Adding after_ui_callback for script ui modification

[ashen-sensored]

Describe what this pull request is trying to achieve.

Adding after_ui_callback for easier gradio component access for extensions during ui creation

Additional notes and description of your changes

Used for opparco/stable-diffusion-webui-two-shot#23
for realizing prompt auto pasting
opparco/stable-diffusion-webui-two-shot@d0163f2

[AUTOMATIC1111]

why is it called twice

[ashen-sensored]

It is called once inside txt2img block, once inside img2img block, so I can do the following.
gradio does not allow calling button.click outside current block context.

def on_after_ui(self):
    if self.prompt_paste_initialized:
        return
    def paste_prompt(*input_prompts):
        finalprompts = input_prompts[:len(self.area_colors)]
        final_prompt_str = '\nAND '.join(finalprompts)
        return final_prompt_str

    prompt_target = self.ui_root.parent.parent.parent.parent.parent.children[0].children[0].children[0].children[0].children[0].children[0].children[0]
    self.prompt_update_button.click(fn=paste_prompt, inputs=self.source_prompts, outputs=prompt_target)

    self.prompt_paste_initialized = True

why is it called twice

[AUTOMATIC1111]

Can you not do that using on_before_component/on_after_component?

[ashen-sensored]

Can you not do that using on_before_component/on_after_component?

I just looked up the implementation in controlnet plugin. I think you're right. Sorry for the trouble caused.