这段时间在研究直接写屏的方法.
此问题的起因是: 在 iMX31(WinCE 5.0)上, 屏的分辨为: 800*480. 调用 BitBlt() API 函数画一整屏的动作, 竟然需要 120ms 左右; 同样的程序, 在 Prima 上只需要 20ms 以内的时间.
直接写屏, 需要用到以下两个主要的函数: CreateDC(TEXT("DISPLAY"),......) 和 CreateDIBSection().
1) CreateDC(TEXT("DISPLAY"),......) 的用法比较简单, 参考 MSDN 就可以很容易的搞定.
2) CreateDIBSection() API 函数的使用, 花了我一些时间. 因为以前没有用过它, 所以将其使用的方法记录如下:
{
HBITMAP hDIBitmap;
LPBYTE lpBitmapBits;
BITMAPINFO DriectBmp;
ZeroMemory(&DriectBmp,sizeof(BITMAPINFO));
DriectBmp.bmiHeader.biSize=sizeof(BITMAPINFOHEADER);
DriectBmp.bmiHeader.biWidth = 800;
DriectBmp.bmiHeader.biHeight = 480;
DriectBmp.bmiHeader.biPlanes = 1;
DriectBmp.bmiHeader.biBitCount = 16;
HDC dcDirect = CreateCompatibleDC(dcBuf);
// 建立 hDIBitmap, dcDirect, 和 lpBitmapBits 之间的关系.
// 通过 DC 操作向 dcDirect 中写入图形数据,
//从 lpBitmapBits 中取得内存数据, 进行内存 Copy 操作, 直接写向显存.
hDIBitmap = CreateDIBSection(dcDirect, (BITMAPINFO *)&DriectBmp,
DIB_RGB_COLORS, (void **)&lpBitmapBits, NULL, 0);
if(NULL != hDIBitmap)
{
HGDIOBJ OldBitmap = SelectObject(dcDirect, hDIBitmap);
BitBlt(dcDirect,0,0,800,480,dcBuf,0,0,SRCCOPY);
CopyMemory(gpbFrameAddress,lpBitmapBits,800 * 480 * 2);
SelectObject(dcDirect,OldBitmap);
}
DeleteObject(hDIBitmap);
DeleteDC(dcDirect);
}
在研究此问题的过程中, 在 CSDN 上找到一个很好的资源, 也记录在自己这里:
http://topic.csdn.net/u/20090629/09/00b25d0d-d461-47dc-88ad-0e2131a5abc7.html
并转载其中关键的代码如下:
#include "stdafx.h"
#include "CopyScreen.h"
#include <windows.h>
#include <commctrl.h>
#include"Jpeg.h"
#define MAX_LOADSTRING 100
// 全局变量:
HINSTANCEg_hInst;// 当前实例
HWNDg_hWndMenuBar;// 菜单栏句柄
// 此代码模块中包含的函数的前向声明:
ATOMMyRegisterClass(HINSTANCE, LPTSTR);
BOOLInitInstance(HINSTANCE, int);
LRESULT CALLBACKWndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACKAbout(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPTSTRlpCmdLine,
int nCmdShow)
{
MSG msg;
// 执行应用程序初始化:
if (!InitInstance(hInstance, nCmdShow))
{
return FALSE;
}
HACCEL hAccelTable;
hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_COPYSCREEN));
// 主消息循环:
while (GetMessage(&msg, NULL, 0, 0))
{
if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
return (int) msg.wParam;
}
//
// 函数: MyRegisterClass()
//
// 目的: 注册窗口类。
//
// 注释:
//
ATOM MyRegisterClass(HINSTANCE hInstance, LPTSTR szWindowClass)
{
WNDCLASS wc;
wc.style = CS_HREDRAW | CS_VREDRAW;
wc.lpfnWndProc = WndProc;
