andlabs-ui/plan.md

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# Go UI package planning
Pietro Gagliardi
http://github.com/andlabs
## Goals
- Simple, easy to use GUI library for hard-coding GUI layouts
- Go-like: uses Go's concurrency features, interfaces, etc. and behaves like other Go libraries
- Portable; runs on all OSs Go supports and uses native toolkits (wherever possible)
- Minimal: only support what's absolutely necessary (for instance, only events that we will actually use in a program); if functionality can be done cleanly in an existing thing, use that (for instnaces, if adjustable sliding dividers are ever added, they can be made part of `Stack` instead of their own thing)
- Lightweight and fast
- Error-safe
- Correct: uses APIs properly and conforms to system-specific UI design guidelines
## Support
- Windows: all versions listed as supported by Go; that means Windows 2000 and newer
- Mac: all versions listed as supported by Go; that means Mac OS X 10.6 (Snow Leopard) and newer
- other Unix: GTK+
- I am deciding to support at least the versions of glib/gobject and GDK/GTK+ supported by Ubuntu 12.04 LTS (Precise Pangolin; the earliest LTS that ships with GTK+ 3); that is, glib/gobject 2.32.1 and GDK/GTK+ 3.4.1
- however the avaialble (on http://developer.gnome.org/) documentation is actually for glib/gobject 2.32.4 and GDK/GTK+ 3.4.4; I hope the point differences won't hurt me
## Layouts
Layouts control positioning and sizing. Layouts are controls, so they can be added recursively. The layout types are:
* `Stack`: a stack of controls, all sized alike, with padding between controls and spacing around the whole set. Controls can be arranged horizontally or vertically. (Analogues: Qt's `QBoxLayout`)
>* TODO change the name?
* `RadioSet`: like `Stack` but for radio buttons: only has radio buttons and handles exclusivity automatically (this is also the only way to add radio buttons)
* `Grid`: a grid of controls; they size themselves. Spacing is handled like `Stack`. (Analogues: Qt's `QGridLayout`)
* `Form`: a set of label-control pairs arranged to resemble options on a dialog form. Sizing, positioning, and spacing are handled in an OS-dependent way. (Analogues: Qt's `QFormLayout`)
## Windows
There's only one (maybe two, if I choose to add floating toolboxes) window type. You can add one control to the content area of a window.
In the case of dialogue boxes, you can call a function, say `RunDaialogue()` , that runs the dialogue modal, and adds standard OK/Cancel/Apply buttons for you.
## An example
``` go
package main
import (
"github.com/andlabs/ui"
)
func main() {
win := ui.NewWindow("Hello")
form := ui.NewForm()
name := ui.NewLineEntry()
form.Append("Enter your name:", name)
button := ui.NewButton("Click Me")
form.Append("", button)
win.SetControl(form)
events, err := win.RunDialogue(ui.OkCancel)
if err != nil {
panic(err)
}
done := false
for !done {
select {
case event := <-events:
switch event {
case ui.Ok:
ui.MsgBox("Hi", "Hello, " + name.Text(), ui.Ok)
case ui.Cancel:
done = true
}
case <-button.Click:
ui.MsgBox("Hi", "You clicked me!", ui.Ok)
}
}
window.Close()
}
```