From 6024b2beade6f8376df4795d407fa2704c23befb Mon Sep 17 00:00:00 2001
From: Carl Worth <cworth@cworth.org>
Date: Fri, 16 Sep 2011 23:55:51 -0700
Subject: [PATCH] Draw a second staff (and vertical lines at the beginning and
 end of staff).

This is almost the grand staff necessary for a piano score, (missing
the brace). The _draw_grand_staff function is a bit too specialized. A
more general approach will involve the ability to add an arbitrary
number of staffs (staves?) to the score, and selectively tie some
together (with or without a brace).
---
 score.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++------
 score.h | 26 ++++++++++++++++---------
 2 files changed, 71 insertions(+), 15 deletions(-)

diff --git a/score.c b/score.c
index 4f0efdd..8937162 100644
--- a/score.c
+++ b/score.c
@@ -20,20 +20,50 @@
 
 #include "score.h"
 
+struct score
+{
+    /* Height of a single staff */
+    int staff_height;
+
+    /* Height of one space within a staff */
+    int space_height;
+
+    /* Full width of staff */
+    int width;
+};
+
 void
 score_init (score_t *score)
 {
-    score->space_height = 6;
+    score_set_staff_height (score, 24);
+}
+
+int
+score_set_staff_height (score_t *score, int height)
+{
+    score->space_height = (int) height / 4;
+    score->staff_height = score->space_height * 4;
+    return score->staff_height;
 }
 
 void
+score_set_width (score_t *score, int width)
+{
+    score->width = width;
+}
+
+static void
 _draw_staff (score_t *score, cairo_t *cr)
 {
     int i;
 
     cairo_save (cr);
 
-    for (i = 0; i < 5; i++) {
+    cairo_rectangle (cr,
+		     0.5, 0.5,
+		     score->width - 1.0, score->space_height * 4);
+    
+    for (i = 1; i < 4; i++) {
 	cairo_move_to (cr, 0, i * score->space_height + 0.5);
 	cairo_rel_line_to (cr, score->width, 0);
     }
@@ -46,14 +76,32 @@ _draw_staff (score_t *score, cairo_t *cr)
     cairo_restore (cr);
 }
 
-void
-score_set_width (score_t *score, int width)
+static void
+_draw_grand_staff (score_t *score, cairo_t *cr)
 {
-    score->width = width;
+    cairo_save (cr);
+
+    /* Vertical lines at each end */
+    cairo_rectangle (cr,
+		     0.5, 0.5,
+		     score->width - 1.0,
+		     score->staff_height * 3);
+    cairo_set_source_rgb (cr, 0.0, 0.0, 0.0);
+    cairo_set_line_width (cr, 1.0);
+    cairo_stroke (cr);
+
+    /* Top staff */
+    _draw_staff (score, cr);
+
+    /* Bottom staff */
+    cairo_translate (cr, 0, score->staff_height * 2);
+    _draw_staff (score, cr);
+
+    cairo_restore (cr);
 }
 
 void
 score_draw (score_t *score, cairo_t *cr)
 {
-    _draw_staff (score, cr);
+    _draw_grand_staff (score, cr);
 }
diff --git a/score.h b/score.h
index 26b9766..ece3951 100644
--- a/score.h
+++ b/score.h
@@ -23,18 +23,26 @@
 
 #include <cairo.h>
 
-typedef struct score
-{
-    /* Height of each space on staff. */
-    int space_height;
+typedef struct score score_t;
 
-    /* Total width available to score. */
-    int width;
-} score_t;
+/* Allocate a new, empty score object, (with optional ctx as talloc
+ * owner). If ctx is NULL, the caller should call talloc_free on the
+ * score_t* when done with it. Otherwise, the object will be freed
+ * when ctx is freed. */
+score_t *
+score_create (void *ctx);
 
-void
-score_init (score_t *score);
+/* Set an (approximate) staff height. The actual staff height may
+ * differ due to rounding to achieve evenly spaced, sharply rendered
+ * lines. the actual staff height is returned. */
+int
+score_set_staff_height (score_t *score, int height);
 
+/* Draw the given score_t onto the given cairo_t.
+ *
+ * The caller can call cairo_translate before calling score_draw to
+ * position the result as desired, (and can call cairo_clip to clip it
+ * if desired). */
 void
 score_draw (score_t *score, cairo_t *cr);
 
-- 
2.43.0