ui/app: add package documentation and document Main

Split Main into the common Main function and platform specific
main functions.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

ui/app/app.go

@@ -134,6 +134,14 @@ func DataDir() (string, error) {
 	return dataDir()
 }
 
+// Main must be called from the a program's main function.
+// Calling Main is necessary because some operating systems
+// require control of the main thread of the program for
+// running user interfaces.
+func Main() {
+	main()
+}
+
 // Config implements the ui.Config interface.
 type Config struct {
 	// Device pixels per dp.

ui/app/doc.go

@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+/*
+Package app provides a platform-independent interface to operating system
+functionality for running graphical user interfaces.
+
+*/
+package app

ui/app/os_android.go

@@ -419,7 +419,7 @@ func (w *window) showTextInput(show bool) {
 	})
 }
 
-func Main() {
+func main() {
 }
 
 func createWindow(window *Window, opts *WindowOptions) error {

ui/app/os_ios.go

@@ -251,5 +251,5 @@ func createWindow(win *Window, opts *WindowOptions) error {
 	return <-mainWindow.errs
 }
 
-func Main() {
+func main() {
 }

ui/app/os_js.go

@@ -374,7 +374,7 @@ func (w *window) config() (int, int, float32, Config) {
 	}
 }
 
-func Main() {
+func main() {
 	<-mainDone
 }
 

ui/app/os_macos.go

@@ -271,7 +271,7 @@ func createWindow(win *Window, opts *WindowOptions) error {
 	return <-mainWindow.errs
 }
 
-func Main() {
+func main() {
 	wopts := <-mainWindow.out
 	view := viewFactory()
 	if view == 0 {

ui/app/os_wayland.go

@@ -152,7 +152,7 @@ var (
 	_XKB_MOD_NAME_SHIFT = []byte("Shift\x00")
 )
 
-func Main() {
+func main() {
 	<-mainDone
 }
 

ui/app/os_windows.go

@@ -157,7 +157,7 @@ const _WM_REDRAW = _WM_USER + 0
 var onceMu sync.Mutex
 var mainDone = make(chan struct{})
 
-func Main() {
+func main() {
 	<-mainDone
 }