一．問題的提出
???在WINDOWS的WINHELPER幫助系統中大量使用一類帶陰影的彈出窗口, 這類窗口非常簡潔,并具有立體感,它們用來顯示一些只讀信息.此類彈出窗口不同于一般的窗口,它們沒有標題和滾動桿,但都具有帶陰影的邊框, 并且其窗口的大小隨顯示字符串多少而自動調節,當顯示信息彈出之后，任何來自鍵盤或鼠標的消息都將導致彈出窗口的消失。 然而WINDOWS API接口中沒有現成的函數來實現此項功能,即使是最新版的 VISUAL C++ MFC也沒有提供現成的類和函數來實現帶陰影的此類窗口。為此,筆者基于面向對象的程序設計思想，從CWnd派生一個新類來實現這個功能，并且將該類窗口的所有函數完全封裝在一起，使用就像調用“ MessageBox()”函數顯示信息一樣簡單。
二．實現方法的幾個關鍵部分說明如下 ,要解決怎樣畫非用戶區的問題:當WINDOWS需要創建一個窗口時,它發送兩個消息：WM_NCPAINT和 WM_PAINT到應用程序消息隊列。WM_NCPAINT用于重畫窗口的非用戶區,如標題,邊框和滾動桿,本程序正是響應WM_NCPAINT消息來重畫帶陰影的彈出窗口的邊框；畫客戶區很簡單,只需響應WM_PAINT消息處理字符的顯示即可.2.如何動態調整彈出窗口的尺寸:大家知道,在一個矩形內顯示文本串時,常用函數DrawText(HDC hDC,LPTSTR lpszText,int cbCount,RECT FAR* lpRect,UINT fuFormat).但是,此時我們的帶陰影的彈出窗口并為建立.當然不能利用它來顯示.然而,我們注意到上述函數中的最后一個參數FuFormat, 它是文字格式的組合,其中有一個鮮為人知的參數 DT_CALCRECT, 使用這個參數,字符串不顯示,但它根據當前字體測量待顯示串的高度, 本程序正是根據這個參數來確定彈出窗口的大小，并以此建立一個隨字符串大小而變化的窗口,下面給出其實現該功能的片斷: void CShadowWnd::ShowText(CString sText) dc.CreateDC("DISPLAY",NULL,NULL,NULL); //創建一個顯示設備描述表 dc.SelectObject(GetStockObject(SYSTEM_FONT)); //選擇字體到設備描述表 CRect rect(0,0,MAXWIDTH,0);//
//獲得待顯示的字符串 sText 的實際高度和寬度,并將其存入矩形rect中
??dc.DrawText(sText,rect,DT_WORDBREAK|DT_CENTER|DT_CALCRECT|DT_NOPREFIX);
3.怎樣獲取對系統的控制權:
???在帶陰影的彈出窗口顯示之后,怎樣獲取對系統的控制權,使得當用戶按下鍵盤任意鍵或鼠標時都將使帶陰影的彈出窗口消失,這里采取的方法是,當彈出窗口創建和顯示之后,立即進入一個消息循環,從應用程序隊列中獲取所有消息,并判斷是否為鼠標消息或鍵盤消息,如是,則摧毀窗口結束,并將控制權歸還給調用程序.實現片斷如下:
//進入消息循環,獲取全部消息,控制整個系統
?1?????MSG?Msg;
?2?????BOOL?bDone;
?3?????SetCapture();
?4?????bDone?=?FALSE;
?5?????while(!bDone)
?6?????{
?7?????????if(PeekMessage(&Msg,NULL,0,0,PM_REMOVE))
?8?????????????if(Msg.message?==?WM_KEYDOWN?||?Msg.message?==?WM_SYSKEYDOWN||
?9?????????????????Msg.message?==?WM_LBUTTONDOWN?||?Msg.message?==?WM_RBUTTONDOWN)
10?????????????????bDone?=?TRUE;
11?????????????else
12?????????????{
13?????????????????TranslateMessage(&Msg);
14?????????????????DispatchMessage(&Msg);
15?????????????}
16?????}
17??ReleaseCapture();
???? ?DestroyWindow();
. 帶陰影的類 CShadowWnd 類的頭文件及其實現文件的全部細節
?1?#pragma?once
?2?
