Sparta

Sparta is an almost stateless vector graphics API for Pharo that provides bindings to the Skia rendering backend.

⚠️ This repository contains the code for Sparta that may be included in the future in Pharo. It retrofits a part of the development made at https://github.com/feenkcom/Sparta. This version will focus on core features and stability. We are currently identifying the core we want for Pharo.

Install

More detailed installation guide is described in INSTALL.md

Sparta requires an extra Skia vm plugin. The plugin for the current OS and VM (64 bit) is downloaded and installed automatically together with all needed packages.

Metacello new
    baseline: 'Sparta';
    repository: 'github://pharo-graphics/sparta:dev-1.0/src';
    load

Overview

(All images are rendered using Sparta in Glamorous Toolkit)

Backends

Skia, and as result Sparta, has support of native OS graphic engines, as well as cross platform ones.

On all platforms Sparta provides support of Cairo and Skia. Additionally, high performant CoreGraphics and CoreGraphics Accelerated on Mac OS and Direct2D on Windows. In total Sparta supports 5 different rendering backends.

Text

One of the biggest improvements compared to existing graphics engines from Pharo is advanced high quality text rendering with multi-language support.

The current Pharo text rendering engines draw a piece of text with one concrete font and style. If the font does not have an appropriate character, a stub glyph will be rendered instead. Sparta introduces a notion of font groups that allow us to achieve a smooth fallback font detection based on the selected font style, language and missing glyphs. Fallback font support requires more complex text measurement, as multiple fonts faces are involved to render a single piece of text.

Filters

Since Sparta is based on the Moz2D backend that was designed for web browsers, we can get support for a wide variety of filter primitives. Sparta provides an ability to compose multiple filter primitives to get a single, advanced filter. For example, with the help of ColorMatrix and TableTransfer filters we can simulate some popular Instagram-like filters, for example Nashville, Inkwell or Brannan.

Basic drawings

We should not forget that first of all Sparta is a vector graphics engine. It allows developers to create, fill and stroke custom paths and shapes. Together with gaussian blur, we can achieve astonishing results that were not possible before.