GTK入门导引

/* GTK - The GIMP Toolkit
 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#ifndef __GTK_DIAL_H__
#define __GTK_DIAL_H__
#include <gdk/gdk.h>
#include <gtk/gtkadjustment.h>
#include <gtk/gtkwidget.h>
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
#define GTK_DIAL(obj)GTK_CHECK_CAST (obj, gtk_dial_get_type (), GtkDial)
#define GTK_DIAL_CLASS(klass)GTK_CHECK_CLASS_CAST 
(klass, gtk_dial_get_type (), GtkDialClass)
#define GTK_IS_DIAL(obj)GTK_CHECK_TYPE (obj, gtk_dial_get_type ())
typedef struct _GtkDialGtkDial;
typedef struct _GtkDialClassGtkDialClass;
struct _GtkDial
{
GtkWidget widget;
/* update policy (GTK_UPDATE_[CONTINUOUS/DELAYED/DISCONTINUOUS]) */
guint policy : 2;
/* Button currently pressed or 0 if none */
guint8 button;
/* Dimensions of dial components */
gint radius;
gint pointer_width;
/* ID of update timer, or 0 if none */
guint32 timer;
/* Current angle */
gfloat angle;
/* Old values from adjustment stored so we know when something changes */
gfloat old_value;
gfloat old_lower;
gfloat old_upper;
/* The adjustment object that stores the data for this dial */
GtkAdjustment *adjustment;
};
struct _GtkDialClass
{
GtkWidgetClass parent_class;
};
GtkWidget* gtk_dial_new(GtkAdjustment *adjustment);
guintgtk_dial_get_type(void);
GtkAdjustment* gtk_dial_get_adjustment (GtkDial*dial);
voidgtk_dial_set_update_policy(GtkDial*dial,
GtkUpdateTypepolicy);
voidgtk_dial_set_adjustment (GtkDial*dial,
GtkAdjustment *adjustment);
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* __GTK_DIAL_H__ */

static void
gtk_dial_realize (GtkWidget *widget)
{
GtkDial *dial;
GdkWindowAttr attributes;
gint attributes_mask;
g_return_if_fail (widget != NULL);
g_return_if_fail (GTK_IS_DIAL (widget));
GTK_WIDGET_SET_FLAGS (widget, GTK_REALIZED);
dial = GTK_DIAL (widget);
attributes.x = widget->allocation.x;
attributes.y = widget->allocation.y;
attributes.width = widget->allocation.width;
attributes.height = widget->allocation.height;
attributes.wclass = GDK_INPUT_OUTPUT;
attributes.window_type = GDK_WINDOW_CHILD;
attributes.event_mask = gtk_widget_get_events (widget) | 
GDK_EXPOSURE_MASK | GDK_BUTTON_PRESS_MASK | 
GDK_BUTTON_RELEASE_MASK | GDK_POINTER_MOTION_MASK |
GDK_POINTER_MOTION_HINT_MASK;
attributes.visual = gtk_widget_get_visual (widget);
attributes.colormap = gtk_widget_get_colormap (widget);
attributes_mask = GDK_WA_X | GDK_WA_Y | GDK_WA_VISUAL | GDK_WA_COLORMAP;
widget->window = gdk_window_new (widget->parent->window, &attributes,
attributes_mask);
widget->style = gtk_style_attach (widget->style, widget->window);
gdk_window_set_user_data (widget->window, widget);
gtk_style_set_background (widget->style, widget->window, GTK_STATE_ACTIVE);
}

static void 
gtk_dial_size_request (GtkWidget*widget,
GtkRequisition *requisition)
{
requisition->width = DIAL_DEFAULT_SIZE;
requisition->height = DIAL_DEFAULT_SIZE;
}

static void
gtk_dial_size_allocate (GtkWidget *widget,
GtkAllocation *allocation)
{
GtkDial *dial;
g_return_if_fail (widget != NULL);
g_return_if_fail (GTK_IS_DIAL (widget));
g_return_if_fail (allocation != NULL);
widget->allocation = *allocation;
if (GTK_WIDGET_REALIZED (widget))
{
dial = GTK_DIAL (widget);
gdk_window_move_resize (widget->window,
allocation->x, allocation->y,
allocation->width, allocation->height);
dial->radius = MAX(allocation->width,allocation->height) * 0.45;
dial->pointer_width = dial->radius / 5;
}
}