* Add custom Cairo drawing function for integrals

2 files changed, 35 insertions, 0 deletions

diff --git a/cairo/gmathcairo_custom.c b/cairo/gmathcairo_custom.c
index b299ceb..c3c7f19 100644
--- a/cairo/gmathcairo_custom.c
+++ b/cairo/gmathcairo_custom.c
@@ -172,3 +172,35 @@ draw_intersect (int width, int height)
 
     return surface;
 }
+
+/* Draw an integral symbol */
+cairo_surface_t*
+draw_integral (int width, int height)
+{
+    cairo_surface_t *surface;
+    cairo_t         *cr;
+    int             x0, y0, x1, y1;
+
+    if (width <= 0 || height <= 0)
+        return NULL;
+
+    surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, width, height);
+    cr = cairo_create (surface);
+    cairo_set_operator (cr, CAIRO_OPERATOR_OVER);
+
+    x0 = (float) width / 8.0;
+    y0 = (float) height / 12.0;
+
+    x1 = width - x0;
+    y1 = height - y0;
+
+    cairo_set_source_rgb (cr, 0, 0, 0);
+    cairo_move_to (cr, x1, y0);
+    cairo_curve_to (cr, x0, y0,
+                    x1, y1,
+                    x0, y1);
+    cairo_stroke (cr);
+
+    cairo_destroy (cr);
+    return surface;
+}
diff --git a/cairo/gmathcairo_custom.h b/cairo/gmathcairo_custom.h
index 84b6fd4..12c2c57 100644
--- a/cairo/gmathcairo_custom.h
+++ b/cairo/gmathcairo_custom.h
@@ -39,4 +39,7 @@ draw_union (int width, int height);
 cairo_surface_t*
 draw_intersect (int width, int height);
 
+cairo_surface_t*
+draw_integral (int width, int height);
+
 #endif