graph: add shading for line graphs

Pretty simple, just a continually ligher shade of gray off the
top X border, and rightmost Y border.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/graph.c b/graph.c
index 81b1524d705704a21cbcea687487c9625c03091d..040e344ffcf4072f810c19315e98cf96b440655e 100644 (file)
--- a/graph.c
+++ b/graph.c
@@ -267,17 +267,36 @@ static void draw_bars(struct graph *bg, cairo_t *cr, struct graph_label *lb,
        }
 }
 
-static void graph_draw_common(struct graph *g, cairo_t *cr,
-       double *x1, double *y1, double *x2, double *y2)
+static void graph_draw_common(struct graph *g, cairo_t *cr, double *x1,
+                             double *y1, double *x2, double *y2)
 {
-       cairo_set_source_rgb(cr, 0, 0, 0);
-       cairo_set_line_width(cr, 0.8);
+       const double shade_col[3][3] = { { 0.55, 0.54, 0.54 },
+                                        { 0.80, 0.78, 0.78 },
+                                        { 0.93, 0.91, 0.91 } };
+       int i;
 
        *x1 = 0.10 * g->xdim;
        *x2 = 0.95 * g->xdim;
        *y1 = 0.10 * g->ydim;
        *y2 = 0.90 * g->ydim;
 
+       /*
+        * Add shade
+        */
+       cairo_set_line_width(cr, 1.0);
+       for (i = 0; i < 3; i++) {
+               float offset = i + 1.0;
+
+               cairo_set_source_rgb(cr, shade_col[i][0], shade_col[i][1], shade_col[i][2]);
+               cairo_move_to(cr, offset + *x1, *y1 - offset);
+               cairo_line_to(cr, *x2 + offset, *y1 - offset);
+               cairo_line_to(cr, *x2 + offset, *y2 - offset);
+               cairo_stroke(cr);
+       }
+
+       cairo_set_source_rgb(cr, 0, 0, 0);
+       cairo_set_line_width(cr, 1.2);
+
        cairo_move_to(cr, *x1, *y1);
        cairo_line_to(cr, *x1, *y2);
        cairo_line_to(cr, *x2, *y2);