gtk_tut.sgml

gtk是linux一款强大的夸平台的图形化开发工具

                                gint       top_attach,
                                gint       bottom_attach );
</verb></tscreen>

The X and Y options default to GTK_FILL | GTK_EXPAND, and X and Y
padding are set to 0. The rest of the arguments are identical to the
previous function.

We also have gtk_table_set_row_spacing() and
gtk_table_set_col_spacing().  This places spacing between the rows at
the specified row or column.

<tscreen><verb>
void gtk_table_set_row_spacing( GtkTable *table,
                                gint      row,
                                gint      spacing );
</verb></tscreen>

and

<tscreen><verb>
void gtk_table_set_col_spacing ( GtkTable *table,
                                 gint      column,
                                 gint      spacing );
</verb></tscreen>

Note that for columns, the space goes to the right of the column, and
for rows, the space goes below the row.

You can also set a consistent spacing of all rows and/or columns with:

<tscreen><verb>
void gtk_table_set_row_spacings( GtkTable *table,
                                 gint      spacing );
</verb></tscreen>

And,

<tscreen><verb>
void gtk_table_set_col_spacings( GtkTable *table,
                                 gint      spacing );
</verb></tscreen>

Note that with these calls, the last row and last column do not get
any spacing.

<!-- ----------------------------------------------------------------- -->
<sect1>Table Packing Example
<p>
Here we make a window with three buttons in a 2x2 table.
The first two buttons will be placed in the upper row.
A third, quit button, is placed in the lower row, spanning both columns.
Which means it should look something like this:

<? <CENTER> >
<?
<IMG SRC="gtk_tut_table.gif" VSPACE="15" HSPACE="10" 
ALT="Table Packing Example Image" WIDTH="180" HEIGHT="120">
>
<? </CENTER> >

Here's the source code:

<tscreen><verb>
/* example-start table table.c */

#include <gtk/gtk.h>

/* Our callback.
 * The data passed to this function is printed to stdout */
void callback( GtkWidget *widget,
               gpointer   data )
{
    g_print ("Hello again - %s was pressed\n", (char *) data);
}

/* This callback quits the program */
void delete_event( GtkWidget *widget,
                   GdkEvent  *event,
		   gpointer   data )
{
    gtk_main_quit ();
}

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

    gtk_init (&amp;argc, &amp;argv);

    /* Create a new window */
    window = gtk_window_new (GTK_WINDOW_TOPLEVEL);

    /* Set the window title */
    gtk_window_set_title (GTK_WINDOW (window), "Table");

    /* Set a handler for delete_event that immediately
     * exits GTK. */
    gtk_signal_connect (GTK_OBJECT (window), "delete_event",
                        GTK_SIGNAL_FUNC (delete_event), NULL);

    /* Sets the border width of the window. */
    gtk_container_set_border_width (GTK_CONTAINER (window), 20);

    /* Create a 2x2 table */
    table = gtk_table_new (2, 2, TRUE);

    /* Put the table in the main window */
    gtk_container_add (GTK_CONTAINER (window), table);

    /* Create first button */
    button = gtk_button_new_with_label ("button 1");

    /* When the button is clicked, we call the "callback" function
     * with a pointer to "button 1" as its argument */
    gtk_signal_connect (GTK_OBJECT (button), "clicked",
              GTK_SIGNAL_FUNC (callback), (gpointer) "button 1");


    /* Insert button 1 into the upper left quadrant of the table */
    gtk_table_attach_defaults (GTK_TABLE(table), button, 0, 1, 0, 1);

    gtk_widget_show (button);

    /* Create second button */

    button = gtk_button_new_with_label ("button 2");

    /* When the button is clicked, we call the "callback" function
     * with a pointer to "button 2" as its argument */
    gtk_signal_connect (GTK_OBJECT (button), "clicked",
              GTK_SIGNAL_FUNC (callback), (gpointer) "button 2");
    /* Insert button 2 into the upper right quadrant of the table */
    gtk_table_attach_defaults (GTK_TABLE(table), button, 1, 2, 0, 1);

    gtk_widget_show (button);

