Linux C 实现屏幕截图

首先安装 libimlib2-dev 软件包，

然后安装 giblib

最后编写源码文件 Makefile、screen.c 和 screen.h ，并执行 make 命令编译。

Makefile:

screen.c:

screen.h:

要用xlib的。

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <X11/Xlib.h>

#include <jpeglib.h>

/***************************************************************

Write XImage data to a JPEG file

Must include <jpeglib.h>

Return value:

0 - failed

1 - success

****************************************************************/

static char err_str[256]

int JpegWriteFileFromImage(char *filename, XImage* img)

{

FILE* fp

struct jpeg_compress_struct cinfo

struct jpeg_error_mgr jerr

fp = fopen(filename,"wb")

if(fp==NULL)

{

memset(err_str, 0, sizeof(err_str))

sprintf(err_str,"cannot write file %s",filename)

err_exit("JpegWriteFileFromImage",err_str)

return 0

}

cinfo.err = jpeg_std_error(&jerr)

jpeg_create_compress(&cinfo)

jpeg_stdio_dest(&cinfo,fp)

cinfo.image_width = img->width

cinfo.image_height = img->height

cinfo.input_components = 3

cinfo.in_color_space = JCS_RGB

jpeg_set_defaults(&cinfo)

jpeg_start_compress(&cinfo,TRUE)

JSAMPROW row_pointer[1]/* pointer to scanline */

unsigned char* pBuf = (unsigned char*)malloc(3*img->width)

row_pointer[0] = pBuf

int i=0

while(cinfo.next_scanline < cinfo.image_height)

{

int j=0

for(i=0i<img->widthi++)

{

//memcpy(pBuf+j,img->data+cinfo.next_scanline*img->bytes_per_line+i*4,3)

*(pBuf+j) = *(img->data+cinfo.next_scanline*img->bytes_per_line+i*4+2)

*(pBuf+j+1) = *(img->data+cinfo.next_scanline*img->bytes_per_line+i*4+1)

*(pBuf+j+2) = *(img->data+cinfo.next_scanline*img->bytes_per_line+i*4)

j+=3

}

jpeg_write_scanlines(&cinfo,row_pointer,1)

}

free(pBuf)

jpeg_finish_compress(&cinfo)

jpeg_destroy_compress(&cinfo)

fclose(fp)

return 1

}

/*****************************************************************

Capture a local screenshot of the desktop,

saving to the file specified by filename.

If type = 0, then write a bitmap file, else

write a JPEG file.

Return Value:

0 - fail

1 - success

******************************************************************/

int CaptureDesktop(char* filename, int type)

{

Window desktop

Display* dsp

XImage* img

int screen_width

int screen_height

dsp = XOpenDisplay(NULL)/* Connect to a local display */

if(NULL==dsp)

{

//sprintf(err_str,"Error:Cannot connect to local display\n")

err_exit("CaptureDesktop","Cannot connect to local display")

return 0

}

desktop = RootWindow(dsp,0)/* Refer to the root window */

if(0==desktop)

{

//printf("cannot get root window\n")

err_exit("CaptureDesktop","cannot get root window")

return 0

}

/* Retrive the width and the height of the screen */

screen_width = DisplayWidth(dsp,0)

screen_height = DisplayHeight(dsp,0)

/* Get the Image of the root window */

img = XGetImage(dsp,desktop,0,0,screen_width,screen_height,~0,ZPixmap)

if(type==0)

BmpWriteFileFromImage(filename,img)

else

JpegWriteFileFromImage(filename,img)

XDestroyImage(img)

XCloseDisplay(dsp)

return 1

}

main()

{

CaptureDesktop("./screenshot.bmp",0)

//CaptureDesktop("./screenshot.jpg",1)

printf("Done.\n")

}

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