GTK v1.2 Tutorial(英文)

来源：Linux-cn.com 作者：Webmaster 时间：2007-05-05 点击： [收藏] [投稿]

　　GTK_SPIN_STEP_FORWARD and GTK_SPIN_STEP_BACKWARD change the value of the Spin Button by the amount specified by increment, unless increment is equal to 0, in which case the value is changed by the value of step_increment in theAdjustment.

　　GTK_SPIN_PAGE_FORWARD and GTK_SPIN_PAGE_BACKWARD simply alter the value of the Spin Button by increment.

　　GTK_SPIN_HOME sets the value of the Spin Button to the bottom of the Adjustments range.

　　GTK_SPIN_END sets the value of the Spin Button to the top of the Adjustments range.

　　GTK_SPIN_USER_DEFINED simply alters the value of the Spin Button by the specified amount.

　　We move away from functions for setting and retreving the range attributes of the Spin Button now, and move onto functions that effect the appearance and behaviour of the Spin Button widget itself.

　　The first of these functions is used to constrain the text box of the Spin Button such that it may only contain a numeric value. This prevents a user from typing anything other than numeric values into the text box of a Spin Button:


void gtk_spin_button_set_numeric( GtkSpinButton *spin_button,
gboolean numeric );

　　You can set whether a Spin Button will wrap around between the upper and lower range values with the following function:


void gtk_spin_button_set_wrap( GtkSpinButton *spin_button,
gboolean wrap );

　　You can set a Spin Button to round the value to the nearest step_increment, which is set within the Adjustment object used with the Spin Button. This is accomplished with the following function:


void gtk_spin_button_set_snap_to_ticks( GtkSpinButton*spin_button,
gbooleansnap_to_ticks );

　　The update policy of a Spin Button can be changed with the following function:


void gtk_spin_button_set_update_policy( GtkSpinButton*spin_button,
GtkSpinButtonUpdatePolicy policy );

　　The possible values of policy are either GTK_UPDATE_ALWAYS or GTK_UPDATE_IF_VALID.

　　These policies affect the behavior of a Spin Button when parsing inserted text and syncing its value with the values of the Adjustment.

　　In the case of GTK_UPDATE_IF_VALID the Spin Button only value gets changed if the text input is a numeric value that is within the range specified by the Adjustment. Otherwise the text is reset to the current value.

　　In case of GTK_UPDATE_ALWAYS we ignore errors while converting text into a numeric value.

　　The appearance of the buttons used in a Spin Button can be changed using the following function:


void gtk_spin_button_set_shadow_type( GtkSpinButton *spin_button,
GtkShadowTypeshadow_type );

　　As usual, the shadow_type can be one of:

　　GTK_SHADOW_IN

　　GTK_SHADOW_OUT

　　GTK_SHADOW_ETCHED_IN

　　GTK_SHADOW_ETCHED_OUT

　　Finally, you can explicitly request that a Spin Button update itself:


void gtk_spin_button_update( GtkSpinButton*spin_button );

　　It's example time again.


