app.py

"""
Text-to-Image Generator
Dataset: rhli/genarena  |  Model: runwayml/stable-diffusion-v1-5
Deploy on: Hugging Face Spaces (Gradio SDK)
"""

import torch
import gradio as gr
from diffusers import StableDiffusionPipeline, DPMSolverMultistepScheduler
from datasets import load_dataset
import random

# ── Model setup ───────────────────────────────────────────────────────────────
MODEL_ID = "runwayml/stable-diffusion-v1-5"
DEVICE   = "cuda" if torch.cuda.is_available() else "cpu"
DTYPE    = torch.float16 if torch.cuda.is_available() else torch.float32

print(f"Loading model on {DEVICE} …")
pipe = StableDiffusionPipeline.from_pretrained(
    MODEL_ID,
    torch_dtype=DTYPE,
    safety_checker=None,
    requires_safety_checker=False,
)
pipe.scheduler = DPMSolverMultistepScheduler.from_config(pipe.scheduler.config)
pipe = pipe.to(DEVICE)
if DEVICE == "cuda":
    pipe.enable_attention_slicing()
print("Model ready ✓")

# ── Dataset: pull example prompts for the "Surprise me" button ───────────────
PROMPT_COLUMN = "prompt"   # adjust if the column name differs
try:
    _ds = load_dataset("rhli/genarena", split="train")
    DATASET_PROMPTS = [_ds[i][PROMPT_COLUMN] for i in range(min(200, len(_ds)))]
    print(f"Loaded {len(DATASET_PROMPTS)} prompts from rhli/genarena ✓")
except Exception as e:
    print(f"Could not load dataset prompts: {e}")
    DATASET_PROMPTS = [
        "a futuristic city at sunset",
        "a cozy cottage in a misty forest",
        "a robot painting a watercolor",
        "an astronaut on a purple alien planet",
    ]

# ── Inference function ────────────────────────────────────────────────────────
def generate_image(
    prompt: str,
    negative_prompt: str,
    num_steps: int,
    guidance_scale: float,
    seed: int,
):
    if not prompt.strip():
        return None, "⚠️  Please enter a prompt."

    generator = torch.Generator(DEVICE).manual_seed(int(seed))

    try:
        with torch.autocast(DEVICE) if DEVICE == "cuda" else torch.no_grad():
            result = pipe(
                prompt,
                negative_prompt=negative_prompt or None,
                num_inference_steps=int(num_steps),
                guidance_scale=float(guidance_scale),
                generator=generator,
                height=512,
                width=512,
            )
        image = result.images[0]
        return image, f"✅ Generated with seed {seed}"
    except Exception as e:
        return None, f"❌ Error: {e}"

def random_prompt():
    """Pick a random prompt from the dataset."""
    return random.choice(DATASET_PROMPTS)

def random_seed():
    return random.randint(0, 2**31 - 1)

# ── Gradio UI ─────────────────────────────────────────────────────────────────
with gr.Blocks(title="Text-to-Image Generator", theme=gr.themes.Soft()) as demo:

    gr.Markdown(
        """
        # 🎨 Text-to-Image Generator
        Powered by **Stable Diffusion v1.5** · Prompts sourced from [`rhli/genarena`](https://huggingface.co/datasets/rhli/genarena)
        """
    )

    with gr.Row():
        # ── Left column: inputs ──────────────────────────────────────────────
        with gr.Column(scale=1):
            prompt_box = gr.Textbox(
                label="Prompt",
                placeholder="Describe the image you want to generate…",
                lines=3,
            )

            surprise_btn = gr.Button("🎲 Surprise me (dataset prompt)", variant="secondary", size="sm")

            neg_prompt_box = gr.Textbox(
                label="Negative prompt (optional)",
                placeholder="blurry, low quality, ugly, distorted",
                value="blurry, low quality, ugly, distorted",
                lines=2,
            )

            with gr.Accordion("⚙️ Advanced settings", open=False):
                steps_slider = gr.Slider(
                    minimum=10, maximum=50, value=20, step=1,
                    label="Inference steps (more = slower but better)",
                )
                guidance_slider = gr.Slider(
                    minimum=1.0, maximum=20.0, value=7.5, step=0.5,
                    label="Guidance scale (how closely to follow the prompt)",
                )
                with gr.Row():
                    seed_box = gr.Number(label="Seed", value=42, precision=0)
                    rand_seed_btn = gr.Button("🔀", size="sm")

            generate_btn = gr.Button("✨ Generate", variant="primary")

        # ── Right column: output ─────────────────────────────────────────────
        with gr.Column(scale=1):
            output_image = gr.Image(label="Generated image", type="pil")
            status_text  = gr.Markdown("")

    # ── Event wiring ─────────────────────────────────────────────────────────
    generate_btn.click(
        fn=generate_image,
        inputs=[prompt_box, neg_prompt_box, steps_slider, guidance_slider, seed_box],
        outputs=[output_image, status_text],
    )

    surprise_btn.click(fn=random_prompt, outputs=prompt_box)
    rand_seed_btn.click(fn=random_seed, outputs=seed_box)

    gr.Examples(
        examples=[
            ["a golden sunset over a calm ocean, photorealistic", "blurry, low quality", 20, 7.5, 42],
            ["a watercolor painting of a Japanese cherry blossom garden", "", 25, 8.0, 7],
            ["a futuristic robot chef cooking in a neon-lit kitchen", "low quality", 20, 7.5, 99],
            ["an ancient library filled with glowing magical books", "", 20, 9.0, 12],
        ],
        inputs=[prompt_box, neg_prompt_box, steps_slider, guidance_slider, seed_box],
        outputs=[output_image, status_text],
        fn=generate_image,
        cache_examples=False,
    )

    gr.Markdown(
        """
        ---
        **Tips**
        - Keep prompts descriptive: add style words like *oil painting*, *photorealistic*, *anime*, *watercolor*.
        - Use the negative prompt to suppress unwanted features.
        - Higher guidance (> 9) locks tightly to the prompt but can look over-saturated.
        - The "Surprise me" button pulls real prompts from the `rhli/genarena` dataset.
        """
    )

# ── Entry point ───────────────────────────────────────────────────────────────
if __name__ == "__main__":
    demo.launch()