gi

README

GoGi is part of the GoKi Go language (golang) full strength tree structure system (ki = 木 = tree in Japanese)

package gi is a scenegraph-based 2D and 3D GUI / graphics interface (Gi) in Go.

NOTE: Requires Go version 1.11+ due to use of math.Round and os.UserCacheDir.

See the Wiki for more docs (increasingly extensive), Install instructions (mostly just standard go get ..., but does now depend on cgo so see details for each platform), and Google Groups goki-gi emailing list.

GoGi uses the GoKi tree infrastructure to implement a scenegraph-based GUI framework in full native idiomatic Go, with minimal OS-specific backend interfaces based originally on the Shiny drivers, now using go-gl/glfw, and supporting MacOS, Linux, and Windows. The overall design is an attempt to integrate existing standards and conventions from widely-used frameworks, including Qt (overall widget design), HTML / CSS (styling), and SVG (rendering). The core Layout object automates most of the complexity associated with GUI construction (inclusing scrolling), so the programmer mainly just needs to add the elements, and set their style properties -- similar to HTML. The main 2D framework also integrates with a 3D scenegraph, supporting interesting combinations of these frameworks (see gi3d package and examples/gi3d). Currently GoGi is focused on desktop systems, but nothing should prevent adaptation to mobile.

See Gide for a complete, complex application written in GoGi (an IDE), and likewise the Emergent neural network simulation environment (the prime motivator for the whole project), along with the various examples in this repository for lots of useful demonstrations -- start with the Widgets example which has a bit of a tutorial introduction.

Main Features

• Has all the standard widgets: Button, Menu, Slider, TextField, SpinBox, ComboBox etc, with tooltips, hover, focus, copy / paste (full native clipboard support), drag-n-drop -- the full set of standard GUI functionality. See gi/examples/widgets for a demo of all the widgets.

• Powerful Layout logic auto-sizes everything -- very easy to configure interfaces that "just work" across different scales, resolutions, platforms. Automatically remembers and reinstates window positions and sizes across sessions, and supports standard Ctrl+ and Ctrl- zooming of display scale.

• CSS-based styling allows easy customization of everything -- native style properties are fully HTML compatible (with all standard em, px, pct etc units), including full HTML "rich text" styling for all text rendering (e.g., in Label widget) -- can decorate any text with inline tags (<strong>, <em> etc), and even include links.

• Compiles in seconds, compared to many minutes to hours for comparable alternatives such as Qt, and with minimal cgo dependency. As of April 2019 we now depend on the glfw cross-platform GUI infrastructure system, and the go-gl/gl OpenGL bindings, to support the 3D (gi3d) aspect of the framework.

• Fully self-contained -- does not use OS-specific native widgets -- results in simpler, consistent code across platforms, and is fully HiDPI capable and scalable using standard Ctrl/Cmd+Plus or Minus key, and in Preferences. This also allows a complete 2D GUI to be embedded into a 3D scene, for example.

• SVG element (in svg sub-package) supports full SVG rendering -- used for Icons internally and available for advanced graphics displays -- see gi/examples/svg for viewer and start on editor, along with a number of test .svg files.

• Powerful Model / View paradigm with reflection-based view elements that display and manipulate all the standard Go types (in giv sub-package), from individual types (e.g., int, float display in a SpinBox, "enum" const int types in a ComboBox chooser) to composite data structures, including StructView editor of struct fields, MapView and SliceView displays of map and slice elements (including full editing / adding / deleting of elements), and full-featured TableView for a slice-of-struct and TreeView for GoKi trees.

  • TreeView enables a built-in GUI editor / inspector for designing gui elements themselves. Just press Control+Alt+I in any window to pull up this editor / inspector. Scene graphs can be automatically saved / loaded from JSON files, to provide a basic GUI designer framework -- just load and add appropriate connections..

Code Overview

There are three main types of 2D nodes:

• Viewport2D nodes that manage their own image.RGBA bitmap and can upload that directly to the oswin.Texture (GPU based) that then uploads directly to the oswin.Window. The parent Window has a master Viewport2D that backs the entire window, and is what most Widget's render into.

  • Popup Dialog and Menu's have their own viewports that are layered on top of the main window viewport.
  • SVG and its subclass Icon are containers for SVG-rendering nodes.

• Widget nodes that use the full CSS-based styling (e.g., the Box model etc), are typically placed within a Layout -- they use units system with arbitrary DPI to transform sizes into actual rendered dots (term for actual raw resolution-dependent pixels -- "pixel" has been effectively co-opted as a 96dpi display-independent unit at this point). Widgets have non-overlapping bounding boxes (BBox -- cached for all relevant reference frames).

• SVG rendering nodes that directly set properties on the Paint object and typically have their own geometry etc -- they should be within a parent SVG viewport, and their geom units are determined entirely by the transforms etc and we do not support any further unit specification -- just raw float values.

General Widget method conventions:

• SetValue kinds of methods are wrapped in UpdateStart / End, but do NOT emit a signal.
• SetValueAction calls SetValue and emits the signal. This allows other users of the widget that also recv the signal to not trigger themselves, but typically you want the update, so it makes sense to have that in the basic version. ValueView in particular requires this kind of behavior.

The best way to see how the system works are in the examples directory, and by interactively modifying any existing gui using the interactive reflective editor via Control+Alt+I.

Backend

The oswin and gpu packages provide interface abstractions for hardware-level implementations. Currently the gpu implementation is OpenGL, but Vulkan is planned, hopefully with not too many changes to the gpu interface. The basic platform-specific details are handled by glfw (version 3.3), along with a few other bits of platform-specific code.

All of the main "front end" code just deals with image.RGBA through the Paint methods, which was adapted from https://github.com/fogleman/gg, and we use https://github.com/srwiley/rasterx for CPU-based rasterization to the image, which is very fast and SVG performant. The Viewport2D image is uploaded to a GPU-backed oswin.Texture and composited with sprite overlays up to the window.

Status

• As of 12/13/2020 the 3D gi3d component of the framework is very near to completion, and the code has been widely tested by students and researchers, and can be considered "production ready". A 1.0 version release is imminent, along with API stability.

• Active users should join Google Groups goki-gi emailing list to receive more detailed status updates.

• Please file Issues for anything that does not work.

• 3/2019: python wrapper is now available! you can do most of GoGi from python now. See README.md file there for more details.

Documentation

Overview

Package gi is the top-level repository for the GoGi GUI framework.

All of the code is in the sub-packages within this repository:

* gi: contains the main 2D GUI code

* giv: are more complex Views of Go data structures, built out of gi widgets, supporting the Model-View paradigm.

* svg is something: provides a full SVG rendering framework, used for Icons, and in its own right.

* oswin: is the OS-specific framework, originally based on Shiny, that provides all the gory guts for dealing with different OS's.

* examples: contains a number of useful examples for learning how to use GoGi -- see widgets and its README file for a basic introduction. marbles is really fun!