rework package to be importable (proof of concept)

README.md

@@ -1,15 +1,15 @@
 <img src="./assets/mascot.png" width="170" align="right">
 
-# Go Flutter desktop embedder 
+# Go Flutter desktop embedder
 
 A Go (golang) [Custom Flutter Engine
 Embedder](https://github.com/flutter/engine/wiki/Custom-Flutter-Engine-Embedders)
 for desktop
 
 # Purpose
 This project doesn't compete with
-[this](https://github.com/google/flutter-desktop-embedding) awesome one.
-The purpose of this project is to support the 
+[this](https://github.com/google/flutter-desktop-embedding) awesome one.  
+The purpose of this project is to support the  
 [Flutter](https://github.com/flutter/flutter) framework on Windows, macOS, and
 Linux using a **SINGLE** code base.  
 
@@ -19,11 +19,9 @@ provides the right abstractions over the OpenGL's Buffer/mouse/keyboard for each
 The choice of [Golang](https://github.com/golang/go) comes from the fact that it
 has the same tooling on every platform.  
 Plus golang is a great language because it keeps everything simple and readable,
-which, I hope, will encourage people to contribute :grin:.
+which, I hope, will encourage people to contribute :grin:.  
 
 ## How to install
-
-
 <details>
 <summary> :package: :penguin: Linux</summary>
 <h4>From binaries</h4>
@@ -33,32 +31,26 @@ Check out the <a href="https://github.com/Drakirus/go-flutter-desktop-embedder/r
 
 Go read first: [go-gl/glfw](https://github.com/go-gl/glfw/)  
 
+
 ```bash
+
 # Clone
 git clone https://github.com/Drakirus/Go-Flutter-desktop-embedder.git
 cd Go-Flutter-desktop-embedder
 
+# build the flutter project
+cd example/stocks/
+
 # Download the share library
-wget https://storage.googleapis.com/flutter_infra/flutter/1ed25ca7b7e3e3e8047df050bba4174074c9b336/linux-x64/linux-x64-embedder \
-  -O temp.zip; unzip temp.zip; 
+wget https://storage.googleapis.com/flutter_infra/flutter/1ed25ca7b7e3e3e8047df050bba4174074c9b336/linux-x64/linux-x64-embedder \ -O .build/temp.zip
 
-# Move the share library
-mv libflutter_engine.so ./flutter/library/linux/
 
-# Clean-up
-rm flutter_embedder.h; rm temp.zip
+unzip .build/temp.zip -x flutter_embedder.h && mv libflutter_engine.so flutter/library/linux/
 
 # build the Embedder
 go get -u github.com/go-gl/glfw/v3.2/glfw
-go build
-
-# build the flutter project
-cd flutter_project/stocks/
-flutter build bundle
-cd ../..
-
-# Play
-./Go-Flutter-desktop-embedder
+cd flutter_project/stocks; flutter build bundle; cd ../..
+CGO_LDFLAGS="-L${PWD}/flutter/library/linux" go run main.go
 ```
 </details>
 

example/stocks/.build/.gitignore

@@ -0,0 +1 @@
+temp.zip

example/stocks/flutter/library/linux/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore

example/stocks/main.go

@@ -0,0 +1,51 @@
+package main
+
+import (
+	"image"
+	_ "image/png"
+	"log"
+	"os"
+	"os/signal"
+
+	gutter "github.com/Drakirus/go-flutter-desktop-embedder"
+
+	"github.com/go-gl/glfw/v3.2/glfw"
+)
+
+// #cgo linux LDFLAGS: -L${SRCDIR}/flutter/library/linux
+import "C"
+
+func main() {
+	var (
+		err error
+	)
+
+	options := []gutter.Option{
+		gutter.OptionAssetPath("flutter_project/stocks/build/flutter_assets"),
+		gutter.OptionICUDataPath("../../flutter/library/icudtl.dat"),
+		gutter.OptionWindowInitializer(setIcon),
+	}
+
+	if err = gutter.Run(options...); err != nil {
+		log.Fatalln(err)
+	}
+
+	signals := make(chan os.Signal, 1)
+	signal.Notify(signals, os.Kill, os.Interrupt)
+	select {
+	case <-signals:
+	}
+}
+
+func setIcon(window *glfw.Window) error {
+	imgFile, err := os.Open("assets/icon.png")
+	if err != nil {
+		return err
+	}
+	img, _, err := image.Decode(imgFile)
+	if err != nil {
+		return err
+	}
+	window.SetIcon([]image.Image{img})
+	return nil
+}

flutter/build.go

@@ -4,7 +4,12 @@ package flutter
 // Linux Build Tags
 // ----------------
 #cgo linux CFLAGS: -I${SRCDIR}/library
-#cgo linux LDFLAGS: -L${SRCDIR}/library/linux -lflutter_engine -Wl,-rpath,$ORIGIN/flutter/library/linux
+#cgo linux LDFLAGS: -lflutter_engine -Wl,-rpath,flutter/library/linux
 
