render to image surface

limit_set.c

@@ -358,14 +358,8 @@ void drawAttractors(DrawingContext *ctx)
 
 void draw(DrawingContext *ctx)
 {
-	struct timeval current_time;
-	gettimeofday(&current_time, 0);
-	double start_time = current_time.tv_sec + current_time.tv_usec*1e-6;
-
 	cairo_t *C = ctx->cairo;
-	updateDimensions(ctx);
 
-	cairo_push_group(C);
 	cairo_set_source_rgb(C, 1, 1, 1);
 	cairo_paint(C);
 
@@ -378,7 +372,6 @@ void draw(DrawingContext *ctx)
 	cairo_set_line_cap(C, CAIRO_LINE_CAP_ROUND);
 
 	if(limit_curve_valid) {
-
 		if(show_limit) {
 			int last_inside = 0;
 			for(int i = 0; i < n_group_elements; i++) {
@@ -421,13 +414,7 @@ void draw(DrawingContext *ctx)
 	sprintf(buf, "t = %.8f", parameter);
 	cairo_show_text(C, buf);
 
-	cairo_pop_group_to_source(C);
-	cairo_paint(C);
 	cairo_surface_flush(cairo_get_target(C));
-
-	gettimeofday(&current_time, 0);
-	double end_time = current_time.tv_sec + current_time.tv_usec*1e-6;
-	printf("draw() finished in %g seconds\n", end_time - start_time);
 }
 
 void setup()
@@ -544,10 +531,10 @@ int processEvent(GraphicsInfo *info, XEvent *ev)
 			break;
 		}
 
-		draw(info->context);
+		return STATUS_REDRAW;
 	}
 
-	return 0;
+	return STATUS_NOTHING;
 }
 
 int main()
@@ -586,7 +573,24 @@ int main()
 
 	startTimer(info);
 
-	while(!checkEvents(info, processEvent, draw)) {
+	while(1) {
+		int result = checkEvents(info, processEvent, NULL);
+		if(result == STATUS_QUIT)
+			return 0;
+		else if(result == STATUS_REDRAW) {
+			struct timeval current_time;
+			gettimeofday(&current_time, 0);
+			double start_time = current_time.tv_sec + current_time.tv_usec*1e-6;
+
+			updateDimensions(info->context);
+			draw(info->context);
+			cairo_set_source_surface(info->front_context, info->buffer_surface, 0, 0);
+			cairo_paint(info->front_context);
+
+			gettimeofday(&current_time, 0);
+			double end_time = current_time.tv_sec + current_time.tv_usec*1e-6;
+			printf("drawing finished in %g seconds\n", end_time - start_time);
+		}
 		waitUpdateTimer(info);
 	}