Provide a working set default Option values (#46)

Good Job 💯

Author: zephylac

example/simpleDemo/main.go

@@ -27,16 +27,14 @@ func main() {
 	_, currentFilePath, _, _ := runtime.Caller(0)
 	dir := path.Dir(currentFilePath)
 
+	initialApplicationHeight := 600
+	initialApplicationWidth := 800
+
 	options := []gutter.Option{
-		gutter.OptionAssetPath(dir + "/flutter_project/demo/build/flutter_assets"),
-		/* Depending on your architecture you need to change the enginer
-		 * Mac OS X : flutter/bin/cache/artifacts/engine/darwin-x64/icudtl.dat
-		 * Linux    : flutter/bin/cache/artifacts/engine/linux-x64/icudtl.dat
-		 * Windows  : flutter/bin/cache/artifacts/engine/windows-x64/icudtl.dat
-		 */
-		gutter.OptionICUDataPath(dir + "/icudtl.dat"),
-		gutter.OptionWindowInitializer(setIcon),
-		gutter.OptionWindowDimension(800, 600),
+		gutter.ProjectAssetPath(dir + "/flutter_project/demo/build/flutter_assets"),
+		/* This path should not be changed. icudtl.dat is handled by engineDownloader.go */
+		gutter.ApplicationICUDataPath(dir + "/icudtl.dat"),
+		gutter.ApplicationWindowDimension(initialApplicationWidth, initialApplicationHeight),
 		gutter.OptionWindowInitializer(setIcon),
 		gutter.OptionPixelRatio(1.2),
 		gutter.OptionVMArguments([]string{"--dart-non-checked-mode", "--observatory-port=50300"}),

example/stocks/main.go

@@ -17,7 +17,7 @@ func main() {
 	)
 
 	options := []gutter.Option{
-		gutter.OptionAssetPath("flutter_project/stocks/build/flutter_assets"),
+		gutter.ProjectAssetPath("flutter_project/stocks/build/flutter_assets"),
 		gutter.OptionICUDataPath("/opt/flutter/bin/cache/artifacts/engine/linux-x64/icudtl.dat"), // Linux (arch)
 		// gutter.OptionICUDataPath("./FlutterEmbedder.framework/Resources/icudtl.dat"),             // OSX
 		gutter.OptionWindowDimension(800, 600),

option.go

@@ -1,21 +1,33 @@
 package gutter
 
 import (
+	"log"
+	"os"
+
 	"github.com/go-gl/glfw/v3.2/glfw"
 )
 
 // Option for gutter
 type Option func(*config)
 
-// OptionAssetPath specify the flutter asset directory.
-func OptionAssetPath(p string) Option {
+// Check path
+func checkPath(p string) {
+	if _, err := os.Stat(p); os.IsNotExist(err) {
+		log.Fatal(err)
+	}
+}
+
+// ProjectAssetPath specify the flutter asset directory.
+func ProjectAssetPath(p string) Option {
+	checkPath(p)
 	return func(c *config) {
 		c.AssetPath = p
 	}
 }
 
-// OptionICUDataPath specify the path to the ICUData.
-func OptionICUDataPath(p string) Option {
+// ApplicationICUDataPath specify the path to the ICUData.
+func ApplicationICUDataPath(p string) Option {
+	checkPath(p)
 	return func(c *config) {
 		c.ICUDataPath = p
 	}
@@ -29,8 +41,18 @@ func OptionVMArguments(a []string) Option {
 	}
 }
 
-// OptionWindowDimension specify the startup's dimention of the window.
-func OptionWindowDimension(x int, y int) Option {
+// ApplicationWindowDimension specify the startup's dimention of the window.
+func ApplicationWindowDimension(x int, y int) Option {
+	// Check for initial application display size
+	if x < 1 {
+		log.Fatal("Wrong initial value for width ")
+	}
+
+	// Check for initial application display size
+	if y < 1 {
+		log.Fatal("Wrong initial value for height ")
+	}
+
 	return func(c *config) {
 		c.WindowDimension.x = x
 		c.WindowDimension.y = y