Saving .png files is now possible in HTML5

Addresses #280. Huge thanks to https://github.com/Pukkah/HTML5-File-Exchange-for-Godot

project.godot

@@ -97,6 +97,7 @@ Global="*res://src/Autoload/Global.gd"
 Import="*res://src/Autoload/Import.gd"
 OpenSave="*res://src/Autoload/OpenSave.gd"
 DrawingAlgos="*res://src/Autoload/DrawingAlgos.gd"
+Html5FileExchange="*res://src/Autoload/HTML5FileExchange.gd"
 
 [debug]
 

src/Autoload/HTML5FileExchange.gd

@@ -0,0 +1,105 @@
+extends Node
+# Code taken and modified from https://github.com/Pukkah/HTML5-File-Exchange-for-Godot
+# Thanks to Pukkah from GitHub for providing the original code
+
+signal InFocus
+
+
+func _ready() -> void:
+	if OS.get_name() == "HTML5" and OS.has_feature('JavaScript'):
+		_define_js()
+
+
+func _notification(notification:int) -> void:
+	if notification == MainLoop.NOTIFICATION_WM_FOCUS_IN:
+		emit_signal("InFocus")
+
+func _define_js() -> void:
+	# Define JS script
+	JavaScript.eval("""
+	var fileData;
+	var fileType;
+	var fileName;
+	var canceled;
+	function upload_image() {
+		canceled = true;
+		var input = document.createElement('INPUT');
+		input.setAttribute("type", "file");
+		input.setAttribute("accept", "image/png, image/jpeg, image/webp");
+		input.click();
+		input.addEventListener('change', event => {
+			if (event.target.files.length > 0){
+				canceled = false;}
+			var file = event.target.files[0];
+			var reader = new FileReader();
+			fileType = file.type;
+			fileName = file.name;
+			reader.readAsArrayBuffer(file);
+			reader.onloadend = function (evt) {
+				if (evt.target.readyState == FileReader.DONE) {
+					fileData = evt.target.result;
+				}
+			}
+		  });
+	}
+	function download(fileName, byte, type) {
+		var buffer = Uint8Array.from(byte);
+		var blob = new Blob([buffer], { type: type});
+		var link = document.createElement('a');
+		link.href = window.URL.createObjectURL(blob);
+		link.download = fileName;
+		link.click();
+	};
+	""", true)
+
+
+func load_image() -> Image:
+	if OS.get_name() != "HTML5" or !OS.has_feature('JavaScript'):
+		return
+
+	# Execute js function
+	JavaScript.eval("upload_image();", true) # opens prompt for choosing file
+
+	yield(self, "InFocus") # wait until js prompt is closed
+
+	yield(get_tree().create_timer(0.1), "timeout") #give some time for async js data load
+
+	if JavaScript.eval("canceled;", true): # if File Dialog closed w/o file
+		return
+
+	# use data from png data
+	var imageData
+	while true:
+		imageData = JavaScript.eval("fileData;", true)
+		if imageData != null:
+			break
+		yield(get_tree().create_timer(1.0), "timeout") # need more time to load data
+
+	var imageType = JavaScript.eval("fileType;", true)
+	var imageName = JavaScript.eval("fileName;", true)
+
+	var image = Image.new()
+	var image_error
+	match imageType:
+		"image/png":
+			image_error = image.load_png_from_buffer(imageData)
+		"image/jpeg":
+			image_error = image.load_jpg_from_buffer(imageData)
+		"image/webp":
+			image_error = image.load_webp_from_buffer(imageData)
+		var invalid_type:
+			print(invalid_type)
+			return
+	if image_error:
+		print("An error occurred while trying to display the image.")
+		return
+	else:
+		return image
+
+
+func save_image(image : Image, file_name : String = "export") -> void:
+	if OS.get_name() != "HTML5" or !OS.has_feature('JavaScript'):
+		return
+
+	var png_data = Array(image.get_data())
+	JavaScript.eval("download('%s', %s, 'image/png');" % [file_name, str(png_data)], true)

src/UI/Dialogs/ExportDialog.gd

@@ -77,6 +77,11 @@ func _ready() -> void:
 		$VBoxContainer/AnimationOptions/AnimationType.selected = AnimationType.MULTIPLE_FILES
 		$VBoxContainer/AnimationOptions/AnimationType.disabled = true
 
+	# If we're on HTML5, don't let the user change the directory path
+	if OS.get_name() == "HTML5":
+		$VBoxContainer/Path.visible = false
+		directory_path = "user://"
+
 
 func show_tab() -> void:
 	$VBoxContainer/FrameOptions.hide()
@@ -348,9 +353,12 @@ func export_processed_images(ignore_overwrites : bool) -> void:
 		$GifExporter.end_export()
 	else:
 		for i in range(processed_images.size()):
-			var err = processed_images[i].save_png(export_paths[i])
-			if err != OK:
-				OS.alert("Can't save file")
+			if OS.get_name() == "HTML5":
+				Html5FileExchange.save_image(processed_images[i], export_paths[i].get_file())
+			else:
+				var err = processed_images[i].save_png(export_paths[i])
+				if err != OK:
+					OS.alert("Can't save file")
 
 	# Store settings for quick export and when the dialog is opened again
 	was_exported = true