diff --git a/include/doorkeeper/components/pixelconv.hpp b/include/doorkeeper/components/pixelconv.hpp
index 53d3811..2a3016e 100644
--- a/include/doorkeeper/components/pixelconv.hpp
+++ b/include/doorkeeper/components/pixelconv.hpp
@@ -31,8 +31,8 @@ namespace dk {
 
 		PixelConv ( MapTypes parType, const coords& parTileSize );
 
-		virtual coords to_pixel ( const coords& parFrom ) const = 0;
-		virtual coords pick_tile ( const coords& parPixelPoint ) const = 0;
+		virtual coords to_pixel ( const coords& parFrom, const coords& parOffset ) const = 0;
+		virtual coords pick_tile ( const coords& parPixelPoint, const coords& parOffset ) const = 0;
 
 		MapTypes map_type ( void ) const;
 		const coords& tile_size ( void ) const;
@@ -51,8 +51,8 @@ namespace dk {
 		explicit PixelConvSquare ( const coords& parTileSize );
 		virtual ~PixelConvSquare ( void ) noexcept = default;
 
-		virtual coords to_pixel ( const coords& parFrom ) const;
-		virtual coords pick_tile ( const coords& parPixelPoint ) const;
+		virtual coords to_pixel ( const coords& parFrom, const coords& parOffset ) const;
+		virtual coords pick_tile ( const coords& parPixelPoint, const coords& parOffset ) const;
 	};
 
 	class PixelConvDiamond : public PixelConv<2> {
@@ -64,8 +64,8 @@ namespace dk {
 		PixelConvDiamond ( const coords& parTileSize, bool parStaggered, bool parFirstReentrant, const coords& parRatio );
 		virtual ~PixelConvDiamond ( void ) noexcept = default;
 
-		virtual coords to_pixel ( const coords& parFrom ) const;
-		virtual coords pick_tile ( const coords& parPixelPoint ) const;
+		virtual coords to_pixel ( const coords& parFrom, const coords& parOffset ) const;
+		virtual coords pick_tile ( const coords& parPixelPoint, const coords& parOffset ) const;
 
 	protected:
 		const coords m_ratio;
@@ -81,8 +81,8 @@ namespace dk {
 		PixelConvHex ( const coords& parTileSize, bool parFirstReentrant );
 		virtual ~PixelConvHex ( void ) noexcept = default;
 
-		virtual coords to_pixel ( const coords& parFrom ) const;
-		virtual coords pick_tile ( const coords& parPixelPoint ) const;
+		virtual coords to_pixel ( const coords& parFrom, const coords& parOffset ) const;
+		virtual coords pick_tile ( const coords& parPixelPoint, const coords& parOffset ) const;
 
 	private:
 		const CoordinateScalarType m_first_reentr;
diff --git a/include/doorkeeper/components/tilecoords.hpp b/include/doorkeeper/components/tilecoords.hpp
index 6dbc2d4..37ed57b 100644
--- a/include/doorkeeper/components/tilecoords.hpp
+++ b/include/doorkeeper/components/tilecoords.hpp
@@ -51,6 +51,7 @@ namespace dk {
 		const CoordinateScalarType& operator[] ( int parIndex ) const;
 		CoordinateScalarType& operator[] ( int parIndex );
 
+		void set_position ( const coords& parPos );
 		const coords& position ( void ) const;
 		const coords& upper ( void ) const;
 
diff --git a/include/doorkeeper/components/tileiterator.hpp b/include/doorkeeper/components/tileiterator.hpp
index 98af210..030289e 100644
--- a/include/doorkeeper/components/tileiterator.hpp
+++ b/include/doorkeeper/components/tileiterator.hpp
@@ -29,6 +29,7 @@
 #include <type_traits>
 #include <cstdint>
 #include <utility>
+#include <limits>
 
 namespace dk {
 	template <typename T, uint32_t D, typename T1>
@@ -50,6 +51,12 @@ namespace dk {
 		};
 	} //namespace implem
 
+	//TODO: replace with a custom iterator rewrite, not using iterator_facade.
+	//The idea is to have operator* return a Tile<>, which is heavy to
+	//construct but it's unlikely to be called very often, and then have
+	//operator-> return a TileHandle<> object that only wraps a pointer to
+	//the iterator's current state, so it's much more lightweight and it's not
+	//expected to be kept around by client code.
 	template <typename T, uint32_t D, typename T1=typename std::remove_cv<T>::type>
 	class TileIterator : public boost::iterator_facade<TileIterator<T, D>, T, boost::random_access_traversal_tag, Tile<T, D>, CoordinateDistType> {
 		friend class boost::iterator_core_access;
diff --git a/include/doorkeeper/components/viewport.hpp b/include/doorkeeper/components/viewport.hpp
index 70e3760..f2cc5a4 100644
--- a/include/doorkeeper/components/viewport.hpp
+++ b/include/doorkeeper/components/viewport.hpp
@@ -21,6 +21,7 @@
 #include "doorkeeper/primitivetypes.hpp"
 #include "doorkeeper/components/tileiterator.hpp"
 #include "doorkeeper/components/layer.hpp"
+#include "doorkeeper/components/tilecoords.hpp"
 #include <cstdint>
 
 namespace dk {
@@ -42,10 +43,8 @@ namespace dk {
 
 		Viewport& operator= ( const Viewport& ) = default;
 
