webview

Documentation

Overview

Package webview implements Go bindings to https://github.com/zserge/webview C library. It is a modified version of webview.go from that repository Bindings closely repeat the C APIs and include both, a simplified single-function API to just open a full-screen webview window, and a more advanced and featureful set of APIs, including Go-to-JavaScript bindings.

The library uses gtk-webkit, Cocoa/Webkit and MSHTML (IE8..11) as a browser engine and supports Linux, MacOS and Windows 7..10 respectively.

Index

• Constants
• func Open(title, url string, w, h int, resizable bool) error
• type DialogType
• type ExternalInvokeCallbackFunc
• type Settings
• type WebView
  • func NewWebview(settings Settings) WebView

Constants

const (
	// DialogFlagFile is a normal file picker dialog
	DialogFlagFile = C.WEBVIEW_DIALOG_FLAG_FILE
	// DialogFlagDirectory is an open directory dialog
	DialogFlagDirectory = C.WEBVIEW_DIALOG_FLAG_DIRECTORY
	// DialogFlagInfo is an info alert dialog
	DialogFlagInfo = C.WEBVIEW_DIALOG_FLAG_INFO
	// DialogFlagWarning is a warning alert dialog
	DialogFlagWarning = C.WEBVIEW_DIALOG_FLAG_WARNING
	// DialogFlagError is an error dialog
	DialogFlagError = C.WEBVIEW_DIALOG_FLAG_ERROR
)

Functions

func Open

func Open(title, url string, w, h int, resizable bool) error

Open is a simplified API to open a single native window with a full-size webview in it. It can be helpful if you want to communicate with the core app using XHR or WebSockets (as opposed to using JavaScript bindings).

Window appearance can be customized using title, width, height and resizable parameters. URL must be provided and can user either a http or https protocol, or be a local file:// URL. On some platforms "data:" URLs are also supported (Linux/MacOS).

Types

type DialogType

type DialogType int

DialogType is an enumeration of all supported system dialog types

const (
	// DialogTypeOpen is a system file open dialog
	DialogTypeOpen DialogType = iota
	// DialogTypeSave is a system file save dialog
	DialogTypeSave
	// DialogTypeAlert is a system alert dialog (message box)
	DialogTypeAlert
)

type ExternalInvokeCallbackFunc

type ExternalInvokeCallbackFunc func(w WebView, data string)

ExternalInvokeCallbackFunc is a function type that is called every time "window.external.invoke()" is called from JavaScript. Data is the only obligatory string parameter passed into the "invoke(data)" function from JavaScript. To pass more complex data serialized JSON or base64 encoded string can be used.

type Settings

type Settings struct {
	// WebView main window title
	Title string
	// URL to open in a webview
	URL string
	// Window width in pixels
	Width int
	// Window height in pixels
	Height int
	// Allows/disallows window resizing
	Resizable bool
	// Enable debugging tools (Linux/BSD/MacOS, on Windows use Firebug)
	Debug bool
	// A callback that is executed when JavaScript calls "window.external.invoke()"
	ExternalInvokeCallback ExternalInvokeCallbackFunc
}

Settings is a set of parameters to customize the initial WebView appearance and behavior. It is passed into the webview.New() constructor.

type WebView

type WebView interface {
	// Run() starts the main UI loop until the user closes the webview window or
	// Terminate() is called.
	Run()
	// Loop() runs a single iteration of the main UI.
	Loop(blocking bool) bool
	// SetTitle() changes window title. This method must be called from the main
	// thread only. See Dispatch() for more details.
	SetTitle(title string)
	// SetFullscreen() controls window full-screen mode. This method must be
	// called from the main thread only. See Dispatch() for more details.
	SetFullscreen(fullscreen bool)
	// SetColor() changes window background color. This method must be called from
	// the main thread only. See Dispatch() for more details.
	SetColor(r, g, b, a uint8)
	// Eval() evaluates an arbitrary JS code inside the webview. This method must
	// be called from the main thread only. See Dispatch() for more details.
	Eval(js string) error
	// InjectJS() injects an arbitrary block of CSS code using the JS API. This
	// method must be called from the main thread only. See Dispatch() for more
	// details.
	InjectCSS(css string)
	// Dialog() opens a system dialog of the given type and title. String
	// argument can be provided for certain dialogs, such as alert boxes. For
	// alert boxes argument is a message inside the dialog box.
	Dialog(dlgType DialogType, flags int, title string, arg string) string
	// Terminate() breaks the main UI loop. This method must be called from the main thread
	// only. See Dispatch() for more details.
	Terminate()
	// Dispatch() schedules some arbitrary function to be executed on the main UI
	// thread. This may be helpful if you want to run some JavaScript from
	// background threads/goroutines, or to terminate the app.
	Dispatch(func())
	// Exit() closes the window and cleans up the resources. Use Terminate() to
	// forcefully break out of the main UI loop.
	Exit()
}

WebView is an interface that wraps the basic methods for controlling the UI loop, handling multithreading and providing JavaScript bindings.

func NewWebview

func NewWebview(settings Settings) WebView

NewWebview creates and opens a new webview window using the given settings. The returned object implements the WebView interface. This function returns nil if a window can not be created.