一个pastebin。 随时自己添加淡入等。 另请注意，这会使整个屏幕变暗，如果您不希望这种行为，则必须调整我的变暗窗口的大小。 查看代码注释。

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

    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：

我为您整理了一些其他代码，以处理衰落。 我仍然不是MFC开发人员，我将代码保持在“粗糙”状态（错误处理很少，不是很可靠），您也可以做一些事情。 :)无论如何，这是一种方法，我认为它很干净：

要使用它，请使您的主窗口包含一个调光器窗口

class CMainFrm : public CFrameWnd
{     
    CDimWnd* dimmer; 

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

// rest of class ...

};  

然后可以像这样使用它：

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

另外，我想如果您想将代码（ Show() / Hide()调用）保留在模态对话框的构造函数和析构函数中，则可以将它们放在其中。 如果您想要“作用域” -dim（如在您发布的示例中一样），则此代码必须放入CDimWnd类的构造函数和析构函数中，并且您将需要诸如静态成员变量之类的内容以确保仅一个调光器一次运行（除非您要使用全局变量）。

对于调光器窗口-我这样做：

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。 就像我说的那样，这是相当快地投入使用的，并且处于粗糙状态，但是它应该为您提供一些可工作的代码，以及在MFC中使用（我认为）计时器的一般思路。 我绝对不是合适的人，但是:)

Answer 2

我已经接受了oystein的回答，因为它可以将我引向解决方案，但我认为我应该发表自己的修改。 我必须对其进行一些修改以使其对我有用，因此它可能对其他人很有用。

记录下来，调光效果很好，但是看起来不像我希望的那样自然。 在经常打开对话框的应用程序中，调光似乎分散了看似打开和关闭主窗口的规律，从而分散了人们的注意力。 为了妥协，我已经使调光相当微妙（约25％的不透明度），以柔和地突出显示活动对话框。 即时调光仍然有点让人分心，但我不确定如何使其淡入或淡出，尤其是在进行范围调整时。

另外，我不是UI专家，但调光给我一种印象，即该对话框与其背后的窗口内容不太相关。 即使对话框直接操作该内容，这也使我感觉与我在应用程序中所做的工作有些脱节。 这可能是另一个分心的问题。

无论如何，这里：

CDimWnd.h

// Dim the application main window over a scope.  Creates dimmer window in constructor.
class CDimWnd : public CFrameWnd
{               
public: 
    CDimWnd();
    BOOL OnEraseBkgnd(CDC* pDC);

    ~CDimWnd();

protected:
    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()

// For preventing two dimmer windows ever appearing
bool is_dimmer_active = false;

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,
    // or if there is already dimming happening.
    if (pParent != NULL && !is_dimmer_active)
    {
        // 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);

        // Bring in front of main window.
        BringWindowToTop();

        // Apply 25% opacity
        SetLayeredWindowAttributes(RGB(0,0,0), 64, LWA_ALPHA);

        // Show the dimmer window
        ShowWindow(SW_SHOW);

        is_dimmer_active = true;
    }
}

CDimWnd::~CDimWnd()
{
    is_dimmer_active = false;
}

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;
}

用法非常简单：因为CDimWnd在其构造函数中创建自己，所以您要做的就是将CDimWnd dimmer添加为对话框类的成员，并且无论您从何处调用对话框，它都会自动使主窗口变暗。

您还可以在范围内使用它来使系统模式对话框变暗：

{
    CDimWnd dimmer;
    MessageBox(...);
}

Answer 3

我无法抗拒这样做。

它是添加了计时器并实现淡入/淡出的代码。 我也改变了使用中间灰色而不是黑色的遮挡块。

您可以通过增加持续时间或增加速率来调整控制淡入淡出的常数以使其更平滑。 实验表明10hz的速率对我来说是平滑的，但是YMMV

// DimWnd.h : header file
#pragma once

class CDimWnd : public CFrameWnd
{
public:
    CDimWnd(class CWnd * pParent);
    virtual ~CDimWnd();
    BOOL OnEraseBkgnd(CDC* pDC);
    int opacity, opacity_increment;
protected:
    DECLARE_MESSAGE_MAP()

public:
    afx_msg void OnTimer(UINT_PTR nIDEvent);
    void fadeOut();
};

---

// DimWnd.cpp : implementation file
//

#include "stdafx.h"
#include "dimmer.h"
#include "DimWnd.h"
#include "MainFrm.h"
#include <math.h>

const int TIMER_ID = 111;

// For preventing two dimmer windows ever appearing
bool is_dimmer_active = false;

// constants to control the fade.
int    ticks_per_second  = 1000; // ms
int    start_opacity     = 44;   // 20%
int    max_opacity       = 220;  // 0->255
double fade_in_duration  = 4;    // seconds to fade in  (appear)
double fade_out_duration = 0.2;    // seconds to fade out (disappear)
int    rate              = 100;  // Timer rate (ms


CDimWnd::CDimWnd(CWnd * pParent)
{
    // Don't do anything if the main frame doesn't appear to be there,
    // or if there is already dimming happening.
    if (pParent != NULL && !is_dimmer_active)
    {
        // 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);

        // Bring in front of main window.
        BringWindowToTop();

        // Show the dimmer window
        ShowWindow(SW_SHOW);


        double increment_per_second = ((max_opacity - start_opacity) / fade_in_duration);
        opacity_increment = ceil(  increment_per_second / (ticks_per_second / rate) ) ;

        is_dimmer_active = true;
        opacity = start_opacity;

        SetLayeredWindowAttributes(RGB(0,0,0), opacity, LWA_ALPHA);

        SetTimer(TIMER_ID, rate,NULL);  

    }
}

CDimWnd::~CDimWnd()
{
    fadeOut(); // fade the window out rather than just disappearing.
    is_dimmer_active = false;
}

void CDimWnd::fadeOut()
{
    // can't use timers as may be in the process of being destroyed so make it quick..

    double increment_per_second = ((opacity - start_opacity) / fade_out_duration);
    opacity_increment = ceil(  increment_per_second / (ticks_per_second / rate) ) ;

    while(opacity  > start_opacity)
    {
        opacity -= opacity_increment;
        SetLayeredWindowAttributes(RGB(0,0,0), opacity, LWA_ALPHA);
        Sleep(100);
    }
}

BOOL CDimWnd::OnEraseBkgnd(CDC* pDC)
{
    // Fill with midgray
    CBrush backBrush(RGB(128,128,128));
    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()
    ON_WM_TIMER()
END_MESSAGE_MAP()

void CDimWnd::OnTimer(UINT_PTR nIDEvent)
{
    if (opacity >= max_opacity) 
    {
        // stop the timer when fade in finished.
        KillTimer(TIMER_ID);
        return;
    }

    opacity += opacity_increment;
    SetLayeredWindowAttributes(RGB(0,0,0), opacity, LWA_ALPHA);

    CFrameWnd::OnTimer(nIDEvent);
}