    /* Create "Quit" button */
    button = gtk_button_new_with_label ("Quit");

    /* When the button is clicked, we call the "delete_event" function
     * and the program exits */
    gtk_signal_connect (GTK_OBJECT (button), "clicked",
                        GTK_SIGNAL_FUNC (delete_event), NULL);

    /* Insert the quit button into the both 
     * lower quadrants of the table */
    gtk_table_attach_defaults (GTK_TABLE(table), button, 0, 2, 1, 2);

    gtk_widget_show (button);

    gtk_widget_show (table);
    gtk_widget_show (window);

    gtk_main ();

    return 0;
}
/* example-end */
</verb></tscreen>

<!-- ***************************************************************** -->
<sect>Widget Overview
<!-- ***************************************************************** -->
<p>
The general steps to creating a widget in GTK are:
<enum>
<item> gtk_*_new - one of various functions to create a new widget.
These are all detailed in this section.

<item> Connect all signals and events we wish to use to the
appropriate handlers.

<item> Set the attributes of the widget.

<item> Pack the widget into a container using the appropriate call
such as gtk_container_add() or gtk_box_pack_start().

<item> gtk_widget_show() the widget.
</enum>

gtk_widget_show() lets GTK know that we are done setting the
attributes of the widget, and it is ready to be displayed. You may
also use gtk_widget_hide to make it disappear again. The order in
which you show the widgets is not important, but I suggest showing the
window last so the whole window pops up at once rather than seeing the
individual widgets come up on the screen as they're formed. The
children of a widget (a window is a widget too) will not be displayed
until the window itself is shown using the gtk_widget_show() function.

<!-- ----------------------------------------------------------------- -->
<sect1> Casting
<p>
You'll notice as you go on, that GTK uses a type casting system. This
is always done using macros that both test the ability to cast the
given item, and perform the cast. Some common ones you will see are:

<itemize>
<item> GTK_WIDGET(widget)
<item> GTK_OBJECT(object)
<item> GTK_SIGNAL_FUNC(function)
<item> GTK_CONTAINER(container)
<item> GTK_WINDOW(window)
<item> GTK_BOX(box)
</itemize>

These are all used to cast arguments in functions. You'll see them in the
examples, and can usually tell when to use them simply by looking at the
function's declaration.

As you can see below in the class hierarchy, all GtkWidgets are
derived from the GtkObject base class. This means you can use a widget
in any place the function asks for an object - simply use the
GTK_OBJECT() macro.

For example:

<tscreen><verb>
gtk_signal_connect( GTK_OBJECT(button), "clicked",
                    GTK_SIGNAL_FUNC(callback_function), callback_data);
</verb></tscreen> 

This casts the button into an object, and provides a cast for the
function pointer to the callback.

Many widgets are also containers. If you look in the class hierarchy
below, you'll notice that many widgets derive from the GtkContainer
class. Any one of these widgets may be used with the GTK_CONTAINER
macro to pass them to functions that ask for containers.

Unfortunately, these macros are not extensively covered in the
tutorial, but I recommend taking a look through the GTK header
files. It can be very educational. In fact, it's not difficult to
learn how a widget works just by looking at the function declarations.

<!-- ----------------------------------------------------------------- -->
<sect1>Widget Hierarchy
<p>
For your reference, here is the class hierarchy tree used to implement widgets.

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

<!-- ----------------------------------------------------------------- -->
<sect1>Widgets Without Windows
<p>
The following widgets do not have an associated window. If you want to
capture events, you'll have to use the GtkEventBox. See the section on
the <ref id="sec_EventBox" name="EventBox"> widget.

<tscreen><verb>
GtkAlignment
GtkArrow
GtkBin
GtkBox
GtkImage
GtkItem
GtkLabel
GtkPixmap
GtkScrolledWindow
GtkSeparator
GtkTable
GtkAspectFrame
GtkFrame
GtkVBox
GtkHBox
GtkVSeparator
GtkHSeparator
</verb></tscreen>

We'll further our exploration of GTK by examining each widge