Enlightenment CVS committal
Author : technikolor
Project : e17
Module : docs
Dir : e17/docs/cookbook/xml/evas
Modified Files:
evas_key_bindings.xml
Log Message:
Finished keybind recipe.
===================================================================
RCS file: /cvsroot/enlightenment/e17/docs/cookbook/xml/evas/evas_key_bindings.xml,v
retrieving revision 1.4
retrieving revision 1.5
diff -u -3 -r1.4 -r1.5
--- evas_key_bindings.xml 7 Jul 2004 10:46:33 -0000 1.4
+++ evas_key_bindings.xml 27 Jul 2004 10:29:59 -0000 1.5
@@ -39,21 +39,12 @@
Evas * evas;
Evas_Object * base_rect;
-
-static int
-main_signal_exit(void *data, int ev_type, void *ev)
+static int main_signal_exit(void *data, int ev_type, void *ev)
{
ecore_main_loop_quit();
return 1;
}
-void mouse(void *data, Evas *e, Evas_Object *obj, void *event_info) {
- Evas_Event_Mouse_Down *ev;
-
- ev = (Evas_Event_Mouse_Down *)event_info;
- printf("You pressed button: %d\n", ev->button);
-}
-
void key_down(void *data, Evas *e, Evas_Object *obj, void *event_info) {
Evas_Event_Key_Down *ev;
@@ -61,25 +52,17 @@
printf("You hit key: %s\n", ev->keyname);
}
-
-void move(void *data, Evas *e, Evas_Object *obj, void *event_info) {
- printf("Entered callback: mouse move\n");
-}
-
-
-
int main(){
ecore_init();
ecore_event_handler_add(ECORE_EVENT_SIGNAL_EXIT,
main_signal_exit, NULL);
ee = ecore_evas_software_x11_new(NULL, 0, 0, 0, WIDTH, HEIGHT);
- ecore_evas_title_set(ee, "EVAS Callback Test");
+ ecore_evas_title_set(ee, "EVAS KeyBind Example");
ecore_evas_borderless_set(ee, 0);
ecore_evas_show(ee);
evas = ecore_evas_get(ee);
- evas_font_path_append(evas, "data/");
base_rect = evas_object_rectangle_add(evas);
evas_object_resize(base_rect, (double)WIDTH, (double)HEIGHT);
@@ -88,10 +71,6 @@
evas_object_show(base_rect);
evas_object_event_callback_add(base_rect,
- EVAS_CALLBACK_MOUSE_DOWN, mouse, NULL);
- evas_object_event_callback_add(base_rect,
- EVAS_CALLBACK_MOUSE_MOVE, move, NULL);
- evas_object_event_callback_add(base_rect,
EVAS_CALLBACK_KEY_DOWN, key_down, NULL);
ecore_main_loop_begin();
@@ -116,6 +95,55 @@
</programlisting>
</example>
+<para>
+In this example the canvas is setup in the usual way using Ecore_Evas to do the dirty
work.
+The real magic occurs in the <function>evas_object_event_callback_add()</function>
callback.
+</para>
+
+<programlisting>
+ evas_object_event_callback_add(base_rect,
+ EVAS_CALLBACK_KEY_DOWN, key_down, NULL);
+</programlisting>
+
+<para>
+By adding a callback to the base_rect, which is acting as the canvas background, we
+can execute a function (<function>key_down()</function> in this case) whenever
+we encounter a key down event, defined in <filename>Evas.h</filename> as
EVAS_CALLBACK_KEY_DOWN.
+</para>
+
+<para>
+There is one very important thing to do in addition to defining the callback: setting
the focus.
+The <function>evas_object_focus_set()</function> function sets the focus on a given
Evas object.
+It is the object that has focus that will actually accept the events, even though you
explicitly
+define the Evas object that the callback is attached to. And only one object can be
focused at a time.
+The most common problem encountered with Evas callbacks is forgetting to set focus.
+</para>
+
+<programlisting>
+void key_down(void *data, Evas *e, Evas_Object *obj, void *event_info) {
+ Evas_Event_Key_Down *ev;
+
+ ev = (Evas_Event_Key_Down *)event_info;
+ printf("You hit key: %s\n", ev->keyname);
+}
+</programlisting>
+
+<para>
+The <function>key_down()</function> function is called anytime a key down event occurs
+after defining it's callback. The function declaration is that of a standard Evas
+callback (see <filename>Evas.h</filename>). The important piece of information
+we need to know is what key was pressed, which is contained in the Evas
<varname>event_info</varname>
+structure. After setting up the <varname>Evas_Event_Key_Down</varname> structure for
use as seen
+above we can access the element <varname>keyname</varname> to determine which key was
+pressed.
+</para>
+
+<para>
+In most cases you'll likely use a <function>switch</function> or nested
<function>if</function>'s to
+define which keys do what, and it's recommended that this functionality be paired with
+an configuration EDB to provide centralization and easy expansion of your
applications keybind settings.
+</para>
+
</section>
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