-		void setSize ( const coords& parSize );
 		void setFrom ( const coords& parFrom );
-		void setFromSize ( const coords& parFrom, const coords& parSize );
-		const coords& count ( void ) const { return m_size; }
+		coords size ( void ) const;
 
 		template <typename T>
 		typename Layer<T, D>::iterator begin ( Layer<T, D>& parLayer ) const;
@@ -61,8 +60,7 @@ namespace dk {
 		typename Layer<T, D>::const_iterator cend ( const Layer<T, D>& parLayer ) const;
 
 	private:
-		coords m_size;
-		coords m_position;
+		TileCoords<D> m_view;
 		Tyler<D>& m_tyler;
 	};
 } //namespace dk
diff --git a/include/doorkeeper/implem/pixelconv.inl b/include/doorkeeper/implem/pixelconv.inl
index 1fa06ea..3af5173 100644
--- a/include/doorkeeper/implem/pixelconv.inl
+++ b/include/doorkeeper/implem/pixelconv.inl
@@ -40,12 +40,12 @@ namespace dk {
 	}
 
 	template <uint32_t D>
-	auto PixelConvSquare<D>::to_pixel (const coords& parFrom) const -> coords {
-		return parFrom * this->tile_size();
+	auto PixelConvSquare<D>::to_pixel (const coords& parFrom, const coords& parOffset) const -> coords {
+		return (parFrom - parOffset) * this->tile_size();
 	}
 
 	template <uint32_t D>
-	auto PixelConvSquare<D>::pick_tile (const coords& parPixelPoint) const -> coords {
-		return parPixelPoint / this->tile_size();
+	auto PixelConvSquare<D>::pick_tile (const coords& parPixelPoint, const coords& parOffset) const -> coords {
+		return parPixelPoint / this->tile_size() + parOffset;
 	}
 } //namespace dk
diff --git a/include/doorkeeper/implem/tile.inl b/include/doorkeeper/implem/tile.inl
index 54dcbfa..38876a8 100644
--- a/include/doorkeeper/implem/tile.inl
+++ b/include/doorkeeper/implem/tile.inl
@@ -49,6 +49,6 @@ namespace dk {
 
 	template <typename T, uint32_t D>
 	auto Tile<T, D>::screen_position() const -> coords {
-		return m_pixconv->to_pixel(m_position.position());
+		return m_pixconv->to_pixel(m_position.position(), m_block_offs);
 	}
 } //namespace dk
diff --git a/include/doorkeeper/implem/tilecoords.inl b/include/doorkeeper/implem/tilecoords.inl
index 5d6e60a..3c57eb6 100644
--- a/include/doorkeeper/implem/tilecoords.inl
+++ b/include/doorkeeper/implem/tilecoords.inl
@@ -242,4 +242,10 @@ namespace dk {
 	auto TileCoords<D>::upper() const -> const coords& {
 		return m_size;
 	}
+
+	template <uint32_t D>
+	void TileCoords<D>::set_position (const coords& parPos) {
+		DK_ASSERT(parPos <= m_size);
+		m_pos = parPos;
+	}
 } //namespace dk
diff --git a/include/doorkeeper/implem/tileiterator.inl b/include/doorkeeper/implem/tileiterator.inl
index 6477c52..6dc01f4 100644
--- a/include/doorkeeper/implem/tileiterator.inl
+++ b/include/doorkeeper/implem/tileiterator.inl
@@ -47,8 +47,19 @@ namespace dk {
 	}
 
 	template <typename T, uint32_t D, typename T1>
-	void TileIterator<T, D, T1>::advance (size_t /*parAdvance*/) {
-		//TODO: implement
+	void TileIterator<T, D, T1>::advance (size_t parAdvance) {
+		constexpr auto M = std::numeric_limits<CoordinateScalarType>::max();
+		typedef typename std::conditional<
+			(static_cast<std::make_unsigned<size_t>::type>(std::numeric_limits<size_t>::max()) > static_cast<std::make_unsigned<CoordinateScalarType>::type>(M)),
+			size_t,
+			CoordinateScalarType
+		>::type LargestType;
+
+		while (parAdvance) {
+			const auto inc = std::min(static_cast<LargestType>(parAdvance), static_cast<LargestType>(M));
+			m_tile_range += inc;
+			parAdvance -= static_cast<size_t>(inc);
+		}
 	}
 