?3?
?4?//?CShadowWnd
?5?
?6?class?CShadowWnd?:?public?CWnd
?7?{
?8?????DECLARE_DYNAMIC(CShadowWnd)
?9?
10?public:
11?????CShadowWnd();
12?????virtual?~CShadowWnd();
13?
14?protected:
15?????DECLARE_MESSAGE_MAP()
16?
17?public:
18?????virtual?BOOL?Create(const?RECT&?rect,?CWnd*?pParentWnd);
19?????CString?m_sShowText;
20?????void?ShowReadOnlyText(CString?sText);
21?????CBrush?m_bmpBrush;
22?protected:
23?????afx_msg?void?OnNcPaint();
24?????afx_msg?void?OnPaint();
25?????afx_msg?int?OnCreate(LPCREATESTRUCT?lpCreateStruct);
26?
27?};
28?
// cpp
??1?//?ShadowWnd.cpp?:?實現文件
??2?//
??3?
??4?#include?"stdafx.h"
??5?#include?"MFCApp.h"
??6?#include?"ShadowWnd.h"
??7?
??8?//陰影位圖數組?
??9?static?int?aPattern[]={0xAA,0x55,0xAA,0x55,0xAA,0x55,0xAA,0x55};
?10?#define?SPOPUP_SHADOWWIDTH?10????//陰影寬度?
?11?#define?SPOPUP_SHADOWHEIGHT?13????//陰影高度?
?12?#define????MAXWIDTH????400????????????//顯示字符矩形的最大寬度?
?13?
?14?
?15?IMPLEMENT_DYNAMIC(CShadowWnd,?CWnd)
?16?
?17?CShadowWnd::CShadowWnd()
?18?{
?19?????CBitmap?bmp;
?20?????bmp.CreateBitmap(8,8,1,1,(void*)aPattern);????//創建一個陰影位圖?
?21?????m_bmpBrush.CreatePatternBrush(&bmp);????????//創建一把陰影刷?
?22?}
?23?
?24?CShadowWnd::~CShadowWnd()
?25?{
?26?}
?27?
?28?
?29?BEGIN_MESSAGE_MAP(CShadowWnd,?CWnd)
?30?????ON_WM_NCPAINT()
?31?????ON_WM_PAINT()
?32?????ON_WM_CREATE()
?33?END_MESSAGE_MAP()
?34?
?35?BOOL?CShadowWnd::Create(const?RECT&?rect,?CWnd*?pParentWnd)
?36?{
?37?????LPCTSTR?pClassName?=?AfxRegisterWndClass(CS_HREDRAW|CS_VREDRAW);
?38?????return?CWnd::CreateEx(WS_EX_STATICEDGE,pClassName,L"Shadow?window",WS_POPUP,
?39?????????rect.left,rect.top,rect.right,rect.bottom,
?40?????????pParentWnd->GetSafeHwnd(),0,NULL);
?41?}
?42?void?CShadowWnd::OnNcPaint()
?43?{
?44?????CWindowDC?dc(this);
?45?????CRect?rc;
?46?????GetWindowRect(&rc);
?47?????rc.right?-=?rc.left;
?48?????rc.bottom?-=?rc.top;
?49?????rc.top?=?0;
?50?????rc.left?=?0;
?51?????m_bmpBrush.UnrealizeObject();
?52?????CBrush?*OldBrush?=?dc.SelectObject(&m_bmpBrush);
?53?????//畫底部陰影?
?54?????dc.PatBlt(rc.left+SPOPUP_SHADOWWIDTH,rc.bottom-SPOPUP_SHADOWHEIGHT,
?55?????????rc.right-SPOPUP_SHADOWWIDTH,SPOPUP_SHADOWHEIGHT,PATCOPY);
?56?????//畫右邊陰影?
