gtkfaq.txt

gtk是linux一款强大的夸平台的图形化开发工具

  You should notice the backquote character which is used in this
  command line.  A common mistake when you start a GTK+ based
  development is to use quote instead of backquotes. If you do so, the
  compiler will complain about an unknown file called 'gtk-config
  --cflags --libs'. The text in backquotes is an instruction to your
  shell to substitute the output of executing this text into the command
  line.

  The command line above ensure that:

  +o  the correct C compiler flags will be used to compile the program
     (including the complete C header directory list)

  +o  your program will be linked with the needed libraries.


  44..33..  WWhhaatt aabboouutt uussiinngg tthhee mmaakkee  uuttiilliittyy??

  This is a sample makefile which compile a GTK+ based program:


















  # basic GTK+ app makefile
  SOURCES = myprg.c foo.c bar.c
  OBJS    = ${SOURCES:.c=.o}
  CFLAGS  = `gtk-config --cflags`
  LDADD   = `gtk-config --libs`
  CC      = gcc
  PACKAGE = myprg

  all : ${OBJS}
          ${CC} -o ${PACKAGE} ${OBJS} ${LDADD}

  .c.o:
          ${CC} ${CFLAGS} -c $<

  # end of file




  For more information about the make utility, you should read either
  the related man page or the relevant info file.


  44..44..  II uussee tthhee bbaacckkqquuoottee ssttuuffff iinn mmyy mmaakkeeffiilleess,, bbuutt mmyy mmaakkee pprroocceessss
  ffaaiilleedd..

  The backquote construction seems to not be accepted by some old make
  utilities. If you use one of these, the make process will probably
  fail.  In order to have the backquote syntax working again, you should
  use the GNU make utility (get it on the GNU ftp server at
  ftp://ftp.gnu.org/).


  44..55..  II wwaanntt ttoo aadddd ssoommee ccoonnffiigguurree ssttuuffff,, hhooww ccoouulldd II ddoo tthhiiss??

  To use autoconf/automake, you must first install the relevant
  packages. These are:


  +o  the m4 preprocessor v1.4 or better

  +o  autoconf v2.13 or better

  +o  automake v1.4 or better

  You'll find these packages on the GNU main ftp server
  (ftp://ftp.gnu.org/) or on any GNU mirror.

  In order to use the powerfull autoconf/automake scheme, you must
  create a configure.in which may look like:
















  dnl Process this file with autoconf to produce a configure script.
  dnl configure.in for a GTK+ based program

  AC_INIT(myprg.c)dnl
  AM_INIT_AUTOMAKE(mypkbname,0.0.1)dnl
  AM_CONFIG_HEADER(config.h)dnl

  dnl Checks for programs.
  AC_PROG_CC dnl check for the c compiler
  dnl you should add CFLAGS="" here, 'cos it is set to -g by PROG_CC

  dnl Checks for libraries.
  AM_PATH_GTK(1.2.0,,AC_MSG_ERROR(mypkgname 0.1 needs GTK))dnl

  AC_OUTPUT(
          Makefile
  )dnl




  You must add a Makefile.am file:



       bin_PROGRAMS    = myprg
       myprg_SOURCES   = myprg.c foo.c bar.c
       INCLUDES        = @GTK_CFLAGS@
       LDADD           = @GTK_LIBS@
       CLEANFILES      = *~
       DISTCLEANFILES  = .deps/*.P




  then, to use these, simply type the following commands:


  aclocal
  autoheader
  autoconf
  automake --add-missing --include-deps --foreign



  For further informations, you should look at the autoconf and the
  automake documentation (the shipped info files are really easy to
  understand, and there are plenty of web resources that deal with
  autoconf and/or automake).


  44..66..  II ttrryy ttoo ddeebbuugg mmyy GGTTKK++ aapppplliiccaattiioonn wwiitthh ggddbb,, bbuutt iitt hhaannggss mmyy XX
  sseerrvveerr wwhheenn II hhiitt ssoommee bbrreeaakkppooiinntt.. AAnnyy IIddeeaa ??

  From Federico Mena Quintero:

       X is not locked up.  It is likely that you are hitting a
       breakpoint inside a callback that is called from a place in
       Gtk that has a mouse grab.

       Run your program with the "--sync" option; it will make it
       easier to debug. Also, you may want to use the console for
       running the debugger, and just let the program run in
       another console with the X server.


  Eric Mouw had another solution:

       An old terminal connected to an otherwise unused serial port
       is also great for debugging X programs. Old vt100/vt220 ter-
       minals are dirt cheap but a bit hard to get (here in The
       Netherlands, YMMV).



  55..  DDeevveellooppmmeenntt wwiitthh GGTTKK++:: ggeenneerraall qquueessttiioonnss

  55..11..  WWhhaatt wwiiddggeettss aarree iinn GGTTKK??