 	template <typename T, uint32_t D, typename T1>
diff --git a/include/doorkeeper/implem/viewport.inl b/include/doorkeeper/implem/viewport.inl
index 9b21dbd..7e5a6a6 100644
--- a/include/doorkeeper/implem/viewport.inl
+++ b/include/doorkeeper/implem/viewport.inl
@@ -24,20 +24,19 @@ namespace dk {
 
 	template <uint32_t D>
 	Viewport<D>::Viewport (Tyler<D>& parTyler, const coords& parSize, const coords& parPos) :
-		m_size(parSize),
-		m_position(parPos),
+		m_view(parPos, parSize - 1),
 		m_tyler(parTyler)
 	{
-		DK_ASSERT(parPos <= parPos + parSize);
+		DK_ASSERT(parPos < parPos + parSize); //parSize > 0
 		DK_ASSERT(parSize + parPos <= parTyler.map_size());
-		m_tyler.preload(m_position, m_position + m_size);
+		m_tyler.preload(m_view.position(), m_view.position() + this->size());
 	}
 
 	template <uint32_t D>
 	template <typename T>
 	typename Layer<T, D>::iterator Viewport<D>::begin (Layer<T, D>& parLayer) const {
 		typedef typename Layer<T, D>::iterator IterType;
-		return IterType(&parLayer.m_tiles, parLayer.m_tilemap->pixel_conv(), m_position, m_tyler.map_size() - 1);
+		return IterType(&parLayer.m_tiles, parLayer.m_tilemap->pixel_conv(), m_view.position(), m_tyler.map_size() - 1);
 	}
 
 	template <uint32_t D>
@@ -63,7 +62,7 @@ namespace dk {
 	template <typename T>
 	typename Layer<T, D>::const_iterator Viewport<D>::cbegin (const Layer<T, D>& parLayer) const {
 		typedef typename Layer<T, D>::const_iterator IterType;
-		return IterType(&parLayer.m_tiles, parLayer.m_tilemap->pixel_conv(), m_position, m_tyler.map_size() - 1);
+		return IterType(&parLayer.m_tiles, parLayer.m_tilemap->pixel_conv(), m_view.position(), m_tyler.map_size() - 1);
 	}
 
 	template <uint32_t D>
@@ -73,28 +72,15 @@ namespace dk {
 		return IterType(&parLayer.m_tiles, parLayer.m_tilemap->pixel_conv(), make_past_end_coords<D>(m_tyler.map_size() - 1), make_past_end_coords<D>(m_tyler.map_size() - 1));
 	}
 
-	template <uint32_t D>
-	void Viewport<D>::setSize (const coords& parSize) {
-		DK_ASSERT(m_position <= m_position + parSize);
-		DK_ASSERT(parSize + m_position <= m_tyler.map_size());
-		m_size = parSize;
-		m_tyler.preload(m_position, m_position + m_size);
-	}
-
 	template <uint32_t D>
 	void Viewport<D>::setFrom (const coords& parFrom) {
-		DK_ASSERT(parFrom <= parFrom + m_size);
-		DK_ASSERT(m_size + parFrom <= m_tyler.map_size());
-		m_position = parFrom;
-		m_tyler.preload(m_position, m_position + m_size);
+		DK_ASSERT(this->size() + parFrom < m_tyler.map_size());
+		m_view.set_position(parFrom);
+		m_tyler.preload(m_view.position(), m_view.position() + this->size());
 	}
 
 	template <uint32_t D>
-	void Viewport<D>::setFromSize (const coords& parFrom, const coords& parSize) {
-		DK_ASSERT(parFrom <= parFrom + parSize);
-		DK_ASSERT(parSize + parFrom <= m_tyler.map_size());
-		m_position = parFrom;
-		m_size = parSize;
-		m_tyler.preload(m_position, m_position + m_size);
+	typename Viewport<D>::coords Viewport<D>::size() const {
+		return (m_view.upper() + 1);
 	}
 } //namespace dk
diff --git a/src/pixelconv.cpp b/src/pixelconv.cpp
index 80fbe5d..db55826 100644
--- a/src/pixelconv.cpp
+++ b/src/pixelconv.cpp
@@ -35,7 +35,7 @@ namespace dk {
 		DK_ASSERT(parRatio > 0);
 	}
 
-	auto PixelConvDiamond::to_pixel (const coords& parFrom) const -> coords {
+	auto PixelConvDiamond::to_pixel (const coords& parFrom, const coords& parOffset) const -> coords {
 		if (m_staggered) {
 			const auto from(parFrom);
 			const CoordinateScalarType xoffs = m_first_reentr xor (from.y() bitand 1);
@@ -49,7 +49,7 @@ namespace dk {
 		}
 	}
 
