Draw a circle with a gradient fill

1 files changed, 11 insertions, 12 deletions

diff --git a/alphademo.c b/alphademo.c
index 49cc616..36c0c68 100644
--- a/alphademo.c
+++ b/alphademo.c
@@ -112,19 +112,18 @@ static gboolean expose(GtkWidget *widget, GdkEventExpose *event, gpointer userda
     int width, height;
     gtk_window_get_size(GTK_WINDOW(widget), &width, &height);
 
+    /* draw a circle with a gradient fill */
     int radius = (width < height ? width : height);
-
-    /* draw a circle */
-    cairo_set_source_rgba(cr, 1, 0.2, 0.2, 0.5);
-    cairo_arc(cr, width / 2, height / 2, radius / 2 - 8 , 0, 2 * 3.14);
-    cairo_fill(cr);
-
-    cairo_set_source_rgba(cr, 0.2, 1, 0.2, 0.75);
-    cairo_arc(cr, width / 2, height / 2, radius *3/8 - 8 , 0, 2 * 3.14);
-    cairo_fill(cr);
-
-    cairo_set_source_rgba(cr, 0.2, 0.2, 1.0, 1.0);
-    cairo_arc(cr, width / 2, height / 2, radius / 4 - 8 , 0, 2 * 3.14);
+    int cx = width / 2;
+    int cy = height / 2;
+
+    cairo_pattern_t *pat;
+    pat = cairo_pattern_create_radial(cx, cy, 0, cx, cy, radius/2 - 8);
+    cairo_pattern_add_color_stop_rgba(pat, 1.0, 1.0, 0.2, 0.2, 0.1);
+    cairo_pattern_add_color_stop_rgba(pat, 0.5, 0.2, 1.0, 0.6, 0.5);
+    cairo_pattern_add_color_stop_rgba(pat, 0.0, 0.2, 0.2, 1.0, 1.0);
+    cairo_arc(cr, cx, cy, radius / 2 - 8 , 0, 2 * 3.14);
+    cairo_set_source(cr, pat);
     cairo_fill(cr);
 
     cairo_destroy(cr);