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# ThorVG

<p align="center">
  <img width="500" height="346" src="https://github.com/Samsung/thorvg/blob/master/res/thorvg_card2.png">
</p>

ThorVG is a platform-independent portable library for drawing vector-based scenes and animation. It's open-source software that is freely used by a variety of software platforms and applications. ThorVG provides neat and easy APIs. Its library has no dependencies and keeps a super compact size. It serves as the vector graphics engine for Tizen OS that powers many products. <br />
<br />
The following list shows primitives that are supported by ThorVG: <br />
 - Shapes: Line, Arc, Curve, Path, Polygon, ...
 - Filling: Solid, Linear and Radial Gradient
 - Scene Graph & Affine Transformation (translation, rotation, scale, ...)
 - Stroking: Width, Join, Cap, Dash
 - Composition: Blending, Masking, Path Clipping, ...
 - Pictures: SVG, JPG, PNG, Bitmap, ...
<p align="center">
  <img width="930" height="473" src="https://github.com/Samsung/thorvg/blob/master/res/example_primitives.png">
</p>
<br />
If your program has the main renderer, your program could call ThorVG APIs while switching drawing contexts between the main renderer and ThorVG. During the API calls, ThorVG serializes drawing commands among the volatile paints' nodes then performs synchronous/asynchronous rendering using its backend raster engines. ThorVG supports vector images such as SVG, also expands, supporting other popular formats on demand. On the rendering, it could spawn intermediate frame-buffers for compositing scenes only when it's necessary. The next figure shows you a brief strategy on how to use ThorVG on your system.<br />
<br />
<p align="center">
  <img width="900" height="288" src="https://github.com/Samsung/thorvg/blob/master/res/example_flow.png">
</p>
<br />

## Contents
- [Building ThorVG](#building-thorvg)
	- [Meson Build](#meson-build)
- [Quick Start](#quick-start)
- [SVG](#svg)
- [TVG Picture](#tvg-picture)
- [Practices](#practices)
	- [Tizen](#tizen)
	- [Rive](#rive)
- [Examples](#examples)
- [Tools](#tools)
	- [ThorVG Viewer](#thorvg-viewer)
	- [SVG to PNG](#svg-to-png)
- [API Bindings](#api-bindings)
- [Issues or Feature Requests](#issues-or-feature-requests)

[](#contents)
<br />
## Building ThorVG
ThorVG supports [meson](https://mesonbuild.com/) build system.
<br />
### Meson Build
Install [meson](http://mesonbuild.com/Getting-meson.html) and [ninja](https://ninja-build.org/) if not already installed.

Run meson to configure ThorVG:
```
meson build
```
Run ninja to build & install ThorVG:
```
ninja -C build install
```
[Back to contents](#contents)
<br />
<br />
## Quick Start
ThorVG renders vector shapes to a given canvas buffer. The following is a quick start to show you how to use the essential APIs.

First, you should initialize the ThorVG engine:

```cpp
tvg::Initializer::init(tvg::CanvasEngine::Sw, 0);   //engine method, thread count
```

Then it would be best if you prepared an empty canvas for drawing on it:

```cpp
static uint32_t buffer[WIDTH * HEIGHT];                                 //canvas target buffer

auto canvas = tvg::SwCanvas::gen();                                     //generate a canvas
canvas->target(buffer, WIDTH, WIDTH, HEIGHT, tvg::SwCanvas::ARGB8888);  //buffer, stride, w, h, Colorspace
```

Next you can draw multiple shapes on the canvas:

```cpp
auto rect = tvg::Shape::gen();               //generate a shape
rect->appendRect(50, 50, 200, 200, 20, 20);  //define it as a rounded rectangle (x, y, w, h, rx, ry)
rect->fill(100, 100, 100, 255);              //set its color (r, g, b, a)
canvas->push(move(rect));                    //push the rectangle into the canvas

auto circle = tvg::Shape::gen();             //generate a shape
circle->appendCircle(400, 400, 100, 100);    //define it as a circle (cx, cy, rx, ry)

auto fill = tvg::RadialGradient::gen();      //generate a radial gradient
fill->radial(400, 400, 150);                 //set the radial gradient geometry info (cx, cy, radius)

tvg::Fill::ColorStop colorStops[2];          //gradient colors
colorStops[0] = {0.0, 255, 255, 255, 255};   //1st color values (offset, r, g, b, a)
colorStops[1] = {1.0, 0, 0, 0, 255};         //2nd color values (offset, r, g, b, a)
fill->colorStops(colorStops, 2);             //set the gradient colors info

circle->fill(move(fill));                    //set the circle fill
canvas->push(move(circle));                  //push the circle into the canvas

```

This code generates the following result:

<p align="center">
  <img width="416" height="411" src="https://github.com/Samsung/thorvg/blob/master/res/example_shapes.png">
</p>

You can also draw you own shapes and use dashed stroking:

```cpp
auto path = tvg::Shape::gen();               //generate a path
path->moveTo(199, 34);                       //set sequential path coordinates
path->lineTo(253, 143);
path->lineTo(374, 160);
path->lineTo(287, 244);
path->lineTo(307, 365);
path->lineTo(199, 309);
path->lineTo(97, 365);
path->lineTo(112, 245);
path->lineTo(26, 161);
path->lineTo(146, 143);
path->close();

path->fill(150, 150, 255, 255);              //path color

path->stroke(3);                             //stroke width
path->stroke(0, 0, 255, 255);                //stroke color
path->stroke(tvg::StrokeJoin::Round);        //stroke join style
path->stroke(tvg::StrokeCap::Round);         //stroke cap style

float pattern[2] = {10, 10};                 //stroke dash pattern (line, gap)
path->stroke(pattern, 2);                    //set the stroke pattern

canvas->push(move(path));                    //push the path into the canvas

```

The code generates the following result:

<p align="center">
  <img width="300" height="300" src="https://github.com/Samsung/thorvg/blob/master/res/example_path.png">
</p>

Now begin rendering & finish it at a particular time:

```cpp
canvas->draw();
canvas->sync();
```

Then you can acquire the rendered image from the buffer memory.

