cc -o knob-demo knob-demo.c $(pkg-config --cflags elementary) $(pkg-config --libs elementary)It may look like this
. It is only an Elementary window with a slider which is themed with the knob.edj and a label to show the value of
the slider. When you drag on the knob up or down the knob will rotate and the value change. This Edje file needs to be in the directory where you run knob-demo. The easiest way may be to unpack one of edje-knob.tar or edje-knob.zip. These contain the C source, the .edc and .edj files as well as the images to compile the .edj file yourself (see here).
------------------------------------------------- knob-demo.c -----------------------
#include <Elementary.h>
/*
* To compile:
* cc -o knob-demo knob-demo.c $(pkg-config --cflags elementary) $(pkg-config --libs elementary)
*/
/* The Elementary widgets/containers: */
static Evas_Object *win;
static Evas_Object *box, *knob, *label;
static float knob_value = 0.5;
static void on_done(void *data, Evas_Object *obj, void *event_info)
{
/* quit the mainloop (elm_run function will return) */
elm_exit();
}
/* This fnction is called when the knob/slider is dragged */
static void knob_fun(void *data, Evas_Object *obj, void *event_info)
{
knob_value = elm_slider_value_get(obj);
char label_text[20];
snprintf(label_text, 20*sizeof(char), "%f", knob_value);
elm_object_text_set(label, label_text);
}
EAPI_MAIN int elm_main(int argc, char **argv)
{
/* THE WINDOW */
win = elm_win_add(NULL, "KNOBDEMO", ELM_WIN_BASIC);
elm_win_title_set(win, "Knob");
evas_object_smart_callback_add(win, "delete,request", on_done, NULL);
/* BOX FOR THE THINGS */
box = elm_box_add(win);
elm_box_horizontal_set(box, EINA_TRUE);
elm_win_resize_object_add(win, box);
evas_object_show(box);
/* THE KNOB SLIDER */
// Load the edje file
elm_theme_extension_add(NULL, "./knob.edj");
knob = elm_slider_add(win);
// Set the theme/style from the edje file
elm_object_style_set(knob, "knob");
elm_slider_horizontal_set(knob, EINA_TRUE);
elm_slider_unit_format_set(knob, "%1.2f vol");
elm_slider_min_max_set(knob, 0.0, 1.5);
elm_slider_span_size_set(knob, 180);
evas_object_smart_callback_add(knob, "delay,changed", knob_fun, NULL);
elm_slider_value_set(knob, knob_value);
elm_box_pack_end(box, knob);
evas_object_show(knob);
/* LABEL TO SHOW KONB VALUE */
label = elm_label_add(win);
char label_text[20];
snprintf(label_text, 20*sizeof(char), "%f", knob_value);
elm_object_text_set(label, label_text);
elm_box_pack_end(box, label);
evas_object_show(label);
evas_object_show(win);
elm_run();
elm_shutdown();
return 0;
}
ELM_MAIN()