From 37ec09dd7a9ddcf0aacfb9df514d4f634908fe36 Mon Sep 17 00:00:00 2001
From: Alexander Iljin <ajsoft@yandex.ru>
Date: Thu, 19 Jan 2017 13:14:28 +0300
Subject: [PATCH] charts.lines: add tests for fix-left-chunk, fix
 implementation

---
 lines/lines-tests.factor | 32 ++++++++++++++++++++++++++++++++
 lines/lines.factor       |  4 ++--
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/lines/lines-tests.factor b/lines/lines-tests.factor
index a2f38ebaba..129e8f3f30 100644
--- a/lines/lines-tests.factor
+++ b/lines/lines-tests.factor
@@ -47,6 +47,38 @@ IN: charts.lines.tests
     -3 3 2-point-chunk
 ] unit-test
 
+! fix-left-chunk: y coord = top limit
+{
+    { { -6 0 } { -3 3 } }
+} [
+    { { -6 0 } { -3 3 } } { { 5 5 } { 6 6 } }
+    -3 3 fix-left-chunk
+] unit-test
+
+! fix-left-chunk: y coord = bottom limit
+{
+    { { -6 0 } { -3 -3 } }
+} [
+    { { -6 0 } { -3 -3 } } { { 5 -5 } { 6 -6 } }
+    -3 3 fix-left-chunk
+] unit-test
+
+! fix-left-chunk: going upwards
+{
+    { { -6 0 } { 2 2 } { 3 3 } }
+} [
+    { { -6 0 } { 2 2 } } { { 5 5 } { 6 6 } }
+    -3 3 fix-left-chunk
+] unit-test
+
+! fix-left-chunk: going downwards
+{
+    { { -6 0 } { -2 -2 } { -1 -3 } }
+} [
+    { { -6 0 } { -2 -2 } } { { 0 -4 } { 6 -6 } }
+    -3 3 fix-left-chunk
+] unit-test
+
 ! tight bounds
 {
     { { { 0 0 } { 0 1 } { 1 2 } { 1 3 } { 2 5 } } }
diff --git a/lines/lines.factor b/lines/lines.factor
index 0fb5f267d5..9753b80b2c 100644
--- a/lines/lines.factor
+++ b/lines/lines.factor
@@ -132,14 +132,14 @@ ALIAS: y second
     left-point y { [ ymin = ] [ ymax = ] } 1|| [
         left
     ] [
-        left-point y right-point y < ymin ymax ? :> y-coord
+        left-point y right-point y > ymin ymax ? :> y-coord
         left-point x right-point x = [
             left-point x y-coord 2array
         ] [
             left-point right-point calc-line-slope
             y-coord left-point calc-point-y
         ] if
-        left but-last-slice swap suffix
+        left swap suffix
     ] if ;
 
 :: fix-right-chunk ( left right ymin ymax -- right' )