穿透全透明

通过改变窗口形状实现穿透效果

#include <stdio.h>
#include <X11/X.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/extensions/shape.h>

int main(int argc, char *argv[])
{
    Display *display;
    Window win;
    int screen_num;
 int dummy, h = 300, w = 400, bwidth = 2;
    XEvent event;
 GC gc;
 XGCValues gcvalues;
 Pixmap mask;
 XFontStruct *font;
 const char *msg = "Wah, Transparent Window!";

    if ( (display = XOpenDisplay (NULL)) == NULL ) {
  fprintf (stderr, "Cannot connect to X server :0\n");
  //exit(0);
    }
    printf ("connect to X server :0\n");

 if ( !XShapeQueryExtension(display, &dummy, &dummy) ) {
  fprintf (stderr, "SHAPE extension not supported\n");
  //exit(0);
 }
  printf ("SHAPE extension  supported\n");
    /* Create a window */
    screen_num = DefaultScreen (display);
    printf ("got screen\n");
    win = XCreateSimpleWindow (display, DefaultRootWindow(display),
     10, 10, w, h, bwidth,
  BlackPixel (display, screen_num),
  WhitePixel (display, screen_num));
  printf ("creat window\n");
 /* Create a pixmap of depth 1 as mask */
 mask = XCreatePixmap(display, win, w, h, 1);
  printf ("creat pixmap\n");
 /* Create GC */
 gc =  XCreateGC(display, mask, 0, &gcvalues);
 printf ("got gc\n");
 font = XLoadQueryFont (display, "8x16");
 if(!font){
  printf ("not suport font\n");
   }
 else{
  printf ("got font\n");
  }
 //XSetFont (display, gc, font->fid);
 printf ("set font\n");
 XSetLineAttributes(display, gc, 4, LineSolid, CapRound, JoinMiter);
 printf ("creat gc\n");
 /* Clear the mask */
 XSetForeground(display, gc, 0);
 XFillRectangle (display, mask, gc, 0, 0, w, h);
 printf ("clear mask\n");
 /* Draw two lines and few texts */
 XSetForeground(display, gc, 1);
 XDrawLine (display, mask, gc, 10, h/4, w-10, h/4);
 //XDrawString (display, mask, gc, w/4, h/2, msg, strlen(msg));
 XDrawLine (display, mask, gc, 10, 3*h/4, w-10, 3*h/4);
 printf ("draw line and string\n");
    /* Map the window */
    XSelectInput (display, win, ButtonPressMask | ExposureMask);
    XMapWindow (display, win);
 printf ("map ok \n");
    while (1) {
  XNextEvent (display, &event);
  switch (event.type) {
   case Expose:
    XShapeCombineMask (display, win, ShapeBounding,
      -bwidth, -bwidth, mask, ShapeSet);
    break;
   case ButtonPress:
    XCloseDisplay (display);
    //exit (0);
  }
    }

    return 0;
}

编译cc -I/usr/X11R6/include testTrans.c -L/usr/X11R6/lib -lX11 -lXext

在ubuntu上跑的很好，有透明效果，在盒子上包段错误，加打印显示在setfont时出错，说明是字体问题。注释这一行，并取消掉显示字符的哪一行。编译通过，显示窗口，不过没有透明效果。说明是不支持透明

 

逐行理解全透明运行的例子testTrans.c，发现是在主循环里
XShapeCombineMask (display, win, ShapeBounding,
      -bwidth, -bwidth, mask, ShapeSet);
      来改变窗口形状，即无内容的部分不再是窗体的一部分，而是被挖空了。因此，透明部分是后面的窗口在响应（测试证明）。
      回到盒子上来在有窗口管理器时没有透明效果，而是一片白底色；关窗口管理器，可见是两条白线画在qmlver前面，在透明处，是qmlver响应，在有内容处是透明窗体响应，可见这种全透明是有效的。只是窗口管理器进行了处理。

http://linux.die.net/man/3/xshapecombinemask

各种改变形状的方法。回头要好好研究，为视频挖一个矩形的洞出来