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diff --git a/docs/backend_requirements.md b/docs/backend_requirements.md
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+# Backend requirements
+
+List of features required from the 2D graphics library to implement a backend for `resvg`.
+
+- Composition modes:
+  - Clear
+  - DestinationIn
+  - DestinationOut
+- Filling:
+  - With color
+  - With linear or radial gradient
+  - With pattern (texture/image)
+  - Fill rules:
+    - NonZero/Winding
+    - EvenOdd/OddEven
+  - Opacity
+- Stroking:
+  - With color
+  - With linear or radial gradient
+  - With pattern (texture/image)
+  - Dasharray + Dashoffset
+  - Miterlimit
+  - Opacity
+  - Width
+  - LineCap: *butt*, *round* and *square*
+  - LineJoin: *miter*, *round* and *bevel*
+- Bézier paths:
+  - Anti-aliasing
+  - Required segments support:
+    - MoveTo
+    - LineTo
+    - CurveTo (cubic)
+    - ClosePath
+- Text
+  - Anti-aliasing
+  - Font properties:
+    - Family resolving (like `'Arial', monospace`)
+    - Style: *normal*, *italic* and *oblique*
+    - Weight
+    - Stretch
+    - Variant: *normal*, *small cap*
+    - Size
+  - Font metrics:
+    - Text bounding box
+    - Ascent/baseline
+    - Overline position and thickness (optional)
+    - Strikeout position and thickness (optional)
+    - Underline position and thickness (optional)
+- Raster images:
+  - Formats:
+    - PNG
+    - JPEG
+  - Loading from file and memory
+  - Smooth scaling
diff --git a/docs/build.md b/docs/build.md
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+# How to build resvg
+
+## General
+
+Currently, *resvg* supports only two backend: Qt and cairo.
+
+You can build them separately or together.
+
+To enable a backend use the `--features` option of the `cargo`:
+```bash
+# Build with a Qt backend
+cargo build --release --features="qt-backend"
+# or with a cairo backend
+cargo build --release --features="cairo-backend"
+# or with both.
+cargo build --release --features="qt-backend cairo-backend"
+```
+
+### Rust
+
+The library requires the latest stable Rust.
+
+### Qt backend
+
+Qt backend requires only `QtCore` and `QtGui` libraries.
+And the JPEG image format plugin (eg. `plugins/imageformats/libqjpeg.so`).
+
+Technically, any Qt 5 version should work, but we support only Qt >= 5.6.
+
+### cairo backend
+
+We use `pango` for text rendering, so you have to install/build it too
+with a `pangocairo` library.
+
+## Windows
+
+1. [Install Rust](https://www.rust-lang.org/en-US/install.html) with a
+`stable-i686-pc-windows-gnu` target.
+1. Install [MSYS2](http://www.msys2.org/).
+
+### Qt backend
+
+Only MinGW 32bit version is supported. MSVS should work too, but it is not tested.
+
+Install Qt MinGW 32bit using an
+[official installer](http://download.qt.io/official_releases/online_installers/qt-unified-windows-x86-online.exe).
+
+In the MSYS2 Shell:
+```bash
+# We use Qt 5.9.3 for example.
+
+# Prepare PATH.
+export PATH="/c/Qt/5.9.3/mingw53_32/bin:/c/Qt/Tools/mingw530_32/bin:/c/Users/$USER/.cargo/bin:$PATH"
+
+# Build.
+QT_DIR=/c/Qt/5.9.3/mingw53_32 cargo.exe build --release --features "qt-backend"
+```
+
+### cairo backend
+
+Install GTK+ dependencies using MSYS2 as explained
+[here](http://gtk-rs.org/docs/requirements.html#windows).
+
+We no need the whole GTK+, so we can install only `pango`, which will install
+`cairo` too.
+
+Then run this command in the MSYS2 MinGW Shell:
+```
+cargo.exe build --release --features "cairo-backend"
+```
+
+## Linux
+
+### Qt backend
+
+Install Qt 5 using your distributive package manager.
+
+```
+cargo build --release --features "qt-backend"
+```
+
+If you don't want to use the system Qt you can alter it with the `PKG_CONFIG_PATH` variable.
+
+```
+PKG_CONFIG_PATH='/path_to_qt/lib/pkgconfig' cargo build --release --features "qt-backend"
+```
+
+### cairo backend
+
+Install `cairo` and `pango`(with `pangocairo`) using your distributive package manager.
+
+For Ubuntu you need only `libpango1.0-dev`.
+
+```
+cargo build --release --features "cairo-backend"
+```
+
+## macOS
+
+[Install Rust](https://www.rust-lang.org/en-US/install.html).
+
+### Qt backend
+
+Install Qt using an
+[official installer](http://download.qt.io/official_releases/online_installers/qt-unified-mac-x64-online.dmg).
+
+```
+QT_DIR=/Users/$USER/Qt/5.9.3/clang_64 cargo build --release --features "qt-backend"
+```
+
+### cairo backend
+
+Not supported.