图片：
camtest是一个命令行程序，运行它可以实现CMOS摄像头的动态预览
CMOS摄像头对应的内核驱动源代码 ：Linux-2.6.29/drivers/media/video/s3c2440camif.c
当然这一个还不够，还有同样目录下的其他源代码文件搭配使用。
解压光盘中的linux\examples.tgz可以得到camtest源代码。
camtest源代码清单：
%:include <iostream>
%:include <fcntl.h>
%:include <sys/ioctl.h>
%:include <sys/types.h>
%:include <sys/stat.h>
%:include <sys/mman.h>
%:include <unistd.h>
%:include <string.h>
%:include <stdlib.h>
%:include <string.h>
%:include <linux/types.h>
%:include <linux/fb.h>
class TError <%
public:
TError(const char *msg) <%
this->msg = msg;
%>
TError(const TError bitand e) <%
msg = e.msg;
%>
void Output() <%
std::cerr << msg << std::endl;
%>
virtual ~TError() <%%>
protected:
TError bitand operator=(const TError bitand);
private:
const char *msg;
%>;
// Linear memory based image
class TRect <%
public:
TRect(): Addr(0), Size(0), Width(0), Height(0), LineLen(0), BPP(16) <%
%>
virtual ~TRect() <%
%>
bool DrawRect(const TRect bitand SrcRect, int x, int y) const <%
if (BPP not_eq 16 or SrcRect.BPP not_eq 16) <%
// don't support that yet
throw TError("does not support other than 16 BPP yet");
%>
// clip
int x0, y0, x1, y1;
x0 = x;
y0 = y;
x1 = x0 + SrcRect.Width - 1;
y1 = y0 + SrcRect.Height - 1;
if (x0 < 0) <%
x0 = 0;
%>
if (x0 > Width - 1) <%
return true;
%>
if( x1 < 0) <%
return true;
%>
if (x1 > Width - 1) <%
x1 = Width - 1;
%>
if (y0 < 0) <%
y0 = 0;
%>
if (y0 > Height - 1) <%
return true;
%>
if (y1 < 0) <%
return true;
%>
if (y1 > Height - 1) <%
y1 = Height -1;
%>
//copy
int copyLineLen = (x1 + 1 - x0) * BPP / 8;
unsigned char *DstPtr = Addr + LineLen * y0 + x0 * BPP / 8;
const unsigned char *SrcPtr = SrcRect.Addr + SrcRect.LineLen *(y0 - y) + (x0 - x) * SrcRect.BPP / 8;
for (int i = y0; i <= y1; i++) <%
memcpy(DstPtr, SrcPtr, copyLineLen);
DstPtr += LineLen;
SrcPtr += SrcRect.LineLen;
%>
return true;
%>
bool DrawRect(const TRect bitand rect) const <% // default is Center
return DrawRect(rect, (Width - rect.Width) / 2, (Height - rect.Height) / 2);
%>
bool Clear() const <%
int i;
unsigned char *ptr;
for (i = 0, ptr = Addr; i < Height; i++, ptr += LineLen) <%
memset(ptr, 0, Width * BPP / 8);
%>
return true;
%>
protected:
TRect(const TRect bitand);
TRect bitand operator=( const TRect bitand);
protected:
unsigned char *Addr;
int Size;
int Width, Height, LineLen;
unsigned BPP;
%>;
class TFrameBuffer: public TRect <%
public:
TFrameBuffer(const char *DeviceName = "/dev/fb0"): TRect(), fd(-1) <%
Addr = (unsigned char *)MAP_FAILED;
fd = open(DeviceName, O_RDWR);
if (fd < 0) <%
throw TError("cannot open frame buffer");
%>
struct fb_fix_screeninfo Fix;
struct fb_var_screeninfo Var;
if (ioctl(fd, FBIOGET_FSCREENINFO, bitand Fix) < 0 or ioctl(fd, FBIOGET_VSCREENINFO, bitand Var) < 0) <%
throw TError("cannot get frame buffer information");
%>
BPP = Var.bits_per_pixel;
if (BPP not_eq 16) <%
throw TError("support 16BPP frame buffer only");
%>
Width = Var.xres;
Height = Var.yres;
LineLen = Fix.line_length;
Size = LineLen * Height;
int PageSize = getpagesize();
Size = (Size + PageSize - 1) / PageSize * PageSize ;
Addr = (unsigned char *)mmap(NULL, Size, PROT_READ|PROT_WRITE,MAP_SHARED, fd, 0);
if (Addr == (unsigned char *)MAP_FAILED) <%
throw TError("map frame buffer failed");
return;
%>
::close(fd);
fd = -1;
Clear();
%>
virtual ~TFrameBuffer() <%
::munmap(Addr, Size);
Addr = (unsigned char *)MAP_FAILED;
::close(fd);
fd = -1;
%>
protected:
TFrameBuffer(const TFrameBuffer bitand);
TFrameBuffer bitand operator=( const TFrameBuffer bitand);
private:
int fd;
%>;
class TVideo : public TRect <%
public:
TVideo(const char *DeviceName = "/dev/camera"): TRect(), fd(-1) <%
Addr = 0;
fd = ::open(DeviceName, O_RDONLY);
if (fd < 0) <%
throw TError("cannot open video device");
%>
Width = 640;
Height = 512;
BPP = 16;
LineLen = Width * BPP / 8;
Size = LineLen * Height;
Addr = new unsigned char<:Size:>;
Clear();
%>
bool FetchPicture() const <%
int count = ::read(fd, Addr, Size);
if (count not_eq Size) <%
throw TError("error in fetching picture from video");
%>
return true;
%>
virtual ~TVideo() <%
::close(fd);
fd = -1;
delete<::> Addr;
Addr = 0;
%>
protected:
TVideo(const TVideo bitand);
TVideo bitand operator=(const TVideo bitand);
private:
int fd;
%>;
int main(int argc, char **argv)
<%
try <%
TFrameBuffer FrameBuffer;
TVideo Video;
for (;;) <%
Video.FetchPicture();
FrameBuffer.DrawRect(Video);
%>
%> catch (TError bitand e) <%
e.Output();
return 1;
%>
return 0;
%>
编译脚本Makefile：
camtest: camtest.cpp
arm-linux-g++ camtest.cpp -Wall -O2 -o camtest
arm-linux-strip -s camtest
clean:
rm camtest