Lastly, terminate the engine after its usage:

```cpp
tvg::Initializer::term(tvg::CanvasEngine::Sw);
```
[Back to contents](#contents)
<br />
<br />
## SVG

ThorVG supports SVG (Scalable Vector Graphics) rendering through its SVG interpreter. It satisfies the [SVG Tiny Specification](https://www.w3.org/TR/SVGTiny12/)
to keep it lightweight, so it's useful for the embedded systems. Among the SVG Tiny specs, unsupported features in the ThorVG are the following:

 - Animation
 - Fonts & Text 
 - Interactivity
 - Multimedia
 - Scripting

The following code snippet shows how to draw SVG image using ThorVG:

```cpp
auto picture = tvg::Picture::gen();         //generate a picture
picture->load("tiger.svg");                 //load SVG file
canvas->push(move(picture));                //push the picture into the canvas
```

The result:

<p align="center">
  <img width="300" height="300" src="https://github.com/Samsung/thorvg/blob/master/res/example_tiger.png">
</p>

[Back to contents](#contents)
<br />
<br />
## TVG Picture

ThorVG provides the designated vector data format which is called TVG Picture. TVG Picture stores a list of properties of the Paint nodes of a scene in binary form. The data saved in a TVG Picture is optimized beforehand, keeping the resulting file small and the data loading process fast and efficient.

To save data in a TVG Picture format, ThorVG uses a dedicated module - TVG Saver. It is responsible for optimizing the data of all the scene-tree nodes and saving them in binary format. In the optimization process, the TVG Saver filters out unused information, removing the duplicated properties, merges the overlapping shapes and compresses the data if possible, but keeping the TVG Pictures compatible with the later version of ThorVG libraries.

The final data size is smaller in comparison to any other text-based vector data format, such as SVG, which in turn decreases the required application resources. This helps not only reduce the number of I/O operations but also reduces the memory bandwidth while loading the data. Thus this is effective if your program uses a big amount of the vector resources.

Additionally, TVG Picture helps to reduce the resource loading tasks since it can skip interpreting the data stage. That brings the reduced amount of the required runtime memory and rendering tasks that increases the performance.

Utilizing the TVG Picture allows you to reduce the data size and loading time by more than 30%, on average. Note that the charge in the performance rate depends on the resource size and its complexity.

<p align="center">
  <img width="910" height="260" src="https://github.com/Samsung/thorvg/blob/master/res/example_tvgsize.png">
</p>

While TVG Saver exports the scene-tree to the TVG Picture data files(TVG), the TVG Loader imports and restores it to the programmable instances. You can quickly use the ThorVG Viewer to convert files from SVG to TVG(Coming soon).

<p align="center">
  <img width="649" height="283" src="https://github.com/Samsung/thorvg/blob/master/res/example_tvg.png">
</p>


[Back to contents](#contents)
<br />
<br />
## Practices
### Tizen
ThorVG is integrated into the [Tizen](https://www.tizen.org) platform as the vector graphics engine. It's being used for vector primitive drawings
and scalable image contents such as SVG and Lottie Animation among the Tizen powered products.

<p align="center">
  <img width="798" height="285" src="https://github.com/Samsung/thorvg/blob/master/res/example_tizen.png">
</p>

[Back to contents](#contents)
<br />
<br />
### Rive
We're also building a [Rive](https://rive.app/) port that supports Rive Animation run through the ThorVG backend. Rive is a brand new animation platform
that supports fancy, user-interactive vector animations. For more details see [Rive-Tizen](https://github.com/rive-app/rive-tizen) on [Github](https://github.com/rive-app/).

<p align="center">
  <img width="600" height="324" src="https://github.com/Samsung/thorvg/blob/master/res/example_rive.gif">
</p>

[Back to contents](#contents)
<br />
<br />
## Examples
There are various examples available in `thorvg/src/examples` to help you understand ThorVG APIs.

To execute these examples, you can build them with the following meson option:
```
meson -Dexamples=true . build
```
Note that these examples require the EFL `elementary` package for launching. If you're using Linux-based OS, you can easily
install this package from your OS distribution server. Otherwise, please visit the official [EFL page](https://enlightenment.org/) for more information.

[Back to contents](#contents)
<br />
<br />
## Tools
### ThorVG Viewer
[ThorVG viewer](https://samsung.github.io/thorvg.viewer) supports immediate rendering through your browser. You can drag & drop SVG files on the page
and see the rendering result on the spot.

[Back to contents](#contents)
<br />
<br />
### SVG to PNG
ThorVG provides an executable `svg2png` converter that generates a PNG file from an SVG file.

To use `svg2png`, you must turn on this feature in the build option:
```
meson -Dtools=svg2png . build
```
Alternatively, you can add the `svg2png` value to the `tools` option in `meson_option.txt`. The build output will be located in `{builddir}/src/bin/svg2png/`.

Examples of the usage of the `svg2png`:
```
Usage:
   svg2png [svgFileName] [Resolution] [bgColor]

Examples:
    $ svg2png input.svg
    $ svg2png input.svg 200x200
    $ svg2png input.svg 200x200 ff00ff
```
[Back to contents](#contents)
<br />
<br />
## API Bindings
Our main development APIs are written in C++, but ThorVG also provides API bindings for C.

[Back to contents](#contents)
<br />
<br />
## Issues or Feature Requests
For support, please reach us in [Gitter](https://gitter.im/thorvg/community).