wc.cbClsExtra= 0;
wc.cbWndExtra= 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_COPYSCREEN));
wc.hCursor = 0;
wc.hbrBackground = (HBRUSH) GetStockObject(WHITE_BRUSH);
wc.lpszMenuName = 0;
wc.lpszClassName = szWindowClass;
return RegisterClass(&wc);
}
//
// 函数: InitInstance(HINSTANCE, int)
//
// 目的: 保存实例句柄并创建主窗口
//
// 注释:
//
//在此函数中，我们在全局变量中保存实例句柄并
//创建和显示主程序窗口。
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
HWND hWnd;
TCHAR szTitle[MAX_LOADSTRING];// 标题栏文本
TCHAR szWindowClass[MAX_LOADSTRING];// 主窗口类名
g_hInst = hInstance; // 将实例句柄存储在全局变量中
// 在应用程序初始化期间，应调用一次 SHInitExtraControls 以初始化
// 所有设备特定控件，例如，CAPEDIT 和 SIPPREF。
SHInitExtraControls();
LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
LoadString(hInstance, IDC_COPYSCREEN, szWindowClass, MAX_LOADSTRING);
//如果它已经在运行，则将焦点置于窗口上，然后退出
hWnd = FindWindow(szWindowClass, szTitle);
if (hWnd)
{
// 将焦点置于最前面的子窗口
// “| 0x00000001”用于将所有附属窗口置于前台并
// 激活这些窗口。
SetForegroundWindow((HWND)((ULONG) hWnd | 0x00000001));
return 0;
}
if (!MyRegisterClass(hInstance, szWindowClass))
{
return FALSE;
}
hWnd = CreateWindow(szWindowClass, szTitle, WS_VISIBLE,
CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
NULL, NULL, hInstance, NULL);
if (!hWnd)
{
return FALSE;
}
// 使用 CW_USEDEFAULT 创建主窗口时，将不会考虑菜单栏的高度(如果创建了一个
// 菜单栏)。因此，我们要在创建窗口后调整其大小
// 如果菜单栏存在
if (g_hWndMenuBar)
{
RECT rc;
RECT rcMenuBar;
GetWindowRect(hWnd, &rc);
GetWindowRect(g_hWndMenuBar, &rcMenuBar);
rc.bottom -= (rcMenuBar.bottom - rcMenuBar.top);
MoveWindow(hWnd, rc.left, rc.top, rc.right-rc.left, rc.bottom-rc.top, FALSE);
}
ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);
return TRUE;
}
HBITMAP CopyScreenToBitmap(int &nWidth,int &nHeight)
{
// 屏幕和内存设备描述表
HDC hScrDC, hMemDC;
// 位图句柄
HBITMAP hBitmap, hOldBitmap;
// 屏幕分辨率
int xScrn, yScrn;
//为屏幕创建设备描述表
hScrDC = CreateDC(_T("DISPLAY"), NULL, NULL, NULL);
//为屏幕设备描述表创建兼容的内存设备描述表
hMemDC = CreateCompatibleDC(hScrDC);
// 获得屏幕分辨率
xScrn = GetDeviceCaps(hScrDC, HORZRES);
yScrn = GetDeviceCaps(hScrDC, VERTRES);
//存储屏幕的长宽
nWidth = xScrn;
nHeight = yScrn;
// 创建一个与屏幕设备描述表兼容的位图
hBitmap = CreateCompatibleBitmap(hScrDC, xScrn, yScrn);
// 把新位图选到内存设备描述表中
hOldBitmap = (HBITMAP)SelectObject(hMemDC, hBitmap);
// 把屏幕设备描述表拷贝到内存设备描述表中
BitBlt(hMemDC, 0, 0, xScrn,yScrn,hScrDC, 0, 0, SRCCOPY);
