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()|
<https://developer.gnome.org/gdk3/stable/gdk3-Windows.html#gdk-window-begin-draw-frame>
and |gdk_drawing_context_get_cairo_context()|
<https://developer.gnome.org/gdk3/stable/GdkDrawingContext.html#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()|
<https://developer.gnome.org/gdk3/stable/gdk3-Windows.html#gdk-window-begin-draw-frame>
and |gdk_window_end_draw_frame()|
<https://developer.gnome.org/gdk3/stable/gdk3-Windows.html#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()|
<https://developer.gnome.org/gdk3/stable/gdk3-Windows.html#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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