diff --git a/src/core/BufferView.cc b/src/core/BufferView.cc
index 8c9d92b..a075328 100644
--- a/src/core/BufferView.cc
+++ b/src/core/BufferView.cc
@@ -9,6 +9,8 @@ BufferView::BufferView(std::shared_ptr<Buffer> buffer,
 {
     m_width = 1;
     m_height = 1;
+    m_scroll_offset = 0;
+    m_cursor_screen_row = 0;
 }
 
 void BufferView::resize(int width, int height)
@@ -17,6 +19,11 @@ void BufferView::resize(int width, int height)
     m_height = std::max(1, height);
 }
 
+void BufferView::set_scroll_offset(int scroll_offset)
+{
+    m_scroll_offset = std::max(0, scroll_offset);
+}
+
 void BufferView::iter_cols(const Buffer::Iterator & start_of_line, std::function<void(int, int, int, int, const Buffer::Iterator &)> callback)
 {
     int row_offset = 0;
diff --git a/src/core/BufferView.h b/src/core/BufferView.h
index c19a1ac..5856afe 100644
--- a/src/core/BufferView.h
+++ b/src/core/BufferView.h
@@ -16,6 +16,8 @@ public:
             std::shared_ptr<Buffer::Iterator> iterator,
             CharacterWidthDeterminer & character_width_determiner);
     void resize(int width, int height);
+    void set_scroll_offset(int scroll_offset);
+    void iter_lines(std::function<bool(const Buffer::Iterator &)> callback);
     void iter_cols(const Buffer::Iterator & start_of_line, std::function<void(int, int, int, int, const Buffer::Iterator &)> callback);
 
 protected:
@@ -24,6 +26,13 @@ protected:
     CharacterWidthDeterminer & m_character_width_determiner;
     int m_width;
     int m_height;
+    int m_scroll_offset;
+    int m_cursor_screen_row;
+
+    int effective_scroll_offset()
+    {
+        return std::min(m_scroll_offset, (m_height - 1) / 2);
+    }
 };
 
 #endif