?57?????dc.PatBlt(rc.right-SPOPUP_SHADOWWIDTH,rc.top+SPOPUP_SHADOWHEIGHT,
?58?????????SPOPUP_SHADOWWIDTH,rc.bottom,PATCOPY);
?59?????dc.SelectObject(OldBrush);
?60?????CBrush?*pBrush?=?CBrush::FromHandle(GetSysColorBrush(COLOR_WINDOWFRAME));
?61?????rc.right?-=?SPOPUP_SHADOWWIDTH;
?62?????rc.bottom?-=?SPOPUP_SHADOWHEIGHT;
?63?????dc.FrameRect(rc,pBrush);????//畫邊框?
?64?}
?65?
?66?void?CShadowWnd::OnPaint()
?67?{
?68?????CPaintDC?dc(this);?//?device?context?for?painting
?69?????CRect?rect;
?70?????GetClientRect(&rect);
?71?????rect.left?+=?5;
?72?????rect.top?+=?5;
?73?????rect.right?-=?SPOPUP_SHADOWWIDTH;
?74?????rect.bottom?-=?SPOPUP_SHADOWHEIGHT;
?75?????dc.SetTextColor(RGB(0,0,255));
?76?????dc.DrawText(m_sShowText,rect,DT_WORDBREAK|DT_NOPREFIX);
?77?}
?78?
?79?void?CShadowWnd::ShowReadOnlyText(CString?sText)
?80?{
?81?????m_sShowText?=?sText;????//存入顯示字符串?
?82?????CDC?dc;
?83?????dc.CreateDC(L"DISPLAY",NULL,NULL,NULL);????//創建一個顯示設備描述表?
?84?????dc.SelectObject(GetStockObject(SYSTEM_FONT));????//選擇字體到設備描述表?
?85?????CRect?rect(0,0,MAXWIDTH,0);
?86?????//獲得待顯示的字符串?sText?的實際高度和寬度?
?87?????dc.DrawText(sText,rect,DT_WORDBREAK|DT_CENTER|DT_CALCRECT|DT_NOPREFIX);
?88?????//為矩形留些余量?
?89?????rect.right?+=?3*SPOPUP_SHADOWWIDTH;
?90?????rect.bottom?+=?3*SPOPUP_SHADOWHEIGHT;
?91?????this->Create(rect,0);????//創建窗口?
?92?????this->ShowWindow(SW_SHOW);
?93?????this->UpdateWindow();????//立刻更新窗口?
?94?????//進入消息循環,獲取全部消息,控制整個系統?
?95?????MSG?Msg;
?96?????BOOL?bDone;
?97?????SetCapture();
?98?????bDone?=?FALSE;
?99?????while(!bDone)
100?????{
101?????????if(PeekMessage(&Msg,NULL,0,0,PM_REMOVE))
102?????????????if(Msg.message?==?WM_KEYDOWN?||?Msg.message?==?WM_SYSKEYDOWN||
103?????????????????Msg.message?==?WM_LBUTTONDOWN?||?Msg.message?==?WM_RBUTTONDOWN)
104?????????????????bDone?=?TRUE;
105?????????????else
106?????????????{
107?????????????????TranslateMessage(&Msg);
108?????????????????DispatchMessage(&Msg);
109?????????????}
110?????}
111?????ReleaseCapture();
112?????DestroyWindow();
113?}
114?
115?int?CShadowWnd::OnCreate(LPCREATESTRUCT?lpCreateStruct)
116?{
117?????if?(CWnd::OnCreate(lpCreateStruct)?==?-1)
118?????????return?-1;
119?????CenterWindow();
120?????return?0;
121?}
122?
四.使用方法:
1.???將該類增加到一個項目文件中
2. 在你欲使用函數的類(一般為視類或框架窗口類)中增加一個成員變量(如:CShadowWnd m_ShadowWnd),當需要使用帶陰影的彈出窗口顯示信息時,調用成員函數(如: m_ShadowWnd.ShowReadOnlyText(String sText)即可,無須考慮其實現細節