LINUX X11剪貼闆/clipboard通路C代碼範例

真奇怪啊。關于LINUX剪貼闆的C代碼，網上完全找不到。找到的都是一些SHELL指令。

經過千辛萬苦，自己了解，終于找到一個代碼範例。

• https://github.com/exebook/x11clipboard
• https://stackoverflow.com/questions/27378318/c-get-string-from-clipboard-on-linux

為了友善他人，提供代碼如下（初步測試表明，圖檔取不到資料）：

• 标準情況：

// gcc -o xclipget xclipget.c -lX11
#include <stdio.h>
#include <limits.h>
#include <X11/Xlib.h>
 
Bool PrintSelection(Display *display, Window window, const char *bufname, const char *fmtname)
{
  char *result;
  unsigned long ressize, restail;
  int resbits;
  Atom bufid = XInternAtom(display, bufname, False),
       fmtid = XInternAtom(display, fmtname, False),
       propid = XInternAtom(display, "XSEL_DATA", False),
       incrid = XInternAtom(display, "INCR", False);
  XEvent event;
 
  XConvertSelection(display, bufid, fmtid, propid, window, CurrentTime);
  do {
    XNextEvent(display, &event);
  } while (event.type != SelectionNotify || event.xselection.selection != bufid);
 
  if (event.xselection.property)
  {
    XGetWindowProperty(display, window, propid, 0, LONG_MAX/4, False, AnyPropertyType,
      &fmtid, &resbits, &ressize, &restail, (unsigned char**)&result);
 
    if (fmtid == incrid)
      printf("Buffer is too large and INCR reading is not implemented yet.\n");
    else
      printf("%.*s", (int)ressize, result);
 
    XFree(result);
    return True;
  }
  else // request failed, e.g. owner can't convert to the target format
    return False;
}
 
int main()
{
  Display *display = XOpenDisplay(NULL);
  unsigned long color = BlackPixel(display, DefaultScreen(display));
  Window window = XCreateSimpleWindow(display, DefaultRootWindow(display), 0,0, 1,1, 0, color, color);
  Bool result = PrintSelection(display, window, "CLIPBOARD", "UTF8_STRING") ||
                PrintSelection(display, window, "CLIPBOARD", "STRING");
  XDestroyWindow(display, window);
  XCloseDisplay(display);
  return !result;
}      

• 超大記憶體情況

// gcc -o xclipget xclipget.c -lX11
#include <stdio.h>
#include <limits.h>
#include <X11/Xlib.h>
 
Bool PrintSelection(Display *display, Window window, const char *bufname, const char *fmtname)
{
  char *result;
  unsigned long ressize, restail;
  int resbits;
  Atom bufid = XInternAtom(display, bufname, False),
       fmtid = XInternAtom(display, fmtname, False),
       propid = XInternAtom(display, "XSEL_DATA", False),
       incrid = XInternAtom(display, "INCR", False);
  XEvent event;
 
  XSelectInput (display, window, PropertyChangeMask);
  XConvertSelection(display, bufid, fmtid, propid, window, CurrentTime);
  do {
    XNextEvent(display, &event);
  } while (event.type != SelectionNotify || event.xselection.selection != bufid);
 
  if (event.xselection.property)
  {
    XGetWindowProperty(display, window, propid, 0, LONG_MAX/4, True, AnyPropertyType,
      &fmtid, &resbits, &ressize, &restail, (unsigned char**)&result);
    if (fmtid != incrid)
      printf("%.*s", (int)ressize, result);
    XFree(result);
 
    if (fmtid == incrid)
      do {
        do {
          XNextEvent(display, &event);
        } while (event.type != PropertyNotify || event.xproperty.atom != propid || event.xproperty.state != PropertyNewValue);
 
        XGetWindowProperty(display, window, propid, 0, LONG_MAX/4, True, AnyPropertyType,
          &fmtid, &resbits, &ressize, &restail, (unsigned char**)&result);
        printf("%.*s", (int)ressize, result);
        XFree(result);
      } while (ressize > 0);
 
    return True;
  }
  else // request failed, e.g. owner can't convert to the target format
    return False;
}
 
int main()
{
  Display *display = XOpenDisplay(NULL);
  unsigned long color = BlackPixel(display, DefaultScreen(display));
  Window window = XCreateSimpleWindow(display, DefaultRootWindow(display), 0,0, 1,1, 0, color, color);
  Bool result = PrintSelection(display, window, "CLIPBOARD", "UTF8_STRING") ||
                PrintSelection(display, window, "CLIPBOARD", "STRING");
  XDestroyWindow(display, window);
  XCloseDisplay(display);
  return !result;
}