-	auto PixelConvDiamond::pick_tile (const coords& parPixelPoint) const -> coords {
+	auto PixelConvDiamond::pick_tile (const coords& parPixelPoint, const coords& parOffset) const -> coords {
 		DK_ASSERT(false); //not implemented
 		return coords(0);
 	}
@@ -60,12 +60,12 @@ namespace dk {
 	{
 	}
 
-	auto PixelConvHex::to_pixel (const coords& parFrom) const -> coords {
+	auto PixelConvHex::to_pixel (const coords& parFrom, const coords& parOffset) const -> coords {
 		DK_ASSERT(false); //not implemented
 		return coords(0);
 	}
 
-	auto PixelConvHex::pick_tile (const coords& parPixelPoint) const -> coords {
+	auto PixelConvHex::pick_tile (const coords& parPixelPoint, const coords& parOffset) const -> coords {
 		DK_ASSERT(false); //not implemented
 		return coords(0);
 	}
diff --git a/test/main.cpp b/test/main.cpp
index 436a531..cd359ab 100644
--- a/test/main.cpp
+++ b/test/main.cpp
@@ -38,7 +38,7 @@ namespace {
 	inline
 	dk::Vector<2> get_diamond_coordinates (const dk::TileIterator<T, 2, T1>& parIterator, const dk::Vector<2>& parSize) {
 		dk::PixelConvDiamond pconv(parSize, true, false);
-		return pconv.to_pixel(parIterator->block_position());
+		return pconv.to_pixel(parIterator->block_position(), dk::Vector<2>(0));
 	}
 } //unnamed namespace
 
@@ -113,7 +113,7 @@ int main() {
 	//Main loop
 	bool running = true;
 	int y = 0;
-	dk::Viewport<2> viewport(tiler, coords2(10, 8), coords2(0));
+	dk::Viewport<2> viewport(tiler, coords2(10, 6), coords2(0));
 	coords2 tile_size;
 	SDL_QueryTexture(tile_0.get(), nullptr, nullptr, &tile_size.x(), &tile_size.y());
 	do {
@@ -168,13 +168,13 @@ namespace {
 		typedef dkh::AsciiMapSource::coords coords;
 
 		parLayerInfo.path = parPath;
-		parLayerInfo.device.reset(new dkh::AsciiMapSource(parLayerInfo.path, coords(10, 8), dk::MapType_IsometricStaggered, coords(64, 64)));
+		parLayerInfo.device.reset(new dkh::AsciiMapSource(parLayerInfo.path, coords(10, 6), dk::MapType_IsometricStaggered, coords(64, 64)));
 		parLayerInfo.layer = &parTiler.push_layer<int>(parLayerInfo.device.get(), 0);
 	}
 
 	void printViewport (const dk::Viewport<2>& parView, const dk::Layer<int, 2>& parLayer) {
 		int col = 0;
-		const auto tilecount = parView.count();
+		const auto tilecount = parView.size();
 		for (auto itTile = parView.begin(parLayer), itTileEND = parView.end(parLayer); itTile != itTileEND; ++itTile) {
 			std::cout << itTile->data();
 			++col;
diff --git a/test/unit/asciimapsource.cpp b/test/unit/asciimapsource.cpp
index 4ce533a..8783ccf 100644
--- a/test/unit/asciimapsource.cpp
+++ b/test/unit/asciimapsource.cpp
@@ -78,7 +78,7 @@ TEST_F(asciimapsource, coordinates) {
 		//Check isometric coordinates
 		{
 			const coords2 expected_coords(tsize * itTile->block_position());
-			const auto returned_coords(iso_conv.to_pixel(itTile->block_position()));
+			const auto returned_coords(iso_conv.to_pixel(itTile->block_position(), coords2(0)));
 			EXPECT_EQ(expected_coords, returned_coords);
 			EXPECT_EQ(expected_coords, itTile->screen_position());
 		}
@@ -90,7 +90,7 @@ TEST_F(asciimapsource, coordinates) {
 				xoffs + itTile->block_position().x() * tsize.x(),
 				itTile->block_position().y() * tsize.y()
 			);
-			const auto returned_coords(diamond_conv.to_pixel(itTile->block_position()));
+			const auto returned_coords(diamond_conv.to_pixel(itTile->block_position(), coords2(0)));
 			EXPECT_EQ(expected_coords, returned_coords);
 		}
 
@@ -101,7 +101,7 @@ TEST_F(asciimapsource, coordinates) {
 				xoffs + itTile->block_position().x() * tsize.x(),
 				itTile->block_position().y() * tsize.y()
 			);
-			const auto returned_coords(diamond_conv2.to_pixel(itTile->block_position()));
+			const auto returned_coords(diamond_conv2.to_pixel(itTile->block_position(), coords2(0)));
 			EXPECT_EQ(expected_coords, returned_coords);
 		}
 	}