Package draw

import "exp/draw"

Package draw provides basic graphics and drawing primitives, in the style of the Plan 9 graphics library (see http://plan9.bell-labs.com/magic/man2html/2/draw) and the X Render extension.

Package files

draw.go event.go

func Border

func Border(dst Image, r image.Rectangle, w int, src image.Image, sp image.Point)

Border aligns r.Min in dst with sp in src and then replaces pixels in a w-pixel border around r in dst with the result of the Porter-Duff compositing operation “src over dst.” If w is positive, the border extends w pixels inside r. If w is negative, the border extends w pixels outside r.

func Draw

func Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point)

Draw calls DrawMask with a nil mask and an Over op.

func DrawMask

func DrawMask(dst Image, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op)

DrawMask aligns r.Min in dst with sp in src and mp in mask and then replaces the rectangle r in dst with the result of a Porter-Duff composition. A nil mask is treated as opaque. The implementation is simple and slow. TODO(nigeltao): Optimize this.

type Context

A Context represents a single graphics window.

type Context interface {
    // Screen returns an editable Image of window.
    Screen() Image

    // FlushImage flushes changes made to Screen() back to screen.
    FlushImage()

    // KeyboardChan returns a channel carrying keystrokes.
    // An event is sent each time a key is pressed or released.
    // The value k represents key k being pressed.
    // The value -k represents key k being released.
    // The specific set of key values is not specified,
    // but ordinary character represent themselves.
    KeyboardChan() <-chan int

    // MouseChan returns a channel carrying mouse events.
    // A new event is sent each time the mouse moves or a
    // button is pressed or released.
    MouseChan() <-chan Mouse

    // ResizeChan returns a channel carrying resize events.
    // An event is sent each time the window is resized;
    // the client should respond by calling Screen() to obtain
    // the new screen image.
    // The value sent on the channel is always ``true'' and can be ignored.
    ResizeChan() <-chan bool

    // QuitChan returns a channel carrying quit requests.
    // After reading a value from the quit channel, the application
    // should exit.
    QuitChan() <-chan bool
}

type Image

A draw.Image is an image.Image with a Set method to change a single pixel.

type Image interface {
    image.Image
    Set(x, y int, c image.Color)
}

type Mouse

A Mouse represents the state of the mouse.

type Mouse struct {
    Buttons     int   // bit mask of buttons: 1<<0 is left, 1<<1 middle, 1<<2 right
    image.Point       // location of cursor
    Nsec        int64 // time stamp
}

type Op

A Porter-Duff compositing operator.

type Op int

const (
    // Over specifies ``(src in mask) over dst''.
    Over Op = iota
    // Src specifies ``src in mask''.
    Src
)

Bugs

This is a toy library and not ready for production use.

Subdirectories

Name		Synopsis
..
x11		This package implements an X11 backend for the exp/draw package.

Name

Synopsis

x11

This package implements an X11 backend for the exp/draw package.