Propose desktop integration

cmd/desktop_demo/main.go

@@ -0,0 +1,100 @@
+//go:build linux
+// +build linux
+
+package main
+
+import (
+	"fyne.io/fyne/v2"
+	"fyne.io/fyne/v2/app"
+	"fyne.io/fyne/v2/container"
+	"fyne.io/fyne/v2/dialog"
+	"fyne.io/fyne/v2/theme"
+	"fyne.io/fyne/v2/widget"
+	xtheme "fyne.io/x/fyne/theme"
+	xdesktop "fyne.io/x/fyne/theme/desktop"
+)
+
+func main() {
+	app := app.New()
+	app.Settings().SetTheme(xtheme.FromDesktopEnvironment())
+	win := app.NewWindow("Desktop integration demo")
+	win.Resize(fyne.NewSize(550, 390))
+	win.CenterOnScreen()
+
+	// Gnome/GTK theme invertion
+	invertButton := widget.NewButton("Invert Gnome theme", func() {
+		if t, ok := app.Settings().Theme().(*xdesktop.GnomeTheme); ok {
+			t.Invert()
+			win.Content().Refresh()
+		}
+	})
+
+	// the invertButton can only work on Gnome / GTK theme.
+	if _, ok := app.Settings().Theme().(*xdesktop.GnomeTheme); !ok {
+		invertButton.Disable()
+		invertButton.SetText("Invert only works on Gnome/GTK")
+	}
+
+	var switched bool
+	switchThemeButton := widget.NewButton("Switch theme", func() {
+		if switched {
+			app.Settings().SetTheme(xtheme.FromDesktopEnvironment())
+		} else {
+			app.Settings().SetTheme(theme.DefaultTheme())
+		}
+		switched = !switched
+		win.Content().Refresh()
+	})
+
+	entry := widget.NewEntry()
+	entry.SetPlaceHolder("Example of text entry...")
+	win.SetContent(container.NewBorder(
+		nil,
+		container.NewHBox(
+			widget.NewButtonWithIcon("Home icon button", theme.HomeIcon(), nil),
+			widget.NewButtonWithIcon("Info icon button", theme.InfoIcon(), nil),
+			widget.NewButtonWithIcon("Example file dialog", theme.FolderIcon(), func() {
+				dialog.ShowFileSave(func(fyne.URIWriteCloser, error) {}, win)
+			}),
+			invertButton,
+		),
+		nil,
+		nil,
+		container.NewVBox(
+			createExplanationLabel(app),
+			entry,
+			widget.NewLabel("Try to switch theme"),
+			switchThemeButton,
+		),
+	))
+
+	win.ShowAndRun()
+}
+
+func createExplanationLabel(app fyne.App) fyne.CanvasObject {
+
+	var current string
+
+	switch app.Settings().Theme().(type) {
+	case *xdesktop.GnomeTheme:
+		current = "Gnome / GTK"
+	case *xdesktop.KDETheme:
+		current = "KDE / Plasma"
+	default:
+		current = "This window manager is not supported for now"
+	}
+
+	text := "Current Desktop: " + current + "\n"
+	text += `
+
+This window should be styled to look like a desktop application. It works with GTK/Gnome based desktops and KDE/Plasma at this time
+For the others desktops, the application will look like a normal window with default theme.
+
+You may try to change icon theme or GTK/KDE theme in your desktop settings, as font, font scaling...
+
+Note that you need to have fontforge package to make Fyne able to convert non-ttf fonts to ttf.
+`
+	label := widget.NewLabel(text)
+	label.Wrapping = fyne.TextWrapWord
+	return label
+}

go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/eclipse/paho.mqtt.golang v1.3.5
 	github.com/gorilla/websocket v1.4.2
 	github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646
+	github.com/srwiley/oksvg v0.0.0-20200311192757-870daf9aa564
 	github.com/stretchr/testify v1.7.2
 	github.com/wagslane/go-password-validator v0.3.0
 	golang.org/x/image v0.0.0-20220601225756-64ec528b34cd

theme/desktop/doc.go

@@ -0,0 +1,25 @@
+// Package desktop provides theme for Linux (for now) desktop environment like Gnome, KDE, Plasma...
+//
+// To be fully used, the system need to have gsettings and gjs for all GTK/Gnome based desktop.
+// KDE/Plasma theme only works when the user has already initialize a session to create ~/.config/kdeglobals
+//
+// The package will try to use fontconfig ("fc-match" and "fontconfig" commands).
+// This is not required but recommended to be able to generate TTF font if the user as configure a non TTF font.
+//
+// The package also tries to use "inkscape" or "convert" command (from ImageMagick) to generate SVG icons when they
+// cannot be parsed by Fyne (it happens when oksvg package fails to load icons).
+//
+// Some recent desktop environment now use Adwaita as default theme. If this theme is applied, the desktop package
+// loads the default Fyne theme colors. It only try to change the scaling factor, font and icons of the applications.
+//
+// The easiest way to use this package is to call the FromDesktopEnvironment function from "theme" package.
+//
+// Example:
+//
+//  app := app.New()
+//  theme := FromDesktopEnvironment()
+//  app.Settings().SetTheme(theme)
+//
+// This loads the theme from the current detected desktop environment. For Windows and MacOS, and mobile devices
+// it will return the default Fyne theme.
+package desktop