Ensure DPITexture::_update_texture only gets called once at the end of the frame.

[WhalesState]

Changes:

• Add _request_update() to avoid calling _update_texture() more than once in a single frame.
• Add force_update_texture() which applies the changes immediately if the texture needs to be updated.
• Made some changes to avoid errors while updating the texture when some parameters are invalid.

[clayjohn]

The usual pattern we use is to defer the update to the end of the frame using call_deferred(). Is there any reason that won't work here?

Exposing a redundant feature for a small theoretical optimization isn't something we like to do

[WhalesState]

For example, If you have 100 icons for your game and you want to update their colors, scale and saturation when the theme changes it will emit changed signal 3 times for each texture instead of just once. All the setters do call DPITexture::_update_texture() which emits changed which calls TextureRect::_texture_changed() or Button::_texture_changed() and both of them calls queue_redraw() and update_minimum_size(). And to avoid that you will have to create 100 new textures instead of just being able to update them with minimal cost.

[clayjohn]

I think you misunderstood my comment.

Our usual pattern is to have an internal setter like this:

void request_update() {
    if (update_requested) {
        return;
    }
    update_requested = true;
    call_deferred("update_props");
}

update_props would handle all the expensive parts of the update (including emitting changed and any other signals)

This ensures that the expensive parts are only called once per frame regardless of what updates you do.

[WhalesState]

Ok I got it now, Thanks for making it clear.

[WhalesState]

Implemented _request_update(). We may also need to add a way to allow users to call _update_texture() if they need the changes to be reflected immediately.

[WhalesState]

To test the changes I have made DPITexture::_update_texture() prints "Internal (Texture is updated)" if update_requested is true and used this script.

@tool
extends Control


func _ready():
	var rect: TextureRect = TextureRect.new()
	add_child(rect)
	var svg: String = FileAccess.get_file_as_string("res://icon.svg")
	var tex: DPITexture = DPITexture.create_from_string(svg)
	rect.texture = tex

	print("create_from_string(svg)")
	print("\"Internal (Texture is updated)\" should print before \"create_from_string(svg)\"")
	print()
	
	tex.set_base_scale(0.5)
	print("set_base_scale(0.5)")
	tex.set_saturation(0.5)
	print("set_saturation(0.5)")
	tex.force_update_texture()
	print("force_update_texture()")
	print("\"Internal (Texture is updated)\" should print before \"force_update_texture()\"")
	print()

	tex.set_base_scale(0.5)
	print("set_base_scale(0.5)")
	tex.set_saturation(0.5)
	print("set_saturation(0.5)")
	tex.force_update_texture()
	print("force_update_texture()")
	print("\"Internal (Texture is updated)\" should not print (ressetting the same values shouldn't update)")
	print()
	
	tex.set_base_scale(0.2)
	print("set_base_scale(0.2)")
	tex.set_saturation(0.2)
	print("set_saturation(0.2)")
	tex.set_base_scale(4)
	print("set_base_scale(4)")
	tex.set_base_scale(2)
	print("set_base_scale(2)")
	tex.set_base_scale(1)
	print("set_base_scale(1)")
	print("\"Internal (Texture is updated)\" should print after this message (queued)")
	
	await get_tree().process_frame
	print()
	print("await get_tree().process_frame")
	print()
	
	tex.force_update_texture()
	print("force_update_texture()")
	tex.force_update_texture()
	print("force_update_texture()")
	print("\"Internal (Texture is updated)\" should not print (already updated)")
	

Internal (Texture is updated)
create_from_string(svg)
"Internal (Texture is updated)" should print before "create_from_string(svg)"

set_base_scale(0.5)
set_saturation(0.5)
Internal (Texture is updated)
force_update_texture()
"Internal (Texture is updated)" should print before "force_update_texture()"

set_base_scale(0.5)
set_saturation(0.5)
force_update_texture()
"Internal (Texture is updated)" should not print (ressetting the same values shouldn't update)

set_base_scale(0.2)
set_saturation(0.2)
set_base_scale(4)
set_base_scale(2)
set_base_scale(1)
"Internal (Texture is updated)" should print after this message (queued)
Internal (Texture is updated)

await get_tree().process_frame

force_update_texture()
force_update_texture()
"Internal (Texture is updated)" should not print (already updated)