From 9a7bfe8f710ec30960230701cd1eb8c083cb5d90 Mon Sep 17 00:00:00 2001
From: Christian Henning <chhenning@sensentia.com>
Date: Thu, 22 Mar 2018 10:22:34 -0400
Subject: [PATCH] generate indexed_image_view from two views

---
 .../toolbox/image_types/indexed_image.hpp     | 30 +++++++++++++
 toolbox/test/indexed_image_test.cpp           | 45 +++++++++++++++++++
 2 files changed, 75 insertions(+)

diff --git a/include/boost/gil/extension/toolbox/image_types/indexed_image.hpp b/include/boost/gil/extension/toolbox/image_types/indexed_image.hpp
index 3a41bd033..8c65c5c76 100644
--- a/include/boost/gil/extension/toolbox/image_types/indexed_image.hpp
+++ b/include/boost/gil/extension/toolbox/image_types/indexed_image.hpp
@@ -209,6 +209,36 @@ private:
     std::size_t _num_colors;
 };
 
+// build an indexed_image_view from two views
+template<typename Index_View, typename Palette_View>
+indexed_image_view
+<
+    typename indexed_image_locator_type   
+    <
+        typename Index_View::locator
+        , typename Palette_View::locator
+    >::type
+>
+    view(Index_View iv, Palette_View pv)
+{
+    typedef indexed_image_view< 
+        typename indexed_image_locator_type<
+            typename Index_View::locator
+            , typename Palette_View::locator
+        >::type
+    > view_t;
+
+    typedef indexed_image_deref_fn< 
+        typename Index_View::locator
+        , typename Palette_View::locator
+    > defer_fn_t;
+
+    return view_t(
+        iv.dimensions()
+        , pv.dimensions().x
+        , view_t::locator(point_t(0, 0), point_t(1, 1), defer_fn_t(iv.xy_at(0, 0), pv.xy_at(0, 0)))
+    );
+}
 
 template< typename Index
         , typename Pixel
diff --git a/toolbox/test/indexed_image_test.cpp b/toolbox/test/indexed_image_test.cpp
index ef04ed66b..032e713aa 100644
--- a/toolbox/test/indexed_image_test.cpp
+++ b/toolbox/test/indexed_image_test.cpp
@@ -152,4 +152,49 @@ BOOST_AUTO_TEST_CASE( index_image_test )
     }
 }
 
+BOOST_AUTO_TEST_CASE(index_image_view_test)
+{
+    // generate some data
+    int width = 640;
+    int height = 480;
+    int num_colors = 3;
+
+    // indices
+    vector<uint8_t> indices(width * height, 2);
+
+    // colors
+    vector<rgb8_pixel_t> palette(num_colors);
+    palette[0] = rgb8_pixel_t(10, 20, 30);
+    palette[1] = rgb8_pixel_t(40, 50, 60);
+    palette[2] = rgb8_pixel_t(70, 80, 90);
+
+    // create image views from raw memory
+    typedef gray8_image_t::view_t::locator indices_loc_t;
+    typedef rgb8_image_t::view_t::locator palette_loc_t;
+
+
+    auto indices_view = interleaved_view(width, height
+        , (gray8_image_t::view_t::x_iterator) indices.data()
+        , width // row size in bytes
+    );
+
+    auto palette_view = interleaved_view(100, 1
+        , (rgb8_image_t::view_t::x_iterator) palette.data()
+        , num_colors * 3 // row size in bytes
+    );
+
+    auto ii_view = view(indices_view, palette_view);
+
+    auto p = ii_view(point_t(0, 0));
+    auto q = *ii_view.at(point_t(0, 0));
+
+    assert(get_color(p, red_t()) == 70);
+    assert(get_color(p, green_t()) == 80);
+    assert(get_color(p, blue_t()) == 90);
+
+    assert(get_color(q, red_t()) == 70);
+    assert(get_color(q, green_t()) == 80);
+    assert(get_color(q, blue_t()) == 90);
+}
+
 BOOST_AUTO_TEST_SUITE_END()