app.py

import gradio as gr
import torch, os
from diffusers import StableCascadeDecoderPipeline, StableCascadePriorPipeline
import gradio as gr
from io import BytesIO
import base64
import re

SECRET_TOKEN = os.getenv('SECRET_TOKEN', 'default_secret')

# Regex pattern to match data URI scheme
data_uri_pattern = re.compile(r'data:image/(png|jpeg|jpg|webp);base64,')

def readb64(b64):
    # Remove any data URI scheme prefix with regex
    b64 = data_uri_pattern.sub("", b64)
    # Decode and open the image with PIL
    img = Image.open(BytesIO(base64.b64decode(b64)))
    return img
    
# convert from PIL to base64
def writeb64(image):
    buffered = BytesIO()
    image.save(buffered, format="PNG")
    b64image = base64.b64encode(buffered.getvalue())
    b64image_str = b64image.decode("utf-8")
    return b64image_str


prior = StableCascadePriorPipeline.from_pretrained("stabilityai/stable-cascade-prior", torch_dtype=torch.bfloat16).to("cuda")
decoder = StableCascadeDecoderPipeline.from_pretrained("stabilityai/stable-cascade", torch_dtype=torch.float16).to("cuda")

def generate_images(
    secret_token="",
    prompt="",
    negative_prompt="bad,ugly,deformed",
    height=1024,
    width=1024, 
    guidance_scale=4.0, 
    seed=42,
    prior_inference_steps=20, 
    decoder_inference_steps=10
    ):
    """
    Generates images based on a given prompt using Stable Diffusion models on CUDA device.
    Parameters:
    - prompt (str): The prompt to generate images for.
    - negative_prompt (str): The negative prompt to guide image generation away from.
    - height (int): The height of the generated images.
    - width (int): The width of the generated images.
    - guidance_scale (float): The scale of guidance for the image generation.
    - prior_inference_steps (int): The number of inference steps for the prior model.
    - decoder_inference_steps (int): The number of inference steps for the decoder model.
    Returns:
    - List[PIL.Image]: A list of generated PIL Image objects.
    """
    if secret_token != SECRET_TOKEN:
        raise gr.Error(
            f'Invalid secret token. Please fork the original space if you want to use it for yourself.')

    generator = torch.Generator(device="cuda").manual_seed(int(seed))

    # Generate image embeddings using the prior model
    prior_output = prior(
        prompt=prompt,
        generator=generator,
        height=height,
        width=width,
        negative_prompt=negative_prompt,
        guidance_scale=guidance_scale,
        num_images_per_prompt=1,
        num_inference_steps=prior_inference_steps
    )

    # Generate images using the decoder model and the embeddings from the prior model
    decoder_output = decoder(
        image_embeddings=prior_output.image_embeddings.half(),
        prompt=prompt,
        generator=generator,
        negative_prompt=negative_prompt,
        guidance_scale=0.0,  # Guidance scale typically set to 0 for decoder as guidance is applied in the prior
        output_type="pil",
        num_inference_steps=decoder_inference_steps
    ).images

    image = decoder_output[0]
        
    image_base64 = writeb64(image)
        
    return image_base64


with gr.Blocks() as gradio_app:
    gr.HTML("""
        <div style="z-index: 100; position: fixed; top: 0px; right: 0px; left: 0px; bottom: 0px; width: 100%; height: 100%; background: white; display: flex; align-items: center; justify-content: center; color: black;">
        <div style="text-align: center; color: black;">
        <p style="color: black;">This space is a REST API to programmatically generate an image.</p>
        <p style="color: black;">Interested in using it? Please use the <a href="https://huggingface.co/spaces/ArtGAN/Diffusion-API" target="_blank">original space</a>, thank you!</p>
        </div>
        </div>""")
    secret_token = gr.Textbox(
        placeholder="Secret token",
        show_label=False,
    )
    text2image_prompt = gr.Textbox(
        lines=1,
        placeholder="Prompt",
        show_label=False,
    )
    text2image_negative_prompt = gr.Textbox(
        lines=1,
        placeholder="Negative Prompt",
        show_label=False,
    )
    text2image_seed = gr.Number(
        value=42,
        label="Seed",
    )
    text2image_height = gr.Slider(
        minimum=128,
        maximum=1024,
        step=32,
        value=1024,
        label="Image Height",
    )
    text2image_width = gr.Slider(
        minimum=128,
        maximum=1024,
        step=32,
        value=1024,
        label="Image Width",
    )
    text2image_guidance_scale = gr.Slider(
        minimum=0.1,
        maximum=15,
        step=0.1,
        value=4.0,
        label="Guidance Scale",
    )                
    text2image_prior_inference_step = gr.Slider(
        minimum=1,
        maximum=50,
        step=1,
        value=20,
        label="Prior Inference Step",
    )                
    text2image_decoder_inference_step = gr.Slider(
        minimum=1,
        maximum=50,
        step=1,
        value=10,
        label="Decoder Inference Step",
    )               
    text2image_predict = gr.Button(value="Generate Image")
    output_image_base64 = gr.Text()
    text2image_predict.click(
        fn=generate_images,
        inputs=[
            secret_token,
            text2image_prompt,
            text2image_negative_prompt,
            text2image_height,
            text2image_width,
            text2image_guidance_scale,
            text2image_seed,
            text2image_prior_inference_step,
            text2image_decoder_inference_step
        ],
        outputs=output_image_base64,
        api_name='run',
    )

gradio_app.queue(max_size=20).launch()