//得到屏幕位图的句柄
hBitmap = (HBITMAP)SelectObject(hMemDC, hOldBitmap);
//清除
DeleteDC(hScrDC);
DeleteDC(hMemDC);
// 返回位图句柄
return hBitmap;
}
//将截屏所得保存为16位的图片
int Save16BitmapToFile(HBITMAP hBitmap,LPCTSTR lpFileName)
{
HDC hDC=CreateDC(TEXT("DISPLAY"),NULL,NULL,NULL);
HDC hOffDC=CreateCompatibleDC(hDC);
SelectObject(hOffDC,hBitmap);
BITMAP Bitmap;
GetObject(hBitmap,sizeof(BITMAP),&Bitmap);
HANDLE fh=CreateFile(lpFileName,GENERIC_WRITE,0,NULL,CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN,NULL);
if(fh == INVALID_HANDLE_VALUE )
return FALSE;
BITMAPFILEHEADER bfh;
memset(&bfh,0,sizeof(bfh));
bfh.bfType=0x4D42/*((WORD) ('M' << 8) | 'B')*/;
bfh.bfSize= sizeof(bfh)+2*Bitmap.bmWidth*Bitmap.bmHeight
+sizeof(BITMAPFILEHEADER);
bfh.bfOffBits=sizeof(BITMAPINFOHEADER)+sizeof(BITMAPFILEHEADER);
DWORD dwWritten=0;
WriteFile(fh,&bfh,sizeof(bfh),&dwWritten,NULL);
BITMAPINFOHEADER bih;
memset(&bih,0,sizeof(bih));
bih.biSize=sizeof(bih);
bih.biWidth=Bitmap.bmWidth;
bih.biHeight=Bitmap.bmHeight;
bih.biPlanes=1;
bih.biBitCount=16;
if( !WriteFile(fh,&bih,sizeof(bih),&dwWritten,NULL) )
{
return FALSE;
}
BITMAPINFO bitmapInfo;
memset((void *)&bitmapInfo,0,sizeof(BITMAPINFO) );
bitmapInfo.bmiHeader=bih;
HDC hMemDC=CreateCompatibleDC(hDC);
BYTE *m_lpBitBmp=new BYTE[bfh.bfSize-sizeof(BITMAPFILEHEADER)];
HBITMAP hDibBitmap=CreateDIBSection(hMemDC,&bitmapInfo,
DIB_RGB_COLORS,(void **)&m_lpBitBmp,NULL,0);
if(hDibBitmap != 0)
{
::SelectObject(hMemDC,hDibBitmap);
BitBlt(hMemDC,0,0,Bitmap.bmWidth,Bitmap.bmHeight,hOffDC,0,0,SRCCOPY);
WriteFile(fh,m_lpBitBmp,bfh.bfSize-sizeof(BITMAPFILEHEADER),
&dwWritten,NULL);
}
DeleteObject(hDibBitmap);
DeleteDC(hDC);
DeleteDC(hMemDC);
CloseHandle(fh);
return 1;
}
//将截屏所得保存为24位的图片
int Save24BitmapToFile(HBITMAP hBitmap,LPCTSTR lpFileName)
{
HDC hDC=CreateDC(TEXT("DISPLAY"),NULL,NULL,NULL);
HDC hOffDC=CreateCompatibleDC(hDC);
SelectObject(hOffDC,hBitmap);
BITMAP Bitmap;
GetObject(hBitmap,sizeof(BITMAP),&Bitmap);
HANDLE fh=CreateFile(lpFileName,GENERIC_WRITE,0,NULL,CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN,NULL);
if(fh == INVALID_HANDLE_VALUE )
return FALSE;
BITMAPFILEHEADER bfh;
memset(&bfh,0,sizeof(bfh));
bfh.bfType=0x4D42/*((WORD) ('M' << 8) | 'B')*/;
bfh.bfSize= sizeof(bfh)+3*Bitmap.bmWidth*Bitmap.bmHeight
+sizeof(BITMAPFILEHEADER);
