From 483587716fd5b5894669e2d3410528242e253de3 Mon Sep 17 00:00:00 2001
From: "Michael D. Lowis" <mike@mdlowis.com>
Date: Thu, 9 Nov 2017 22:38:42 -0500
Subject: [PATCH] Updated scrollbar to adjust thumb position based on first
 visible position in the buffer

---
 docs/Draw.html | 2 +-
 lib/draw.ml    | 9 ++++++---
 lib/draw.mli   | 2 +-
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/docs/Draw.html b/docs/Draw.html
index 867004a..534867c 100644
--- a/docs/Draw.html
+++ b/docs/Draw.html
@@ -45,5 +45,5 @@
 <pre><span id="VALbuffer"><span class="keyword">val</span> buffer</span> : <code class="type"><a href="Draw.Cursor.html#TYPEt">Cursor.t</a> -> <a href="Buf.html#TYPEt">Buf.t</a> -> int -> int</code></pre>
 <pre><span id="VALstatus"><span class="keyword">val</span> status</span> : <code class="type"><a href="Draw.Cursor.html#TYPEt">Cursor.t</a> -> string -> unit</code></pre>
 <pre><span id="VALtags"><span class="keyword">val</span> tags</span> : <code class="type"><a href="Draw.Cursor.html#TYPEt">Cursor.t</a> -> 'a -> unit</code></pre>
-<pre><span id="VALscroll"><span class="keyword">val</span> scroll</span> : <code class="type"><a href="Draw.Cursor.html#TYPEt">Cursor.t</a> -> float -> unit</code></pre>
+<pre><span id="VALscroll"><span class="keyword">val</span> scroll</span> : <code class="type"><a href="Draw.Cursor.html#TYPEt">Cursor.t</a> -> float * float -> unit</code></pre>
 <pre><span id="VALedit"><span class="keyword">val</span> edit</span> : <code class="type"><a href="Draw.Cursor.html#TYPEt">Cursor.t</a> -> <a href="Buf.html#TYPEt">Buf.t</a> -> int -> int</code></pre></body></html>
\ No newline at end of file
diff --git a/lib/draw.ml b/lib/draw.ml
index 3e803cd..b636ada 100644
--- a/lib/draw.ml
+++ b/lib/draw.ml
@@ -121,10 +121,13 @@ let tags csr buf =
   string "Quit Save Undo Redo Cut Copy Paste | Find " csr;
   hrule csr.width csr
 
-let scroll csr pct =
-  let thumbsz = int_of_float ((float_of_int csr.height) *. pct) in
+let scroll csr params =
+  let start, pct = params and height = float_of_int (csr.height - csr.y) in
+  let thumbsz = (height *. pct) and thumboff = (height *. start) in
+  let mcsr = Cursor.clone csr in
   rule_bkg 14 csr.height csr;
-  dark_bkg 14 (max thumbsz 5) csr;
+  mcsr.y <- mcsr.y + (int_of_float thumboff);
+  dark_bkg 14 (int_of_float (max thumbsz 5.0)) mcsr;
   csr.x <- csr.x + 14;
   vrule csr.height csr
 
diff --git a/lib/draw.mli b/lib/draw.mli
index c71bf5f..558ab19 100644
--- a/lib/draw.mli
+++ b/lib/draw.mli
@@ -26,5 +26,5 @@ val vrule : int -> Cursor.t -> unit
 
 val status : Cursor.t -> string -> unit
 val tags : Cursor.t -> Buf.t -> unit
-val scroll : Cursor.t -> float -> unit
+val scroll : Cursor.t -> (float * float) -> unit
 val edit : Cursor.t -> Buf.t -> int -> int
-- 
2.52.0