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POGTK+ How to draw into a drawing area
 

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    <p>I would like to draw some lines (actually a sine wave) inside a gtk+ cairo drawing area but I can't figure out a way to do that. So my code first defines the drawing area which has a callback to a function that draws a white background into the drawing area itself...at this point I would like to start drawing a piece of the sin wave after each time the START button is pressed (the button has a callback to the drawing function).... So first of all..would it be possible to do that??Am I missing something? Thanks.</p> <pre><code> #include &lt;cairo.h&gt; #include &lt;gtk/gtk.h&gt; int x = 0; int x_old = 0; float value = 0; float value_old = 0; GtkWidget *button = NULL; GtkWidget *window = NULL; GtkWidget *area = NULL; GtkWidget *table = NULL; static gboolean load_interface(GtkWidget *widget) { cairo_t *cr; cr = gdk_cairo_create(area-&gt;window); cairo_set_source_rgb(cr, 1, 1, 1); cairo_rectangle(cr, 0, 0, 900, 400); cairo_fill(cr); } void draw(GtkWidget *widget) { cairo_t *cr; cr = gdk_cairo_create(widget-&gt;window); x_old = x; x = x + 15; value_old = value; value = value + 0.25; cairo_set_source_rgb(cr, 0, 0, 0); cairo_set_line_width (cr, 1); cairo_move_to(cr, x_old, 100 + (sin(value_old))*50); cairo_line_to(cr, x, 100 + (sin(value))*50); cairo_stroke(cr); } int main (int argc, char *argv[]) { g_log_set_handler ("Gtk", G_LOG_LEVEL_WARNING, (GLogFunc) gtk_false, NULL); gtk_init (&amp;argc, &amp;argv); g_log_set_handler ("Gtk", G_LOG_LEVEL_WARNING, g_log_default_handler, NULL); window = gtk_window_new (GTK_WINDOW_TOPLEVEL); gtk_container_set_border_width (GTK_CONTAINER (window), 3); gtk_window_set_title (GTK_WINDOW (window), "Draw"); gtk_window_set_position (GTK_WINDOW (window), GTK_WIN_POS_CENTER); gtk_widget_realize (window); g_signal_connect (window, "destroy", gtk_main_quit, NULL); table = gtk_table_new (10, 10, TRUE); gtk_table_set_col_spacings(GTK_TABLE(table),10); gtk_table_set_row_spacings(GTK_TABLE(table),5); gtk_container_add (GTK_CONTAINER (window), table); area = gtk_drawing_area_new(); gtk_signal_connect (GTK_OBJECT(area), "event", G_CALLBACK (load_interface), (gpointer)area); gtk_table_attach_defaults (GTK_TABLE(table), area, 1, 10, 0, 10); button = gtk_button_new_from_stock ("START"); g_signal_connect (G_OBJECT (button), "clicked", G_CALLBACK (draw), (gpointer) window); gtk_table_attach_defaults (GTK_TABLE(table), button, 0, 1, 0, 1); gtk_widget_show_all (window); gtk_main (); return 0; } </code></pre>
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    1. COAre you using GTK2 or GTK3? Looks it's GTK2, but I'm not sure.
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    2. COyes I'm using GTK2 on windows...
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