bfh.bfOffBits=sizeof(BITMAPINFOHEADER)+sizeof(BITMAPFILEHEADER);
DWORD dwWritten=0;
WriteFile(fh,&bfh,sizeof(bfh),&dwWritten,NULL);
BITMAPINFOHEADER bih;
memset(&bih,0,sizeof(bih));
bih.biSize=sizeof(bih);
bih.biWidth=Bitmap.bmWidth;
bih.biHeight=Bitmap.bmHeight;
bih.biPlanes=1;
bih.biBitCount=24;
if( !WriteFile(fh,&bih,sizeof(bih),&dwWritten,NULL) )
{
return FALSE;
}
BITMAPINFO bitmapInfo;
memset((void *)&bitmapInfo,0,sizeof(BITMAPINFO) );
bitmapInfo.bmiHeader=bih;
HDC hMemDC=CreateCompatibleDC(hDC);
BYTE *m_lpBitBmp=new BYTE[3*Bitmap.bmWidth*Bitmap.bmHeight];
HBITMAP hDibBitmap=CreateDIBSection(hMemDC,&bitmapInfo,
DIB_RGB_COLORS,(void **)&m_lpBitBmp,NULL,0);
if(hDibBitmap != 0)
{
::SelectObject(hMemDC,hDibBitmap);
BitBlt(hMemDC,0,0,Bitmap.bmWidth,Bitmap.bmHeight,hOffDC,0,0,SRCCOPY);
WriteFile(fh,m_lpBitBmp,3*Bitmap.bmWidth*Bitmap.bmHeight,&dwWritten,NULL);
}
DeleteObject(hDibBitmap);
DeleteDC(hDC);
DeleteDC(hMemDC);
CloseHandle(fh);
return 1;
}
/*索引颜色/颜色表
位图常用的一种压缩方法。从位图图片中选择最有代表性的若干种颜色（通常不超过256种）
编制成颜色表，然后将图片中原有颜色用颜色表的索引来表示。
这样原图片可以被大幅度有损压缩。适合于压缩网页图形等颜色数较少的图形，
不适合压缩照片等色彩丰富的图形。 */
//将截屏所得保存为32位带颜色表的图片
int Save32BitmapToFile(HBITMAP hBitmap,LPCTSTR lpFileName)
{
/*若不使用颜色表，则去掉bih.biCompression=BI_BITFIELDS;这句，然后
不设置bitmapInfo.bmiColors[0].rgbRed=255;
bitmapInfo.bmiColors[0].rgbGreen=255;
bitmapInfo.bmiColors[0].rgbBlue=255;*/
HDC hDC=CreateDC(TEXT("DISPLAY"),NULL,NULL,NULL);
HDC hOffDC=CreateCompatibleDC(hDC);
SelectObject(hOffDC,hBitmap);
BITMAP Bitmap;
GetObject(hBitmap,sizeof(BITMAP),&Bitmap);
HANDLE fh=CreateFile(lpFileName,GENERIC_WRITE,0,NULL,CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN,NULL);
if(fh == INVALID_HANDLE_VALUE )
return FALSE;
BITMAPFILEHEADER bfh;
memset(&bfh,0,sizeof(bfh));
bfh.bfType=0x4D42/*((WORD) ('M' << 8) | 'B')*/;
bfh.bfSize= sizeof(bfh)+4*Bitmap.bmWidth*Bitmap.bmHeight
+sizeof(BITMAPFILEHEADER);
bfh.bfOffBits=sizeof(BITMAPINFOHEADER)+sizeof(BITMAPFILEHEADER);
DWORD dwWritten=0;
WriteFile(fh,&bfh,sizeof(bfh),&dwWritten,NULL);
BITMAPINFOHEADER bih;
memset(&bih,0,sizeof(bih));
bih.biSize=sizeof(bih);
bih.biWidth=Bitmap.bmWidth;
bih.biHeight=Bitmap.bmHeight;
bih.biPlanes=1;
bih.biBitCount=32;
bih.biCompression=BI_BITFIELDS;
if( !WriteFile(fh,&bih,sizeof(bih),&dwWritten,NULL) )
{
return FALSE;