 */
 import "C"
+
+import (
+	// prevents dep from stripping out the c source files in flutter library.
+	_ "github.com/Drakirus/go-flutter-desktop-embedder/flutter/library"
+)

flutter/library/library.go

@@ -0,0 +1,4 @@
+package library
+
+// this file along with its _ import in build.go prevent this package
+// from being pruned by dep. see https://github.com/golang/dep/issues/1847

main.go → gutter.go

@@ -1,49 +1,77 @@
-package main
+package gutter
 
 import (
 	"encoding/json"
-	"flutter_desktop_go_embedding/flutter"
-	"image"
-	_ "image/png"
 	"log"
-	"os"
-	"runtime"
 	"time"
 	"unsafe"
 
+	"github.com/Drakirus/go-flutter-desktop-embedder/flutter"
 	"github.com/go-gl/glfw/v3.2/glfw"
 )
 
-// TextInput model
-var state = textModel{}
+// Option for gutter
+type Option func(*config)
 
-func init() {
-	runtime.LockOSThread()
+// OptionAssetPath specify the flutter asset directory.
+func OptionAssetPath(p string) Option {
+	return func(c *config) {
+		c.AssetPath = p
+	}
 }
 
-func main() {
-	err := glfw.Init()
-	if err != nil {
-		panic(err)
+// OptionICUDataPath specify the path to the ICUData.
+func OptionICUDataPath(p string) Option {
+	return func(c *config) {
+		c.ICUDataPath = p
 	}
-	defer glfw.Terminate()
+}
 
-	window, err := glfw.CreateWindow(800, 600, "Loading..", nil, nil)
-	if err != nil {
-		panic(err)
+// OptionWindowInitializer allow initializing the window.
+func OptionWindowInitializer(ini func(*glfw.Window) error) Option {
+	return func(c *config) {
+		c.WindowInitializer = ini
 	}
+}
 
-	defer window.Destroy()
+type config struct {
+	AssetPath         string
+	ICUDataPath       string
+	WindowInitializer func(*glfw.Window) error
+}
 
-	// set icon
-	if err := setIcon(window); err != nil {
-		log.Printf("unable to set window icon: %v\n", err)
+func (t config) merge(options ...Option) config {
+	for _, opt := range options {
+		opt(&t)
 	}
 
-	assetsPath := "./flutter_project/stocks/build/flutter_assets"
-	icuDataPath := "./flutter/library/icudtl.dat"
+	return t
+}
+
+// Run executes a flutter application with the provided options.
+// given limitations this method must be called by the main function directly.
+func Run(options ...Option) (err error) {
+	var (
+		window *glfw.Window
+		c      config
+	)
+	c = c.merge(options...)
 
-	engine := runFlutter(window, assetsPath, icuDataPath)
+	if err = glfw.Init(); err != nil {
+		return err
+	}
+	defer glfw.Terminate()
+
+	if window, err = glfw.CreateWindow(800, 600, "Loading..", nil, nil); err != nil {
+		return err
+	}
+	defer window.Destroy()
+
+	if err = c.WindowInitializer(window); err != nil {
+		return err
+	}
+
+	engine := runFlutter(window, c.AssetPath, c.ICUDataPath)
 
 	defer engine.Shutdown()
 
@@ -53,10 +81,10 @@ func main() {
 		flutter.EngineFlushPendingTasksNow()
 	}
 
+	return nil
 }
 
 // GLFW callbacks to the Flutter Engine
-
 func glfwCursorPositionCallbackAtPhase(
 	window *glfw.Window, phase flutter.PointerPhase,
 	x float64, y float64,
@@ -91,6 +119,8 @@ func glfwMouseButtonCallback(window *glfw.Window, key glfw.MouseButton, action g
 
 }
 
+var state = textModel{}
+
 func glfwKeyCallback(w *glfw.Window, key glfw.Key, scancode int, action glfw.Action, mods glfw.ModifierKey) {
 
 	if key == glfw.KeyEscape && action == glfw.Press {
@@ -146,16 +176,13 @@ func glfwKeyCallback(w *glfw.Window, key glfw.Key, scancode int, action glfw.Act
 						state.addChar([]rune(clpString))
 					}
 				}
-
 			}
-
 		}
 	}
 
 }
 
 func glfwWindowSizeCallback(window *glfw.Window, width int, height int) {
-
 	event := flutter.WindowMetricsEvent{
 		Width:      width,
 		Height:     height,
@@ -173,7 +200,6 @@ func glfwCharCallback(w *glfw.Window, char rune) {
 }
 
 // Flutter Engine
-
 func runFlutter(window *glfw.Window, assetsPath string, icuDataPath string) *flutter.EngineOpenGL {
 
 	flutterOGL := flutter.EngineOpenGL{
@@ -301,16 +327,3 @@ func updateEditingState(window *glfw.Window) {
 	flutterOGL := *(*flutter.EngineOpenGL)(window.GetUserPointer())
 	flutterOGL.EngineSendPlatformMessage(mess)
 }
-
-func setIcon(window *glfw.Window) error {
-	imgFile, err := os.Open("assets/icon.png")
-	if err != nil {
-		return err
-	}
-	img, _, err := image.Decode(imgFile)
-	if err != nil {
-		return err
-	}
-	window.SetIcon([]image.Image{img})
-	return nil
-}

textModel.go

@@ -1,4 +1,4 @@
-package main
+package gutter
 
 import (
 	"sort"