ScreenBase实现屏幕任意区域的截取

//========================================================================
//TITLE:
// ScreenBase实现屏幕任意区域的截取
//AUTHOR:
// norains
//DATE:
// Tuesday 16-January -2007
//Environment:
// EVC4.0 + Standard SDK
//========================================================================

1.ScreenBase 源码

ScreenBase为自己写代码方便而封装的一个API类,该类的的主要功能是截取屏幕任意区域的图像,并将之保存为BMP文件.

源代码如下:

// ScreenBase.h: interface for the CScreenBase class.
#ifndef SCREENBASE_H
#define SCREENBASE_H
//-------------------------------------------------------------------

class CScreenBase

//--------------------------------------------------------------------------
#endif // !defined SCREENBASE_H

// ScreenBase.cpp: implementation of the CScreenBase class.

#include "stdafx.h"
#include "ScreenBase.h"

// Construction/Destruction

CScreenBase::CScreenBase()

CScreenBase::~CScreenBase()

//----------------------------------------------------------------------
//Description:
// Destroy the save DC
//--------------------------------------------------------------------
void CScreenBase::DestroySaveDC(LPSAVEDCINFO lpSaveDCInfo, LPSAVEBITMAPINFO lpSaveBitmapInfo)

//----------------------------------------------------------------------
//Description:
// Initialize the save DC
//--------------------------------------------------------------------
void CScreenBase::InitializeSaveDC(LPSAVEDCINFO lpSaveDCInfo, LPSAVEBITMAPINFO lpSaveBitmapInfo,const RECT *prcSave)

//----------------------------------------------------------------------
//Description:
// Save the bitmap of save dc to the file
//--------------------------------------------------------------------
void CScreenBase::SaveFile(LPSAVEBITMAPINFO lpSaveBitmapInfo, TCHAR *pszPath)

//----------------------------------------------------------------------
//Description:
// Copy the screen DC to the dest DC
//--------------------------------------------------------------------
void CScreenBase::CopyScreenDC(HDC *pHdcDest,const LPSAVEBITMAPINFO lpSaveBitmapInfo,const RECT *prcSrc)

//----------------------------------------------------------------------
//Description:
// Initialize the instance
//--------------------------------------------------------------------
void CScreenBase::Initialize(const RECT *prcScr)

//----------------------------------------------------------------------
//Description:
// Destroy all the resource
//--------------------------------------------------------------------
void CScreenBase::Destroy()

//----------------------------------------------------------------------
//Description:
// Save the bitmap of screen to the file
//--------------------------------------------------------------------
void CScreenBase::SaveFile(TCHAR *pszPath)

//----------------------------------------------------------------------
//Description:
// Copy the screen to the save DC
//--------------------------------------------------------------------
void CScreenBase::CopyScreen()

2.如何截取屏幕

采用CScreenBase类截取全屏非常简单:

首先声明一个CScreenBase类对象:

CScreenBase scrBase;

接着便是初始化:

scrBase.Initialize();

拷贝屏幕图像:

scrBase.CopyScreen();

最后,把截屏保存到文件中:

scrBase.SaveFile(TEXT("Capture.bmp"));

如果是截取屏幕的某个区域,需要在初始化的时候确定区域.
例如,我们需要截取屏幕上以(20,20)为起点,对角为(50,60)的区域,只需更改初始化代码即可:

scrBase.Initialize(&rcWnd);

3.进阶用法:将截取的区域直接显示到屏幕

因为CScreenBase类本意是作为一个截图的基本类,所以没有封装直接显示到屏幕的方法.不过,我们可以继承该类,然后返回保存区域图片的句柄,最后将其显示于屏幕即可.

派生一个ScreenPro类,用来返回所需的句柄.

class ScreenPro: public CScreenBase
//----------------------------------------------------------------------
//Description:
// On message WM_PAINT
//--------------------------------------------------------------------
void OnPaint(HWND hWnd, UINT wMsg, WPARAM wParam, LPARAM lParam)
...{




if(m_bScrCapture == TRUE)




...{


//如果已经截屏,则将其显示于屏幕上




PAINTSTRUCT ps;


HDC hdc = BeginPaint(hWnd,&ps);




//获取截屏的区域


RECT rcWnd ;


rcWnd = m_ScrCapture.GetSaveRect();




//获取截屏数据保存的DC


HDC hSaveDC = NULL;


hSaveDC = m_ScrCapture.GetSaveDC();




//绘制到屏幕


BitBlt(hdc,rcWnd.left,rcWnd.top,rcWnd.right,rcWnd.bottom,hSaveDC,0,0,SRCCOPY);


EndPaint(hWnd,&ps);


}


else




...{


DefWindowProc(hWnd,wMsg,wParam,lParam);


}


}