}
BITMAPINFO bitmapInfo;
memset((void *)&bitmapInfo,0,sizeof(BITMAPINFO) );
bitmapInfo.bmiHeader=bih;
bitmapInfo.bmiColors[0].rgbRed=255;
bitmapInfo.bmiColors[0].rgbGreen=255;
bitmapInfo.bmiColors[0].rgbBlue=255;
HDC hMemDC=CreateCompatibleDC(hDC);
BYTE *m_lpBitBmp=new BYTE[4*Bitmap.bmWidth*Bitmap.bmHeight];
HBITMAP hDibBitmap=CreateDIBSection(hMemDC,&bitmapInfo,
DIB_RGB_COLORS,(void **)&m_lpBitBmp,NULL,0);
if(hDibBitmap != 0)
{
::SelectObject(hMemDC,hDibBitmap);
BitBlt(hMemDC,0,0,Bitmap.bmWidth,Bitmap.bmHeight,hOffDC,0,0,SRCCOPY);
WriteFile(fh,m_lpBitBmp,4*Bitmap.bmWidth*Bitmap.bmHeight,&dwWritten,NULL);
}
DeleteObject(hDibBitmap);
DeleteDC(hDC);
DeleteDC(hMemDC);
CloseHandle(fh);
return 1;
}
//将截屏所得保存为jpeg图片
int SaveJPEGToFile(HBITMAP hBitmap,LPCSTR lpFileName)
{
HDC hDC=CreateDC(TEXT("DISPLAY"),NULL,NULL,NULL);
HDC hOffDC=CreateCompatibleDC(hDC);
SelectObject(hOffDC,hBitmap);
BITMAP Bitmap;
GetObject(hBitmap,sizeof(BITMAP),&Bitmap);
HANDLE fh=CreateFile((LPCWSTR)lpFileName,GENERIC_WRITE,0,NULL,CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN,NULL);
if(fh == INVALID_HANDLE_VALUE )
return FALSE;
BITMAPFILEHEADER bfh;
memset(&bfh,0,sizeof(bfh));
bfh.bfType=0x4D42/*((WORD) ('M' << 8) | 'B')*/;
bfh.bfSize= sizeof(bfh)+3*Bitmap.bmWidth*Bitmap.bmHeight+sizeof(BITMAPFILEHEADER);
bfh.bfOffBits=sizeof(BITMAPINFOHEADER)+sizeof(BITMAPFILEHEADER);
DWORD dwWritten=0;
//WriteFile(fh,&bfh,sizeof(bfh),&dwWritten,NULL);
BITMAPINFOHEADER bih;
memset(&bih,0,sizeof(bih));
bih.biSize=sizeof(bih);
bih.biWidth=Bitmap.bmWidth;
bih.biHeight=Bitmap.bmHeight;
bih.biPlanes=1;
bih.biBitCount=24;
/*if( !WriteFile(fh,&bih,sizeof(bih),&dwWritten,NULL) )
{
return FALSE;
}*/
BITMAPINFO bitmapInfo;
memset((void *)&bitmapInfo,0,sizeof(BITMAPINFO) );
bitmapInfo.bmiHeader=bih;
HDC hMemDC=CreateCompatibleDC(hDC);
BYTE *m_lpBitBmp=new BYTE[bfh.bfSize-sizeof(BITMAPFILEHEADER)];
HBITMAP hDibBitmap=CreateDIBSection(hMemDC,&bitmapInfo,
DIB_RGB_COLORS,(void **)&m_lpBitBmp,NULL,0);
if(hDibBitmap != 0)
{
::SelectObject(hMemDC,hDibBitmap);
BitBlt(hMemDC,0,0,Bitmap.bmWidth,Bitmap.bmHeight,hOffDC,0,0,SRCCOPY);
//WriteFile(fh,m_lpBitBmp,bfh.bfSize-sizeof(BITMAPFILEHEADER),&dwWritten,NULL);
WriteJPEGFile(lpFileName, m_lpBitBmp,Bitmap.bmWidth,Bitmap.bmHeight,TRUE, 60);
}
