分类: LINUX
2010-08-27 18:59:29
最近要写有关于QT的文档了,需要大量截图,由于目前QT是在2410开发平台上跑,在PC下懒得再编译QT的lib出来,所以如何将2410开发板上的LCD的图像截下来成了一个不大不小的问题。
反正以后可能会经常用到,索性写一个可以在2410开发板,Linxu平台下,截取LCD屏幕内容的小程序,呵呵~~
程 序主要是利用/dev/fb/0这个设备节点。/dev/fb/0代表了LCD的FrameBuffer缓冲区驱动程序,操作该驱动,即相当于操作LCD 的FrameBuffer。所以,由此出发,通过读取/dev/fb/0的内容,可以很容易就得到LCD屏幕上当前正在显示的内容。
由于2410的FrameBuffer是16bit的RGB565格式,所以在利用/dev/fb/0拿到屏幕图像的原始数据后,还需要做一个小小的转换,将其变为普通的bmp文件的形式。
在2410平台下,针对640*480的屏幕,代码如下:
#include
#include
#include
static unsigned char sg_BHeader[] = {
0x42, 0x4D, 0x36, 0x58, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x36, 0x00, 0x00, 0x00, 0x28, 0x00,
0x00, 0x00, 0x40, 0x01, 0x00, 0x00, 0xF0, 0x00, 0x00, 0x00, 0x01, 0x00, 0x10, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
#define RGB565TO1555(rgb) ((unsigned short)((unsigned
short)(rgb & 0x001f) | ((unsigned short)(rgb & 0xffe0) >>
1)))
void SaveBMPFile(unsigned char *raw, char *filename)
{
unsigned short *p = (unsigned short *)raw;
typedef unsigned int UINT;
typedef unsigned char UCHAR;
UINT m_Width = 640, m_Height = 480;
UINT i, j;
int bmp = open(filename, O_WRONLY | O_CREAT);
if(bmp < 0)
return;
sg_BHeader[0x02] = (UCHAR)(m_Width * m_Height * 2 + 0x36) & 0xff;
sg_BHeader[0x03] = (UCHAR)((m_Width * m_Height * 2 + 0x36) >> 8) & 0xff;
sg_BHeader[0x04] = (UCHAR)((m_Width * m_Height * 2 + 0x36) >> 16) & 0xff;
sg_BHeader[0x05] = (UCHAR)((m_Width * m_Height * 2 + 0x36) >> 24) & 0xff;
sg_BHeader[0x12] = (UCHAR)m_Width & 0xff;
sg_BHeader[0x13] = (UCHAR)(m_Width >> 8) & 0xff;
sg_BHeader[0x14] = (UCHAR)(m_Width >> 16) & 0xff;
sg_BHeader[0x15] = (UCHAR)(m_Width >> 24) & 0xff;
sg_BHeader[0x16] = (UCHAR)m_Height & 0xff;
sg_BHeader[0x17] = (UCHAR)(m_Height >> 8) & 0xff;
sg_BHeader[0x18] = (UCHAR)(m_Height >> 16) & 0xff;
sg_BHeader[0x19] = (UCHAR)(m_Height >> 24) & 0xff;
write(bmp, sg_BHeader, sizeof(sg_BHeader));
for(i = 0; i < m_Height; i++)
{
unsigned short *c = p + (m_Height - 1 - i) * m_Width;
unsigned short cc;
for(j = 0; j < m_Width; j++)
{
cc = RGB565TO1555(*(c + j));
// cc = *(c + j);
write(bmp, &cc, 2);
}
}
close(bmp);
}
int main(int argc, char *argv[])
{
unsigned char buf[640*480*2];
char *filename = "/mnt/yaffs/screenshot.bmp";
int fb;
fb = open("/dev/fb/0", O_RDONLY);
if(fb < 0)
exit(1);
if(argc == 2)
filename = argv[1];
printf("reading screen...\n");
read(fb, buf, 640*480*2);
close(fb);
printf("saving screen...\n");
SaveBMPFile(buf, filename);
printf("file %s created successfully\n", filename);
exit(0);
}