lorca

Documentation

Index

• Constants
• Variables
• func LocateChrome() string
• func PDF(url, script string, width, height int) ([]byte, error)
• func PNG(url, script string, x, y, width, height int, bg uint32, scale float32) ([]byte, error)
• func PromptDownload()
• type Bounds
• type UI
  • func New(url, dir string, width, height int, customArgs ...string) (UI, error)
• type Value
• type WindowState

Constants

const (
	// PageA4Width is a width of an A4 page in pixels at 96dpi
	PageA4Width = 816
	// PageA4Height is a height of an A4 page in pixels at 96dpi
	PageA4Height = 1056
)

Variables

var ChromeExecutable = LocateChrome

ChromeExecutable returns a string which points to the preferred Chrome executable file.

Functions

func LocateChrome

func LocateChrome() string

LocateChrome returns a path to the Chrome binary, or an empty string if Chrome installation is not found.

func PDF

func PDF(url, script string, width, height int) ([]byte, error)

PDF converts a given URL (may be a local file) to a PDF file. Script is evaluated before the page is printed to PDF, you may modify the contents of the page there of wait until the page is fully rendered. Width and height are page bounds in pixels. PDF by default uses 96dpi density. For A4 page you may use PageA4Width and PageA4Height constants.

func PNG

func PNG(url, script string, x, y, width, height int, bg uint32, scale float32) ([]byte, error)

PNG converts a given URL (may be a local file) to a PNG image. Script is evaluated before the "screenshot" is taken, so you can modify the contents of a URL there. Image bounds are provides in pixels. Background is in ARGB format, the default value of zero keeps the background transparent. Scale allows zooming the page in and out.

This function is most convenient to convert SVG to PNG of different sizes, for example when preparing Lorca app icons.

func PromptDownload

func PromptDownload()

PromptDownload asks user if he wants to download and install Chrome, and opens a download web page if the user agrees.

Types

type Bounds

type Bounds struct {
	Left        int         `json:"left"`
	Top         int         `json:"top"`
	Width       int         `json:"width"`
	Height      int         `json:"height"`
	WindowState WindowState `json:"windowState"`
}

Bounds defines settable window properties.

type UI

type UI interface {
	Load(url string) error
	Bounds() (Bounds, error)
	SetBounds(Bounds) error
	Bind(name string, f interface{}) error
	Eval(js string) Value
	Done() <-chan struct{}
	GetPid() int
	Close() error
}

UI interface allows talking to the HTML5 UI from Go.

func New

func New(url, dir string, width, height int, customArgs ...string) (UI, error)

New returns a new HTML5 UI for the given URL, user profile directory, window size and other options passed to the browser engine. If URL is an empty string - a blank page is displayed. If user profile directory is an empty string - a temporary directory is created and it will be removed on ui.Close(). You might want to use "--headless" custom CLI argument to test your UI code.

type Value

type Value interface {
	Err() error
	To(interface{}) error
	Float() float32
	Int() int
	String() string
	Bool() bool
	Object() map[string]Value
	Array() []Value
	Bytes() []byte
}

Value is a generic type of a JSON value (primitive, object, array) and optionally an error value.

type WindowState

type WindowState string

WindowState defines the state of the Chrome window, possible values are "normal", "maximized", "minimized" and "fullscreen".

const (
	// WindowStateNormal defines a normal state of the browser window
	WindowStateNormal WindowState = "normal"
	// WindowStateMaximized defines a maximized state of the browser window
	WindowStateMaximized WindowState = "maximized"
	// WindowStateMinimized defines a minimized state of the browser window
	WindowStateMinimized WindowState = "minimized"
	// WindowStateFullscreen defines a fullscreen state of the browser window
	WindowStateFullscreen WindowState = "fullscreen"
)