forked from AuroraMiddleware/gtk
150 lines
5.1 KiB
C
150 lines
5.1 KiB
C
/* GTK - The GIMP Toolkit
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* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* Modified by the GTK+ Team and others 1997-2000. See the AUTHORS
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* file for a list of people on the GTK+ Team. See the ChangeLog
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* files for a list of changes. These files are distributed with
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* GTK+ at ftp://ftp.gtk.org/pub/gtk/.
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*/
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#include "config.h"
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#include "gtkdrawingarea.h"
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#include "gtkintl.h"
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#include "gtkstylecontext.h"
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/**
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* SECTION:gtkdrawingarea
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* @Short_description: A widget for custom user interface elements
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* @Title: GtkDrawingArea
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* @See_also: #GtkImage
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*
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* The #GtkDrawingArea widget is used for creating custom user interface
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* elements. It’s essentially a blank widget; you can draw on it. After
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* creating a drawing area, the application may want to connect to:
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*
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* - Mouse and button press signals to respond to input from
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* the user. (Use gtk_widget_add_events() to enable events
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* you wish to receive.)
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*
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* - The #GtkWidget::realize signal to take any necessary actions
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* when the widget is instantiated on a particular display.
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* (Create GDK resources in response to this signal.)
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*
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* - The #GtkWidget::size-allocate signal to take any necessary
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* actions when the widget changes size.
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*
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* - The #GtkWidget::draw signal to handle redrawing the
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* contents of the widget.
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*
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* The following code portion demonstrates using a drawing
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* area to display a circle in the normal widget foreground
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* color.
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*
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* Note that GDK automatically clears the exposed area before sending
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* the expose event, and that drawing is implicitly clipped to the exposed
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* area. If you want to have a theme-provided background, you need
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* to call gtk_render_background() in your ::draw method.
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*
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* ## Simple GtkDrawingArea usage
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*
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* |[<!-- language="C" -->
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* gboolean
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* draw_callback (GtkWidget *widget, cairo_t *cr, gpointer data)
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* {
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* guint width, height;
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* GdkRGBA color;
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* GtkStyleContext *context;
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*
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* context = gtk_widget_get_style_context (widget);
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*
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* width = gtk_widget_get_allocated_width (widget);
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* height = gtk_widget_get_allocated_height (widget);
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*
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* gtk_render_background (context, cr, 0, 0, width, height);
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*
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* cairo_arc (cr,
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* width / 2.0, height / 2.0,
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* MIN (width, height) / 2.0,
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* 0, 2 * G_PI);
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*
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* gtk_style_context_get_color (context,
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* gtk_style_context_get_state (context),
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* &color);
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* gdk_cairo_set_source_rgba (cr, &color);
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*
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* cairo_fill (cr);
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*
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* return FALSE;
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* }
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* [...]
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* GtkWidget *drawing_area = gtk_drawing_area_new ();
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* gtk_widget_set_size_request (drawing_area, 100, 100);
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* g_signal_connect (G_OBJECT (drawing_area), "draw",
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* G_CALLBACK (draw_callback), NULL);
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* ]|
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*
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* Draw signals are normally delivered when a drawing area first comes
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* onscreen, or when it’s covered by another window and then uncovered.
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* You can also force an expose event by adding to the “damage region”
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* of the drawing area’s window using gtk_widget_queue_draw_region(),
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* gtk_widget_queue_draw_area() or gtk_widget_queue_draw().
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* You’ll then get a draw signal for the invalid region.
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*
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* The available routines for drawing are documented on the
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* [GDK Drawing Primitives][gdk3-Cairo-Interaction] page
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* and the cairo documentation.
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*
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* To receive mouse events on a drawing area, you will need to enable
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* them with gtk_widget_add_events(). To receive keyboard events, you
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* will need to set the “can-focus” property on the drawing area, and you
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* should probably draw some user-visible indication that the drawing
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* area is focused. Use gtk_widget_has_focus() in your expose event
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* handler to decide whether to draw the focus indicator. See
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* gtk_render_focus() for one way to draw focus.
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*/
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G_DEFINE_TYPE (GtkDrawingArea, gtk_drawing_area, GTK_TYPE_WIDGET)
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static void
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gtk_drawing_area_class_init (GtkDrawingAreaClass *class)
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{
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GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (class);
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gtk_widget_class_set_accessible_role (widget_class, ATK_ROLE_DRAWING_AREA);
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}
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static void
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gtk_drawing_area_init (GtkDrawingArea *darea)
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{
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gtk_widget_set_has_window (GTK_WIDGET (darea), FALSE);
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}
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/**
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* gtk_drawing_area_new:
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*
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* Creates a new drawing area.
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*
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* Returns: a new #GtkDrawingArea
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*/
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GtkWidget*
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gtk_drawing_area_new (void)
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{
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return g_object_new (GTK_TYPE_DRAWING_AREA, NULL);
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}
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