thorvg/README.md

ThorVG

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.

The following list shows primitives that are supported by ThorVG:

• 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, ...

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.

Contents

• Building ThorVG
  • Meson Build
• Quick Start
• SVG
• Practices
  • Tizen
  • Rive
• Examples
• Tools
  • ThorVG Viewer
  • SVG to PNG
• API Bindings
• Issues or Feature Requests

Building ThorVG

ThorVG supports meson build system.

Meson Build

Install meson and ninja if not already installed.

Run meson to configure ThorVG:

meson build

Run ninja to build & install ThorVG:

ninja -C build install

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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:

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:

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:

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:

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

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:

Now begin rendering & finish it at a particular time:

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

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

Lastly, terminate the engine after its usage:

tvg::Initializer::term(tvg::CanvasEngine::Sw);

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SVG

ThorVG supports SVG (Scalable Vector Graphics) rendering through its SVG interpreter. It satisfies the SVG Tiny Specification 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:

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:

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Practices

Tizen

ThorVG is integrated into the Tizen 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.

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Rive

We're also building a Rive 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 on Github.

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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 for more information.

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Tools

ThorVG Viewer

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.

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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

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API Bindings

Our main development APIs are written in C++, but ThorVG also provides API bindings for C.

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Issues or Feature Requests

For support, please reach us in Gitter.