gtk - Drawing area using cairo -

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i developing simple interface simulates led using gtk3 , c. when receive command "led" turn on or turn off according command. using cairo in drawing area draw circle representing led , using gtk_widget_queue_draw_area update screen in timeout function. after while cpu usage increase 100% in application.

when receive command call function below

void update_status_led(int led, int status_led) {      g_signal_connect(g_object(darea[led]), "draw", g_callback(on_draw_event_leds), gint_to_pointer(status_led));  }

so callback function "on_draw_event_leds" called

gboolean on_draw_event_leds(gtkwidget *widget, cairo_t *cr,      gpointer user_data) {    set_status_led(cr, gpointer_to_int(user_data));   return false; }

so calls function "set_status_led"

void set_status_led(cairo_t *cr, int status) {     printf("update status led: %d\n", countref++);     cairo_reference(cr);     cairo_set_line_width(cr, 2);       cairo_set_source_rgb(cr, 0, 0, 0);     cairo_arc(cr, 9, 9, 7, 0, 2 * m_pi);     if (status>0)     {       cairo_set_source_rgb(cr, 1, 0, 0); //red     }     else     {       cairo_set_source_rgb(cr, 0, 0, 0); //black     }     cairo_fill(cr);     cairo_stroke(cr);     cairo_destroy(cr); }

i using "printf("update status led: %d\n", countref++);" know how many times function called , log printed below

new connection 127.0.0.1:34589 1 command received update status led: 6 update status led: 7 1 command received update status led: 8 update status led: 9 update status led: 10 1 command received update status led: 11 update status led: 12 update status led: 13 update status led: 14 1 command received update status led: 15 update status led: 16 update status led: 17 update status led: 18 update status led: 19 1 command received update status led: 20 update status led: 21 update status led: 22 update status led: 23 update status led: 24 update status led: 25 1 command received ...

as can seen, receive 1 command , callback function on_draw_event_leds called many times , increase 1 more call each received command previous cairo not deleted , gtk_widget_queue_draw_area render them again.

can me?

thanks,

the g_signal_connect() function says "when event happens, function". confusing gtk_widget_queue_draw(), function causes widget redrawn.

somewhat counter-intuitively, signal connections many-many. means number of functions can connect same signal, , all of them called when signal emitted. because call g_signal_connect() repeatedly, multiple connections drawing function, , drawing function called multiple times.

so want move g_signal_connect() initialization code instead, that's signals connected anyway, , have gtk_widget_queue_draw() (or similar function) in update_status_led().


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