impress

package module
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 Go to latest Published: Jul 9, 2020 License: MIT Imports: 5 Imported by: 20

README

impress

Cross platform GUI Library for Go

GoDoc

Proof of Concept Version

Notes:

  • This project is still in the early stages of development and is not yet in a usable state.
  • The project tested on Debian 9, 10 and MacOS 10.13, 10.14.

Basic Principles of Library Building Design

  • Performance of the application as well as native applications.
  • Simple and clean application code for using GUI.
  • Limited use of other libraries (graphic, low-level or native).
  • Creating a GUI application without form designer or hard-coded widgets.

The basic idea is to avoid the event-driven programming paradigm. See "Whats wrong with event-driven programming" page.

Examples

Let's say hello:

package main

import (
	"log"

	"github.com/codeation/impress"
	_ "github.com/codeation/impress/duo"
)

func main() {
	app := impress.NewApplication(impress.NewRect(0, 0, 640, 480), "Hello World Application")
	defer app.Close()

	font, err := impress.NewFont(`{"family":"Verdana"}`, 15)
	if err != nil {
		log.Fatal(err)
	}
	defer font.Close()

	w := app.NewWindow(impress.NewRect(0, 0, 640, 480), impress.NewColor(255, 255, 255))
	w.Text("Hello, world!", font, impress.NewPoint(280, 210), impress.NewColor(0, 0, 0))
	w.Line(impress.NewPoint(270, 230), impress.NewPoint(380, 230), impress.NewColor(255, 0, 0))
	w.Show()

	app.Wait()
}

Some usage examples are located in examples folder.

Installation

The library uses a separate application as a GUI driver for rendering, event collecting, etc. You can download the compiled binary file or make it again from the source.

You can specify the full path and name for the GUI driver via the environment variable, for example:

IMPRESS_TERMINAL_PATH=/path/it go run ./examples/simple/simple.go

or just copy the downloaded GUI driver to the working directory and launch example:

go run ./examples/simple/simple.go

GUI driver

The library uses a separate application for drawing instead of binding low-level library to a Golang.

Pros:

  • To compile the application, it is not necessary to install low-level libraries.
  • There are no additional restrictions on the application, such as GTK functions should only be called by the main thread.
  • It will be possible to run several applications for a low-level drawing from different devices, thereby using the screens of different devices for the same application.
  • Abnormal termination of low-level drawing application may not result in data loss.

Cons:

  • Some loss of speed due to data transfer between applications.
  • Additional complexity due to state synchronization between applications.

Contributing

First of all, welcome:

  • any advice on the library design and principles
  • help to correct grammatical and writing errors
  • contribution in the near future

Using

See documentation and examples folder.

A cross-platform mind-map application is being developed to check the library's applicability.

Stay tuned for more.

Documentation

Index

Constants

View Source 
const (
	GeneralEventType  = 10
	KeyboardEventType = 20
	ButtonEventType   = 30
	MotionEventType   = 40
)

Event types

View Source 
const (
	ButtonActionPress   = 4
	ButtonActionDouble  = 5
	ButtonActionTriple  = 6
	ButtonActionRelease = 7
)

Button action type

View Source 
const (
	ButtonLeft   = 1
	ButtonMiddle = 2
	ButtonRight  = 3
)

Button number

Variables

View Source 
var (
	UnknownEvent     = GeneralEvent{Event: 0}
	DestroyEvent     = GeneralEvent{Event: 1}
	DoneEvent        = GeneralEvent{Event: 2}
	ActivatedEvent   = GeneralEvent{Event: 3}
	DeactivatedEvent = GeneralEvent{Event: 4}
)

Signal events

View Source 
var (
	KeyLeft      = KeyboardEvent{Name: "Left"}
	KeyRight     = KeyboardEvent{Name: "Right"}
	KeyUp        = KeyboardEvent{Name: "Up"}
	KeyDown      = KeyboardEvent{Name: "Down"}
	KeyEnter     = KeyboardEvent{Rune: 13, Name: "Return"}
	KeyBackSpace = KeyboardEvent{Rune: 8, Name: "BackSpace"}
)

Keyboard events

View Source 
var (
	KeySave = KeyboardEvent{Rune: 115, Name: "s", Meta: true}
	KeyExit = KeyboardEvent{Rune: 113, Name: "q", Meta: true}
)

Platform specified keyboard events

Functions

func Register 

func Register(d Driver)

Register makes a GUI driver available

Types

type Actor 

type Actor interface {
	Chan() chan Eventer
}

Actor is an event receiver interface

type Application 

type Application struct {
	// contains filtered or unexported fields
}

Application represents application top level window

func NewApplication 

func NewApplication(rect Rect, title string) *Application

NewApplication creates main application window

func (*Application) Activate 

func (app *Application) Activate(actor Actor)

Activate sets the active event receiver under mutex protection

func (*Application) Activated 

func (app *Application) Activated(actor Actor) bool

Activated returns true when the actor is an active recipient

func (*Application) AddActor 

func (app *Application) AddActor(actor Actor, rect Rect)

AddActor adds actor for rect

func (*Application) Close 

func (app *Application) Close()

Close makes invocation of the main loop return

func (*Application) Done 

func (app *Application) Done() <-chan struct{}

Done returns a channel that's closed when the application is stopped

func (*Application) Event 

func (app *Application) Event() Eventer

Event returns next application event

func (*Application) NewWindow 

func (app *Application) NewWindow(rect Rect, color Color) *Window

NewWindow creates new inner window with a specified size and background color

func (*Application) OnEvent 

func (app *Application) OnEvent(event Eventer, handler func())

