用gdk实现抓屏与X Window ID
最近看GDK，看到一段抓屏的代码还不错，所以贴出来分享。环境：Ubuntu 8.04编译：gcc -o capture capture.c `pkg-config --libs --cflags gtk+-2.0`执行：capture [-options...]，不带参数延迟3秒，输出文件名为当前时间.jpg??? -o?outputfilename?
??? -s?delayseconds?除了这段代码外，还有几点相关的知识点：1.GDK_WINDOW_XID(GdkWindow)或GDK_DRAWABLE_XID(GdkDrawable)可以将GdkWindow/GdkDrawable转化为X windowid，如果是GtkWindow，这么转:GTK_WIDGET(GtkWindow)->window注意: windows id必须在show(比如gtk_widget_show)以后才能得到id的，否则会报warning并返回02. 在Ubuntu里测试的结果rootwindow是0x41，而桌面的id往往是0X12000xx，桌面背景覆盖在root窗口上，所以rootwindow你在GNOME环境下看不见，不过如果开机启动到控制台然后执行xinit（或者有些机器在进入GNOME加载显卡驱动前）你看到的灰色网格背景的窗口就是root window了；3. 你可以自己新建一个窗口让mplayer的video输出到这个窗口上：mplayer -wid 0Xxxxx xxx.avi4. 参考Ubuntu下的一个工具xwininfo,可以抓窗口的id,位置,大小等信息
usage:? xwininfo [-options ...]where options include:
??? -help??????????????? print this message
??? -display host:dpy??? X server to contact
??? -root??????????????? use the root window
??? -id windowid???????? use the window with the specified id
??? -name windowname???? use the window with the specified name
??? -int???????????????? print window id in decimal
??? -children??????????? print parent and child identifiers
??? -tree??????????????? print children identifiers recursively
??? -stats?????????????? print window geometry [DEFAULT]
??? -bits??????????????? print window pixel information
??? -events????????????? print events selected for on window
??? -size??????????????? print size hints
??? -wm????????????????? print window manager hints
??? -shape?????????????? print shape extents
??? -frame?????????????? don't ignore window manager frames
??? -english???????????? print sizes in english units
??? -metric????????????? print sizes in metric units
??? -all???????????????? -tree, -stats, -bits, -events, -wm, -size, -shape

/*--------------Begin:capture.c------------------*/#include <gtk/gtk.h>
#include <stdlib.h>
#include <unistd.h>
#include <assert.h>
#include <string.h>
#include <gdk/gdkx.h>void do_capture_screenshot (char *file, int sec)
{
?gint x, y;
?GdkScreen* cur_screen = NULL;
?GdkWindow* window = NULL;
?GdkPixbuf* pixbuf_screenshot = NULL;
?GdkRectangle rect;
?GdkRectangle screen_rect;?g_printf("ready to capture.....\r\n");
?sleep(sec);?if (cur_screen == NULL)
?cur_screen = gdk_screen_get_default ();?//get screen?screen_rect.x = 0;
?screen_rect.y = 0;
?screen_rect.width = gdk_screen_get_width (cur_screen);?//get screen width
?screen_rect.height = gdk_screen_get_height (cur_screen);?//get screen height
?g_print("screen_rect: x=%d,y=%d,w=%d,h=%d\n",screen_rect.x,screen_rect.y,screen_rect.width,screen_rect.height);
?window = gdk_screen_get_root_window (cur_screen);?//get window by screen
?//Window xwin = GDK_WINDOW_XID(window);? //get window id
?//g_print("xwindow id is %x\n",xwin);?gdk_window_get_origin (window, &x, &y);?//get origin point?rect.x = x;
?rect.y = y;?gdk_drawable_get_size (GDK_DRAWABLE (window), &rect.width,&rect.height);?//get drawable size
?g_print("rect: x=%d,y=%d,w=%d,h=%d\n",rect.x,rect.y,rect.width,rect.height);?if (! gdk_rectangle_intersect (&rect, &screen_rect, &rect)) {?//obtain the intersect area from rect and screen_rect
?g_print("Capture failed!...\r\n");
?return;
?}
?g_print("capture rect: x=%d,y=%d,w=%d,h=%d\n",rect.x,rect.y,rect.width,rect.height);
?pixbuf_screenshot = gdk_pixbuf_get_from_drawable (NULL, window,
?NULL,rect.x - x, rect.y - y, 0, 0,
?rect.width, rect.height);?//get pixbuf from drawable widget?gdk_pixbuf_save (pixbuf_screenshot, file, "jpeg", NULL, "quality","100", NULL); //save pixbuf to jpeg format?file
?g_object_unref (pixbuf_screenshot);??//free pixbuf
?g_print("Capture saved!!!\r\n");?return;
}int main( int argc, char *argv[])
{
?int cmd, sec;
?char *file = NULL;
?time_t tt;
?struct tm *tm_ptr = NULL;?file = (char *)malloc(32);
?time(&tt);
?tm_ptr = localtime(&tt);
?strftime(file, 32, "%Y%m%d%H%M%S", tm_ptr);
?strcat(file, ".jpg");
?sec = 3;?gtk_init (&argc, &argv);?while ((cmd = getopt(argc, argv, "o:s:")) != -1) {
?switch (cmd) {
?case 'o':
?file = optarg;
?break;
?case 's':
?sec = atoi(optarg);
?break;
?default:
?break;
?}
}do_capture_screenshot(file, sec);return 0;
}
/*--------------End:capture.c------------------*/