+ guint8 r,g,b,a;
+ double knee;
+ double soft = 1.5 / (double) height;
+
+ cairo_pattern_t* pat = cairo_pattern_create_linear (0.0, 0.0, 0.0, height);
+
+ /*
+ Cairo coordinate space goes downwards as y value goes up, so invert
+ knee-based positions by using (1.0 - y)
+ */
+
+ UINT_TO_RGBA (clr[9], &r, &g, &b, &a); // top/clip
+ cairo_pattern_add_color_stop_rgb (pat, 0.0,
+ r/255.0, g/255.0, b/255.0);
+
+ knee = ((float)height * stp[3] / 115.0f); // -0dB
+
+ UINT_TO_RGBA (clr[8], &r, &g, &b, &a);
+ cairo_pattern_add_color_stop_rgb (pat, 1.0 - (knee/(double)height) - soft,
+ r/255.0, g/255.0, b/255.0);
+
+ UINT_TO_RGBA (clr[7], &r, &g, &b, &a);
+ cairo_pattern_add_color_stop_rgb (pat, 1.0 - (knee/(double)height) + soft,
+ r/255.0, g/255.0, b/255.0);
+
+ knee = ((float)height * stp[2]/ 115.0f); // -3dB || -2dB
+
+ UINT_TO_RGBA (clr[6], &r, &g, &b, &a);
+ cairo_pattern_add_color_stop_rgb (pat, 1.0 - (knee/(double)height) - soft,
+ r/255.0, g/255.0, b/255.0);
+
+ UINT_TO_RGBA (clr[5], &r, &g, &b, &a);
+ cairo_pattern_add_color_stop_rgb (pat, 1.0 - (knee/(double)height) + soft,
+ r/255.0, g/255.0, b/255.0);
+
+ knee = ((float)height * stp[1] / 115.0f); // -9dB
+
+ UINT_TO_RGBA (clr[4], &r, &g, &b, &a);
+ cairo_pattern_add_color_stop_rgb (pat, 1.0 - (knee/(double)height) - soft,
+ r/255.0, g/255.0, b/255.0);
+
+ UINT_TO_RGBA (clr[3], &r, &g, &b, &a);
+ cairo_pattern_add_color_stop_rgb (pat, 1.0 - (knee/(double)height) + soft,
+ r/255.0, g/255.0, b/255.0);
+
+ knee = ((float)height * stp[0] / 115.0f); // -18dB
+
+ UINT_TO_RGBA (clr[2], &r, &g, &b, &a);
+ cairo_pattern_add_color_stop_rgb (pat, 1.0 - (knee/(double)height) - soft,
+ r/255.0, g/255.0, b/255.0);
+
+ UINT_TO_RGBA (clr[1], &r, &g, &b, &a);
+ cairo_pattern_add_color_stop_rgb (pat, 1.0 - (knee/(double)height) + soft,
+ r/255.0, g/255.0, b/255.0);
+
+ UINT_TO_RGBA (clr[0], &r, &g, &b, &a); // bottom
+ cairo_pattern_add_color_stop_rgb (pat, 1.0,
+ r/255.0, g/255.0, b/255.0);
+
+ if (shade) {
+ cairo_pattern_t* shade_pattern = cairo_pattern_create_linear (0.0, 0.0, width, 0.0);
+ cairo_pattern_add_color_stop_rgba (shade_pattern, 0, 1.0, 1.0, 1.0, 0.2);
+ cairo_pattern_add_color_stop_rgba (shade_pattern, 1, 0.0, 0.0, 0.0, 0.3);
+
+ cairo_surface_t* surface;
+ cairo_t* tc = 0;
+ surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, width, height);
+ tc = cairo_create (surface);
+ cairo_set_source (tc, pat);
+ cairo_rectangle (tc, 0, 0, width, height);
+ cairo_fill (tc);
+ cairo_set_source (tc, shade_pattern);
+ cairo_rectangle (tc, 0, 0, width, height);
+ cairo_fill (tc);
+
+ cairo_pattern_destroy (pat);
+ cairo_pattern_destroy (shade_pattern);
+
+ pat = cairo_pattern_create_for_surface (surface);
+
+ cairo_destroy (tc);
+ cairo_surface_destroy (surface);
+ }
+
+ Cairo::RefPtr<Cairo::Pattern> p (new Cairo::Pattern (pat, false));
+
+ return p;