DeleteObject(hDibBitmap);
DeleteDC(hDC);
DeleteDC(hMemDC);
CloseHandle(fh);
return 1;
}
// 函数: WndProc(HWND, UINT, WPARAM, LPARAM)
// 目的: 处理主窗口的消息。
// WM_COMMAND- 处理应用程序菜单
// WM_PAINT- 绘制主窗口
// WM_DESTROY- 发送退出消息并返回
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
int wmId, wmEvent;
PAINTSTRUCT ps;
HDC hdc;
static SHACTIVATEINFO s_sai;
int iWidth,iHeight;
HBITMAP hBitmap;
static int s_cxBegin;
static int s_cyBegin;
static int s_cxEnd;
static int s_cyEnd;
switch (message)
{
case WM_COMMAND:
wmId= LOWORD(wParam);
wmEvent = HIWORD(wParam);
// 分析菜单选择:
switch (wmId)
{
case IDM_HELP_ABOUT:
DialogBox(g_hInst, (LPCTSTR)IDD_ABOUTBOX, hWnd, About);
break;
case IDM_OK:
SendMessage (hWnd, WM_CLOSE, 0, 0);
break;
case ID_RGB16:
hBitmap=CopyScreenToBitmap(iWidth,iHeight);
Save16BitmapToFile(hBitmap,TEXT("\\a.bmp"));
break;
case ID_RGB24:
hBitmap=CopyScreenToBitmap(iWidth,iHeight);
Save24BitmapToFile(hBitmap,TEXT("\\b.bmp"));
break;
case ID_RGB32:
hBitmap=CopyScreenToBitmap(iWidth,iHeight);
Save32BitmapToFile(hBitmap,TEXT("\\c.bmp"));
break;
case ID_JPEG:
hBitmap=CopyScreenToBitmap(iWidth,iHeight);
SaveJPEGToFile(hBitmap,"d.jpg");
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
break;
case WM_CREATE:
SHMENUBARINFO mbi;
memset(&mbi, 0, sizeof(SHMENUBARINFO));
mbi.cbSize = sizeof(SHMENUBARINFO);
mbi.hwndParent = hWnd;
mbi.nToolBarId = IDR_MENU;
mbi.hInstRes = g_hInst;
if (!SHCreateMenuBar(&mbi))
{
g_hWndMenuBar = NULL;
}
else
{
g_hWndMenuBar = mbi.hwndMB;
}
// 初始化外壳程序激活信息结构
memset(&s_sai, 0, sizeof (s_sai));
s_sai.cbSize = sizeof (s_sai);
break;
case WM_LBUTTONDOWN:
HCURSOR hCursor;
hCursor=SetCursor( LoadCursor(NULL,MAKEINTRESOURCE(IDC_WAIT) ) );
s_cxBegin=LOWORD(lParam);
s_cyBegin=HIWORD(lParam);
break;
case WM_LBUTTONUP:
s_cxEnd=LOWORD(lParam);
s_cyEnd=HIWORD(lParam);
SetCursor( LoadCursor( GetModuleHandle(NULL),MAKEINTRESOURCE(IDC_ARROW) ) );
break;
case WM_PAINT:
hdc = BeginPaint(hWnd, &ps);
// TODO: 在此添加任意绘图代码...
EndPaint(hWnd, &ps);
break;
case WM_DESTROY:
CommandBar_Destroy(g_hWndMenuBar);
PostQuitMessage(0);
break;
case WM_ACTIVATE:
// 向外壳程序通知我们的激活消息
SHHandleWMActivate(hWnd, wParam, lParam, &s_sai, FALSE);
break;
case WM_SETTINGCHANGE:
SHHandleWMSettingChange(hWnd, wParam, lParam, &s_sai);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