/* example-start spinbutton spinbutton.c */
#include <stdio.h>
#include <gtk/gtk.h>
static GtkWidget *spinner1;
void toggle_snap( GtkWidget *widget,
GtkSpinButton *spin )
{
gtk_spin_button_set_snap_to_ticks (spin, GTK_TOGGLE_BUTTON
(widget)->active);
}
void toggle_numeric( GtkWidget *widget,
 GtkSpinButton *spin )
{
gtk_spin_button_set_numeric (spin, GTK_TOGGLE_BUTTON (widget)->active);
}
void change_digits( GtkWidget *widget,
GtkSpinButton *spin )
{
gtk_spin_button_set_digits (GTK_SPIN_BUTTON (spinner1),
gtk_spin_button_get_value_as_int (spin));
}
void get_value( GtkWidget *widget,
gpointer data )
{
gchar buf[32];
GtkLabel *label;
GtkSpinButton *spin;
spin = GTK_SPIN_BUTTON (spinner1);
label = GTK_LABEL (gtk_object_get_user_data (GTK_OBJECT (widget)));
if (GPOINTER_TO_INT (data) == 1)
sprintf (buf, "%d", gtk_spin_button_get_value_as_int (spin));
else
sprintf (buf, "%0.*f", spin->digits,
 gtk_spin_button_get_value_as_float (spin));
gtk_label_set_text (label, buf);
}
int main( int argc,
char *argv[] )
{
GtkWidget *window;
GtkWidget *frame;
GtkWidget *hbox;
GtkWidget *main_vbox;
GtkWidget *vbox;
GtkWidget *vbox2;
GtkWidget *spinner2;
GtkWidget *spinner;
GtkWidget *button;
GtkWidget *label;
GtkWidget *val_label;
GtkAdjustment *adj;
/* Initialise GTK */
gtk_init(&argc, &argv);
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_signal_connect (GTK_OBJECT (window), "destroy",
GTK_SIGNAL_FUNC (gtk_main_quit),
NULL);
gtk_window_set_title (GTK_WINDOW (window), "Spin Button");
main_vbox = gtk_vbox_new (FALSE, 5);
gtk_container_set_border_width (GTK_CONTAINER (main_vbox), 10);
gtk_container_add (GTK_CONTAINER (window), main_vbox);
frame = gtk_frame_new ("Not accelerated");
gtk_box_pack_start (GTK_BOX (main_vbox), frame, TRUE, TRUE, 0);
vbox = gtk_vbox_new (FALSE, 0);
gtk_container_set_border_width (GTK_CONTAINER (vbox), 5);
gtk_container_add (GTK_CONTAINER (frame), vbox);
/* Day, month, year spinners */
hbox = gtk_hbox_new (FALSE, 0);
gtk_box_pack_start (GTK_BOX (vbox), hbox, TRUE, TRUE, 5);
vbox2 = gtk_vbox_new (FALSE, 0);
gtk_box_pack_start (GTK_BOX (hbox), vbox2, TRUE, TRUE, 5);
label = gtk_label_new ("Day :");
gtk_misc_set_alignment (GTK_MISC (label), 0, 0.5);
gtk_box_pack_start (GTK_BOX (vbox2), label, FALSE, TRUE, 0);
adj = (GtkAdjustment *) gtk_adjustment_new (1.0, 1.0, 31.0, 1.0,
5.0, 0.0);
spinner = gtk_spin_button_new (adj, 0, 0);
gtk_spin_button_set_wrap (GTK_SPIN_BUTTON (spinner), TRUE);
gtk_spin_button_set_shadow_type (GTK_SPIN_BUTTON (spinner),
 GTK_SHADOW_OUT);
gtk_box_pack_start (GTK_BOX (vbox2), spinner, FALSE, TRUE, 0);
vbox2 = gtk_vbox_new (FALSE, 0);
gtk_box_pack_start (GTK_BOX (hbox), vbox2, TRUE, TRUE, 5);
label = gtk_label_new ("Month :");
gtk_misc_set_alignment (GTK_MISC (label), 0, 0.5);
gtk_box_pack_start (GTK_BOX (vbox2), label, FALSE, TRUE, 0);
adj = (GtkAdjustment *) gtk_adjustment_new (1.0, 1.0, 12.0, 1.0,
5.0, 0.0);
spinner = gtk_spin_button_new (adj, 0, 0);
gtk_spin_button_set_wrap (GTK_SPIN_BUTTON (spinner), TRUE);
gtk_spin_button_set_shadow_type (GTK_SPIN_BUTTON (spinner),
 GTK_SHADOW_ETCHED_IN);
gtk_box_pack_start (GTK_BOX (vbox2), spinner, FALSE, TRUE, 0);
vbox2 = gtk_vbox_new (FALSE, 0);
gtk_box_pack_start (GTK_BOX (hbox), vbox2, TRUE, TRUE, 5);
label = gtk_label_new ("Year :");
gtk_misc_set_alignment (GTK_MISC (label), 0, 0.5);
gtk_box_pack_start (GTK_BOX (vbox2), label, FALSE, TRUE, 0);
adj = (GtkAdjustment *) gtk_adjustment_new (1998.0, 0.0, 2100.0,
1.0, 100.0, 0.0);
spinner = gtk_spin_button_new (adj, 0, 0);
gtk_spin_button_set_wrap (GTK_SPIN_BUTTON (spinner), FALSE);
