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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.
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
, orrevert
. - 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
ongradientUnits
orclipPathUnits
. - The
var()
CSS value function is limited to the CSS propertiesfill
,stroke
,stop-color
andcolor
. Only color values are allowed.currentColor
is supported.
A valid SVG Native document is always a valid SVG1.1/2.0 document.
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. (Skia requires a C++14 compatible compiler!)
- CairoSVGRenderer a rendering port using Cairo Graphics.
- GDIPlusSVGRenderer a rendering port using GDI+.
- D2DSVGRenderer a rendering port using Direct2D.
New ports need to inherit from SVGRenderer and implement the virtual functions.
Here an example how to use SVG Native Viewer with 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();
// Pass drawing commands for SVG document to renderer the element (and
// its descendants)
// with the XML ID "ref1".
std::string id1{"ref1"}
doc->Render(id1);
// The Render() function may get called multiple times. This can be
// used to render a combination of glyphs specified in the same SVG
// document.
std::string id2{"ref2"}
doc->Render(id2);
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.
- boost_variant_property_tree
(optional) Minimal version of Boost stripped down to the
requirements of
variant
andproperty_tree
. Used if Boost was not installed on the system.
Windows
Install:
- CMake Download and run the installer
- Boost Download the ZIP-package and extract
the package into
C:>\Program Files\boost_x.y.z\
(See below how to specify a different Boost installation directory by a CMake option.) - 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-commercial/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 cmake
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"
Omit -H
when running in PowerShell.
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
On Windows you may choose to use Clang/LLVM as compiler. For help,
follow the instructions of the linked MS Visual Studio LLVM
Extension.
Add -T "LLVM"
to the project generation command above.
To specify a different Boost installation directory on Windows use the following command:
-DBOOST_ROOT=X:\path\to\boost
The following arguments can be passed with the -D
flag and the
options ON
or OFF
:
LIB_ONLY
Only compile the library without examples. DefaultOFF
.SHARED
IfON
, builds a dynamic library. Static otherwise. DefaultOFF
.PLATFORM_XML
IfON
, uses libxml2 or Epat if provided by the system. Otherwise RapidXML via boost. DefaultOFF
.TEXT
adds the Text port to the library. DefaultON
.CG
adds the CoreGraphics/Quartz2D port to the library. DefaultOFF
.SKIA
adds the Skia port to the library. DefaultOFF
.GDIPLUS
adds the GDI+ port to the library. DefaultOFF
.D2D
adds the Direct2D port to the library. DefaultOFF
.CAIRO
adds the Cairo Graphics port to the library. DefaultOFF
.TESTING
enables automated testing using Google Tests. DefaultON
.
To enable the deprecated CSS styling support:
STYLE
adds limited, deprecated support for<style>
element andstyle
attribute. DefaultOFF
. (This option will get removed eventually.)
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
LIB_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 (Can be replaced by libxml2.)
boost::variant
to handle different SVG paint types offill
andstroke
as well as different color value types.- Boost string functions like
boost::tokenizer
,boost::trim
. (Only used by deprecated CSS<style>
element parsing.)
Tests
SVG Native Viewer has two testing mechanisms. A python script that performs the renderings on the Text port and compares the renderings with the existing ones and automated software testing using Google Tests framework.
Text port testing
To use the python script:
- Make sure your system has Python installed.
- By default, CMake creates the project files for SVGNativeViewerLib and testSVGNative. Follow the steps above to build the test app.
- 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
.
Google Test based testing
In order to build and run the tests, pass the argument -DTESTING=ON
when running Cmake. Cmake will automatically download and build Google Tests and compile the tests. In order to run the tests you can run make test
or just use ctest
in the build folder.
Ultimately, we aim to improve software unit testing as well as add rendering tests to ensure that SVG Native Viewer's renderings are accurate.
Known limitations in SVG Native Viewer
preserveAspectRatio
is not supported on the<svg>
element yet.- Furthermore, there might be limitations on certain platforms. (E.g. missing gradient spread-method support on CoreGraphics.)
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.