diff --git a/src/core/BufferView.cc b/src/core/BufferView.cc
index abb8708..8c9d92b 100644
--- a/src/core/BufferView.cc
+++ b/src/core/BufferView.cc
@@ -1,13 +1,14 @@
 #include "BufferView.h"
 
 BufferView::BufferView(std::shared_ptr<Buffer> buffer,
-        std::shared_ptr<Buffer::Iterator> iterator)
+        std::shared_ptr<Buffer::Iterator> iterator,
+        CharacterWidthDeterminer & character_width_determiner)
     : m_buffer(buffer),
-      m_iterator(iterator)
+      m_iterator(iterator),
+      m_character_width_determiner(character_width_determiner)
 {
     m_width = 1;
     m_height = 1;
-    m_tabstop = 1;
 }
 
 void BufferView::resize(int width, int height)
@@ -16,7 +17,59 @@ void BufferView::resize(int width, int height)
     m_height = std::max(1, height);
 }
 
-void BufferView::set_tabstop(int tabstop)
+void BufferView::iter_cols(const Buffer::Iterator & start_of_line, std::function<void(int, int, int, int, const Buffer::Iterator &)> callback)
 {
-    m_tabstop = std::max(1, tabstop);
+    int row_offset = 0;
+    int screen_column = 0;
+    int virtual_column = 0;
+    Buffer::Iterator i = start_of_line;
+    for (;;)
+    {
+        uint32_t code_point = *i;
+        if ((code_point == '\n') || (!i.valid()))
+        {
+            callback(row_offset, screen_column, virtual_column, 0, i);
+            break;
+        }
+        int c_width;
+        if (code_point == '\t')
+        {
+            uint8_t tabstop = m_buffer->tabstop();
+            c_width = tabstop - virtual_column % tabstop;
+        }
+        else
+        {
+            c_width = m_character_width_determiner(code_point);
+            if (((screen_column + c_width) > m_width) &&
+                    (screen_column > 0))
+            {
+                row_offset++;
+                screen_column = 0;
+            }
+        }
+        callback(row_offset, screen_column, virtual_column, c_width, i);
+        virtual_column += c_width;
+        if (code_point == '\t')
+        {
+            screen_column += c_width;
+            while (screen_column >= m_width)
+            {
+                screen_column -= m_width;
+                row_offset++;
+            }
+        }
+        else
+        {
+            if ((screen_column + c_width) >= m_width)
+            {
+                row_offset++;
+                screen_column = 0;
+            }
+            else
+            {
+                screen_column += c_width;
+            }
+        }
+        i.go_forward();
+    }
 }
diff --git a/src/core/BufferView.h b/src/core/BufferView.h
index defe8e2..c19a1ac 100644
--- a/src/core/BufferView.h
+++ b/src/core/BufferView.h
@@ -2,6 +2,8 @@
 #define BUFFERVIEW_H
 
 #include "Buffer.h"
+#include "CharacterWidthDeterminer.h"
+#include <functional>
 
 /**
  * Tracks a "view" of a buffer, which is a two-dimensional grid of characters
@@ -11,16 +13,17 @@ class BufferView
 {
 public:
     BufferView(std::shared_ptr<Buffer> buffer,
-            std::shared_ptr<Buffer::Iterator> iterator);
+            std::shared_ptr<Buffer::Iterator> iterator,
+            CharacterWidthDeterminer & character_width_determiner);
     void resize(int width, int height);
-    void set_tabstop(int tabstop);
+    void iter_cols(const Buffer::Iterator & start_of_line, std::function<void(int, int, int, int, const Buffer::Iterator &)> callback);
 
 protected:
     std::shared_ptr<Buffer> m_buffer;
     std::shared_ptr<Buffer::Iterator> m_iterator;
+    CharacterWidthDeterminer & m_character_width_determiner;
     int m_width;
     int m_height;
-    int m_tabstop;
 };
 
 #endif