Setting a text that contains emojis to a textedit is slow

[derkork]

Tested versions

• v4.2.stable.mono.official [46dc277]
• v4.2.1.stable.mono.official [b09f793]

System information

Godot v4.2.stable.mono - Windows 10.0.22631 - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 4080 (NVIDIA; 31.0.15.5123) - AMD Ryzen 9 7950X3D 16-Core Processor (32 Threads)

Issue description

I have a TextEdit node that I pre-fill with some text that contains a range of emojis. In my example I set about 300 lines of text each line containing an emoji. Setting this text of 300 lines with emojis to the text property of the TextEdit takes about 16-18ms on my machine. If I remove the emojis from the text, the same operation only takes about 2-3ms on my machine.

Steps to reproduce

In the example project I have this script which will produce a text at the start and then try to set it every frame:

extends Control

@onready var text_edit = $TextEdit

var text:String

func _ready():
	text = make_300_lines()

func _process(delta):
	text_edit.text = text


func make_300_lines():
	var emojis = ["🔴", "🟢", "⚡", "↪️"]
	var result:String = ""
	for i in 300:
		# use the following line to get a text without emojis
		# result += " this is a line " + "[c]" + "\n"
		
		# this will produce a text with emojis 
		# comment it to use the other line
		result += " this is a line " + emojis.pick_random() + "\n"
	
	return result

You can use the alternative line to produce a text without emojis. Profile each variant to see the difference in performance.

Minimal reproduction project (MRP)

emoji_reproducer.zip

[AThousandShips]

Can you please test this with 4.2.1 or 4.2.2.rc1? Your version is no longer supported and this might already have been fixed

[MidZik]

I'm using 4.2.1 and the issue exists there, I'll double check 4.2.2.rc1 and report back.

[derkork]

Added a reference to 4.2.1 to the top.

[MidZik]

Same issue in 4.2.2.rc1. (In case it matters, I tested the standard, non-.net versions.)

[Mickeon]

Have not tested anything, but the test without emojis is a bit skewed since pick_random is not even called.

[derkork]

The function to create the text is only called a single time during ready. What is slow is the setting of the text in process.

[Mickeon]

Ok, that's silly then. Since the text remains unchanged, setting it every _process frame should do nothing, and yet...

[MidZik]

extends Node

func _generate_text(characters:Array, amount = 200):
	var result = ""
	for i in amount:
		result += characters.pick_random()
	return result

# Called every frame. 'delta' is the elapsed time since the previous frame.
func _process(delta):
	_set_with_emojis()
	_set_without_emojis()
	_set_with_emojis_no_newline()
	_set_without_emojis_no_newline()

func _set_with_emojis():
	%TextEdit.text = _generate_text(["🔴\n", "🟢\n", "⚡\n", "↪️\n"])

func _set_without_emojis():
	%TextEdit.text = _generate_text(["AAA\n", "BBB\n", "CCC\n", "DDD\n"])

func _set_with_emojis_no_newline():
	%TextEdit.text = _generate_text(["🔴", "🟢", "⚡", "↪️"])

func _set_without_emojis_no_newline():
	%TextEdit.text = _generate_text(["AAA", "BBB", "CCC", "DDD"])

Results (4.2.1 stable official standard):

[derkork]

Interesting how just adding newlines makes it an order of magnitude slower...

[Calinou]

Can you test a build that uses the fallback text server instead of the advanced text server? To do so, compile from source with the module_text_server_adv_enabled=no module_text_server_fb_enabled=yes SCons options.

This disables support for right-to-left typesetting and complex scripts, but emoji support should remain intact.

[MidZik]

Built with scons platform=windows module_text_server_adv_enabled=no module_text_server_fb_enabled=yes debug_symbols=yes:

I profiled a bit with VS, and a large amount of time is spent here, regardless of which text server is used:

godot/platform/windows/os_windows.cpp

Line 1114 in bb6b06c

Vector<String> OS_Windows::get_system_font_path_for_text(const String &p_font_name, const String &p_text, const String &p_locale, const String &p_script, int p_weight, int p_stretch, bool p_italic) const {

~33% of all CPU time is spent on line 1191 HANDLE fnd = FindFirstFileW((LPCWSTR)&file_path[0], &d);
~10% of all CPU time is spent on line 1197 FindClose(fnd);
~10% of all CPU time is spent on line 1133 hr = system_font_fallback->MapCharacters(...)

[Calinou]

This is likely due to the same cause as #83688.

[MidZik]

I added a font override to the TextEdit that has the system font "Segoe UI Emoji" as a fallback font and the performance becomes nearly identical:

(4.2.1 stable)