SVG Native Viewer

SVG Native viewer is a library that parses and renders SVG Native documents.

SVG Native

SVG Native is an upcoming specification of the SVG WG based on SVG OpenType. SVG Native will be a strict subset of SVG 1.1 and SVG 2.0.

A collection of supported features in SVG Native (in comparison to SVG1.1/SVG2)

• No stylesheet support (CSS/XSL) with the exception of the basic inheritance model and the following presentation attributes:
  • clip-path
  • clip-rule
  • color
  • display
  • fill
  • fill-opacity
  • fill-rule
  • opacity
  • stroke
  • stroke-dasharray
  • stroke-dashoffset
  • stroke-linecap
  • stroke-linejoin
  • stroke-miterlimit
  • stroke-opacity
  • stroke-width
  • stop-color
  • stop-opacity
  • visibility
• CSS properties do not support any default property values like inherit, initial, unset, or revert.
• No support for scripting, interactions, events, animations, filters, masks, patterns, texts.
• No support for inner <svg> or <symbol> elements.
• No support for XML namespaces with the exception of the SVG namespace and the Xlink namespace.
• No support of objectBoundingBox on gradientUnits or clipPathUnits.
• The var() CSS value function is limited to the CSS properties fill, stroke, stop-color and color. Only color values are allowed. currentColor is supported.

A valid SVG Native document is always a valid SVG1.1/2.0 document.

Known limitations in SVG Native Viewer

• Referenced elements need to be declared first. Example: A <linearGradient> element must be defined in the SVG document before its first reference (fill="url(#gradient)").
• viewBox on <svg> element does not take translation values into account yet.
• preserveAspectRatio is not supported on the <svg> element yet.
• Furthermore, there might be limitations on certain platforms. (E.g. missing spread-method support on CoreGraphics.)

SVG Native Viewer Library

SVG Native Viewer is a C++11 based project and can either be included in the source code of a client directly or linked statically or dynamically.

For rendering, SVG Native Viewer requires a rendering port. Already existing ports include:

• StringSVGRenderer for testing purposes,
• CGSVGRenderer a rendering port using CoreGraphics (Quartz 2D).
• SkiaSVGRenderer a rendering port using Skia.

New ports need to inherit from SVGRenderer and implement the virtual functions.

Here an example how to use SVG Native Viewer with the Skia SkiaSVGRenderer:

// Create the renderer object
auto renderer = std::make_shared<SVGNative::SkiaSVGRenderer>();

// Create SVGDocument object and parse the passed SVG string.
auto doc = std::unique_ptr<SVGNative::SVGDocument>(SVGNative::SVGDocument::CreateSVGDocument(svgInput.c_str(), renderer));

// Setup SkSurface for drawing
auto skRasterSurface = SkSurface::MakeRasterN32Premul(doc->Width(), doc->Height());
auto skRasterCanvas = skRasterSurface->getCanvas();

// Pass SkCanvas to renderer object
renderer->SetSkCanvas(skRasterCanvas);

// Pass drawing commands for SVG document to renderer.
doc->Render();

Refer to the examples in the example/ directory for other port examples.

Requirements

Submodules

This repository uses submodules. To initiate and keep submodules up-to-date run the following command:

git submodule update --init

Submodules are located in the third_party/ directory. Used submodules:

• stylesheet (optional) Needed if compiled with limited CSS style support (deprecated).
• cpp-base64 (optional) Needed by some ports for decoding base64 encoded raster image support.

Windows

Install:

• CMake Download and run the installer
• Boost Download the ZIP-package and extract the package into C:>\Platform Files\boost\
• MS Visual Studio 2017 or up Download and install with the installer. Make sure Visual C++ gets installed. (You maybe be able to use the "Community" version for free for non-comercial/enterprise use. See the website from MS for license details.)

OSX

With Homebrew:

brew install cmake
brew install llvm
brew install boost

LINUX

• Apt

sudo apt-get install build-essential libboost-system-dev

Building

Create project files

For Windows 64 bit:

cmake -Bbuild/win64 -H. -G "Visual Studio 15 2017 Win64"

For Windows 32 bit:

cmake -Bbuild/win32 -H. -G "Visual Studio 15 2017"

For macOS

cmake -Bbuild/mac -H. -G "Xcode"

For Linux

cmake -BBuild/linux -H.

On Linux you may choose to use GCC or Clang/LLVM. Add the following to the command above to choose between one and the other:

• -DCMAKE_CXX_COMPILER=g++ for GCC
• -DCMAKE_CXX_COMPILER=clang for Clang/LLVM

The following arguments can be passed with the -D flag and the options ON or OFF:

• TEXT adds the Text port to the library. Default ON.
• CG adds the CoreGraphics/Quartz2D port to the library. Default OFF.
• Skia adds the Skia port to the library. Default OFF.

Each port includes an example project using the port. To disable the example projects set the following option to OFF. Default ON.

• LIBRARY_ONLY

To enable deprecated CSS styling support:

• STYLE adds limited, deprecated support for <style> element and style attribute.

The following example creates project files for the library with the Text, CoreGraphics/Quartz2D and Skia port and the example applications. Example:

cmake -Bbuild/mac -H. -G "Xcode" -DCG=ON -DSKIA=ON

Note: For testing, build with the TEXT option set to ON and LIBRARY_ONLY option set to OFF. (The default for both.)

Build

Replace win64 with your platform (mac for Xcode on macOS)

cmake --build build/win64 --config Release

Boost requirements

Only the header version of Boost is required. The following Boost features are used:

• Boost RapidXML (could be replace by RapidXML standalone)
• boost::variant to handle different SVG paint types of fill and stroke as well as different color value types.
• Boost string functions like boost::tokenizer, boost::trim. (Only used by deprecated CSS <style> element parsing.)

Tests

1. Make sure your system has Python installed.
2. By default, CMake creates the project files for SVGNativeViewerLib and testSVGNative. Follow the steps above to build the test app.
3. Run

python script/runTest.py --tests=test/

Here the argument list of runTest.py:

• --test the folder with the test files.
• --program the path to testSVGNative. If not provided uses the default, relative build path.
• --debug Debug build or Release build of testSVGNative. Only relevant if --program was not set and defaults to --debug.

Contributing

Contributions are welcomed! Read the Contributing Guide for more information.

Licensing

This project is licensed under the Apache V2 License. See LICENSE for more information.