gtk_spin_button_set_shadow_type (GTK_SPIN_BUTTON (spinner),
 GTK_SHADOW_IN);
gtk_widget_set_usize (spinner, 55, 0);
gtk_box_pack_start (GTK_BOX (vbox2), spinner, FALSE, TRUE, 0);
frame = gtk_frame_new ("Accelerated");
gtk_box_pack_start (GTK_BOX (main_vbox), frame, TRUE, TRUE, 0);
vbox = gtk_vbox_new (FALSE, 0);
gtk_container_set_border_width (GTK_CONTAINER (vbox), 5);
gtk_container_add (GTK_CONTAINER (frame), vbox);
hbox = gtk_hbox_new (FALSE, 0);
gtk_box_pack_start (GTK_BOX (vbox), hbox, FALSE, TRUE, 5);
vbox2 = gtk_vbox_new (FALSE, 0);
gtk_box_pack_start (GTK_BOX (hbox), vbox2, TRUE, TRUE, 5);
label = gtk_label_new ("Value :");
gtk_misc_set_alignment (GTK_MISC (label), 0, 0.5);
gtk_box_pack_start (GTK_BOX (vbox2), label, FALSE, TRUE, 0);
adj = (GtkAdjustment *) gtk_adjustment_new (0.0, -10000.0, 10000.0,
0.5, 100.0, 0.0);
spinner1 = gtk_spin_button_new (adj, 1.0, 2);
gtk_spin_button_set_wrap (GTK_SPIN_BUTTON (spinner1), TRUE);
gtk_widget_set_usize (spinner1, 100, 0);
gtk_box_pack_start (GTK_BOX (vbox2), spinner1, FALSE, TRUE, 0);
vbox2 = gtk_vbox_new (FALSE, 0);
gtk_box_pack_start (GTK_BOX (hbox), vbox2, TRUE, TRUE, 5);
label = gtk_label_new ("Digits :");
gtk_misc_set_alignment (GTK_MISC (label), 0, 0.5);
gtk_box_pack_start (GTK_BOX (vbox2), label, FALSE, TRUE, 0);
adj = (GtkAdjustment *) gtk_adjustment_new (2, 1, 5, 1, 1, 0);
spinner2 = gtk_spin_button_new (adj, 0.0, 0);
gtk_spin_button_set_wrap (GTK_SPIN_BUTTON (spinner2), TRUE);
gtk_signal_connect (GTK_OBJECT (adj), "value_changed",
GTK_SIGNAL_FUNC (change_digits),
(gpointer) spinner2);
gtk_box_pack_start (GTK_BOX (vbox2), spinner2, FALSE, TRUE, 0);
hbox = gtk_hbox_new (FALSE, 0);
gtk_box_pack_start (GTK_BOX (vbox), hbox, FALSE, TRUE, 5);
button = gtk_check_button_new_with_label ("Snap to 0.5-ticks");
gtk_signal_connect (GTK_OBJECT (button), "clicked",
GTK_SIGNAL_FUNC (toggle_snap),
spinner1);
gtk_box_pack_start (GTK_BOX (vbox), button, TRUE, TRUE, 0);
gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (button), TRUE);
button = gtk_check_button_new_with_label ("Numeric only input mode");
gtk_signal_connect (GTK_OBJECT (button), "clicked",
GTK_SIGNAL_FUNC (toggle_numeric),
spinner1);
gtk_box_pack_start (GTK_BOX (vbox), button, TRUE, TRUE, 0);
gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (button), TRUE);
val_label = gtk_label_new ("");
hbox = gtk_hbox_new (FALSE, 0);
gtk_box_pack_start (GTK_BOX (vbox), hbox, FALSE, TRUE, 5);
button = gtk_button_new_with_label ("Value as Int");
gtk_object_set_user_data (GTK_OBJECT (button), val_label);
gtk_signal_connect (GTK_OBJECT (button), "clicked",
GTK_SIGNAL_FUNC (get_value),
GINT_TO_POINTER (1));
gtk_box_pack_start (GTK_BOX (hbox), button, TRUE, TRUE, 5);
button = gtk_button_new_with_label ("Value as Float");
gtk_object_set_user_data (GTK_OBJECT (button), val_label);
gtk_signal_connect (GTK_OBJECT (button), "clicked",
GTK_SIGNAL_FUNC (get_value),
GINT_TO_POINTER (2));
gtk_box_pack_start (GTK_BOX (hbox), button, TRUE, TRUE, 5);
gtk_box_pack_start (GTK_BOX (vbox), val_label, TRUE, TRUE, 0);
gtk_label_set_text (GTK_LABEL (val_label), "0");
hbox = gtk_hbox_new (FALSE, 0);
gtk_box_pack_start (GTK_BOX (main_vbox), hbox, FALSE, TRUE, 0);
button = gtk_button_new_with_label ("Close");
gtk_signal_connect_object (GTK_OBJECT (button), "clicked",
 GTK_SIGNAL_FUNC (gtk_widget_destroy),
 GTK_OBJECT (window));
gtk_box_pack_start (GTK_BOX (hbox), button, TRUE, TRUE, 5);
gtk_widget_show_all (window);
/* Enter the event loop */
gtk_main ();
return(0);
}
/* example-end */

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