Gradient color picker insanely slow

[yaboy365]

Pixelorama version:

0.92

Issue description:

When using the gradient tool, and choosing 1 of the 2 colors, the color selector is very slow. Even more for larger images. The application remains frozen until it eventually catches up. This issue is also present in 0.91, but surprisingly NOT in 0.9, where it's very quick.

ALSO is the gradient preview, actually the same dimensions as the image? If yes, then maybe, for optimization, it could be replaced by a smaller image of the same proportions. (Like a 100x100 for any square image, since that's the max number of gradient steps.)

Steps to reproduce:

1. Create new image (Bigger dimensions like 512x512 make it more noticeable)
2. Select the gradient tool.
3. Click any of the 2 colors to open the color selector.
4. Move the RGB sliders, or wiggle the crosshair in the color square.

[Variable-ind]

I can confirm it. Maybe we should make a shader for it as well.

[OverloadedOrama]

I enabled deferred mode for the color pickers, which means that the color gets applied only when the user releases the mouse button when inside the color square, so it won't be slow anymore when the user wiggles the crosshair in the color square. Still, there is some room for optimizations which we could look into in the future.

[OverloadedOrama]

Nevermind, I am going to re-open this issue because I just realized that, while the color square issue is gone, moving the RGB sliders is still very slow. My guess is that something changed in the frequency of the color application of the ColorPicker in Godot's side. v0.9 was using Godot 3.3, v0.9.1 and v0.9.2 were using Godot 3.4. There was no change in the gradient generation code in Pixelorama between versions 0.9 and 0.9.1.