  The GTK+ Tutorial lists the following widgets:




















































    GtkObject
     +GtkData
     | +GtkAdjustment
     | `GtkTooltips
     `GtkWidget
       +GtkContainer
       | +GtkBin
       | | +GtkAlignment
       | | +GtkEventBox
       | | +GtkFrame
       | | | `GtkAspectFrame
       | | +GtkHandleBox
       | | +GtkItem
       | | | +GtkListItem
       | | | +GtkMenuItem
       | | | | `GtkCheckMenuItem
       | | | |   `GtkRadioMenuItem
       | | | `GtkTreeItem
       | | +GtkViewport
       | | `GtkWindow
       | |   +GtkColorSelectionDialog
       | |   +GtkDialog
       | |   | `GtkInputDialog
       | |   `GtkFileSelection
       | +GtkBox
       | | +GtkButtonBox
       | | | +GtkHButtonBox
       | | | `GtkVButtonBox
       | | +GtkHBox
       | | | +GtkCombo
       | | | `GtkStatusbar
       | | `GtkVBox
       | |   +GtkColorSelection
       | |   `GtkGammaCurve
       | +GtkButton
       | | +GtkOptionMenu
       | | `GtkToggleButton
       | |   `GtkCheckButton
       | |     `GtkRadioButton
       | +GtkCList
       |   `GtkCTree
       | +GtkFixed
       | +GtkList
       | +GtkMenuShell
       | | +GtkMenuBar
       | | `GtkMenu
       | +GtkNotebook
       | +GtkPaned
       | | +GtkHPaned
       | | `GtkVPaned
       | +GtkScrolledWindow
       | +GtkTable
       | +GtkToolbar
       | `GtkTree
       +GtkDrawingArea
       | `GtkCurve
       +GtkEditable
       | +GtkEntry
       | | `GtkSpinButton
       | `GtkText
       +GtkMisc
       | +GtkArrow
       | +GtkImage
       | +GtkLabel
       | | `GtkTipsQuery
       | `GtkPixmap
       +GtkPreview
       +GtkProgressBar
       +GtkRange
       | +GtkScale
       | | +GtkHScale
       | | `GtkVScale
       | `GtkScrollbar
       |   +GtkHScrollbar
       |   `GtkVScrollbar
       +GtkRuler
       | +GtkHRuler
       | `GtkVRuler
       `GtkSeparator
         +GtkHSeparator
         `GtkVSeparator




  55..22..  IIss GGTTKK++ tthhrreeaadd ssaaffee?? HHooww ddoo II wwrriittee mmuullttii--tthhrreeaaddeedd GGTTKK++ aapppplliiccaa--
  ttiioonnss??

  The GLib library can be used in a thread-safe mode by calling
  g_thread_init() before making any other GLib calls. In this mode GLib
  automatically locks all internal data structures as needed.  This does
  not mean that two threads can simultaneously access, for example, a
  single hash table, but they can access two different hash tables
  simultaneously. If two different threads need to access the same hash
  table, the application is responsible for locking itself.

  When GLib is intialized to be thread-safe, GTK+ is _t_h_r_e_a_d _a_w_a_r_e. There
  is a single global lock that you must acquire with gdk_threads_enter()
  before making any GDK calls, and release with gdk_threads_leave()
  afterwards.

  A minimal main program for a threaded GTK+ application looks like:


  int
  main (int argc, char *argv[])
  {
    GtkWidget *window;

    g_thread_init(NULL);
    gtk_init(&argc, &argv);

    window = create_window();
    gtk_widget_show(window);

    gdk_threads_enter();
    gtk_main();
    gdk_threads_leave();

    return(0);
  }



  Callbacks require a bit of attention. Callbacks from GTK+ (signals)
  are made within the GTK+ lock. However callbacks from GLib (timeouts,
  IO callbacks, and idle functions) are made outside of the GTK+ lock.
  So, within a signal handler you do not need to call
  gdk_threads_enter(), but within the other types of callbacks, you do.



  55..33..  WWhhyy ddoo tthhiiss ssttrraannggee ''xx iioo eerrrroorr'' ooccccuurr wwhheenn II ffoorrkk(())  iinn mmyy GGTTKK++
  aapppp??

  This is not really a GTK+ problem, and the problem is not related to
  fork() too. If the 'x io error' occurs then you probably use the
  exit() function in order to exit from the child process.

  When GDK opens an X display, it creates a socket file descriptor. When
  you use the exit() function, you implicitly close all the open file
  descriptors, and the underlying X library really doesn't like this.

  The right function to use here is _exit().

  Erik Mouw gave the following piece of code about the fork()/exit()
  problem (slightly modified)



         int pid = fork();

         if(pid==-1)
           {
             perror("fork");
             exit(-1);
           }
         else if(pid==0) /* child */
           {
             retval=system("a command"); /* can use exec* functions here */
             _exit(retval);  /* notice _exit() instead of exit() */
           }
         else /* parent */
           {
             for(;;)
               {
                 if(waitpid(pid, &status, WNOHANG) == pid)
                   {
                     waitpid(pid, &status, WUNTRACED); /* anti zombie code */
                     break;
                   }
               }

             return(WEXITSTATUS(status));