cmd/systray: add extra padding around notification icon

Some notification managers crop the application icon to a circle, so
ensure we have enough padding to account for that.

Updates #1708

Change-Id: Ia101a4a3005adb9118051b3416f5a64a4a45987d
Signed-off-by: Will Norris <will@tailscale.com>

cmd/systray/logo.go

@@ -128,8 +128,14 @@ var (
 
 // render returns a PNG image of the logo.
 func (logo tsLogo) render() *bytes.Buffer {
-	const radius = 25
 	const borderUnits = 1
+	return logo.renderWithBorder(borderUnits)
+}
+
+// renderWithBorder returns a PNG image of the logo with the specified border width.
+// One border unit is equal to the radius of a tailscale logo dot.
+func (logo tsLogo) renderWithBorder(borderUnits int) *bytes.Buffer {
+	const radius = 25
 	dim := radius * (8 + borderUnits*2)
 
 	dc := gg.NewContext(dim, dim)

cmd/systray/systray.go

@@ -62,7 +62,7 @@ func onReady() {
 
 	// dbus wants a file path for notification icons, so copy to a temp file.
 	appIcon, _ = os.CreateTemp("", "tailscale-systray.png")
-	io.Copy(appIcon, connected.render())
+	io.Copy(appIcon, connected.renderWithBorder(3))
 
 	chState = make(chan ipn.State, 1)