app.py

import spaces
import gradio as gr
import numpy as np
import random
import torch
from PIL import Image
from torchvision import transforms
from diffusers import DiffusionPipeline, AutoencoderKL

# Constants
dtype = torch.bfloat16
device = "cuda" if torch.cuda.is_available() else "cpu"
MAX_SEED = np.iinfo(np.int32).max
MAX_IMAGE_SIZE = 2048

# Load models
pipe = DiffusionPipeline.from_pretrained("black-forest-labs/FLUX.1-schnell", torch_dtype=dtype).to(device)
pipe.enable_model_cpu_offload()
pipe.vae.enable_slicing()
pipe.vae.enable_tiling()

vae = AutoencoderKL.from_pretrained("runwayml/stable-diffusion-v1-5", subfolder="vae").to(device)

def preprocess_image(image, image_size):
    preprocess = transforms.Compose([
        transforms.Resize((image_size, image_size), interpolation=transforms.InterpolationMode.LANCZOS),
        transforms.ToTensor(),
        transforms.Normalize([0.5], [0.5])
    ])
    image = preprocess(image).unsqueeze(0).to(device, dtype=torch.float32)
    return image

def encode_image(image):
    with torch.no_grad():
        latents = vae.encode(image).latent_dist.sample() * 0.18215
    return latents

@spaces.GPU()
def infer(prompt, init_image=None, seed=42, randomize_seed=False, width=1024, height=1024, num_inference_steps=4, progress=gr.Progress(track_tqdm=True)):
    if randomize_seed:
        seed = random.randint(0, MAX_SEED)
    generator = torch.Generator(device=device).manual_seed(seed)

    try:
        if init_image is None:
            # text2img case
            image = pipe(
                prompt=prompt,
                height=height,
                width=width,
                num_inference_steps=num_inference_steps,
                generator=generator,
                guidance_scale=0.0
            ).images[0]
        else:
            # img2img case
            init_image = init_image.convert("RGB")
            init_image = preprocess_image(init_image, 1024)  # Using 1024 as FLUX VAE sample size
            latents = encode_image(init_image)
            
            latents = torch.nn.functional.interpolate(latents, size=(height // 8, width // 8), mode='bilinear')
            
            if latents.shape[1] != pipe.vae.config.latent_channels:
                conv = torch.nn.Conv2d(latents.shape[1], pipe.vae.config.latent_channels, kernel_size=1).to(device, dtype=dtype)
                latents = conv(latents.to(dtype))

            latents = latents.permute(0, 2, 3, 1).contiguous().view(-1, pipe.vae.config.latent_channels)

            image = pipe(
                prompt=prompt,
                height=height,
                width=width,
                num_inference_steps=num_inference_steps,
                generator=generator,
                guidance_scale=0.0,
                latents=latents
            ).images[0]

        return image, seed
    except Exception as e:
        print(f"Error during inference: {e}")
        return Image.new("RGB", (width, height), (255, 0, 0)), seed  # Red fallback image

# Gradio interface setup
with gr.Blocks() as demo:
    with gr.Row():
        prompt = gr.Textbox(label="Prompt")
        init_image = gr.Image(label="Initial Image (optional)", type="pil")

    with gr.Row():
        generate = gr.Button("Generate")
        
    with gr.Row():
        result = gr.Image(label="Result")
        seed_output = gr.Number(label="Seed")

    with gr.Accordion("Advanced Settings", open=False):
        seed = gr.Slider(label="Seed", minimum=0, maximum=MAX_SEED, step=1, value=42)
        randomize_seed = gr.Checkbox(label="Randomize seed", value=True)
        width = gr.Slider(label="Width", minimum=256, maximum=MAX_IMAGE_SIZE, step=32, value=1024)
        height = gr.Slider(label="Height", minimum=256, maximum=MAX_IMAGE_SIZE, step=32, value=1024)
        num_inference_steps = gr.Slider(label="Number of inference steps", minimum=1, maximum=50, step=1, value=4)

    generate.click(
        infer,
        inputs=[prompt, init_image, seed, randomize_seed, width, height, num_inference_steps],
        outputs=[result, seed_output]
    )

demo.launch()