OnEvent connects function call back to an event

func (*Application) RemoveActor 

func (app *Application) RemoveActor(actor Actor)

RemoveActor removes actor from actor list

func (*Application) Size 

func (app *Application) Size(rect Rect)

Size sets application window size

func (*Application) Start 

func (app *Application) Start(f func())

Start starts the specified func but does not wait for it to complete

func (*Application) Title 

func (app *Application) Title(title string)

Title sets application window title

func (*Application) Wait 

func (app *Application) Wait()

Wait waits for main application loop to complete

type ButtonEvent 

type ButtonEvent struct {
	Action int
	Button int
	Point  Point
}

ButtonEvent is mouse button event

func (ButtonEvent) Type 

func (e ButtonEvent) Type() int

Type returns event type

type Color 

type Color struct {
	R, G, B int
}

Color represents a 24-bit color, having 8 bits for each of red, green, blue.

func NewColor 

func NewColor(r, g, b int) Color

NewColor is same as Color{r, g, b}

type Driver 

type Driver interface {
	Init()
	Done()
	Title(title string)
	Size(rect Rect)
	NewWindow(rect Rect, color Color) Painter
	NewFont(font *Font) (Fonter, error)
	NewImage(img *Image) (Imager, error)
	Chan() <-chan Eventer
}

Driver is the interface to a application level functions

type Eventer 

type Eventer interface {
	Type() int
}

Eventer is the interface that groups GUI events

type Font 

type Font struct {
	Fonter   Fonter
	Height   int
	Baseline int
	Ascent   int
	Descent  int
	Attr     map[string]string
}

Font represents a font selection

func NewFont 

func NewFont(options string, height int) (*Font, error)

NewFont return a font selection struct

func (*Font) Close 

func (f *Font) Close()

Close destroys font selection

func (*Font) Size 

func (f *Font) Size(text string) Size

Size returns the width and height of the drawing area

func (*Font) Split 

func (f *Font) Split(text string, edge int) []string

Split breaks the text into lines that fit in the specified width

type Fonter 

type Fonter interface {
	Close()
	Split(text string, edge int) []string
	Size(text string) Size
}

Fonter is the interface to a font functions

type GeneralEvent 

type GeneralEvent struct {
	Event int
}

GeneralEvent is a general purpose notification

func (GeneralEvent) Type 

func (e GeneralEvent) Type() int

Type returns event type

type Image 

type Image struct {
	Imager        Imager
	Width, Height int
	PixNRGBA      []byte
}

Image represents a draw-ready image

func NewImage 

func NewImage(img image.Image) (*Image, error)

NewImage returns a image resources struct

func (*Image) Close 

func (i *Image) Close()

Close destroys image resources

type Imager 

type Imager interface {
	Close()
}

Imager is the interface to a image functions

type KeyboardEvent 

type KeyboardEvent struct {
	Rune    rune
	Shift   bool
	Control bool
	Alt     bool
	Meta    bool
	Name    string
}

KeyboardEvent is a keyboard event

func (KeyboardEvent) IsGraphic 

func (e KeyboardEvent) IsGraphic() bool

IsGraphic tests printable rune

func (KeyboardEvent) Type 

func (e KeyboardEvent) Type() int

Type returns event type

type MotionEvent 

type MotionEvent struct {
	Point   Point
	Shift   bool
	Control bool
	Alt     bool
	Meta    bool
}

MotionEvent is mouse motion event

func (MotionEvent) Type 

func (e MotionEvent) Type() int

Type returns event type

type Painter 

type Painter interface {
	Drop()
	Size(rect Rect)
	Clear()
	Show()
	Fill(rect Rect, color Color)
	Line(from Point, to Point, color Color)
	Image(from Point, img *Image)
	Text(text string, font *Font, from Point, color Color)
}

Painter is the interface to a window functions

type Point 

type Point struct {
	X, Y int
}

A Point is an X, Y coordinate pair. The axes increase right and down.

func NewPoint 

func NewPoint(x, y int) Point

NewPoint is same as Point{x, y}.

func (*Point) In 

func (p *Point) In(rect Rect) bool

In returns true when point is inside rect

type Rect 

type Rect struct {
	Point
	Size
}

A Rect contains the upper left corner coordinates and rectangle size.

func NewRect 

func NewRect(x, y, width, height int) Rect

NewRect is same as Rect{Point:Point{x,y}, Size:Size{width, height}}.

type Size 

type Size struct {
	Width, Height int
}

A Size is an Width and Height pair.

func NewSize 

func NewSize(width, height int) Size

NewSize is same as Size{width, height}.

type Window 

type Window struct {
	// contains filtered or unexported fields
}

Window represents inner window

func (*Window) Clear 

func (w *Window) Clear()

Clear clears current window

func (*Window) Drop 

func (w *Window) Drop()

Drop deletes window Note that a dropped window can no longer be used

func (*Window) Fill 

func (w *Window) Fill(rect Rect, color Color)

Fill draws a rectangle with specified size and foreground color

func (*Window) Image 

func (w *Window) Image(from Point, img *Image)

Image draw a CAIRO_FORMAT_RGB24 data

func (*Window) Line 

func (w *Window) Line(from Point, to Point, color Color)

Line draws a color line connecting two specified points

func (*Window) Show 

func (w *Window) Show()

Show sends the contents of the window to the screen

func (*Window) Size 

func (w *Window) Size(rect Rect)

Size changes window size and position

func (*Window) Text 

func (w *Window) Text(text string, font *Font, from Point, color Color)

Text draws a text at specified location using a specified font and foreground color

Source Files

View all Source files

Directories

Path Synopsis
examples
actions command
image command
simple command

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