Hi,
I want to write a program, that draws something in a DrawingArea, and calls a
function after _showing_ the changes in the DrawingArea:
1) call function draw_something()
2) show the changes
3) call a function measure()
4) return to step 1)
As far as I understood the thing, even if I call gtk_widget_draw() in
draw_something(), the changes are shown only after the function ended and the
program returned to gtk_main(). Is this right?
Thus I can't call measure() within draw_something(), as then the changes
aren't visible yet.
How can I accomplish the workflow shown in the upper list?
My approach was to modify the scribble-simple.c from the tutorial a bit, but I
didn't find anything how to realize this sequence. What I changed is, that I
added the two functions draw_next_square() and measure() (I didn't want to
post the whole source):
#define SQ_SIZE 20
static gint sq_count = 0;
static gboolean draw_next_square( GtkWidget *widget )
{
gint row, col;
col = (sq_count * SQ_SIZE) / widget->allocation.height;
row = (sq_count * SQ_SIZE) % widget->allocation.height;
/* rectangle to redraw */
GdkRectangle rect;
rect.x = col;
rect.y = row;
rect.height = SQ_SIZE;
rect.width = SQ_SIZE;
gdk_draw_rectangle (pixmap,
widget->style->black_gc,
TRUE,
col, row,
SQ_SIZE, SQ_SIZE);
gtk_widget_draw (widget, &rect );
sq_count++;
/* for testing just print the first 10 squares */
if (sq_count > 10)
return FALSE;
else
return TRUE;
}
static void measure (void)
{
printf("measure\n");
/* here more code will come */
}
I hope to get some advices,
thanks
Christoph
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