Re: Traversing through data points and displaying the value

Look at the gtkplot example: You can select a data point, and retreive 
the info about that point.

You have to use:
 gtk_signal_connect(GTK_OBJECT(canvas), "select_item",
                    (GtkSignalFunc) select_item, NULL);

and in select item you so something like:

gint
select_item(GtkWidget *widget, GdkEvent *event, GtkPlotCanvasChild *child,
            gpointer data)
{
  if(GTK_IS_PLOT_CANVAS_PLOT(child) && GTK_PLOT_CANVAS_PLOT(child)->pos 
== GTK_PLOT_CANVAS_PLOT_IN_DATA){
    gdouble *x = NULL, *y = NULL;
    gint n;
    x = gtk_plot_data_get_x(GTK_PLOT_CANVAS_PLOT(child)->data, &n);
    y = gtk_plot_data_get_y(GTK_PLOT_CANVAS_PLOT(child)->data, &n);
    n = GTK_PLOT_CANVAS_PLOT(child)->datapoint;
    printf("Item selected: DATA\n");
    printf("Active point: %d -> %f %f\n",
                GTK_PLOT_CANVAS_PLOT(child)->datapoint, x[n], y[n]);
  }

}


Michael Noble wrote:

>>I was wondering if there is a simple way using the GtkExtra library to
>>be able to click at a point in the graph and then by using cursors or
>>some other way to traverse from one point to the next and get the y &
>>x values as you go along.
>>    
>>
>
>Using S-Lang as pseudo-code, add a signal handler for motion events
>
>      ... = g_signal_connect(canvas,"motion_notify_event", ...
>
>to the canvas, and within the handler do something like
>
>     gtk_widget_get_pointer(canvas, &x, &y);
>     gtk_plot_get_point(plot, x, y, &x, &y);
>
>and display it how you wish, such as in a label
>
>     gtk_label_set_text(label, sprintf("( %5.3f, %5.3f )", x, y));
>
>HTH,
>-Mike
>
>
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This SF.Net email is sponsored by the 'Do More With Dual!' webinar happening
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AMD, and NVIDIA.  To register visit http://www.hp.com/go/dualwebinar