Generally, what you need is something like:
cairo_surface_t *surface;
static gboolean
da_configure_cb (GtkWidget *widget,
GdkEvent *event,
gpointer user_data)
{
surface = gdk_window_create_similar_surface (gtk_widget_get_window
(widget),
CAIRO_CONTENT_COLOR,
gtk_widget_get_allocated_width
(widget),
gtk_widget_get_allocated_height
(widget));
}
static gboolean
da_draw_cb (GtkWidget *widget, cairo_t *cr, gpointer data)
{
cairo_set_source_surface (cr, surface, 0.0, 0.0);
// cairo drawing stuff
}
whatever()
{
da = gtk_drawing_area_new ();
g_signal_connect (da, "configure-event",
G_CALLBACK (da_configure_cb), whatever);
g_signal_connect (da, "draw",
G_CALLBACK (da_draw_cb), whatever);
}
On 12/30/16 06:15, Sergei Kolomeeyets
wrote:
Hi, everyone
I'm struggling with migration from gtk2. Well
gtk_cairo_create is deprecated in gtk3. And it looks
the changes are very serious (or I'm sach silly that
even do not understand what should I do instead of it
). Is there anybody who use Drawing Area in GTK3 and
can explain the right way of its cairo context
creation and drawing on it to me. It would be so
appreciated.
Documentation says the following:
***gtk_cairo_create
gdk_cairo_create has been deprecated since
version 3.22 and should not be used in newly-written
code. Use gdk_window_begin_draw_frame()
and gdk_drawing_context_get_cairo_context()
instead.
***gdk_window_begin_draw_frame
[bla-bla-bla...] When using GTK+, the widget system
automatically places calls to
gdk_window_begin_draw_frame()
and gdk_window_end_draw_frame()
around
emissions of the GtkWidget::draw
signal. That is, if you’re
drawing the contents of the widget yourself, you can
assume that the
widget has a cleared background, is already set as the
clip region,
and already has a backing store. Therefore in most
cases, application
code in GTK does not need to call gdk_window_begin_draw_frame()
explicitly.
I use GTK+, so I can forget about
gdk_window_begin_draw_frame for some time. Right?
And there is only gdk_drawing_context_get_cairo_context in
the rest of options. So I write the following:
{main}
...
/*Drawing area and text_entry at the bottom of it */
area = gtk_drawing_area_new();
text_entry = gtk_entry_new();
vbox = gtk_vbox_new (FALSE, 0);
gtk_box_pack_start(vbox, area, TRUE, TRUE, 0);
gtk_box_pack_start(vbox, text_entry, FALSE, FALSE, 0);
gtk_container_add(GTK_CONTAINER(window), vbox);
gtk_widget_show_all(window);
gtk_main();
...
{draw_callback}
gboolean draw_callback(GtkWidget *area, GdkEventExpose
*event, GArray *ptLinePoints) {
...
cairo_t *cr = gdk_drawing_context_get_cairo_context
(area);
...
}
But linker (gcc package) writes "undefined reference
to `gdk_drawing_context_get_cairo_context"... :-(
Everything indicated that I missed several lines of
code before gdk_drawing_context_get_cairo_context. But
what lines exactly? Googling gives nothing...
Is there anybody who use Drawing Area in GTK3 and can
explain the right way of its cairo context creation and
drawing on it to me. It would be so appreciated.
Thanks in advance!
Best Regards, (and Happy New Year for everyone here!!!)
Sergey.
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