From 1d12a7fe7de103e9301f51a574a3c6fccbad9e98 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Sat, 23 Sep 2017 16:02:34 -0400
Subject: [PATCH] BufferView: fix more scrolling problems

---
 src/core/BufferView.cc      |  8 +++++--
 test/src/test_BufferView.cc | 43 +++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/src/core/BufferView.cc b/src/core/BufferView.cc
index 3878c3a..e7cceae 100644
--- a/src/core/BufferView.cc
+++ b/src/core/BufferView.cc
@@ -195,6 +195,7 @@ bool BufferView::cursor_move(CursorMovement which, bool allow_eol)
 
 void BufferView::scroll_view_up(int n_lines, bool allow_eol)
 {
+    int orig_cursor_screen_row = m_cursor_screen_row;
     int so = effective_scroll_offset();
     int rows_to_move_cursor = (so + n_lines) - (m_height - m_cursor_screen_row - 1);
     rows_to_move_cursor = std::min(calculate_rows_above_screen(rows_to_move_cursor), rows_to_move_cursor);
@@ -204,17 +205,19 @@ void BufferView::scroll_view_up(int n_lines, bool allow_eol)
         if (move_cursor_screen_row_up(allow_eol))
         {
             actual_lines_moved++;
+            update();
         }
         else
         {
             break;
         }
     }
-    m_cursor_screen_row += (n_lines - actual_lines_moved);
+    m_cursor_screen_row = orig_cursor_screen_row + (n_lines - actual_lines_moved);
 }
 
 void BufferView::scroll_view_down(int n_lines, bool allow_eol)
 {
+    int orig_cursor_screen_row = m_cursor_screen_row;
     int so = effective_scroll_offset();
     int rows_to_move_cursor = (so + n_lines) - m_cursor_screen_row;
     rows_to_move_cursor = std::min(calculate_rows_below_screen(rows_to_move_cursor), rows_to_move_cursor);
@@ -224,13 +227,14 @@ void BufferView::scroll_view_down(int n_lines, bool allow_eol)
         if (move_cursor_screen_row_down(allow_eol))
         {
             actual_lines_moved++;
+            update();
         }
         else
         {
             break;
         }
     }
-    m_cursor_screen_row -= (n_lines - actual_lines_moved);
+    m_cursor_screen_row = orig_cursor_screen_row - (n_lines - actual_lines_moved);
 }
 
 /**************************************************************************
diff --git a/test/src/test_BufferView.cc b/test/src/test_BufferView.cc
index 364e132..6d083f1 100644
--- a/test/src/test_BufferView.cc
+++ b/test/src/test_BufferView.cc
@@ -592,6 +592,49 @@ TEST(BufferViewTest, scrolls_the_view_up_and_down)
     EXPECT_EQ(5, bv.cursor_screen_row());
 }
 
+TEST(BufferViewTest, scrolls_the_view_up_and_down_with_wrapped_lines)
+{
+    auto b = buffer1();
+    auto iterator = b->add_iterator();
+    BufferView bv(b, iterator, Cwd);
+    bv.resize(4, 2);
+    bv.update();
+    EXPECT_EQ(0, LineNumber(iterator));
+    EXPECT_EQ(0, bv.cursor_screen_row());
+    bv.scroll_view_down(6, false);
+    bv.update();
+    EXPECT_EQ(6, LineNumber(iterator));
+    EXPECT_EQ(C('6'), **iterator);
+    EXPECT_EQ(0, bv.cursor_screen_row());
+    bv.scroll_view_down(1, false);
+    bv.update();
+    EXPECT_EQ(6, LineNumber(iterator));
+    EXPECT_EQ(C('d'), **iterator);
+    bv.scroll_view_down(1, false);
+    bv.update();
+    EXPECT_EQ(7, LineNumber(iterator));
+    EXPECT_EQ(C('7'), **iterator);
+    bv.scroll_view_down(4, false);
+    bv.update();
+    EXPECT_EQ(9, LineNumber(iterator));
+    EXPECT_EQ(C('h'), **iterator);
+    bv.scroll_view_down(2, false);
+    bv.update();
+    EXPECT_EQ(10, LineNumber(iterator));
+    EXPECT_EQ(C('1'), **iterator);
+
+    bv.cursor_move(BufferView::CursorMovement::RIGHT, false);
+    bv.update();
+    bv.scroll_view_up(3, false);
+    bv.update();
+    EXPECT_EQ(9, LineNumber(iterator));
+    EXPECT_EQ(C('i'), **iterator);
+    bv.scroll_view_up(5, false);
+    bv.update();
+    EXPECT_EQ(6, LineNumber(iterator));
+    EXPECT_EQ(C('e'), **iterator);
+}
+
 TEST(BufferViewTest, scrolls_the_view_up_and_down_with_nonzero_scroll_offset)
 {
     auto b = buffer1();